iRhythm
Annual Report 2017

Plain-text annual report

LUNITED STATESSECURITIES AND EXCHANGE COMMISSIONWashington, D.C. 20549 FORM 10-K (Mark One)☒☒ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934For the fiscal year ended December 31, 2017OR☐☐TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITIONPERIOD FROM TO Commission File Number 001-37918 iRhythm Technologies, Inc.(Exact name of Registrant as specified in its Charter) Delaware20-8149544(State or other jurisdiction ofincorporation or organization)(I.R.S. EmployerIdentification No.) 650 Townsend Street, Suite 500San Francisco, California94103(Address of principal executive offices)(Zip Code)Registrant’s telephone number, including area code: (415) 632-5700 Securities registered pursuant to Section 12(b) of the Act: Common Stock, Par Value $.0001 Per Share; Common stock traded on the NASDAQ stock marketSecurities registered pursuant to Section 12(g) of the Act: NoneIndicate by check mark if the Registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. YES ☒ NO ☐Indicate by check mark if the Registrant is not required to file reports pursuant to Section 13 or 15(d) of the Act. YES ☐ NO ☒Indicate by check mark whether the Registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding12 months (or for such shorter period that the Registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. YES ☒ NO ☐Indicate by check mark whether the Registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and postedpursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the Registrant was required to submit and post suchfiles). YES ☒ NO ☐Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K (§229.405) is not contained herein, and will not be contained, to the best ofRegistrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. ☐Indicate by check mark whether the Registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definition of “largeaccelerated filer”, “accelerated filer”, and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one): Large accelerated filer ☒ Accelerated filer ☐ Non-accelerated filer ☐ (Do not check if a small reporting company) Small reporting company ☐Emerging growth company ☐ Indicate by check mark whether the Registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). YES ☐ NO ☒The aggregate market value of the voting and non-voting common equity held by non-affiliates of the Registrant, based on the closing price of the shares of common stock on TheNASDAQ Stock Market on June 30, 2017, was approximately $937.5 million.The number of shares of Registrant’s Common Stock outstanding as of February 23, 2018 was 23,451,535.DOCUMENTS INCORPORATED BY REFERENCE:Portions of the information called for by Part III of this Form 10-K is hereby incorporated by reference from the definitive Proxy Statements for our annual meeting of stockholders,which will be filed with the Securities and Exchange Commission not later than 120 days after December 31, 2017.  Table of Contents PagePART I Item 1.Business 2Item 1A.Risk Factors 28Item 1B.Unresolved Staff Comments 58Item 2.Properties 58Item 3.Legal Proceedings 58Item 4.Mine Safety Disclosures 58 PART II Item 5.Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities 59Item 6.Selected Consolidated Financial Data 62Item 7.Management’s Discussion and Analysis of Financial Condition and Results of Operations 63Item 7A.Quantitative and Qualitative Disclosures About Market Risk 75Item 8.Financial Statements and Supplementary Data 76Item 9.Changes in and Disagreements with Accountants on Accounting and Financial Disclosure 107Item 9A.Controls and Procedures 107Item 9B.Other Information 107 PART III Item 10.Directors, Executive Officers and Corporate Governance 108Item 11.Executive Compensation 108Item 12.Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters 108Item 13.Certain Relationships and Related Transactions, and Director Independence 108Item 14.Principal Accounting Fees and Services 108 PART IV Item 15.Exhibits, Financial Statement Schedules 109 ii SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS This Annual Report on Form 10-K contains forward-looking statements concerning our business, operations and financial performance andcondition, as well as our plans, objectives and expectations for our business, operations and financial performance and condition. Any statements containedherein that are not statements of historical facts may be deemed to be forward-looking statements. In some cases, you can identify forward-looking statementsby terminology such as “anticipate,” “assume,” “believe,” “contemplate,” “continue,” “could,” “due,” “estimate,” “expect,” “goal,” “intend,” “may,”“objective,” “plan,” “predict,” “potential,” “positioned,” “seek,” “should,” “target,” “will,” “would” and other similar expressions that are predictions of orindicate future events and future trends, or the negative of these terms or other comparable terminology. These forward-looking statements include, but arenot limited to, statements about: •plans to conduct further clinical studies •our plans to modify our current products, or develop new products, to address additional indications •the expected growth of our business and our organization •our expectations regarding government and third-party payor coverage and reimbursement •our expectations regarding the size of our sales organization and expansion of our sales and marketing efforts in international geographies •our expectations regarding revenue, cost of revenue, cost of service per device, operating expenses, including research and developmentexpense, sales and marketing expense and general and administrative expenses •our ability to retain and recruit key personnel, including the continued development of a sales and marketing infrastructure •our ability to obtain and maintain intellectual property protection for our products •our estimates of our expenses, ongoing losses, future revenue, capital requirements and our needs for, or ability to obtain, additionalfinancing •our expectations regarding the time during which we will be an emerging growth company under the JOBS Act •our ability to identify and develop new and planned products and acquire new products •our financial performance •developments and projections relating to our competitors or our industry We believe that it is important to communicate our future expectations to our investors. However, there may be events in the future that we are notable to accurately predict or control and that may cause our actual results to differ materially from the expectations we describe in our forward-lookingstatements. These forward-looking statements are based on management’s current expectations, estimates, forecasts and projections about our business andthe industry in which we operate and management’s beliefs and assumptions and are not guarantees of future performance or development and involveknown and unknown risks, uncertainties and other factors that are in some cases beyond our control. As a result, any or all of our forward-looking statementsin this Annual Report on Form 10-K may turn out to be inaccurate. Factors that may cause actual results to differ materially from current expectations include,among other things, those listed under “Risk Factors” and elsewhere in this Annual Report on Form 10-K. Potential investors are urged to consider thesefactors carefully in evaluating the forward-looking statements. These forward-looking statements speak only as of the date of this Annual Report on Form 10-K. We assume no obligation to update or revise these forward-looking statements for any reason, even if new information becomes available in the future. You should not rely upon forward-looking statements as predictions of future events. Although we believe that the expectations reflected in theforward-looking statements are reasonable, we cannot guarantee that the future results, levels of activity, performance or events and circumstances reflected inthe forward-looking statements will be achieved or occur. We undertake no obligation to update publicly any forward-looking statements for any reason afterthe date of this Annual Report on Form 10-K to conform these statements to actual results or to changes in our expectations. You should read this Annual Report on Form 10-K and the documents that we reference in this Annual Report on Form 10-K and have filed with theSEC as exhibits to the Annual Report on Form 10-K with the understanding that our actual future results, levels of activity, performance and events andcircumstances may be materially different from what we expect.1 PART IItem 1. Business.OverviewWe are a commercial-stage digital healthcare company redefining the way cardiac arrhythmias are clinically diagnosed by combining our wearablebio-sensing technology with cloud-based data analytics and machine-learning capabilities. Our goal is to be the leading provider of first-line ambulatoryelectrocardiogram, or ECG, monitoring for patients at risk for arrhythmias. We have created a unique platform, called the Zio service, which combines aneasy-to-wear and unobtrusive biosensor that can be worn for up to 14 days with powerful proprietary algorithms that distill data from millions of heartbeatsinto clinically actionable information. We believe that the Zio service allows physicians to diagnose many arrhythmias more quickly and efficiently thantraditional technologies and avoid multiple indeterminate tests. Early detection of heart rhythm disorders, such as atrial fibrillation, or AF, and otherclinically relevant arrhythmias, allows for appropriate medical intervention and helps avoid more serious downstream medical events, including stroke. Sincereceiving clearance from the Food and Drug Administration, or FDA, in 2009, we have provided the Zio service to over one million patients and havecollected over 250 million hours of curated heartbeat data, creating what we believe to be the world’s largest repository of ambulatory ECG patient data. Thisdata provides us with a competitive advantage by informing our proprietary machine-learned algorithms, which may enable operating efficiencies, grossmargin improvement and business scalability. We believe the Zio service is well aligned with the goals of the U.S. healthcare system: improving populationhealth, enhancing the patient care experience and reducing per-capita cost.According to the Centers for Disease Control and Prevention, approximately 11 million patients in the United States have a heart rhythm disorder, orarrhythmia. The most common sustained type of arrhythmia is AF. The American Heart Association, or AHA, estimates that as many as six million people inthe United States have AF and individuals with AF are five times more likely to suffer a stroke. However, the National Stroke Association, or NSA, estimatesthat up to 80% of strokes suffered by people with AF are preventable with early detection and proper treatment.The ambulatory cardiac monitoring market is well-established with an estimated 4.6 million diagnostic tests performed annually in the United States,which we believe to be an existing $1.4 billion market opportunity for our Zio service. Traditional ambulatory cardiac monitoring tools used by physiciansfor diagnosing patients with suspected arrhythmias, such as Holter and cardiac event monitors, are constrained by one or more of the following: shortprescribed monitoring times, non-continuous data collection, cumbersome equipment and low patient compliance. As an example of these traditionalconstraints, patients often remove these traditional monitors when sleeping, showering or exercising, leading to failure to capture critical data. Theselimitations contribute to incomplete diagnoses and repeat testing, which in turn result in suboptimal patient care and higher costs to the health system.While some existing products may address a subset of these limitations, we believe the Zio service provides a comprehensive solution that addressesall of these limitations and offers a clear value proposition to patients, providers, and payors by providing an easy-to-use, clinically proven, low-costsolution. Our Zio service is prescribed by physicians for both identifying arrhythmias as well as for identifying risk factors which may be associated with apreviously-identified arrhythmia. It improves physician management and diagnosis of arrhythmias by providing a patient-friendly wearable biosensor,curating and analyzing voluminous ECG data, and ultimately creating a concise report that is used by the physician to make a diagnosis and which can beintegrated into a patient’s electronic health record. We believe our Zio service can continue taking significant market share from the existing ambulatorycardiac monitoring market and expand the market for new clinical use cases and indications. We believe the Zio service has the potential to supplanttraditional technology and become the primary monitoring option for patients who are candidates for ambulatory cardiac monitoring due to its ability todetect more arrhythmias, which allows for earlier changes in clinical patient management.2 The Zio service consists of: •a wearable patch-based biosensor, also capable of real time monitoring, which continuously records and stores ECG data from every patientheartbeat for up to 14 days •cloud-based analysis of the recorded cardiac rhythms using our proprietary, machine-learned algorithms •a final quality assessment review of the data by our certified cardiac technicians •an easy-to-read Zio Report, a curated summary of findings that includes high quality and clinically-actionable information which is sentdirectly to a patient’s physician and can be integrated into a patient’s electronic health recordWe have reviewed a body of clinical evidence which we interpret to show, among other advantages, that the Zio service helps reduce healthcare costsand improves arrhythmia detection, characterization and diagnosis by prescribing physicians. These improvements have the potential to change clinicalmanagement of patients. Our clinical evidence is helping to drive physician adoption and payor reimbursement coverage. We interpreted one study of theZio service, published in The American Journal of Cardiology in August 2013, to show that among 16,142 consecutive Zio service patients in whom anarrhythmia was detected, over 50% of symptomatic arrhythmias detected by the Zio service occur more than 48 hours into the wear period. Although thisstudy did not directly compare the Zio service to Holter monitoring performance, it should be noted that 48 hours is outside of the typical wear period forHolter monitors. Based upon our review of another prospective comparative study against Holter monitor, published in The American Journal of Medicine inJanuary 2014, we concluded that the Zio service detected 96 arrhythmia events compared to 61 arrhythmia events detected by the Holter monitor (P < 0.001),providing a 57% improvement in diagnostic yield, which is the percentage of patients in whom an arrhythmia was detected during the monitoring period.From our review, we concluded that the Zio service was preferred by 81% of patients when compared to Holter monitors. This clinical study, however, was asingle-center study with a relatively small sample size that directly compared the Zio service to a Holter monitor, but not to other ambulatory cardiacmonitoring products. In summary, we interpreted the clinical results to show that the Zio service is preferred by patients and allows for significantly longercontinuous monitoring, improved clinical accuracy, increased detection of arrhythmias by physicians, and meaningful changes in clinical management.Over one million patients have utilized the Zio service since its commercialization, and as of December 31, 2017, approximately 290 millionindividuals in the United States have government or private insurance policies that cover reimbursement for the Zio service. We have designed acomprehensive strategy to allow us to compete favorably in the ambulatory cardiac monitoring market, which includes capturing market share from existingmonitoring devices as well as expanding the market through new indications. We expect to drive sales and margin growth in our business by expanding oursales organization, securing additional contracts with commercial payors, maintaining technology leadership through research and development, andcontinuing to build clinical evidence supporting the benefits of the Zio service.We have collected over 250 million hours of curated heartbeat data, creating what we believe to be the world’s largest repository of annotated,continuous ambulatory ECG recordings with contextual patient information. This extensive database, along with our proprietary analytic platform,differentiates the Zio service and gives us a competitive advantage. We will continue to seek opportunities to capitalize on our product design, proprietaryanalytic capabilities and data repository to capture additional opportunities in the digital healthcare market.We are a vertically-integrated company headquartered in San Francisco, California, and we have additional commercial operations and facilities inLincolnshire, Illinois and Houston, Texas. We manufacture our devices in Cypress, California. As of December 31, 2017, we had 575 full-time employees.Our revenue was $98.5 million and $64.1 million for the years ended December 31, 2017 and 2016, respectively and we incurred a net loss of $29.4 millionand $20.9 million for those same periods.3 Market OpportunityEvery year, millions of patients experience symptoms potentially associated with cardiac arrhythmias, a condition in which the electrical impulsesthat coordinate heartbeats do not occur properly, causing the heart to beat too quickly, too slowly or irregularly. Examples of arrhythmias include superventricular arrhythmias which are fast heart rates that originate from the upper chambers of the heart, atrial tachycardia, atrial flutter and AF. The symptoms ofarrhythmias include palpitations or a skipped heartbeat, rapid heartbeat, shortness of breath, dizziness, light-headedness, fainting spells, vertigo, anxiety andfatigue. Early detection is essential in order to obtain early treatment and help avoid more serious medical conditions, such as stroke, and additional medicalcosts.Atrial Fibrillation and StrokeIn patients with AF, the upper chambers of the heart beat irregularly and blood does not flow properly to the lower chambers of the heart. The AHAestimates that AF affects as many as six million patients in the United States and 33.5 million patients worldwide. The NSA estimates that one-third of AFpatients are asymptomatic and still undiagnosed. More than 750,000 hospitalizations occur each year because of AF, and the condition contributes to anestimated 130,000 deaths each year. Since AF is more common among people over the age of 60, these numbers are expected to increase as the U.S.population ages.In addition, AF is the leading risk factor for stroke because AF can cause blood to collect in the heart and potentially form a clot, which can travel tothe brain. While individuals with AF are approximately five times more likely to suffer a stroke, the NSA estimates that up to 80% of strokes in people withAF can be prevented through early detection and proper treatment. According to the AHA, stroke costs the United States an estimated $34 billion each year inhealthcare costs and lost productivity, and is a leading cause of serious long-term disability. The AHA estimates that ischemic strokes represent 87% of allstrokes in the United States and that between 15% and 20% of the estimated 690,000 ischemic strokes are attributable to AF.Currently, the Zio service is prescribed by physicians primarily for symptomatic patients. However, we believe that high-risk asymptomatic patientsrepresent an additional market opportunity for the Zio service. Monitoring high-risk asymptomatic patients may lead to increased diagnoses and earliertreatment and potentially avoid more severe downstream conditions, because, as the Framingham Study published in Stroke in September 1995demonstrated, 18% of AF-related strokes present with asymptomatic AF that is only detected at the time of stroke.Early detection of AF is critical in optimizing patient care, delivering earlier treatment to help avoid further adverse clinical events, managingsymptoms caused by AF, and reducing the total public health burden of treating stroke. The AHA and American Stroke Association, or ASA, have publishedtreatment guidelines for patients diagnosed with AF to manage heart rhythm and rate and prevent stroke. These early treatments include: •medications such as oral anticoagulants, new variations of which have been shown in multiple recent studies to safely reduce stroke rates by60% •treatment with anti-arrhythmic drugs •interventions such as cardiac ablation therapy to help control heart rhythm and rateAtrial fibrillation burden, the amount of time a patient spends in AF, has been identified in the clinical community as an important measure fordetermining appropriate and effective therapeutic interventions to manage patients with AF and assessing stroke risk. The calculated AF burden is only asgood as the data available for analysis during the monitoring period. Since the most common type of AF occurs intermittently, continuous patch-basedmonitoring, such as the Zio service, more accurately measures AF burden because every heartbeat is recorded without interruption during the entiremonitoring period. We are currently conducting a study to determine the correlation between AF burden, as measured by the Zio service, and the risk ofstroke in patients.4 The Zio XT monitor was designed specifically to be patient-friendly to facilitate high patient compliance and allow data to be recorded continuouslyfor up to 14 days. Other non-invasive monitoring modalities are limited due to intermittent monitoring, short prescribed monitoring periods and patientcompliance issues due to removal of the device during the monitoring period. Ambulatory Cardiac Monitoring Overview Arrhythmia symptoms are generally monitored either in a physician’s office or healthcare facility or remotely with the use of ambulatory cardiacmonitoring devices. Typically, physicians will administer a resting ECG in their offices to record and analyze the electrical impulses of patients’ hearts. Ifphysicians determine that patients require monitoring for a longer period of time to generate a diagnosis, they have historically prescribed a first-lineambulatory cardiac monitoring device such as a Holter monitor. If the diagnosis is not definitive following the first monitoring period, physicians mayprescribe a repeat Holter monitoring period, or alternatively, prescribed event monitors, mobile cardiac telemetry or implantable loop recorders as second-linetools. Some physicians own their own ambulatory cardiac monitoring devices and provide ambulatory monitoring services directly to their patients, whileothers outsource these services to third-party providers. Holter Monitors Holter monitors are non-invasive, ambulatory, battery-operated monitoring products that continuously record the ECG data of a patient, during atypical prescribed wear period of 24 to 48 hours. A Holter monitor consists of a recorder, electrodes that are attached to the patient’s chest and wiresconnecting the electrodes to the recorder. After the prescribed wear period, the data recorded by the device is delivered by hand, mail or internet forprocessing and analysis by the physician’s office or a third-party provider. For patients with suspected arrhythmias, Holter monitors have a relatively lowdiagnostic yield of approximately 24% due to a limited prescribed wear period of typically no more than 48 hours and low patient compliance, likelyresulting from bulky equipment and cumbersome wires. The low diagnostic yield is also attributable to missing data, because patients typically remove theelectrodes and disconnect their Holter monitors in order to shower, sleep and exercise.Cardiac Event Monitors and Mobile Cardiac TelemetryCardiac event monitoring is another type of non-invasive, ambulatory monitoring. Event monitoring differs from Holter monitoring in that themonitor is prescribed and worn for a longer period of time, up to 30 days, and the data recorded during the wear period is symptom driven. Event monitorsgenerally record several minutes of activity at a time and then start over, a process referred to as memory loop recording. There are many types of eventrecorders available with a range of features including patient-triggered or auto-detected symptom recording, and manual data transmission or auto-send.Mobile cardiac telemetry, also known as MCOT or outpatient telemetry, is another form of event monitor that usually uses wireless technology, such as a cellphone network, to transmit data to a monitoring facility where the ECG data is analyzed. Event monitors have several limitations, including limited datastorage, the lack of trend data, and poor patient compliance due to electrode replacement, bulky equipment and the fact the patient must both activate andtransmit events in some cases. Additionally, MCOT technology has unique limitations including the need for patients to keep the transmitter close at alltimes and frequently change the battery or recharge the device to ensure timely transmissions. These limitations can severely impact a physician’s ability toprovide a timely diagnosis and result in a lower diagnostic yield.Implantable Loop RecordersA separate segment of ambulatory cardiac monitoring consists of implantable diagnostic products such as implantable loop recorders, also known asinsertable cardiac monitors. Implantable loop recorders are implanted underneath a patient’s skin during a hospital-based, minimally invasive procedure.These devices remain implanted in a patient for up to three years, capturing data in a looping manner for patient-triggered or automatically-detected events.Limitations of this monitoring option include the semi-permanent nature of the implant, infection risks during insertion and removal, non-continuous datacollection, under- or over-sensing which may exhaust the memory of the loop recorder, risk of missing events due to the looping nature of the recording, andthe high cost of the device.5 Limitations of Traditional Ambulatory Cardiac MonitorsLimitations of the various types of traditional ambulatory cardiac monitors can include the following: •short prescribed monitoring periods leading to low diagnostic yield •non-continuous data collection, resulting in an incomplete picture of a patient’s arrhythmia experience •bulky monitoring equipment with dangling electrode leads causing discomfort and low patient compliance •the need to use costly second-line diagnostic options that would not be necessary if first-line tests had produced a higher diagnostic yield •the generation of excessive and uncurated data for the physician to analyzeWe believe there is a significant opportunity for a disruptive arrhythmia monitoring solution that offers low-cost, first-line, continuous ambulatorymonitoring, combined with patient-friendly design, to enhance compliance and simplify the monitoring experience while maximizing diagnostic yield.Our SolutionWe have developed a 14-day, continuous, ambulatory cardiac monitoring solution known as the Zio service. The FDA-cleared Zio service combinesa wire-free, patch-based, wearable biosensor with a proprietary cloud-based data analytic platform to help physicians monitor patients and diagnosearrhythmias. Since commercialization, over one million patients have utilized the Zio service and we have collected over 250 million hours of heartbeats,creating what we believe to be the world’s largest repository of ambulatory ECG patient data.Patients have the ability to mark when symptoms occur while wearing the Zio XT monitor by pressing a trigger button on the device, and separatelyrecording contextual data like activities and circumstances in a symptom diary. This allows physicians to match symptoms and activity with ECG data.Following the wear period, the monitor is returned and data is uploaded to our secure cloud and run through our proprietary, machine-learned algorithms. Aconcise report of preliminary findings is prepared by our certified cardiac technicians and made available to physicians electronically. We believe the Zio service is a disruptive option for ambulatory cardiac monitoring. Although the Zioservice is less well-known than some of the devices sold by our competitors, our solution is the only patch-based monitor to achieve meaningful scale to date,with over one million monitored patients. The Zio service addresses patient compliance, continuously monitors patients up to 14 days and produces easy toread, comprehensive digital reports which provide the information physicians need to make accurate and timely clinical decisions. Clinical studies haveshown that our innovative digital healthcare solution improves physicians’ abilities to detect6 arrhythmias by increasing diagnostic yield, and potentially allows them to change the course of treatment. Our proprietary machine-learned algorithms giveus a competitive advantage due to the depth and breadth of ECG data available from the over 250 million hours of curated and annotated ECG data collectedto date. Additionally, we believe we have the first mover advantage in the market, particularly related to our efforts to secure commercial payor contracts andin-network arrangements covering approximately three quarters of the U.S. population as of December 31, 2017. The Zio XT monitor, does not provide real-time reporting capabilities, however we received FDA clearance for the Zio AT monitor in June 2017 andthis addition to our product portfolio seeks to address the segment of the patient population who require real-time notification of critical arrhythmias throughwireless transmission capabilities during the wear period. The Zio AT monitor is currently in limited release to assess market acceptance.We are actively working to make the Zio service the preferred monitoring option for patients who require ambulatory cardiac monitoring. Oursolution helps reduce healthcare costs and improves arrhythmia detection, characterization and diagnosis by providing simple, seamless integration of heartrhythm data from patient to cloud to physician. We believe we offer a high value, low cost, disruptive solution to a market ready for innovative technology.Key BenefitsValue to PatientsWe designed the Zio XT monitor specifically to address patient compliance issues common to other ambulatory cardiac monitors. Our wire-freewearable biosensor is easy to apply, comfortable, lightweight and unobtrusive. It does not require patient action for battery changes, adhesive changes, orlead wire or electrode management. Patients wear it discreetly during activities of daily life including exercising and showering for up to 14 consecutivedays. We interpreted a clinical study by Barrett et al published in The American Journal of Medicine in January 2014, or the Barrett Study, to confirm thatthe Zio service is a patient-friendly monitoring option, and the study noted that 94% of patients found the Zio XT monitor comfortable to wear, and 81% ofpatients preferred the Zio XT monitor over a Holter monitor. The Zio XT monitor allows patients to mark when a symptom occurs by pressing a button on theZio XT monitor and logging the surrounding circumstances into a diary, thus allowing physicians to link symptoms with the ECG data. Additionally,patients have access to our professional 24/7 customer service team to address any product, service, enrollment or billing questions.Value to ProvidersProviders, such as physicians, receive high-quality, easy-to-read, actionable digital reports that help them diagnose patients and streamline clinicalworkflow. The Zio service has been shown in multiple peer-reviewed published clinical studies to detect more arrhythmias compared to Holter monitoringduring their respective prescribed wear periods. We analyze and generate patient reports at our CMS-certified independent diagnostic testing facilities, orIDTFs, staffed with our certified cardiac technicians who specialize in advanced arrhythmia interpretation to help ensure high accuracy and quality of reportsbefore delivering them to the prescribing physician. Due to high patient compliance, the reports include up to 14 days of non-interrupted data correlated withpatient-triggered and diary symptom events. Physicians can use this continuous correlated data to more conclusively diagnose arrhythmias as a source ofsymptoms.7 Accurate detection and higher diagnostic yield allow physicians to more quickly prescribe the appropriate treatment options for patients. From ourreview, we determined that in 28% of cases observed in a clinical study by Rosenberg et al published in Pacing and Clinical Electrophysiology in March2013, or the Rosenberg Study, the physician changed the patient’s clinical management after prescribing the Zio service as compared to a Holter monitor. Additionally, the Zio service allows clinical staff to focus on more value-added activities by not requiring electrode changes or battery rechargingduring use, device cleaning and maintenance following use, and by reducing physician and hospital staff time needed to review and curate ECG data. Our24/7 customer service team provides troubleshooting for patient-related issues, removing this burden from the physician practice.8 Value to PayorsThe Zio service offers a high yield, low cost solution compared to other monitoring modalities. The graph above compares the costs of monitoring to the diagnostic yield of various ambulatory cardiac monitors. The analysis, completed byDecision Drivers Analytics and commissioned by us, uses cost data from the Centers for Medicare & Medicaid Services, or CMS, published diagnostic yields,and our internal database, and demonstrates that the Zio XT monitor has a diagnostic yield on par with much more expensive devices but superior to lessexpensive options. This implies that it is the most cost-effective modality among its peer group, optimizing the cost, time, and reliability of reaching a timelydiagnosis.This data, however, demonstrates that the Zio service is not the least expensive solution on the market. Additionally, other devices may enjoyadvantages such as established brand recognition and real-time reporting capabilities that the Zio XT monitor does not provide.Patients who use traditional Holter monitors often do not receive a diagnosis after one monitoring period. A recent retrospective, longitudinal studyconducted by Arnold et al published in the Journal of Health Economics and Outcomes Research in February 2015, evaluated the clinical consequences andcosts of CMS patients who had no previous evidence of a cardiac arrhythmia and were undergoing their first Holter monitoring test. Our review of data fromthis study indicates that there was no diagnosis reached for 70% of patients after an initial Holter test. The Zio service has been shown to have a low cost perdiagnosis compared to existing monitoring modalities due to its high diagnostic yield.We believe that the Zio service is the best test for most patients requiring ambulatory cardiac monitoring because it allows physicians to identify atimely course of treatment and avoids healthcare costs associated with additional monitoring. The Zio service is patient-friendly and allows significantlylonger and more continuous monitoring than a Holter monitor, resulting in improved clinical accuracy and potentially a meaningful change in clinicalmanagement. Better diagnostic yield results in decreased costs due to fewer additional first and second-line tests. We believe that the Zio service couldreplace both first and second-line testing solutions because it offers the right test, the first time.9 Early detection of arrhythmias allows physicians to assess a patient’s risk factors, and decide on the best treatment course for avoiding potentiallymore severe downstream conditions. Specifically, the early detection of AF allows physicians to consider strategies to mitigate the risk of stroke. Accordingto multiple studies, preventative treatments, such as oral anticoagulants, have been shown to reduce stroke rates by 60%, thereby potentially avoiding thepatient effects of stroke and the high costs associated with post-stroke management.Our TechnologyThe Zio service combines our proprietary products and services to provide continuous ambulatory cardiac monitoring. A wearable patch-basedbiosensor called the Zio XT monitor, collects up to 1.5 million heartbeats for each patient during a wear period of up to 14 days. Our Zio service includes amachine-learned analytics engine which curates the heartbeat data into a concise, clinically actionable report, which is delivered to the prescribingphysician.Zio XTThe Zio XT monitor is a single-use, wire-free, wearable patch-based biosensor that records a patient’s heartbeats and ECG data. The Zio XT monitorwas specifically designed with the patient and physician in mind. The Zio XT monitor includes the following features: •patented clear, flexible, lightweight, wire-free design •unobtrusive and inconspicuous profile •proprietary adhesive backing that keeps the patch securely in place for the duration of the prescribed wear period •water resistant functionality, allowing patients to shower and perform normal daily activities, including moderate exercise •hydrogel electrodes for a clear ECG with minimal artifact from movement •large symptom button, or patient trigger, that is easy to find and press •indicated wear period of up to 14 days •sufficient battery life for the entire wear period Symptoms can be logged through a paper symptom diary or through two digital platforms: •myZIO.com website •myZIO iPhone App10 Monitoring with the Zio serviceThe Zio service is administered through the process described below:Enrollment and Initiation of the Zio serviceOnce a physician determines a patient is a candidate for 14-day continuous monitoring, the patient is enrolled through our online portal. The wire-free Zio XT monitor is applied to the patient’s chest by the clinical staff, and monitoring is initiated. There is also an option for physicians to enroll patientsremotely, although this option is less frequently utilized. With this option, the physician enrolls the patient and the patient receives the Zio XT monitor inthe mail along with a detailed set of self-application instructions.MonitoringThe Zio XT monitor is worn continuously by the patient for up to 14 days. The Zio XT monitor can be worn in the shower, while sleeping, and duringmoderate exercise. During the wear period, the device continuously stores and records all ECG data. The Zio XT monitor features a patient trigger button formarking any symptoms during the wear period; the patient is instructed to push the button when a symptom occurs and make a corresponding entry into thewritten or electronic symptom diary. At the end of the prescribed wear period, the patient removes the device and places it and the diary into a pre-paid postalbox, which ships to one of our clinical centers.Data Analysis and AssessmentAt one of our clinical centers, the returned device is validated with patient identifiers that are compliant with the Health Insurance Portability andAccountability Act of 1996, or HIPAA, and up to 14 days of heartbeat data is uploaded to be processed through our cloud-based, FDA-cleared proprietaryalgorithms for highly accurate ECG analysis. When complete, a preliminary curated report is created. Our process can take the equivalent of 30,000 pages ofECG strips and distill it into an actionable summary report of about 10 to 15 pages, summarizing the key findings and providing supporting details onclinically relevant events and metrics during the wear period. Our certified cardiac technicians play a critical role in report curation by providing a qualityreview of the data before the final ZIO Report is electronically delivered to the patient’s physician for final interpretation and diagnosis.Zio ReportThe Zio Report provides information in a concise format for review and interpretation by the patient’s physician. Data provided includes totalanalysis time, AF burden, AF duration, comprehensive symptom/rhythm correlation, detailed findings per day, and arrhythmia type. If pre-determinedphysician notification criteria for symptoms are met, the prescribing physician is notified by phone of the serious findings prior to the Zio Report being madeavailable electronically. The Zio Report is delivered through our secure, HIPAA compliant web portal. Physicians can open the Zio Report and add theirinterpretation into the report file. These reports can be uploaded into the physicians’ electronic record system for storage and are available for use by thepatient’s other physicians. Excerpts of these reports are included below to highlight the key features.11 Up to 14-days continuous recording and storage Up to 20,000 minutesof continuous ECGdata, equivalent toapproximately 1.5million heartbeats Easy-to-read summary Preliminary findingsbased on both theproprietary algorithmsand certified cardiactechniciansFinal interpretation bya patient’s physician Comprehensive symptom/rhythm correlation Patient-triggered andsymptom diary eventsmapped to arrhythmia 12 AF Burden Total AF during wearperiod and daily AFburden AF Duration Total number of AFepisodes categorizedby durationBusiness StrategyOur goal is to be the leading ambulatory cardiac monitoring option for patients at risk for arrhythmias. The key elements of our strategy include: •Further penetrating the existing ambulatory cardiac monitoring market. We intend to expand our market penetration by targeting the largeexisting ambulatory cardiac monitoring market in the United States. We will continue to position the Zio XT service as the right test, the firsttime, thereby offering certainty in a single test and Zio AT for the smaller percentage of the population that requires outpatient telemetry.Marketing and education throughout the medical community are key to communicate the strong clinical evidence demonstrating highpatient satisfaction and compliance as well as the monitoring superiority of the Zio service over Holter monitoring. In addition, we expect tocontinue developing clinical evidence to demonstrate the advantages of the Zio service. Also, within existing accounts, we will continue tomarket our Zio service beyond cardiology and electrophysiology into other departments, including neurology, emergency rooms andprimary care offices. •Increasing reimbursement coverage and contracts with commercial payors to increase patient access. As of December 31, 2017,approximately 290 million individuals in the United States have government or private insurance policies that cover reimbursement for theZio XT service. We have reimbursement arrangements in place with CMS and other government agencies as well as contracts and in-networkarrangements in place with commercial payors across the country covering approximately three quarters of the U.S. population as ofDecember 31, 2017. We will continue to pursue expanded reimbursement coverage and contracting for both Zio XT and Zio AT byhighlighting the unique attributes of the Zio service. Our payor relations team is actively engaging national and state-level commercialpayors to put contracts in place that will increase and simplify access to the Zio service.13 •Driving conversion of business to direct billing of third-party payors. In 2017, approximately 82% of our revenue was derived from directlybilling third-party payors for the Zio XT service. In accounts that have converted to this model, we have seen an increase in utilizationvolume because providers no longer need to be concerned with the complexities of coverage or reimbursement for the Zio service. Newaccounts that otherwise may not have been willing to accept the risk of directly billing payors are expected to expand our marketopportunity. Our sales teams work diligently with accounts to review workflow and protocols and ensure they are effectively using ouravailable resources, including our 24/7 customer service and billing specialists. We have developed communication tools and programs andcontinually evaluate and refine those tools to support this initiative. We intend to expand our business toward direct third-party payorbilling in both existing and new accounts. •Expanding our sales organization, both in the U.S. and internationally to support growth. To capture new account opportunities andsupport growth in existing accounts, we implemented a direct sales organization consisting of sales management, field billing specialists,and quota-carrying sales representatives. We will continue to invest in the expansion of this scalable infrastructure and believe thisinvestment will drive adoption of the Zio service. While our initial commercial focus is the U.S. market, we have initiated efforts that willallow for future expansion into international geographies. •Expanding indications and clinical use cases. We intend to continue expanding indications and clinical use cases for the Zio service inuntapped patient populations at risk for arrhythmias through our clinical and market development efforts. We believe these additionalindications and clinical use cases represent a significant opportunity for us. This market development initiative includes expanding use forour Zio service into the following patient populations: •patients at high risk for asymptomatic (silent) AF, estimated to be at least 3 million patients at any given time •post-ischemic stroke patients, with an annual incidence of 690,000 •post-cardiac catheter ablation patients, estimated to be 100,000 annual procedures •pre-op cardiac surgery patients, estimated to be 280,000 annual procedures •Advancing our technology offering and continuing to solidify our footprint in digital healthcare. We continue to invest in building aunique, innovative product portfolio that addresses unmet needs in the ambulatory cardiac monitoring market. Additionally, we believe thatwe have collected the world’s largest repository of ambulatory ECG patient data, and we will continue to look for ways to utilize ourproprietary data to create value-driving opportunities in digital healthcare, such as expansion of indications for the Zio service, newtherapeutic discoveries, development of an analytical engine for ambulatory consumer and other medical data, including the curation ofthird-party biosensor data and payor and provider decision support, as well as internal operating improvements.Reimbursement and Revenue from the Zio serviceWe receive revenue for the Zio service primarily from two sources: third-party payors and institutions. Third-party payors include commercial payorsand government agencies, such as CMS and the Veterans Administration, or VA, and represent the largest, as well as an increasing, source of revenue.Institutions, which are typically hospitals or private physician practices also account for a meaningful percentage of our revenue. We bill these organizationsfor our Zio service, and they are responsible for payment, and, in turn, for seeking reimbursement from third-party payors where applicable. In addition, asmall percentage of patients whose physicians prescribe the Zio service pay us directly.Third-party payors require us to identify the service for which we are seeking reimbursement by using a CPT code set maintained by the AmericanMedical Association, or AMA. For the year ended December 31, 2017, we received 82% of our revenue through third-party payors. As we continue tocontract with more commercial insurers and the patient population ages and becomes eligible for CMS programs, we believe more of our revenue will convertto third-party payor billing.14 We have successfully secured Current Procedural Terminology, or CPT, codes specific to this novel category of diagnostic monitoring by workingwith the AMA and other professional societies who recognize the unique value and efficiency provided by the Zio service. The CPT reimbursement code forthe Zio service is a global code which can be broken out into three separate codes: (1) hook-up of the monitoring device; (2) technical analysis services; and(3) the interpretation of the report. The hook-up refers to the application of the Zio XT monitor to the patient’s chest along with patient training by theclinical staff on proper handling and instructions for use during the wear period. The technical component involves the cost of the Zio XT monitor or the ZioAT monitor, analysis and curation of the ECG data and report generation. The interpretation component involves the physician review and interpretation ofthe generated report. While the physician or institution bills for hook-up and interpretation, we bill for the technical component.Our clinical centers, where we conduct the analysis of ECG data captured by the Zio XT monitor and the Zio AT monitor, are CMS-certified IDTFs,that qualify us as a provider and allow us to bill CMS directly for the Zio service. We meet CMS requirements, including having an independent medicaldirector for oversight and Certified Cardiac Technicians for quality assurance of our Zio Reports.Commercial payors also reimburse for the Zio service utilizing the aforementioned unique CPT codes. We continue to engage with commercialpayors to secure active contracts with set reimbursement rates for the Zio service.Clinical Results and StudiesThe Zio service has been the subject of many peer-reviewed publications on its effectiveness to date. This body of clinical evidence is drivingclinical adoption, payor coverage, and clinical use case expansion. The following sections summarize a few of the key clinical studies which have beendriving adoption of the Zio service. In our discussion of the results of these publications, we have indicated changes in percentage terms, regardless of samplesize, and the statistical significance is demonstrated by the relevant p-values, all of which are less than 0.05, which is the commonly accepted threshold forstatistical significance. This follows the convention used by the authors of the study as well as standard clinical practice.15 Benefit of 14-Day Continuous MonitoringA retrospective study by Turakhia et al, published in The American Journal of Cardiology in August 2013, analyzed data from 26,751 patients usingthe Zio service for the first time between January 1, 2011 and December 31, 2011. While there was not a direct comparison of the Zio service to Holtermonitoring performance, we interpreted results from the study to show that among the 16,142 patients with detected, clinically relevant arrhythmias, over50% of the first-diagnosed symptomatic arrhythmias occurred after 48 hours of monitoring, suggesting that these arrhythmias could have been missed bytraditional Holter monitoring during the typical maximum prescribed monitoring time. Diagnostic Yield and Monitoring PreferenceIn the Barrett study, a prospective head-to-head study comparing the detection of arrhythmias between a 24-hour Holter monitor, which has a typicalprescribed wear period of 24-48 hours, and the 14-day Zio service, a total of 146 patients referred for evaluation of cardiac arrhythmias between April 2012and July 2012 underwent simultaneous ambulatory ECG recording with both devices. The purpose of the Barrett study was to determine the number ofarrhythmia events and the percentage of patients in whom an arrhythmia was detected, known as “diagnostic yield,” during the comparative prescribed wearperiods. Our interpretation of the results of the Barrett study are that over the total wear period of each device, the Zio service detected 96 arrhythmia eventscompared with 61 arrhythmia events by the Holter monitor (P < 0.001) providing a 57% improvement in diagnostic yield. An increase in diagnostic yieldprovides increased data for the prescribing physician to use when making a diagnosis. In addition, we interpreted survey results to show that 94% of patientsfound the Zio XT monitor comfortable to wear, whereas only 52% patients found the Holter monitor comfortable to wear, and 81% indicated they preferredthe Zio XT monitor to the Holter monitor. Of the 102 physicians surveyed, from our review, we concluded that 90% thought a definitive diagnosis wasachieved using data from the Zio service, as opposed to 64% using data from the 24-hour Holter monitor. This clinical trial, however, was a single centerstudy with a relatively small sample size which did not compare the Zio service with any product except the Holter monitor.16 Changing Clinical Management for AFIn the Rosenberg Study, a prospective single center study of 74 patients undergoing management of AF, patients received both the Zio XT monitorand a 24-hour Holter monitor simultaneously to determine the pattern of AF, to document a response to therapy and to potentially diagnose otherarrhythmias. From our review, we concluded that the Zio service identified AF events in 24% more patients (18 patients) than Holter monitors (P < 0.0001)and the diagnosed pattern of AF was changed in 28% of patients (21 patients) after Zio service monitoring.Based on our review of the study, we concluded that 28% of patients (21 patients) had a change in their clinical management. The most commonchanges included a change in antiarrhythmic medication, initiation or discontinuation of anticoagulation medication, recommendation of pacemakerplacement, atrioventricular junction ablation, pulmonary vein isolation procedure and cardioversion. This clinical trial, however, was also a single centerstudy with a relatively small sample size which did not compare the Zio service with any product except the Holter monitor.AF Burden as a Predictor of Stroke RiskThe RHYTHM Study, a retrospective cohort study of 771 Kaiser Permanente patients with paroxysmal AF who were monitored with the Zio servicebetween October 1, 2011 and December 31, 2014, examined the independent association between AF burden, which is the amount of time that a patientspends in AF, as measured by the Zio service, and the risk of ischemic stroke. The findings were derived by linking detailed clinical outcome data from KaiserPermanente’s electronic medical records with our database of analyzed ECG recordings. We interpreted the study results, presented at the Heart RhythmSociety’s 37th Annual Scientific Sessions in May 2016 by Alan Go M.D. and his colleagues, to show that a doubling of AF burden was associated with a 33%increased risk of stroke in patients who were not taking medication to prevent blood clots. We concluded that these results suggest that information on AFburden, which is measured by the Zio service, may help patients and providers better evaluate treatment options for reducing risk of stroke. This clinicalstudy was limited to Kaiser Permanente’s patients from the Northern and Southern California regions.Monitoring of Asymptomatic AF in High Risk PatientsSTUDY-AF was a single-center, single-arm prospective study by Turakhia et al published in Clinical Cardiology in May 2015 that enrolled 75 high-risk but previously undiagnosed AF patients from May 2012 to August 2013. Patients were 55 years of age or older and considered high risk with two or moreof the following risk factors: coronary disease, heart failure, hypertension, diabetes or sleep apnea, but had no prior documented AF or history of blood clotscausing blockage in blood vessels. We interpreted the results to show that extended monitoring with the Zio service identified 11% of patients withpreviously undiagnosed AF or atrial tachycardia, a rapid heartbeat where electrical signals initiate abnormally in the upper chamber of the heart. Weconcluded from our review that in patients with AF, 75% of patients experienced the longest AF episode after the first 48 hours of monitoring and there wasalso a high prevalence of asymptomatic atrial tachycardia and frequent supraventricular ectopic complexes identified, which may be relevant to developmentof AF or stroke. This clinical trial, however, was also a single center study with a relatively small sample size.Currently, the Zio service is prescribed by physicians primarily for symptomatic patients. However, the NSA estimates that one-third of the AFpopulation suffers from asymptomatic, or silent, AF. We see a future opportunity in proactively monitoring the at least three million patients who are at highrisk of asymptomatic AF to identify those with the illness.There are additional studies underway examining early detection of AF using Zio service monitoring in high-risk patients. The mHealth Screening toPrevent Strokes, or mSToPS study, initiated in November 2015 in collaboration with Janssen Scientific Affairs, LLC, remotely recruited subjects from theAetna Commercial Fully Insured and Medicare Advantage programs through a web-based platform. Women over the age of 65 and men over 55 with certainrisk factors were selected to participate based on information derived from claims data that placed them at a potentially increased risk of undiagnosedasymptomatic AF. The mSToPS study completed enrollment in 2017. 17 The Home-based Screening for Early Detection of AF, or SCREEN-AF, study is screening approximately 800 patients older than 75 years withhypertension. Started in April 2015, the intervention group will undergo ambulatory screening for AF for two weeks with the Zio service utilized at baselineand again at three months, in addition to standard care for six months.Research and DevelopmentOur research and development activities are focused on: •Improvements and extensions to existing products and services. We are continuously working to improve the Zio service to increase patientcomfort, product quality, operational scalability and security •Advancing our technology offering. Our product pipeline includes patch-based solutions that combine continuous monitoring for extendedperiods with accelerated notification of actionable events through mobile telemetry capabilities •Customer workflow optimization. We have initiatives that aim to increase customer productivity by optimizing workflow through easierpatient enrollment and integration of Zio Reports directly into electronic health records •Data analytics. We are focused on improving and enhancing our backend machine-learned analytic platform, building on our corecompetency in data analytics •Developing clinical evidence. We are involved in clinical studies to further support the benefits of the Zio service and expand indications foruse •Continuing to solidify our footprint in digital healthcare. Using our repository of ambulatory ECG patient data, we will continue to look forways to create value-driving opportunities in digital healthcare, such as expansion of indications for the Zio service, new therapeuticdiscoveries, development of an analytical engine for ambulatory consumer and other medical data and payor and provider decision supportOur research and development department consists of software development, algorithm and product development, regulatory affairs, and clinicalresearch. Our research and development expense was $13.3 million, $7.2 million and $6.3 million for the years ended December 31, 2017, 2016 and 2015,respectively.Sales and MarketingWe market our ambulatory cardiac monitoring solution in the United States through a direct sales organization comprised of sales management, fieldbilling specialists, and quota-carrying sales representatives. As of December 31, 2017 we had 86 sales representatives on a full-time equivalent basis,compared to 66 in 2016, and 52 in 2015. Our sales representatives’ focus on initial introduction into new accounts, penetration across a sales region, drivingadoption within existing accounts and conveying our message of clinical and economic value to service line managers, hospital administrators, and otherclinical departments. We continue to increase the size of our U.S. sales organization to expand the current customer account base and increase utilization ofour Zio service. In addition, we will continue exploring sales and marketing expansion opportunities in international geographies.We market our Zio service to a variety of physician specialties including general cardiologists, electrophysiologists, neurologists, and otherphysician specialists who diagnose and manage care for patients with arrhythmias. We have found success focusing on integrated delivery networks, or IDNs,in which large networks of facilities and providers work together to offer a continuum of care to a specific geographic area or market. Focusing on sales toIDNs gives us the opportunity to conduct a holistic sale for health systems interested in making value-based purchasing decisions.18 CompetitionWe operate in a highly competitive and fragmented industry, subject to rapid change and significantly affected by new product introductions, resultsof clinical research, corporate combinations and other factors. We principally compete with companies that sell standard Holter monitors including GEHealthcare, Philips Healthcare, Mortara Instrument, Inc., Spacelabs Healthcare Inc. and Welch Allyn Holdings, Inc., which was acquired by Hill-RomHoldings, Inc. Additional competitors who offer ambulatory cardiac monitoring services include BioTelemetry, Inc. and Medtronic plc.These competitors have also developed other patch-based mobile cardiac monitors that have recently received FDA and foreign regulatoryclearances. For example, LifeWatch AG, which was subsequently acquired by BioTelemetry, received FDA clearance and CE mark for its mobile cardiactelemetry monitoring patch in January 2016 and December 2015, respectively. We are also aware of some small start-up companies entering the patch-basedcardiac monitoring market. Large medical device companies may continue to acquire or form alliances with these smaller companies in order to diversifytheir product offering and participate in the digital health space. For example, in 2014 Medtronic plc. acquired Corventis, Inc. Many of our competitors havesubstantially greater financial, manufacturing, marketing and technical resources than we do. Furthermore, many of our competitors have well-establishedbrands, widespread distribution channels, broader product offerings and an established customer base.We believe the principal competitive factors in our market include: •ease of use, comfort and unobtrusiveness of the device for the patient •quality of the algorithms to detect arrhythmias •concise and comprehensive reports supporting efficient physician interpretation •contracted rates with third-party payors •government reimbursement rates associated with our products and services •quality of clinical data and publication in peer-reviewed journals •size, experience, knowledge and training of sales and marketing teams •availability and reliability of sales representatives and customer support services •workflow protocols for solution implementation in existing care pathways •reputation of existing device manufacturers and service providers •relationships with physicians, hospitals, administrators, and other third-party payorsIntellectual PropertyTo protect our proprietary rights, we rely on a combination of trademark, copyright, patent, trade secret and other intellectual property laws,employment, confidentiality and invention assignment agreements and protective contractual provisions with our employees, contractors, consultants,suppliers, partners and other third parties.19 As of December 31, 2017, we owned, or retained an exclusive license to, nine issued U.S. patents, three issued patents from the Japan Patent Office,two issued patents from each of the Australian and Canadian Patent Offices, and one issued patent from the Patent Offices in each of the European Union andKorea: Country Pat. No. Issue Date Expiration DateUSA 8,160,682 4/17/2012 2/3/2029USA 8,244,335 8/14/2012 1/21/2029USA 8,150,502 4/3/2012 11/20/2028USA 8,560,046 10/15/2013 6/2/2031USA 8,538,503 9/17/2013 5/12/2031USA 9,173,670 11/3/2015 4/7/2034USA 9,241,649 1/26/2016 10/19/2031USA 9,451,975 9/27/2016 4/7/2034USA 9,597,004 3/21/2017 10/30/2035Japan 5,203,973 2/22/2013 2/6/2027Japan 5,559,425 6/13/2014 5/12/2031Japan 6,198,849 9/1/2017 1/23/2034Australia 2011252998 12/10/2015 5/12/2031Australia 2014209376 6/29/2017 1/23/2034Canada 2,651,203 9/19/2017 2/6/2027Canada 2,797,980 8/18/2015 5/12/2031Korea 10-1513288 4/13/2015 5/12/2031The European Union EP1981402 8/10/2016 2/6/2027 As of December 31, 2017, we had twenty pending patent applications globally, including four in the United States, five in the European Union, fourin Japan, two in each of Korea and Canada, and one in each of Australia, China and India.As of December 31, 2017, our trademark portfolio contained a U.S. trademark registration for the mark My ZIO, ZIO and a pending U.S. applicationfor Zio AT. It also contained registered trademarks for the mark IRHYTHM in Australia and the European Union and pending applications for that mark inAustralia, Austria, Canada, China, Denmark, Finland, France, Germany, Japan, Norway, Sweden, Switzerland, United Kingdom and United States. It furthercontained pending applications for the mark ZIO in Australia, Canada, China, Japan, Norway and Switzerland and a registered trademark for ZIO in theEuropean Union.We also seek to maintain certain intellectual property and proprietary know-how as trade secrets, and generally require our partners to execute non-disclosure agreements prior to any substantive discussions or disclosures of our technology or business plans. Our trade secrets include proprietaryalgorithms, adhesive formulations, workflow tools and operational processes.Manufacturing and SupplyWe manufacture our ambulatory cardiac monitors, the Zio XT and the Zio AT, in our leased facilities in Cypress, California. This 9,866 square footfacility provides space for our assembly and production operations, including packaging, storage and shipping. We believe our manufacturing facilities willbe sufficient to meet our manufacturing needs for at least the next two years.20 Our manufacturing operations are subject to regulatory requirements of the FDA’s Quality System Regulation, or QSR, for medical devices sold in theUnited States, set forth at 21 CFR part 820, and the Medical Devices Directive 93/42/EEC, or MDD, which is required for doing business in the EuropeanUnion, or EU. We are also subject to applicable requirements relating to the environment, waste management and health and safety matters, includingmeasures relating to the release, use, storage, treatment, transportation, discharge, disposal, sale, labeling, collection, recycling, treatment and remediation ofhazardous substances. The FDA enforces the QSR through periodic unannounced inspections that may include our manufacturing facilities or those of oursuppliers. Our EU Notified Body, the National Standard Authority of Ireland, or NSAI, enforces the MDD through both scheduled and unscheduledinspections of our manufacturing facilities.Our failure or the failure of our suppliers to maintain compliance with either the QSR or MDD requirements could result in the shutdown of ourmanufacturing operations or the recall of our products, which would harm our business. In the event that one of our suppliers fails to maintain compliancewith our or governmental quality requirements, we may have to qualify a new supplier and could experience manufacturing delays as a result.Our quality control management programs have earned us a number of quality-related manufacturing designations. Our Cypress, Californiamanufacturing facilities have received EN ISO 13485:2012 and ISO 13485:2003 certification. The NSAI most recently conducted an ISO 13485recertification audit in 2017, and ISO certification was received. We have been an FDA-registered medical device manufacturer since 2008 and have been aCalifornia-licensed medical device manufacturer since 2009. The most recent FDA audit of our manufacturing facility occurred in August 2017 and no formalobservations resulted. No additional follow up with the FDA was required and we believe that we are in substantial compliance with the QSR.Circuit board components of the Zio XT and Zio AT monitors are provided by contract electronic manufacturers, Kimball Electronics, Inc. and VerisManufacturing, Inc. We have manufacturing service agreements with both providers that allow either party to terminate the agreement with 90 days priorwritten notice. There are a number of additional critical components and sub-assemblies sourced by other vendors. The vendors for these materials arequalified through stringent evaluation and testing of their performance. We implement a strict no-change policy with our contract manufacturers to ensurethat no components are changed without our approval. Our production group in Cypress, California performs inspection, assembly, testing and productrelease.Order quantities and lead times for components purchased from suppliers are based on our forecasts derived from historical demand and anticipatedfuture demand. Lead times for components may vary significantly depending on the size of the order, time required to fabricate and test the components,specific supplier requirements and current market demand for the components and subassemblies. To date, we have not experienced significant delays inobtaining any of our components or subassemblies.Government RegulationUnited States Food & Drug Administration (FDA)The Zio XT and Zio AT monitors are considered medical devices subject to extensive and ongoing regulation by the FDA under the Federal Food,Drug, and Cosmetic Act, or FD&C Act, and its implementing regulations, as well as other federal and state regulatory bodies in the United States. The lawsand regulations govern, among other things, product design and development, pre-clinical and clinical testing, manufacturing, packaging, labeling, storage,recordkeeping and reporting, clearance or approval, marketing, distribution, promotion, import and export, and post-marketing surveillance.The FDA regulates the medical device market to ensure the safety and efficacy of these products. The FDA allows for two primary pathways for amedical device to gain approval for commercialization: a successful premarket approval, or PMA, application or 510(k) clearance pursuant to Section 510(k)of the FD&C Act. A novel product must go through the more rigorous PMA process if it cannot receive authorization through a 510(k) clearance. FDA hasestablished three different classes of medical devices that indicate the level of risk associated with using a device and the consequent degree of regulatorycontrols needed to govern its safety and efficacy. Most Class I devices are exempt from 510(k) requirements. Most Class II devices, including the Zio XT andZio AT monitors, require 510(k) clearance from the FDA in order to be marketed in the United States. A 510(k) submission21 must demonstrate that the device is substantially equivalent to a device legally in commercial distribution in the United States: (1) before May 28, 1976; or(2) to another device that has been cleared through the 510(k) process and determined by FDA to be substantially equivalent. To be substantially equivalent,the proposed device must have the same intended use as the predicate device and either have the same technological characteristics as the predicate device orhave different technological characteristics and not raise different questions of safety or effectiveness than the predicate device. Clinical data is sometimesrequired to support substantial equivalence. In some instances, data from human clinical trials must also be submitted in support of a 510(k) submission. If so,this data must be collected in a manner that conforms with specific requirements in federal regulations. Most Class III devices are high risk devices that pose asignificant risk of illness or injury or devices found not to be substantially equivalent to Class I and II predicate devices through the 510(k) process andrequire PMA. The PMA process for Class III devices is more involved and includes the submission of clinical data to support claims made for the device.The Zio XT and Zio AT monitors maintain FDA 510(k) clearance as Class II devices, with each new generation of a device receiving individualclearance. In addition, the Zio ECG Utilization Service System, or the ZEUS System, originally received FDA 510(k) clearance in 2009 as a Class II device.The ZEUS System is the combination of proprietary algorithms and software tools that our certified cardiac technicians utilize to curate the ECG data andcreate the Zio Report electronically. Significant modifications made to the ZEUS System since its original clearance were evaluated by the FDA and received510(k) clearance in November 2014. The ZEUS System is also a key component of the Zio AT monitor, which received 510(k) clearance in June 2017.Pervasive and Continuing RegulationAfter a device is placed on the market, numerous regulatory requirements continue to apply. These include: •the FDA’s QSR, which requires manufacturers, including their suppliers, to follow stringent design, testing, control, documentation and otherquality assurance procedures during all aspects of the manufacturing process •labeling regulations and FDA prohibitions against the promotion of products for un-cleared, unapproved or off-label uses •medical device reporting, or MDR, regulations, which require that manufacturers report to the FDA if their device may have caused orcontributed to a death or serious injury or malfunctioned in a way that would likely cause or contribute to a death or serious injury if themalfunction were to recur •medical device recalls, which require that manufacturers report to the FDA any recall of a medical device, provided the recall was initiated toeither reduce a risk to health posed by the device, or to remedy a violation of the FD&C Act caused by the device that may present a risk tohealth •post-market surveillance regulations, which apply when necessary to protect the public health or to provide additional safety andeffectiveness data for the deviceAfter a device receives 510(k) clearance or PMA approval, any modification that could significantly affect its safety or effectiveness, or that wouldconstitute a major change in its intended use, will require a new clearance or approval. The FDA requires each manufacturer to make this determinationinitially, but the FDA can review any such decision and can disagree with a manufacturer’s determination. If the FDA disagrees with the determination not toseek a new 510(k) clearance or PMA, the FDA may retroactively require a new 510(k) clearance or premarket approval. The FDA could also require amanufacturer to cease marketing and distribution and/or recall the modified device until 510(k) clearance or premarket approval is obtained. Also, in thesecircumstances, the manufacturer may be subject to significant regulatory fines, penalties, and warning letters.We have registered with the FDA as a medical device manufacturer and have obtained a manufacturing license from the California Department ofPublic Health, or CDPH. The FDA and CDPH have broad post-market and regulatory enforcement powers. We are subject to unannounced inspections by theFDA and the Food and Drug Branch of CDPH to determine our compliance with the QSR and other regulations, and these inspections may include themanufacturing facilities of our suppliers. Additionally, NSAI regularly inspects our manufacturing, design and operational facilities to ensure ongoing ISO13485 compliance in order to maintain our CE mark.22 Failure to comply with applicable regulatory requirements can result in enforcement action by the FDA, which may include any of the followingsanctions: •warning letters, fines, injunctions, consent decrees and civil penalties •repair, replacement, refunds, recall or seizure of our products •operating restrictions, partial suspension or total shutdown of production •refusing our requests for 510(k) clearance or premarket approval of new products, new intended uses or modifications to existing products •withdrawing 510(k) clearance or premarket approvals that have already been granted •criminal prosecutionEuropean UnionThe Zio XT monitor is regulated in the European Union as a medical device per the European Union Directive 93/42/EEC, also known as theMedical Device Directive. The MDD sets out the basic regulatory framework for medical devices in the European Union. The system of regulating medicaldevices operates by way of a certification for each medical device. Each certified device is marked with the CE mark which shows that the device has aCertificat de Conformité. There are national bodies known as Competent Authorities in each member state which oversee the implementation of the MDDwithin their jurisdiction. The means for achieving the requirements for the CE mark vary according to the nature of the device. Devices are classified inaccordance with their perceived risks, similarly to the U.S. system. The class of a product determines the conformity assessment required before the CE markcan be placed on a product. Conformity assessments for our products are carried out as required by the MDD. Each member state can appoint Notified Bodieswithin its jurisdiction. If a Notified Body of one member state has issued a Certificat de Conformité, the device can be sold throughout the European Unionwithout further conformance tests being required in other member states. The CE mark is contingent upon continued compliance with the applicableregulations and the quality system requirements of the ISO 13485 standard. Our current CE mark is issued by the National Standards Authority of Ireland, orNSAI.Health Insurance Portability and Accountability ActThe Health Insurance Portability and Accountability Act of 1996, or HIPAA, established comprehensive federal protection for the privacy andsecurity of health information. Under HIPAA, the Department of Health and Human Services, or HHS, has issued regulations to protect the privacy andsecurity of protected health information used or disclosed by Covered Entities, including healthcare providers, such as us. HIPAA also regulatesstandardization of data content, codes and formats used in healthcare transactions and standardization of identifiers for health plans and providers. Theprivacy regulations protect medical records and other protected health information by limiting their use and release, giving patients the right to access theirmedical records and limiting most disclosures of health information to the minimum amount necessary to accomplish an intended purpose. The HIPAAsecurity standards require the adoption of administrative, physical, and technical safeguards and the adoption of written security policies and procedures.HIPAA requires Covered Entities to execute Business Associate Agreements with individuals and organizations, or Business Associates, who provide servicesto Covered Entities and who need access to protected health information. We are a Covered Entity under HIPAA and subject to HIPAA regulations.In 2009, Congress enacted Subtitle D of the Health Information Technology for Economic and Clinical Health Act, or HITECH. HITECH amendsHIPAA and, among other things, creates new targets for enforcement, imposes new penalties for noncompliance and establishes new breach notificationrequirements for Covered Entities and Business Associates.23 Under HITECH’s breach notification requirements, Covered Entities must report breaches of protected health information that has not been encryptedor otherwise secured in accordance with guidance from HHS. Required breach notices must be made as soon as is reasonably practicable, but no later than 60days following discovery of the breach. Reports must be made to affected individuals and to HHS, and in some cases they must be reported through local andnational media, depending on the size of the breach. We are subject to audit under HHS’s HITECH-mandated audit program. We may also be audited inconnection with a privacy complaint. We are subject to prosecution and/or administrative enforcement and increased civil and criminal penalties for non-compliance, including a new, four-tiered system of monetary penalties adopted under HITECH. We are also subject to enforcement by state attorneys generalwho were given authority to enforce HIPAA under HITECH. To avoid penalties under the HITECH breach notification provisions, we must ensure thatbreaches of protected health information are promptly detected and reported within the company, so that we can make all required notifications on a timelybasis. However, even if we make required reports on a timely basis, we may still be subject to penalties for the underlying breach.In addition to the federal privacy regulations, there are a number of state laws regarding the privacy and security of health information and personaldata that apply to us. The compliance requirements of these laws, including additional breach reporting requirements, and the penalties for violation varywidely, and new privacy and security laws in this area are evolving. Requirements of these laws and penalties for violations vary widely.If we or our operations are found to be in violation of HIPAA, HITECH, or their implementing regulations, we may be subject to penalties, includingcivil and criminal penalties, fines, and exclusion from participation in federal or state healthcare programs, and the curtailment or restructuring of ouroperations. HITECH increased the civil and criminal penalties that may be imposed against Covered Entities, their Business Associates and possibly otherpersons, and gave state attorneys general new authority to file civil actions for damages or injunctions in federal courts to enforce the federal HIPAA laws andseek attorney’s fees and costs associated with pursuing federal civil actions.Federal, State and Foreign Fraud and Abuse LawsBecause of the significant federal funding involved in CMS programs such as Medicare and Medicaid, Congress and the states have enacted, andactively enforce, a number of laws to eliminate fraud and abuse in federal healthcare programs. Our business is subject to compliance with these laws. InMarch 2010, the Patient Protection and Affordable Care Act, as amended by the Healthcare and Education Affordability Reconciliation Act, which we refer tocollectively as the Affordable Care Act, was enacted in the United States. The Affordable Care Act expands the government’s investigative and enforcementauthority and increases the penalties for fraud and abuse, including amendments to both the Anti-Kickback Statute and the False Claims Act, to make it easierto bring suit under these statutes. The Affordable Care Act also allocates additional resources and tools for the government to police healthcare fraud, withexpanded subpoena power for HHS, additional funding to investigate fraud and abuse across the healthcare system and expanded use of recovery auditcontractors for enforcement.Anti-Kickback StatuteThe federal Anti-Kickback Statute prohibits persons from knowingly and willfully soliciting, offering, receiving or providing remuneration, directlyor indirectly, in exchange for or to induce either the referral of an individual, or the furnishing or arranging for a good or service, for which payment may bemade under a federal healthcare program, such as Medicare or Medicaid.The definition of “remuneration” has been broadly interpreted to include anything of value, including, for example, gifts, certain discounts, thefurnishing of free supplies, equipment or services, credit arrangements, payment of cash and waivers of payments. Several courts have interpreted the statute’sintent requirement to mean that if any one purpose of an arrangement involving remuneration is to induce referrals of federal healthcare covered businesses,the statute has been violated. Penalties for violations include criminal penalties and civil sanctions such as fines, imprisonment and possible exclusion fromMedicare, Medicaid and other federal healthcare programs. In addition, some kickback allegations have been claimed to violate the federal False Claims Act.24 The Anti-Kickback Statute is broad and prohibits many arrangements and practices that are otherwise lawful in businesses outside of the healthcareindustry. Recognizing that the Anti- Kickback Statute is broad and may technically prohibit many innocuous or beneficial arrangements, Congressauthorized the Office of Inspector General (OIG) of the HHS to issue a series of regulations known as “safe harbors.” These safe harbors set forth provisionsthat, if all their applicable requirements are met, will assure healthcare providers and other parties that they will not be prosecuted under the Anti-KickbackStatute. The failure of a transaction or arrangement to fit precisely within one or more safe harbors does not necessarily mean that it is illegal or thatprosecution will be pursued. However, conduct and business arrangements that do not fully satisfy an applicable safe harbor may result in increased scrutinyby government enforcement authorities such as OIG.Many states have adopted laws similar to the Anti-Kickback Statute. Some of these state prohibitions apply to referral of recipients for healthcareproducts or services reimbursed by any source, not only CMS programs.Government officials have focused their enforcement efforts on the marketing of healthcare services and products, among other activities, andrecently have brought cases against companies, and certain individual sales, marketing and executive personnel, for allegedly offering unlawful inducementsto potential or existing customers in an attempt to procure their business.Federal False Claims ActAnother development affecting the healthcare industry is the increased use of the federal False Claims Act, or FCA, and in particular, action broughtpursuant to the FCA’s “whistleblower” or “ qui tam ” provisions. The FCA imposes liability on any person or entity that, among other things, knowinglypresents, or causes to be presented, a false or fraudulent claim for payment by a federal healthcare program. The qui tam provisions of the FCA allow a privateindividual to bring actions on behalf of the federal government alleging that the defendant has violated the FCA and to share in any monetary recovery. As aresult, in recent years, the number of suits brought against healthcare providers by private individuals has increased dramatically. In addition, various stateshave enacted false claims laws analogous to the FCA, and many of these state laws apply where a claim is submitted to any third-party payor and not only afederal healthcare program.When an entity is determined to have violated the FCA, it may be required to pay up to three times the actual damages sustained by the government,plus civil penalties of between approximately $11,000 and $22,000 for each separate instance of false claim. As part of any settlement, the government willusually require the entity to enter into a corporate integrity agreement, which imposes certain compliance, certification and reporting obligations. There aremany potential bases for liability under the FCA. Liability arises, primarily, when an entity knowingly submits, or causes another to submit, a false claim forreimbursement to the federal government. The federal government has used the FCA to assert liability on the basis of inadequate care, kickbacks and otherimproper referrals, and improper use of CMS billing numbers, in addition to the more predictable allegations of misrepresentations with respect to theservices rendered. In addition, the federal government has prosecuted companies under the FCA in connection with off-label promotion of products.Activities relating to the reporting of discount and rebate information and other information affecting federal, state and third-party reimbursement of ourproducts and services and the sale and marketing of our products and services may be subject to scrutiny under these laws.While we are unaware of any current matters, we are unable to predict whether we will be subject to actions under the FCA or a similar state law, orthe impact of such actions. However, the costs of defending such claims, as well as any sanctions imposed, could significantly affect our financialperformance.Open PaymentsThe Physician Payment Sunshine Act, known as “Open Payments” and enacted as part of the Affordable Care Act, requires all pharmaceutical andmedical device manufacturers of products covered by Medicare, Medicaid or the Children’s Health Insurance Program to report annually to HHS:(i) payments and transfers of value to teaching hospitals and licensed physicians, (ii) physician ownership in the manufacturer, and (iii) research payments.The payments required to be reported include the cost of meals provided to a physician, travel reimbursements and other transfers of value, including thoseprovided as part of contracted services such as speaker programs, advisory25 boards, consultation services and clinical trial services. The statute requires the federal government to make reported information available to the public.Failure to comply with the reporting requirements can result in significant civil monetary penalties ranging from $1,000 to $10,000 for each payment or othertransfer of value that is not reported (up to a maximum per annual report of $150,000) and from $10,000 to $100,000 for each knowing failure to report (up toa maximum per annual report of $1.0 million). Additionally, there are criminal penalties if an entity intentionally makes false statements in such reports. Weare subject to Open Payments and the information we disclose may lead to greater scrutiny, which may result in modifications to established practices andadditional costs. Additionally, similar reporting requirements have also been enacted on the state level domestically, and an increasing number of countriesworldwide either have adopted or are considering similar laws requiring transparency of interactions with healthcare professionals.Foreign Corrupt Practices ActThe Foreign Corrupt Practices Act, or FCPA, prohibits any U.S. individual or business from paying, offering, or authorizing payment or offering ofanything of value, directly or indirectly, to any foreign official, political party or candidate for the purpose of influencing any act or decision of the foreignentity in order to assist the individual or business in obtaining or retaining business. The FCPA also obligates companies whose securities are listed in theUnited States to comply with accounting provisions requiring us to maintain books and records that accurately and fairly reflect all transactions of thecorporation, including international subsidiaries, if any, and to devise and maintain an adequate system of internal accounting controls for internationaloperations.International LawsIn Europe, various countries have adopted anti-bribery laws providing for severe consequences in the form of criminal penalties and significant finesfor individuals or companies committing a bribery offense. Violations of these anti-bribery laws, or allegations of such violations, could have a negativeimpact on our business, results of operations and reputation.For instance, in the United Kingdom, under the U.K. Bribery Act 2010, a bribery occurs when a person offers, gives or promises to give a financial orother advantage to induce or reward another individual to improperly perform certain functions or activities, including any function of a public nature.Bribery of foreign public officials also falls within the scope of the U.K. Bribery Act 2010. An individual found in violation of the U.K. Bribery Act 2010,faces imprisonment of up to 10 years. In addition, the individual can be subject to an unlimited fine, as can commercial organizations for failure to preventbribery.There are also international privacy laws that impose restrictions on the access, use, and disclosure of health information. All of these laws mayimpact our business. Our failure to comply with these privacy laws or significant changes in the laws restricting our ability to obtain required patientinformation could significantly impact our business and our future business plans.U.S. Centers for Medicare and Medicaid Services (CMS)Medicare is a federal program administered by CMS through fiscal intermediaries and carriers. Available to individuals age 65 or over, and certainother individuals, the Medicare program provides, among other things, healthcare benefits that cover, within prescribed limits, the major costs of mostmedically necessary care for such individuals, subject to certain deductibles and copayments.CMS has established guidelines for the coverage and reimbursement of certain products, supplies and services. In general, in order to be reimbursedby Medicare, a healthcare product or service furnished to a Medicare beneficiary must be reasonable and necessary for the diagnosis or treatment of an illnessor injury, or to improve the functioning of a malformed body part. The methodology for determining coverage status and the amount of Medicarereimbursement varies based upon, among other factors, the setting in which a Medicare beneficiary received healthcare products and services. Any changes infederal legislation, regulations and policy affecting Medicare coverage and reimbursement relative to our Zio service could have a material effect on ourperformance.26 CMS also administers the Medicaid program, a cooperative federal/state program that provides medical assistance benefits to qualifying low incomeand medically needy persons. State participation in Medicaid is optional, and each state is given discretion in developing and administering its ownMedicaid program, subject to certain federal requirements pertaining to payment levels, eligibility criteria and minimum categories of services. The coverage,method and level of reimbursement varies from state to state and is subject to each state’s budget restraints. Changes to the coverage, method or level ofreimbursement for our Zio service may affect future revenue negatively if reimbursement amounts are decreased or discontinued.All CMS programs are subject to statutory and regulatory changes, retroactive and prospective rate adjustments, administrative rulings,interpretations of policy, intermediary determinations, and government funding restrictions, all of which may materially increase or decrease the rate ofprogram payments to healthcare facilities and other healthcare providers, including those paid for our Zio service.Our facilities in Illinois, California and Texas are enrolled as independent diagnostic testing facilities, or IDTFs, defined by CMS as entitiesindependent of a hospital or physician’s office in which diagnostic tests are performed by licensed or certified non-physician personnel under appropriatephysician supervision. CMS has set certain performance standards that every IDTF must meet in order to obtain or maintain its billing privileges.United States Healthcare ReformChanges in healthcare policy could increase our costs and subject us to additional regulatory requirements that may interrupt commercialization ofour current and future solutions. Changes in healthcare policy could increase our costs, decrease our revenue and impact sales of and reimbursement for ourcurrent and future products and services. The Affordable Care Act (“ACA”) substantially changes the way healthcare is financed by both governmental andprivate insurers, and significantly impacts our industry. The ACA contains a number of provisions that impact our business and operations, some of which inways we cannot currently predict, including those governing enrollment in federal healthcare programs and reimbursement changes.The current presidential administration and Congress are expected to attempt to make sweeping changes to the current health care laws. It isuncertain how modification or repeal of any of the provisions of the ACA, including as a result of current and future executive orders and legislative actions,will impact us and the medical device industry as a whole. Any changes to, or repeal of, the ACA may have a material adverse effect on our results ofoperations. We cannot predict what other health care programs and regulations will ultimately be implemented at the federal or state level or the effect of anyfuture legislation or regulation in the United States may have on our business.EmployeesAs of December 31, 2017, we had 575 full-time employees. None of our employees is represented by a labor union or is a party to a collectivebargaining agreement, and we believe that our employee relations are good.Corporate and Other InformationWe were incorporated in Delaware on September 14, 2006. Our principal executive offices are located at650 Townsend Street, Suite 500, San Francisco, CA 94103, and our telephone number is (415) 632-5700. Our website address is www.iRhythmTech.com.References to our website address do not constitute incorporation by reference of the information contained on the website, and the information containedon, or accessible through, our website is not part of this document.27 We make available, free of charge on our corporate website, copies of our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, CurrentReports on Form 8-K, Proxy Statements, and all amendments to these reports, as soon as reasonably practicable after such material is electronically filed withor furnished to the Securities and Exchange Commission pursuant to Section 13(a) or 15(d) of the Securities Exchange Act. We also show detail about stocktrading by corporate insiders by providing access to SEC Forms 3, 4 and 5. This information may also be obtained from the SEC's on-line database, which islocated at www.sec.gov. Our common stock is traded on the NASDAQ Stock Market under the symbol “IRTC.”Item 1A. Risk Factors.Investing in our common stock involves a high degree of risk. You should carefully consider the risks and uncertainties described below, togetherwith all of the other information contained in this Annual Report on Form 10-K, including our financial statements and the related notes thereto, beforemaking a decision to invest in our common stock. The realization of any of the following risks could materially and adversely affect our business, financialcondition, operating results and prospects. In that event, the price of our common stock could decline, and you could lose part or all of your investment.Risks Related to Our BusinessWe have a history of net losses, which we expect to continue, and we may not be able to achieve or sustain profitability in the future.We have incurred net losses since our inception in September 2006. For the years ended December 31, 2017 and 2016 we had a net loss of $29.4million and $20.9 million, respectively, and we expect to continue to incur additional losses. As of December 31, 2017, we had an accumulated deficit of$156.6 million. The losses and accumulated deficit were primarily due to the substantial investments we made to develop and improve our technology andproducts and improve our business and the Zio service through research and development efforts and infrastructure improvements. Over the next severalyears, we expect to continue to devote substantially all of our resources to increase adoption of and reimbursement for our Zio service and to developadditional arrhythmic detection and management products and services. These efforts may prove more expensive than we currently anticipate and we maynot succeed in increasing our revenue sufficiently to offset these higher expenses or at all. In addition, as a public company, we will continue to incursignificant legal, accounting and other expenses that we did not incur as a private company. Accordingly, we cannot assure you that we will achieveprofitability in the future or that, if we do become profitable, we will sustain profitability. Our failure to achieve and sustain profitability in the future couldcause the market price of our common stock to decline.Our business is dependent upon physicians adopting our Zio service and if we fail to obtain broad adoption, our business would be adversely affected.Our success will depend on our ability to educate physicians regarding the benefits of our Zio service over existing products and services, such asHolter monitors and event monitors, and to persuade them to prescribe the Zio service as a first-line diagnostic product for their patients. We do not know ifthe Zio service will be successful over the long term and market acceptance may be hindered if physicians are not presented with compelling datademonstrating the efficacy of our service compared to alternative technologies. Any studies we, or third parties which we sponsor, may conduct comparingour Zio service with alternative technologies will be expensive, time consuming and may not yield positive results. Additionally, adoption will be directlyinfluenced by a number of financial factors, including the ability of providers to obtain sufficient reimbursement from third-party commercial payors, and theCenters for Medicare & Medicaid Services, or CMS, for the professional services they provide in applying the Zio XT monitor and analyzing the Zio Report.The efficacy, safety, performance and cost-effectiveness of our Zio service, on a stand-alone basis and relative to competing services, will determine theavailability and level of reimbursement received by us and providers. Some payors do not have pricing contracts with us setting forth the Zio servicereimbursement rates for us and providers. Physicians may be reluctant to prescribe the Zio service to patients covered by such non-contracted insurancepolicies because of the uncertainty surrounding reimbursement rates and the administrative burden of interfacing with patients to answer their questions andsupport their efforts to obtain adequate reimbursement for the Zio service. If physicians do not adopt and prescribe our Zio service, our revenue will notincrease and our financial condition will suffer as a result.28 Our revenue relies substantially on the Zio service, which is currently our only product offering. If the Zio XT or Zio AT service or future product offeringsfail to gain, or lose, market acceptance, our business will suffer.Our current revenue is dependent on prescriptions of the Zio service, and we expect that sales of the Zio service will account for substantially all ofour revenue through at least 2018. We are in various stages of research and development for other diagnostic solutions and new indications for ourtechnology and the Zio service; however, there can be no assurance that we will be able to successfully develop and commercialize any new products orservices. Any new products may not be accepted by physicians or may merely replace revenue generated by our Zio service and not generate additionalrevenue. If we have difficulty launching new products, our reputation may be harmed and our financial results adversely affected. In order to substantiallyincrease our revenue, we will need to target physicians other than cardiologists, such as emergency room doctors, primary care physicians and otherphysicians with whom we have had little contact and may require a different type of selling effort. If we are unable to increase prescriptions of the Zio service,expand reimbursement for the Zio service, or successfully develop and commercialize new products and services, our revenue and our ability to achieve andsustain profitability would be impaired.Our limited operating history makes it difficult to evaluate our current business and future prospectsWe first commercialized the Zio XT service in the first quarter of 2011 and do not have a long history operating as a commercial company. As aresult, our operating results are not predictable. Since 2011, our revenue has been derived, and we expect it to continue to be derived, substantially from salesof the Zio service and its predecessor products. Because of its recent commercial introduction, the Zio service has limited product and brand recognition. Inaddition, demand for our services may decline or may not increase as quickly as we expect. Failure of the Zio service to significantly penetrate current or newmarkets would harm our business, financial condition and results of operations.Our quarterly and annual results may fluctuate significantly and may not fully reflect the underlying performance of our business.Our quarterly and annual results of operations, including our revenue, profitability and cash flow, may vary significantly in the future and period-to-period comparisons of our operating results may not be meaningful. Accordingly, the results of any one quarter or period should not be relied upon as anindication of future performance. Our quarterly and annual financial results may fluctuate as a result of a variety of factors, many of which are outside ourcontrol and, as a result, may not fully reflect the underlying performance of our business. Fluctuation in quarterly and annual results may decrease the valueof our common stock. Factors that may cause fluctuations in our quarterly and annual results include, without limitation: •market acceptance of the Zio service •our ability to get payors under contract at acceptable reimbursement rates •the availability of reimbursement for the Zio service through government programs •our ability to attract new customers and improve our business with existing customers •results of our clinical trials and publication of studies by us, competitors or third parties •the timing and success of new product introductions by us or our competitors or any other change in the competitive dynamics of ourindustry, including consolidation among competitors, customers or strategic partners •our revenue recognition policy, which generally provides that we recognize revenue only upon the earlier of notification of payment or whenpayment is received •the amount and timing of costs and expenses related to the maintenance and expansion of our business and operations •changes in our pricing policies or those of our competitors •general economic, industry and market conditions29 •the regulatory environment •expenses associated with unforeseen product quality issues •timing of physician prescriptions and demand for our Zio service •seasonality factors, such as patient and physician vacation schedules, severe weather conditions and insurance deductibles, that hamper orotherwise restrict when a patient seeking diagnostic services such as the Zio service visits the prescribing physician •the hiring, training and retention of key employees, including our ability to expand our sales team •litigation or other claims against us for intellectual property infringement or otherwise •our ability to obtain additional financing as necessary •advances and trends in new technologies and industry standardsBecause our quarterly results may fluctuate, period-to-period comparisons may not be the best indication of the underlying results of our businessand should only be relied upon as one factor in determining how our business is performing.We have noticed seasonality in the use of our Zio service which, along with other factors such as severe weather, may cause quarterly fluctuations in ourrevenue.During the summer months and the holiday season, we have observed that the use of our Zio service decreases, which reduces our revenue duringthose periods. We believe that the decrease in demand may result from physicians or their patients taking vacations. Severe weather conditions or naturaldisasters also may hamper or otherwise restrict when patients seeking diagnostic services such as the Zio service visit prescribing physicians. Similarly, wegenerally experience some effects of seasonality due to the renewal of insurance deductibles at the beginning of the calendar year. These factors may causeour results of operations to vary from quarter to quarter.Reimbursement by CMS is highly regulated and subject to change; our failure to comply with applicable regulations could result in decreased revenue andmay subject us to penalties or have an adverse impact on our business.For the year ended December 31, 2017, we received approximately 28% of our revenue from reimbursement for our Zio service by CMS. CMSimposes extensive and detailed requirements on manufacturers of medical devices and providers of medical services, including but not limited to, rules thatgovern how we structure our relationships with physicians, how and when we submit reimbursement claims, how we operate our monitoring facilities andhow and where we provide our monitoring solutions. Our failure to comply with applicable CMS rules could result in a discontinuation of our reimbursementunder the CMS payment programs, our being required to return funds already paid to us, civil monetary penalties, criminal penalties and/or exclusion fromthe CMS programs. In addition, regional Medicare Administrative Contractors, or MACs, change from time to time, which may result in changes to ourreimbursement rates, increased administrative burden and reimbursement delay.Changes in public health insurance coverage and CMS reimbursement rates for the Zio service could affect the adoption of the Zio service and our futurerevenue.Government payors may change their coverage and reimbursement policies, as well as payment amounts, in a way that would prevent or limitreimbursement for our Zio service, which would significantly harm our business. For example, government and other third-party payors require us to identifythe service for which we are seeking reimbursement by using a Current Procedural Terminology, or CPT, code set maintained by the American MedicalAssociation. We have secured CPT codes specific to our category of diagnostic monitoring through 2022, but these codes are not exclusive to the Zio serviceand our competitors’ products and services may also qualify for reimbursement under these codes. To the extent one of our competitors or a future competitorproduces a product or service at a less expensive price, it may cause the reimbursement under these CPT codes to decrease. In addition, third-party payorsoften reimburse based on CMS reimbursement rates. To the extent CMS reduces its30 reimbursement rates for the Zio service, third-party payors may reduce the rates at which they reimburse the Zio service, which could adversely affect ourrevenue.Determinations of which products or services will be reimbursed under Medicare can be developed at the national level through a national coveragedetermination, or an NCD, by CMS, or at the local level through a local coverage determination, or an LCD, by one or more of the regional MedicareAdministrative Contractors, or MACs, which are private contractors that process and pay claims on behalf of CMS for different regions. In the absence of anNCD, as is the case with the Zio service, the MAC with jurisdiction over a specific geographic region will have the discretion to make an LCD and determinethe fee schedule and reimbursement rate within the region, and regional LCDs may not always be consistent in their determinations. We have in the pastbeen, and in the future may be, required to respond to potential changes in reimbursement rates for our products. Reductions in reimbursement rates, ifenacted, could have a material adverse effect on our business. Further, a reduction in coverage by Medicare could cause some commercial third-party payersto implement similar reductions in their coverage or level of reimbursement of the Zio service. Given the evolving nature of the healthcare industry and on-going healthcare cost reforms, we are and will continue to be subject to changes in the level of Medicare coverage for our products, and unfavorable coveragedeterminations at the national or local level could adversely affect our business and results of operations.Controls imposed by CMS and commercial third-party payors designed to reduce costs, commonly referred to as “utilization review”, may affect ouroperations. Federal law contains numerous provisions designed to ensure that services rendered to CMS patients meet professionally recognized standardsand are medically necessary, appropriate for the specific patient and cost-effective. These provisions include a requirement that a sampling of CMS patientsmust be reviewed by quality improvement organizations, which review the appropriateness of product prescriptions, the quality of care provided, and theappropriateness of reimbursement costs. Quality improvement organizations may deny payment for services or assess fines and also have the authority torecommend to the U.S. Department of Health and Human Services, or DHHS, that a provider which is in substantial noncompliance with the standards of thequality improvement organization be excluded from participation in the Medicare program. The Patient Protection and Affordable Care Act, as amended bythe Health Care and Education Affordability Reconciliation Act, or Affordable Care Act, potentially expands the use of prepayment review by Medicarecontractors by eliminating statutory restrictions on their use, and, as a result, efforts to impose more stringent cost controls are expected to continue.Utilization review is also a requirement of most non-governmental managed care organizations and other third-party payors. To date these controls have nothad a significant effect on our operations, but significant limits on the scope of services reimbursed and on reimbursement rates and fees could have amaterial, adverse effect on our business, financial position and results of operations in the future.Also, healthcare reform legislation or regulation may be proposed or enacted in the future that may adversely affect such policies and amounts.Changes in the healthcare industry directed at controlling healthcare costs or perceived over-utilization of ambulatory cardiac monitoring products andservices could reduce the volume of Zio services prescribed by physicians. If more healthcare cost controls are broadly instituted throughout the healthcareindustry, the volume of cardiac monitoring solutions prescribed could decrease, resulting in pricing pressure and declining demand for our Zio service. Wecannot predict whether and to what extent existing coverage and reimbursement will continue to be available. If physicians, hospitals and clinics are unableto obtain adequate coverage and government reimbursement of the Zio service, they are significantly less likely to use the Zio service and our business andoperating results would be harmed.The current presidential administration and Congress may attempt to make sweeping changes to the current health care laws and their implementingregulations. It is uncertain how modification or repeal of any of the provisions of the ACA or its implementing regulations, including as a result of currentand future executive orders and legislative actions, will impact us and the medical device industry as a whole. Any changes to, or repeal of, the ACA or itsimplementing regulations may have a material adverse effect on our results of operations. We cannot predict what other health care programs and regulationswill ultimately be implemented at the federal or state level or the effect of any future legislation or regulation in the United States may have on our business.31 If third-party commercial payors do not provide any or adequate reimbursement, rescind or modify their reimbursement policies or delay payments for ourproducts, including the Zio service, or if we are unable to successfully negotiate reimbursement contracts, our commercial success could be compromised.We receive a substantial portion of our revenue from third-party private commercial payors, such as medical insurance companies. These commercialpayors may reimburse our products, including the Zio service, at inadequate rates, suspend or discontinue reimbursement at any time or require or increaseco-payments from patients. Any such actions could have a negative effect on our revenue and the revenue of providers prescribing our products. Physiciansmay not prescribe our products unless payors reimburse a substantial portion of the submitted costs, including the physician’s, hospital’s or clinic’s chargesrelated to the application of certain products, including the Zio XT monitor and the interpretation of results which may inform a diagnosis. Additionally,certain payors may require that physicians prescribe a Holter monitor as the first-line monitoring option. There is significant uncertainty concerning third-party reimbursement of any new product or service until a contracted rate is established. Reimbursement by a commercial payor may depend on a number offactors, including a payor’s determination that the prescribed service is: •not experimental or investigational •appropriate for the specific patient •cost effective •supported by peer-reviewed publications •advocated by key opinion leadersSince each payor makes its own decision as to whether to establish a policy concerning reimbursement or enter into a contract with us to set the priceof reimbursement, seeking reimbursement on a payor-by-payor basis is a time consuming and costly process to which we dedicate substantial resources. If wedo not dedicate sufficient resources to establishing contracts with third-party commercial payors, the amount that we are reimbursed for our products maydecline, our revenue may become less predictable, and we will need to expend more efforts on a claim-by-claim basis to obtain reimbursement for ourproducts.A substantial portion of our revenue is derived from third-party commercial payors who have pricing contracts with us, which means that the payorhas agreed to a defined reimbursement rate for our products. These contracts provide a high degree of certainty to us, physicians and hospitals and clinicswith respect to the rate at which our products will be reimbursed. These contracts also impose a number of obligations regarding billing and other matters,and our noncompliance with a material term of such contracts may result in termination of the contract and loss of any associated revenue. A portion of ourrevenue is derived from third-party commercial payors without such contracts in place. Without a contracted rate, reimbursement claims for our products areoften denied upon submission, and we or our billing partner, XIFIN, Inc., or XIFIN, must appeal the denial. The appeals process is time-consuming andexpensive, and may not result in full or any payment. In cases where there is no contracted rate for reimbursement, it may be more difficult for us to acquirenew accounts with physicians, hospitals and clinics. In addition, in the absence of a contracted rate, there is typically a greater out-of-network, co-insuranceor co-payment requirement which may result in payment delays or decreased likelihood of full collection. In some cases involving non-contracted insurancecompanies, we may not be able to collect any amount or only a portion of the invoiced amount for our products.32 We expect to continue to dedicate significant resources to establishing pricing contracts with non-contracted insurance companies; however, we canprovide no assurance that we will be successful in obtaining such pricing contracts or that such pricing contracts will contain reimbursement for our productsat rates that are favorable to us. If we fail to establish these contracts, we will be able to recognize revenue only upon the earlier of notification of payorbenefits allowed or when payment is received. In addition, XIFIN may need to expend significant resources obtaining reimbursement on a claim-by-claimbasis and in adjudicating claims which are denied altogether or not reimbursed at acceptable rates. We currently pay XIFIN a percentage of the amounts itcollects on our behalf and this percentage may increase in the future if it needs to expend more resources in adjudicating such claims. We sometimesinformally engage physicians, hospitals and clinics to help establish contracts with third-party payors who insure their patients. We cannot provide anyassurance that such physicians, hospitals and clinics will continue to help us establish contracts in the future. If we fail to establish contracts with more third-party payors it may adversely affect our ability to increase our revenue. In addition, a failure to enter into contracts could affect a physician’s willingness toprescribe our products because of the administrative work involved in interacting with patients to answer their questions and help them obtain reimbursementfor our products. If physicians are unwilling to prescribe our products due to the lack of certainty and administrative work involved with patients covered bynon-contracted insurance companies, or patients covered by non-contracted insurance companies are unwilling to risk that their insurance may chargeadditional out-of-pocket fees, our revenue could decline or fail to increase.Our continued rapid growth could strain our personnel resources and infrastructure, and if we are unable to manage the anticipated growth of ourbusiness, our future revenue and operating results may be harmed.We have experienced rapid growth in our headcount and in our operations. Any growth that we experience in the future will provide challenges toour organization, requiring us to expand our sales personnel and manufacturing operations and general and administrative infrastructure. In addition to theneed to scale our clinical operations capacity, future growth will impose significant added responsibilities on management, including the need to identify,recruit, train and integrate additional employees. Rapid expansion in personnel could mean that less experienced people manufacture our Zio XT and Zio ATmonitors, market and sell our Zio service and analyze the data to produce Zio Reports, which could result in inefficiencies and unanticipated costs, reducedquality in our Zio Reports and disruptions to our operations. As we seek to gain greater efficiency, we may expand the automated portion of our Zio serviceand require productivity improvements from our certified cardiac technicians. Such improvements could compromise the quality of our Zio Reports. Inaddition, rapid and significant growth may strain our administrative and operational infrastructure. Our ability to manage our business and growth willrequire us to continue to improve our operational, financial and management controls, reporting systems and procedures. If we are unable to manage ourgrowth effectively, it may be difficult for us to execute our business strategy and our business could be harmed.If we are unable to support demand for the Zio XT and Zio AT services or any of our future products or services, our business could suffer.As demand for the Zio XT and Zio AT services or any of our future products or services increases, we will need to continue to scale our manufacturingcapacity and algorithm processing technology, expand customer service, billing and systems processes and enhance our internal quality assurance program.We will also need additional certified cardiac technicians and other personnel to process higher volumes of data. We cannot assure you that any increases inscale, related improvements and quality assurance will be successfully implemented or that appropriate personnel will be available to facilitate growth of ourbusiness. Failure to implement necessary procedures, transition to new processes or hire the necessary personnel could result in higher costs of processingdata or inability to meet increased demand. There can be no assurance that we will be able to perform our data analysis on a timely basis at a level consistentwith demand, quality standards and physician expectations. If we encounter difficulty meeting market demand, quality standards or physician expectations,our reputation could be harmed and our future prospects and business could suffer.33 We plan to introduce new products and services and our business will be harmed if we are not successful in selling these new products and services to ourexisting customers and new customersWe recently received FDA clearance for our Zio AT ECG Monitoring System, which is designed to provide timely transmission of data during thewear period. We refer to both the Zio AT ECG Monitoring System, or the Zio AT monitor, and the Zio XT monitor herein as our Zio monitors, unlessotherwise specified. We do not yet know whether Zio AT or any other new products and services will be well received and broadly adopted by physicians andtheir patients or whether sales will be sufficient for us to offset the costs of development, implementation, support, operation, sales and marketing. Althoughwe have performed extensive testing of our new products and services, their broad-based implementation may require more support than we anticipate, whichwould further increase our expenses. Additionally, new products and services may subject us to additional risks of product performance, customer complaintsand litigation. If sales of our new products and services are lower than we expect, or if we expend additional resources to fix unforeseen problems and developmodifications, our operating margins are likely to decrease.If we are unable to keep up with demand for the Zio XT and Zio AT services, our revenue could be impaired, market acceptance for the Zio XT and Zio ATservices could be harmed and physicians may instead prescribe our competitors’ products and services.As demand for the Zio XT and Zio AT service increases, we may encounter production or service delays or shortfalls. Such production or servicedelays or shortfalls may be caused by many factors, including the following: •we intend to continue to expand our manufacturing capacity, and our production processes may have to change to accommodate this growth •key components of the Zio monitors are provided by a single supplier or limited number of suppliers, and we do not maintain large inventorylevels of these components; if we experience a shortage or quality issues in any of these components, we would need to identify and qualifynew supply sources, which could increase our expenses and result in manufacturing delays •we may experience a delay in completing validation and verification testing for new production processes and/or equipment at ourmanufacturing facilities •we are subject to state, federal and international regulations, including the FDA’s Quality System Regulation, or the QSR, for both themanufacture of the Zio monitor and the provision of the Zio service, noncompliance with which could cause an interruption in ourmanufacturing and services •to increase our manufacturing output significantly and scale our services, we will have to attract and retain qualified employees for ouroperationsOur inability to successfully manufacture our Zio monitors in sufficient quantities, or provide the Zio service in a timely manner, would materiallyharm our business.Our manufacturing facilities and processes and those of our third-party suppliers are subject to unannounced FDA, state and Notified Body regulatoryinspections for compliance with the QSR and MDD requirements. Developing and maintaining a compliant quality system is time consuming and expensive.Failure to maintain compliance with, or not fully complying with the requirements of the FDA and state regulators could result in enforcement actions againstus or our third-party suppliers, which could include the issuance of warning letters, adverse publicity, seizures, prohibitions on product sales, recalls and civiland criminal penalties, any one of which could significantly impact our manufacturing supply and provision of services and impair our financial results.We depend on third-party vendors to manufacture some of our components, which could make us vulnerable to supply shortages and price fluctuationsthat could harm our business.We rely on third-party vendors for components used in our Zio monitors. Our reliance on third-party vendors subjects us to a number of risks,including: •inability to obtain adequate supply in a timely manner or on commercially reasonable terms •interruption of supply resulting from modifications to, or discontinuation of, a supplier’s operations34 •production delays related to the evaluation and testing of products from alternative suppliers and corresponding regulatory qualifications •inability of the manufacturer or supplier to comply with the QSR and state regulatory authorities •delays in product shipments resulting from uncorrected defects, reliability issues, or a supplier’s failure to consistently produce qualitycomponents •price fluctuations due to a lack of long-term supply arrangements with our suppliers for key components •inability to control the quality of products manufactured by third parties •delays in delivery by our suppliers due to changes in demand from us or their other customersAny significant delay or interruption in the supply of components or sub-assemblies, or our inability to obtain substitute components, sub-assembliesor materials from alternate sources at acceptable prices and in a timely manner could impair our ability to meet the demand for our Zio service and harm ourbusiness.We rely on single suppliers for some of the materials used in our products, and if any of those suppliers are unable or unwilling to produce these materialsor supply them in the quantities that we need at the quality we require, we may not be able to find replacements or transition to alternative suppliers beforeour business is materially impacted.We rely on single suppliers for the supply of our adhesive substrate, disposable plastic housings, instruments and other materials that we use tomanufacture our Zio monitors. These components and materials are critical and there are relatively few alternative sources of supply. We have not qualifiedadditional suppliers for some of these components and materials and we do not carry a significant inventory of these items. While we believe that alternativesources of supply may be available, we cannot be certain whether they will be available if and when we need them and that any alternative suppliers wouldbe able to provide the quantity and quality of components and materials that we would need to manufacture our Zio monitors if our existing suppliers wereunable to satisfy our supply requirements. To utilize other supply sources, we would need to identify and qualify new suppliers to our quality standards,which could result in manufacturing delays and increase our expenses. Any supply interruption could limit our ability to manufacture our products and couldtherefore harm our business, financial condition and results of operations. If our current suppliers and any alternative suppliers do not provide us with thematerials we need to manufacture our products or perform our services, if the materials do not meet our quality specifications, or if we cannot obtainacceptable substitute materials, an interruption in our Zio service could occur. Any such interruption may significantly affect our future revenue and harm ourrelations and reputation with physicians, hospitals, clinics and patients.If our manufacturing facility becomes damaged or inoperable, or if we are required to vacate a facility, we may be unable to manufacture our Zio monitorsor we may experience delays in production or an increase in costs which could adversely affect our results of operations.We currently manufacture and assemble the Zio monitors in only one location. Our products are comprised of components sourced from a variety ofcontract manufacturers, with final assembly completed at our facility in Cypress, California. Our facility and equipment, or those of our suppliers, could beharmed or rendered inoperable by natural or man-made disasters, including fire, earthquake, terrorism, flooding and power outages. Any of these may render itdifficult or impossible for us to manufacture products for some period of time. If our Cypress facility is inoperable for even a short period of time, the inabilityto manufacture our Zio monitors, and the interruption in research and development of any future products, may result in harm to our reputation, increasedcosts, the loss of orders and lower revenue. Furthermore, it could be costly and time consuming to repair or replace our facilities and the equipment we use toperform our research and development work and manufacture our products.If we fail to increase our sales and marketing capabilities and develop broad brand awareness in a cost effective manner, our growth will be impeded andour business may suffer.We plan to continue to expand and optimize our sales and marketing infrastructure in order to increase our prescribing physician base and ourbusiness. Identifying and recruiting qualified personnel and training them in the35 application of the Zio service, on applicable federal and state laws and regulations and on our internal policies and procedures requires significant time,expense and attention. It often takes several months or more before a sales representative is fully trained and productive. Our business may be harmed if ourefforts to expand and train our sales force do not generate a corresponding increase in revenue. In particular, if we are unable to hire, develop and retaintalented sales personnel or if new sales personnel are unable to achieve desired productivity levels in a reasonable period of time, we may not be able torealize the expected benefits of this investment or increase our revenue.Our ability to increase our customer base and achieve broader market acceptance of our products will depend to a significant extent on our ability toexpand our marketing efforts. We plan to dedicate significant resources to our marketing programs. Our business may be harmed if our marketing efforts andexpenditures do not generate a corresponding increase in revenue.In addition, we believe that developing and maintaining broad awareness of our brand in a cost effective manner is critical to achieving broadacceptance of the Zio service and penetrating new accounts. Brand promotion activities may not generate patient or physician awareness or increase revenue,and even if they do, any increase in revenue may not offset the costs and expenses we incur in building our brand. If we fail to successfully promote, maintainand protect our brand, we may fail to attract or retain the physician acceptance necessary to realize a sufficient return on our brand building efforts, or toachieve the level of brand awareness that is critical for broad adoption of the Zio service.Billing for our Zio XT and Zio AT services are complex, and we must dedicate substantial time and resources to the billing process.Billing for independent diagnostic testing facility, or IDTF, services is complex, time consuming and expensive. Depending on the billingarrangement and applicable law, we bill several types of payors, including CMS, third-party commercial payors, institutions and patients, which may havedifferent billing requirements procedures or expectations. We also must bill patient co-payments, co-insurance and deductibles. We face risk in our collectionefforts, including potential write-offs of doubtful accounts and long collection cycles, which could adversely affect our business, financial condition andresults of operations.Several factors make the billing and collection process uncertain, including: •differences between the submitted price for our Zio service and the reimbursement rates of payors •compliance with complex federal and state regulations related to billing CMS •differences in coverage among payors and the effect of patient co-payments, co-insurance and deductibles •differences in information and billing requirements among payors •incorrect or missing patient history, indications or billing informationAdditionally, our billing activities require us to implement compliance procedures and oversight, train and monitor our employees and undertakeinternal review procedures to evaluate compliance with applicable laws, regulations and internal policies. Payors also conduct audits to evaluate claims,which may add further cost and uncertainty to the billing process. These billing complexities, and the related uncertainty in obtaining payment for our Zioservice, could negatively affect our revenue and cash flow, our ability to achieve profitability, and the consistency and comparability of our results ofoperations.The operation of our call centers and monitoring facilities is subject to rules and regulations governing IDTFs; failure to comply with these rules couldprevent us from receiving reimbursement from CMS and some commercial payors.In order to get reimbursed by CMS, we must establish an IDTF. IDTFs are defined by CMS as entities independent of a hospital or physician’s officein which diagnostic tests are performed by licensed or certified nonphysician personnel under appropriate physician supervision. Our IDTFs are staffed bycertified cardiac36 technicians, who are overseen by a medical director who reviews the accuracy of the data we curate and from which we prepare reports. The existence of anIDTF allows us to bill a government payor for the Zio service through one or more MACs, such as Novitas Solutions, Noridian Healthcare Solutions andPalmetto GBA. MACs are companies that operate on behalf of the federal government to process claims for reimbursement and allow us to obtainreimbursement for our Zio service at CMS defined rates. Certification as an IDTF requires that we follow strict regulations governing how the center operates,such as requirements regarding the experience and certifications of the certified cardiac technicians. In addition, many commercial payors require our IDTFsto maintain accreditation and certification with the Joint Commission of American Hospitals. To do so we must demonstrate a specified quality standard andare subject to routine inspection and audits. These rules and regulations vary from location to location and are subject to change. If they change, we mayhave to change the operating procedures at our IDTFs, which could increase our costs significantly. If we fail to obtain and maintain IDTF certification, ourZio service may no longer be reimbursed by CMS and some commercial payors, which would have a material adverse impact on our business.In 2017, we recognized approximately eleven percent of our revenue from non-contracted third-party payors, and as a result, our quarterly operatingresults are difficult to predict.If we do not have a contracted rate with a payor, or have an insufficient or unpredictable history of collections, we recognize revenue only upon theearlier of notification of the payor benefits allowed or when payment is received. We have limited visibility as to when we will receive payment for our Zioservice with non-contracted payors and we or XIFIN must appeal any negative payment decisions, which often delay collections further. Additionally, aportion of the revenue from non-contracted payors is received from patient co-pays, which we may not receive for several months following delivery ofservice or at all. There is currently no predictable payment history for direct-billed non-contracted payors, and thus because a reasonable estimate ofreimbursement cannot be made, we recognize revenue from such accounts only when we are notified of payment or it is received. Fluctuations in revenuemay make it difficult for us, research analysts and investors to accurately forecast our revenue and operating results or to assess our actual performance. Whenmanagement’s judgement indicates a reasonable estimate of reimbursement can be made we will begin recognizing the revenue on an accrual basis upondelivery. If our revenue or operating results fall below expectations, the price of our common stock would likely decline.We rely on a third-party billing company, XIFIN, to transmit and pursue claims with payors. A delay in transmitting or pursuing claims could have anadverse effect on our revenue.While we manage the overall processing of claims, we rely on XIFIN, Inc. to transmit substantially all of our claims to payors, and pursue most claimdenials. If claims for our Zio service are not submitted to payors on a timely basis, not properly adjudicated upon a denial, or if we are required to switch to adifferent claims processor, we may experience delays in our ability to process receipt of payments from payors, which would have an adverse effect on ourrevenue and our business.The market for ambulatory cardiac monitoring solutions is highly competitive. If our competitors are able to develop or market monitoring products andservices that are more effective, or gain greater acceptance in the marketplace, than any products and services we develop, our commercial opportunitieswill be reduced or eliminated.The market for ambulatory cardiac monitoring products and services is evolving rapidly and becoming increasingly competitive. Our Zio servicecompetes with a variety of products and services that provide alternatives for ambulatory cardiac monitoring, including Holter monitors and mobile cardiactelemetry monitors. Our industry is highly fragmented and characterized by a small number of large manufacturers and a large number of smaller regionalservice providers. These third parties compete with us in marketing to payors and prescribing physicians, recruiting and retaining qualified personnel,acquiring technology and developing products and services that compete with the Zio service. Our ability to compete effectively depends on our ability todistinguish our company and the Zio service from our competitors and their products, and includes such factors as: •safety and efficacy •acute and long term outcomes37 •ease of use •price •physician, hospital and clinic acceptance •third-party reimbursementLarge competitors in the ambulatory cardiac market include companies that sell standard Holter monitor equipment such as GE Healthcare, PhilipsHealthcare, Mortara Instrument, Inc., Spacelabs Healthcare, Inc. and Welch Allyn Holdings, Inc., which was acquired by Hill-Rom Holdings, Inc. Additionalcompetitors who offer Holter and event monitors, and also function as service providers, include BioTelemetry, Inc., and Medtronic plc. These companieshave also developed other patch-based mobile cardiac monitors that have recently received FDA and foreign regulatory clearances. For example, LifeWatchAG, which was subsequently acquired by BioTelemetry in July 2017, received FDA clearance and CE mark for its mobile cardiac telemetry monitoring patchin January 2016 and December 2015, respectively. In addition, in July 2016, BioTelemetry, Inc. announced FDA clearance for its own patch-based mobilecardiac telemetry monitor. There are also several small start-up companies trying to compete in the patch-based cardiac monitoring space. We have seen atrend in the market for large medical device companies to acquire, invest in or form alliances with these smaller companies in order to diversify their productofferings and participate in the digital health space. For example, in 2014 Medtronic plc acquired Corventis, Inc. Future competition could come from makersof wearable fitness products or large information technology companies focused on improving healthcare. These competitors and potential competitors mayintroduce new products that compete with our Zio service. Many of our competitors and potential competitors have significantly greater financial and otherresources than we do and have well-established reputations, broader product offerings, and worldwide distribution channels that are significantly larger andmore effective than ours. If our competitors and potential competitors are better able to develop new ambulatory cardiac monitoring solutions than us, ordevelop more effective or less expensive cardiac monitoring solutions, they may render our current Zio service obsolete or non-competitive. Competitorsmay also be able to deploy larger or more effective sales and marketing resources than we currently have. Competition with these companies could result inprice cutting, reduced profit margins and loss of market share, any of which would harm our business, financial condition and results of operations.Our ability to compete depends on our ability to innovate successfully.The market for medical devices, including the ambulatory cardiac monitoring segment, is competitive, dynamic, and marked by rapid and substantialtechnological development and product innovation. There are few barriers that would prevent new entrants or existing competitors from developing productsthat compete directly with ours. Demand for the Zio service and future related products or services could be diminished by equivalent or superior productsand technologies offered by competitors. If we are unable to innovate successfully, our products and services could become obsolete and our revenue woulddecline as our customers purchase our competitors’ products and services.In order to remain competitive, we must continue to develop new product offerings and enhancements to the Zio service. We can provide noassurance that we will be successful in monetizing our electrocardiogram, or ECG, database, expanding the indications for our Zio service, developing newproducts or commercializing them in ways that achieve market acceptance. In addition, if we develop new products, sales of those products may reducerevenue generated from our existing products. Maintaining adequate research and development personnel and resources to meet the demands of the market isessential. If we are unable to develop new products, applications or features or improve our algorithms due to constraints, such as insufficient cash resources,high employee turnover, inability to hire personnel with sufficient technical skills or a lack of other research and development resources, we may not be ableto maintain our competitive position compared to other companies. Furthermore, many of our competitors devote a considerably greater amount of funds totheir research and development programs than we do, and those that do not may be acquired by larger companies that would allocate greater resources toresearch and development programs. Our failure or inability to devote adequate research and development resources or compete effectively with the researchand development programs of our competitors could harm our business.38 The continuing clinical acceptance of the Zio service depends upon maintaining strong working relationships with physicians.The development, marketing, and sale of the Zio service depends upon our ability to maintain strong working relationships with physicians andother key opinion leaders. We rely on these professionals’ knowledge and experience for the development, marketing and sale of our products. Among otherthings, physicians assist us in clinical trials and product development matters and provide public presentations at trade conferences regarding the Zio service.If we cannot maintain our strong working relationships with these professionals and continue to receive their advice and input, the development andmarketing of the Zio service could suffer, which could harm our business, financial condition and results of operations.The medical device industry’s relationship with physicians is under increasing scrutiny by the Health and Human Services Office of the InspectorGeneral, or OIG, the Department of Justice, or DOJ, state attorneys general, and other foreign and domestic government agencies. Our failure to comply withlaws, rules and regulations governing our relationships with physicians, or an investigation into our compliance by the OIG, DOJ, state attorneys general orother government agencies, could significantly harm our business.We have a significant amount of debt, which may affect our ability to operate our business and secure additional financing in the future.As of December 31, 2017, we had $34.0 million outstanding under our credit facilities consisting of our loan agreements with Pharmakon and SVBand a promissory note issued to California HealthCare Foundation. We must make significant annual debt payments under the loan agreements and thepromissory note, which will divert resources from other activities. Our debt with Pharmakon and SVB is collateralized by substantially all of our assets andcontains customary financial and operating covenants limiting our ability to, among other things, dispose of assets, undergo a change in control, merge orconsolidate, enter into certain transactions with affiliates, make acquisitions, incur debt, incur liens, pay dividends, repurchase stock and make investments,in each case subject to certain exceptions. The covenants in these loan agreements, the promissory note and the note purchase agreement pursuant to whichthe promissory note was issued, as well as in any future financing agreements into which we may enter, may restrict our ability to finance our operations andengage in, expand or otherwise pursue our business activities and strategies. Our ability to comply with these covenants may be affected by events beyondour control and future breaches of any of these covenants could result in a default under the loan agreements, the promissory note and the note purchaseagreement. If not waived, future defaults could cause all of the outstanding indebtedness under the loan agreements and the promissory note to becomeimmediately due and payable and terminate commitments to extend further credit. If we do not have or are unable to generate sufficient cash available torepay our debt obligations when they become due and payable, either upon maturity or in the event of a default, we may not be able to obtain additional debtor equity financing on favorable terms, if at all, which may negatively impact our ability to operate and continue our business as a going concern.We depend on our senior management team and the loss of one or more key employees or an inability to attract and retain highly skilled employees couldharm our business.Our success depends largely on the continued services of key members of our executive management team and others in key management positions.For example, the services of Kevin M. King, our Chief Executive Officer, and Matthew C. Garrett, our Chief Financial Officer, are essential to formulating andexecuting on corporate strategy and to ensuring the continued operations and integrity of financial reporting within our company. In addition, the servicesprovided by David A. Vort, our Executive Vice President of Sales, are critical to the growth that we have experienced in the sales of our Zio service. Ouremployees may terminate their employment with us at any time. If we lose one or more key employees, we may experience difficulties in competingeffectively, developing our technologies and implementing our business strategy. We do not currently maintain key person life insurance policies on these orany of our employees.In addition, our research and development programs and clinical operations depend on our ability to attract and retain highly skilled engineers andcertified cardiac technicians. We may not be able to attract or retain qualified engineers and certified cardiac technicians in the future due to the competitionfor qualified personnel. We have from time to time experienced, and we expect to continue to experience, difficulty in hiring and retaining employees39 with appropriate qualifications. Many of the companies with which we compete for experienced personnel have greater resources than us. If we hireemployees from competitors or other companies, their former employers may attempt to assert that these employees or we have breached legal obligations,resulting in a diversion of our time and resources and, potentially, damages. In addition, job candidates and existing employees, particularly in the SanFrancisco Bay Area, often consider the value of the stock awards they receive in connection with their employment. If the perceived value of our stock awardsdeclines, it may harm our ability to recruit and retain highly skilled employees. If we fail to attract new personnel or fail to retain and motivate our currentpersonnel, our business and future growth prospects would be harmed.We added two new directors to our board of directors in July 2017, which may lead to changes in our operations.Two new directors were elected to our board of directors on July 17, 2017. One of these directors, Bruce G. Bodaken, served as Chairman and ChiefExecutive Officer of a payor, and the other director, Dr. Ralph Snyderman, served as founding Chief Executive Officer and President of a provider. Another ofour directors has served on our board of directors for less than two years. Because of these recent additions, our board of directors has not worked together as agroup for an extended period of time. This change in the composition of our board of directors from directors affiliated with financial investors to directorswith industry experience may lead to changes in our operations as these new directors analyze our business and contribute to the formulation of businessstrategies and objectives. If our board of directors does not align on the business strategies and objectives of our company, our operating results could beadversely affected.International expansion of our business exposes us to market, regulatory, political, operational, financial and economic risks associated with doingbusiness outside of the United States.Our business strategy includes international expansion. Doing business internationally involves a number of risks, including: •multiple, conflicting and changing laws and regulations such as tax laws, privacy laws, export and import restrictions, employment laws,regulatory requirements and other governmental approvals, permits and licenses •obtaining regulatory approvals where required for the sale of our products and services in various countries •requirements to maintain data and the processing of that data on servers located within such countries •complexities associated with managing multiple payor reimbursement regimes, government payors or patient self-pay systems •logistics and regulations associated with shipping and returning our Zio monitors following use •limits on our ability to penetrate international markets if we are required to process the Zio service locally •financial risks, such as longer payment cycles, difficulty collecting accounts receivable, the effect of local and regional financial pressures ondemand and payment for our products and services and exposure to foreign currency exchange rate fluctuations •natural disasters, political and economic instability, including wars, terrorism, political unrest, outbreak of disease, boycotts, curtailment oftrade and other market restrictions •regulatory and compliance risks that relate to maintaining accurate information and control over activities subject to regulation under theUnited States Foreign Corrupt Practices Act of 1977, or FCPA, U.K. Bribery Act of 2010 and comparable laws and regulations in othercountriesAny of these factors could significantly harm our future international expansion and operations and, consequently, our revenue and results ofoperations.40 Our relationships with business partners in new international markets may subject us to an increased risk of litigation.As we expand our business internationally, if we cannot successfully manage the unique challenges presented by international markets and ourrelationships with new business partners within those markets, our expansion activities may be adversely affected and we may become subject to an increasedrisk of litigation.We may become involved in disputes relating to our products, contracts and business relationships. Such disputes include litigation against personswhom we believe have infringed on our intellectual property, infringement litigation filed against us, litigation against a competitor or litigation filedagainst us by distributors or service providers resulting from a breach of contract or other claim. Any of these disputes may result in substantial costs to us,judgments, settlements and diversion of our management’s attention, which could adversely affect our business, financial condition or operating results.There is also a risk of adverse judgments, as the outcome of litigation in foreign jurisdictions can be inherently uncertain.We could be adversely affected by violations of the U.S. Foreign Corrupt Practices Act, or FCPA, and similar worldwide anti-bribery laws and the ongoinginvestigation, and outcome of the investigation, by government agencies of possible violations by us of the FCPA could have a material adverse effect onour business.The FCPA and similar worldwide anti-bribery laws generally prohibit companies and their intermediaries from corruptly providing any benefits togovernment officials for the purpose of obtaining or retaining business. We are in the process of designing and implementing policies and proceduresintended to help ensure compliance with these laws. In the future, we may operate in parts of the world that have experienced governmental corruption tosome degree. We cannot assure you that our internal control policies and procedures will protect us from improper acts committed by our employees oragents. Violations of these laws, or allegations of such violations, could disrupt our business and have a material adverse effect on our business andoperations.In addition, the DOJ or other governmental agencies could impose a broad range of civil and criminal sanctions under the FCPA and other laws andregulations including, but not limited to, injunctive relief, disgorgement, fines, penalties, modifications to business practices including the termination ormodification of existing business relationships, the imposition of compliance programs and the retention of a monitor to oversee compliance with the FCPA.The imposition of any of these sanctions or remedial measures could have a material adverse effect on our business and results of operations.Our proprietary data analytics engine may not operate properly, which could damage our reputation, give rise to claims against us or divert application ofour resources from other purposes, any of which could harm our business and operating results.The ECG data that is gathered through our Zio monitors is curated by algorithms that are part of our Zio service and a ZIO Report is delivered to theprescribing physician for diagnosis. The continuous development, maintenance and operation of our machine-learned backend data analytics engine isexpensive and complex, and may involve unforeseen difficulties including material performance problems, undetected defects or errors. We may encountertechnical obstacles, and it is possible that we may discover additional problems that prevent our proprietary algorithms from operating properly. If our dataanalytics platform does not function reliably or fails to meet physician or payor expectations in terms of performance, physicians may stop prescribing theZio service and payors could attempt to cancel their contracts with us.Any unforeseen difficulties we encounter in our existing or new software, cloud-based applications and analytics services, and any failure by us toidentify and address them could result in loss of revenue or market share, diversion of development resources, injury to our reputation and increased serviceand maintenance costs. Correction of defects or errors could prove to be impossible or impracticable. The costs incurred in correcting any defects or errorsmay be substantial and could adversely affect our operating results.41 Provision of the Zio service is dependent upon third-party vendors who are subject to disruptions, which could directly or indirectly harm our business andoperating results.The analysis we perform to create the diagnostic report for the Zio service is dependent upon a recording made by each device, which requires thephysical return of the Zio monitor to one of our clinical centers. We predominantly rely on the U.S. Postal Service, or USPS, to perform this delivery service.Delivery of the Zio monitor to one of our clinical centers may be subject to disruption by natural disasters such as earthquake or flooding, labordisagreements or errors on behalf of USPS staff, or other disruption to the USPS delivery infrastructure. Further, for the Zio AT monitor, we rely on theprovision of cellular communication services for the timely transmission of patient information and reportable events. The robustness of thesecommunication services is also subject to natural disasters, labor disruptions, human error, and infrastructure failure.Any of these disruptions may render it difficult or temporarily impossible for us to provide some or all of the Zio service, adversely affecting ouroperating results, causing significant distraction for management, and negatively impacting our business reputation.Security breaches, loss of data and other disruptions could compromise sensitive information related to our business or patients, or prevent us fromaccessing critical information and expose us to liability, which could adversely affect our business and our reputation.In the ordinary course of our business, we and our third-party billing and collections provider, XIFIN, collect and store sensitive data, includinglegally-protected personally identifiable health information about patients in the United States and the United Kingdom. We also process and store, and useadditional third parties to process and store, sensitive intellectual property and other proprietary business information, including that of our customers,payors and collaborative partners. Our patient information is encrypted but not de-identified. We manage and maintain our applications and data utilizing acombination of on-site systems, managed data center systems and cloud-based computing center systems. These applications and data encompass a widevariety of business critical information, including research and development information, commercial information and business and financial information.We are highly dependent on information technology networks and systems, including the internet and services hosted by Amazon Web Services, tosecurely process, transmit and store this critical information. Security breaches of this infrastructure, including physical or electronic break-ins, computerviruses, attacks by hackers and similar breaches, can create system disruptions, shutdowns, or unauthorized disclosure or modifications of confidentialinformation involving patient health information to become publicly available. The secure processing, storage, maintenance and transmission of this criticalinformation are vital to our operations and business strategy, and we devote significant resources to protecting such information. Although we take measuresto protect sensitive information from unauthorized access or disclosure, our information technology and infrastructure, and that of XIFIN, may be vulnerableto attacks by hackers or viruses or breaches due to employee error, malfeasance or other disruptions. While we have implemented data privacy and securitymeasures that we believe are compliant with applicable privacy laws and regulations, some confidential and protected health information, is transmitted to usby third parties, who may not implement adequate security and privacy measures.A security breach or privacy violation that leads to disclosure or modification of, or prevents access to, patient information, including protectedhealth information, could harm our reputation, compel us to comply with disparate state breach notification laws, require us to verify the correctness ofdatabase contents and otherwise subject us to liability under laws that protect personal data, resulting in increased costs or loss of revenue. If we are unable toprevent such security breaches or privacy violations or implement satisfactory remedial measures, our operations could be disrupted, we may be unable toprovide the Zio service and we may suffer loss of reputation, financial loss and other regulatory penalties because of lost or misappropriated information,including sensitive patient data. In addition, these breaches and other inappropriate access can be difficult to detect, and any delay in identifying them maylead to increased harm.Any such breach or interruption of our systems, or those of XIFIN or any of our third-party information technology partners, could compromise ournetworks or data security processes and sensitive information could be inaccessible or could be accessed by unauthorized parties, publicly disclosed, lost orstolen. Any such interruption in42 access, improper access, disclosure or other loss of information could result in legal claims or proceedings, liability under laws that protect the privacy ofpatient information, such as the federal Health Insurance Portability and Accountability Act of 1996, or HIPAA, the General Data Protection Regulation, orGDPR, and the European Union Data Protection Directive, and regulatory penalties. Unauthorized access, loss or dissemination could also disrupt ouroperations, including our ability to perform our services, bill payors or patients, process claims and appeals, provide customer assistance services, conductresearch and development activities, collect, process and prepare company financial information, provide information about our current and future solutionsand engage in other patient and clinician education and outreach efforts. Any such breach could also result in the compromise of our trade secrets and otherproprietary information, which could adversely affect our business and competitive position.In addition, the interpretation and application of consumer, health-related and data protection laws, rules and regulations in the United States, Europeand elsewhere are often uncertain, contradictory and in flux. It is possible that these laws, rules and regulations may be interpreted and applied in a mannerthat is inconsistent with our practices or those of our distributors and partners. If we or these third parties are found to have violated such laws, rules orregulations, it could result in government-imposed fines, orders requiring that we or these third parties change our or their practices, or criminal charges,which could adversely affect our business. Complying with these various laws could cause us to incur substantial costs or require us to change our businesspractices, systems and compliance procedures in a manner adverse to our business.The use, misuse or off-label use of the Zio service may result in injuries that lead to product liability suits, which could be costly to our business.The use, misuse or off-label use of the Zio service may in the future result in outcomes and complications potentially leading to product liabilityclaims. For example, we are aware that physicians have prescribed the Zio service off-label for pediatric patients. We have also received and may in the futurereceive product liability or other claims with respect to the Zio service, including claims related to skin irritation and alleged burns. In addition, if the Ziomonitor is defectively designed, manufactured or labeled, contains defective components or is misused, we may become subject to costly litigation initiatedby physicians, or the hospitals and clinics where physicians prescribing our Zio service work, or their patients. Product liability claims are especiallyprevalent in the medical device industry and could harm our reputation, divert management’s attention from our core business, be expensive to defend andmay result in sizable damage awards against us.Although we maintain product liability insurance, we may not have sufficient insurance coverage for future product liability claims. We may not beable to obtain insurance in amounts or scope sufficient to provide us with adequate coverage against all potential liabilities. Any product liability claimsbrought against us, with or without merit, could increase our product liability insurance rates or prevent us from securing continuing coverage, harm ourreputation, significantly increase our expenses, and reduce product sales. Product liability claims in excess of our insurance coverage would be paid out ofcash reserves, harming our financial condition and operating results.Our forecasts of market growth may prove to be inaccurate, and even if the markets in which we compete achieve the forecasted growth, our business maynot increase at similar rates, if at all.Growth forecasts are subject to significant uncertainty and are based on assumptions and estimates that may not prove to be accurate. Our forecastsrelating to, among other things, the expected growth in the ambulatory cardiac monitoring solutions market may prove to be inaccurate.Our growth is subject to many factors, including whether the market for first-line ambulatory cardiac monitoring solutions continues to improve, therate of market acceptance of the Zio service as compared to the products of our competitors and our success in implementing our business strategies, each ofwhich is subject to many risks and uncertainties. If our Zio service works as anticipated to provide a correct first-line diagnosis, it may lead to a decrease inthe amount of ambulatory cardiac monitoring prescriptions each year in the United States. This outcome would result if our Zio service is proven to producethe right diagnosis the first time, thereby reducing the need for additional testing. Accordingly, our forecasts of market opportunity should not be taken asindicative of our future growth.43 We may acquire other companies or technologies, which could divert our management’s attention, result in additional dilution to our stockholders andotherwise disrupt our operations and harm our operating results.We may in the future seek to acquire or invest in businesses, applications or technologies that we believe could complement or expand ourambulatory cardiac monitoring solutions portfolio, enhance our technical capabilities or otherwise offer growth opportunities. The pursuit of potentialacquisitions may divert the attention of management and cause us to incur various costs and expenses in identifying, investigating and pursuing suitableacquisitions, whether or not they are consummated. We may not be able to identify desirable acquisition targets or be successful in entering into anagreement with any particular target or obtain the expected benefits of any acquisition or investment.To date, the growth of our operations has been largely organic, and we have limited experience in acquiring other businesses or technologies. Wemay not be able to successfully integrate acquired personnel, operations and technologies, or effectively manage the combined business following anacquisition. Acquisitions could also result in dilutive issuances of equity securities, the use of our available cash, or the incurrence of debt, which could harmour operating results. In addition, if an acquired business fails to meet our expectations, our operating results, business and financial condition may suffer.Consolidation of commercial payors could result in payors eliminating coverage or reducing reimbursement rates for our Zio service.When payors combine their operations, the combined company may elect to reimburse our Zio service at the lowest rate paid by any of theparticipants in the consolidation or use its increased size to negotiate reduced rates. If one of the payors participating in the consolidation does not reimbursefor the Zio service at all, the combined company may elect not to reimburse for the Zio service, which would adversely impact our operating results. Whileattempts by Aetna Inc. to acquire Humana Inc. and Anthem Inc. to acquire Cigna Corp. have been largely abandoned due to antitrust challenges by the DOJ,it is possible that these or other payor consolidations may occur in the future.Our ability to utilize our net operating loss carryovers may be limited.As of December 31, 2017, we had federal and state net operating loss carryforwards, or NOLs, of $143.1 million and $82.4 million, respectively,which if not utilized will begin to expire in 2027 for federal purposes and 2018 for state purposes. We may use these NOLs to offset against taxable incomefor U.S. federal and state income tax purposes. However, Section 382 of the Internal Revenue Code, as amended, may limit the NOLs we may use in any yearfor U.S. federal income tax purposes in the event of certain changes in ownership of our company. A Section 382 “ownership change” generally occurs if oneor more stockholders or groups of stockholders who own at least 5% of a company’s stock increase their ownership by more than 50 percentage points overtheir lowest ownership percentage within a rolling three year period. Similar rules may apply under state tax laws. Future issuances or sales of our stock,including certain transactions involving our stock that are outside of our control, could cause an “ownership change.” If an “ownership change” has occurredin the past or occurs in the future, Section 382 would impose an annual limit on the amount of pre-ownership change NOLs and other tax attributes we canuse to reduce our taxable income, potentially increasing and accelerating our liability for income taxes, and also potentially causing those tax attributes toexpire unused. Any limitation on using NOLs could, depending on the extent of such limitation and the NOLs previously used, result in our retaining lesscash after payment of U.S. federal and state income taxes during any year in which we have taxable income, rather than losses, than we would be entitled toretain if such NOLs were available as an offset against such income for U.S. federal and state income tax reporting purposes, which could adversely impactour operating results.If we are unable to implement and maintain effective internal control over financial reporting in the future, investors may lose confidence in the accuracyand completeness of our financial reports and the market price of our common stock may decrease.The Sarbanes-Oxley Act requires, among other things, that we assess the effectiveness of our internal controls over financial reporting annually andthe effectiveness of our disclosure controls and procedures quarterly. Section 404 of the Sarbanes-Oxley Act, or Section 404, requires us to perform systemand process evaluation and testing of44 our internal control over financial reporting to allow management to report on, and our independent registered public accounting firm to attest to, theeffectiveness of our internal control over financial reporting. Prior to December 31, 2017, we availed ourselves of the exemption from the requirement thatour independent registered public accounting firm attest to the effectiveness of our internal control over financial reporting under Section 404. As ofDecember 31, 2017, we ceased to be an “emerging growth company.” We expect that the cost of our compliance with Section 404 will correspondinglyincrease as a result of our independent registered public accounting firm being required to undertake an assessment of our internal control over financialreporting. Our compliance with applicable provisions of Section 404 have required and will continue to require that we incur substantial accounting expenseand expend significant management time on compliance-related issues as we implement additional corporate governance practices and comply withreporting requirements. Section 404 also requires that we evaluate and determine the effectiveness of our internal control over financial reporting and,beginning with this Annual Report on Form 10-K, provide a management report on our internal control over financial reporting along with auditorattestation. If we have material weaknesses in our internal control over financial reporting, we may not detect errors on a timely basis and our financialstatements may be materially misstated. We have implemented the process and documentation necessary to perform the evaluation needed to comply withSection 404, but we may not be able to complete our evaluation, testing and any required remediation in a timely fashion in any given quarterly period.During the evaluation and testing process, if we identify one or more material weaknesses in our internal control over financial reporting, ourmanagement will be unable to conclude that our internal control over financial reporting is effective and our independent registered public accounting firmwill be unable to issue an attestation report on the effectiveness of our internal control over financial reporting. Even if our management concludes that ourinternal control over financial reporting is effective, our independent registered public accounting firm may conclude that there are material weaknesses withrespect to our internal controls or the level at which our internal controls are documented, designed, implemented or reviewed.If we identify material weaknesses in our internal control over financial reporting, if we are unable to comply with the requirements of Section 404 ina timely manner, if we are unable to conclude that our internal control over financial reporting is effective, or if our auditors were to express an adverseopinion on the effectiveness of our internal control over financial reporting because we had one or more material weaknesses, investors could lose confidencein the accuracy and completeness of our financial disclosures, which could cause the price of our common stock to decline. Internal control deficienciescould also result in a restatement of our financial results in the future. We could also become subject to stockholder or other third-party litigation as well asinvestigations by the stock exchange on which our securities are listed, the Securities and Exchange Commission, or other regulatory authorities, whichcould require additional financial and management resources and could result in fines, trading suspensions or other remedies.Risks Related to Our Intellectual PropertyWe may become a party to intellectual property litigation or administrative proceedings that could be costly and could interfere with our ability to providethe Zio service.The medical device industry has been characterized by extensive litigation regarding patents, trademarks, trade secrets, and other intellectualproperty rights, and companies in the industry have used intellectual property litigation to gain a competitive advantage. It is possible that U.S. and foreignpatents and pending patent applications or trademarks controlled by third parties, especially those held by our competitors, may be alleged to cover ourproducts or services, or that we may be accused of misappropriating third parties’ trade secrets. Additionally, our products include hardware and softwarecomponents that we purchase from vendors, and may include design components that are outside of our direct control. Our competitors, many of which havesubstantially greater resources and have made substantial investments in patent portfolios, trade secrets, trademarks, and competing technologies, may haveapplied for or obtained, or may in the future apply for or obtain, patents or trademarks that will prevent, limit or otherwise interfere with our ability to make,use, sell and/or export our products and services or to use product names. Moreover, in recent years, individuals and groups that are non-practicing entities,commonly referred to as “patent trolls,” have purchased patents and other intellectual property assets for the purpose of making claims of infringement inorder to extract settlements. From time to time, we may receive threatening letters, notices or “invitations to license,” or may be the subject of claims that ourproducts and business operations infringe or violate the intellectual property rights of others. The defense of these matters can be time consuming, costly to45 defend in litigation, divert management’s attention and resources, damage our reputation and brand and cause us to incur significant expenses or makesubstantial payments to satisfy judgments or settle claims. Vendors from whom we purchase hardware or software may not indemnify us in the event that suchhardware or software is accused of infringing a third-party’s patent or trademark or of misappropriating a third-party’s trade secret.Further, if such patents, trademarks, or trade secrets are successfully asserted against us, this may harm our business and result in injunctionspreventing us from selling our products, license fees, damages and the payment of attorney fees and court costs. In addition, if we are found to willfullyinfringe third-party patents or trademarks or to have misappropriated trade secrets, we could be required to pay treble damages in addition to other penalties.Although patent, trademark, trade secret, and other intellectual property disputes in the medical device and services area have often been settled throughlicensing or similar arrangements, costs associated with such arrangements may be substantial and could include ongoing royalties. We may be unable toobtain necessary licenses on satisfactory terms, if at all. If we do not obtain necessary licenses, we may not be able to redesign our Zio monitors or our Zioservice to avoid infringement and our product development efforts may be negatively affected as a result.Similarly, interference or derivation proceedings provoked by third parties or brought by the U.S. Patent and Trademark Office, or USPTO, may benecessary to determine priority with respect to our patents, patent applications, trademarks or trademark applications. We may also become involved in otherproceedings, such as reexamination, inter partes review, derivation or opposition proceedings before the USPTO or other jurisdictional body relating to ourintellectual property rights or the intellectual property rights of others. Adverse determinations in a judicial or administrative proceeding or failure to obtainnecessary licenses could prevent us from manufacturing the Zio monitors and selling the Zio service or using product names, which would have a significantadverse impact on our business.Additionally, we may need to commence proceedings against others to enforce our patents or trademarks, to protect our trade secrets or know how, orto determine the enforceability, scope and validity of the proprietary rights of others. These proceedings would result in substantial expense to us andsignificant diversion of effort by our technical and management personnel. We may not prevail in any lawsuits that we initiate and the damages or otherremedies awarded, if any, may not be commercially meaningful. We may not be able to stop a competitor from marketing and selling products that are thesame or similar to our products and services or from using product or service names that are the same or similar to ours, and our business may be harmed as aresult.We use certain open source software in the Zio service. We may face claims from companies that incorporate open source software into their productsor from open source licensors, claiming ownership of, or demanding release of, the source code, the open source software or derivative works that weredeveloped using such software, or otherwise seeking to enforce the terms of the applicable open source license. These claims could result in litigation andcould require us to cease offering the Zio service unless and until we can re-engineer it to avoid infringement. This re-engineering process could requiresignificant additional research and development resources, and we may not be able to complete it successfully. These risks could be difficult to eliminate ormanage, and, if not addressed, could harm our business, financial condition and operating results.Intellectual property rights may not provide adequate protection, which may permit third parties to compete against us more effectively.In order to remain competitive, we must develop and maintain protection of the proprietary aspects of our technologies. We rely on a combination ofpatents, copyrights, trademarks, trade secret laws and confidentiality and invention assignment agreements with employees and third parties to protect ourintellectual property rights. As of December 31, 2017, we owned, or retained exclusive license to, nine issued U.S. patents, the earliest of which will expire in2028. As of December 31, 2017, we also owned, or retained an exclusive license to, three issued patents from the Japan Patent Office, two issued patents fromthe patent offices in each of Australia and Canada, and one issued patent from the patent offices in each of the European Union and Korea. The earliestexpiration date of these international patents is 2027. As of December 31, 2017, we had twenty pending patent applications globally, including four in theUnited States, five in the European Union, four in Japan, two in each of Korea and Canada, and one in each of Australia, China and India. Our patents andpatent applications include claims covering key aspects of the design, manufacture and use of the Zio monitor and the Zio service.46 We rely, in part, on our ability to obtain and maintain patent protection for our proprietary products and processes. The process of applying for andobtaining a patent is expensive, time consuming and complex, and we may not be able to file, prosecute, maintain, enforce or license all necessary ordesirable patent applications at a reasonable cost, in a timely manner, or in all jurisdictions where protection may be commercially advantageous, or we maynot be able to protect our proprietary rights at all. Despite our efforts to protect our proprietary rights, unauthorized parties may be able to obtain and useinformation that we regard as proprietary. In addition, the issuance of a patent does not ensure that it is valid or enforceable, so even if we obtain patents, theymay not be valid or enforceable against third parties. Our patent applications may not result in issued patents and our patents may not be sufficiently broad toprotect our technology. Furthermore, the issuance of a patent does not give us the right to practice the patented invention. Third parties may have blockingpatents that could prevent us from marketing our own products and practicing our own technology. Alternatively, third parties may seek approval to markettheir own products similar to or otherwise competitive with our products. In these circumstances, we may need to defend and/or assert our patents, includingby filing lawsuits alleging patent infringement. In any of these types of proceedings, a court or agency with jurisdiction may find our patents invalid orunenforceable; competitors may then be able to market products and use manufacturing and analytical processes that are substantially similar to ours. Even ifwe have valid and enforceable patents, these patents still may not provide protection against competing products or processes sufficient to achieve ourbusiness objectives.If we are unable to protect the confidentiality of our trade secrets and other proprietary information, our business and competitive position may beharmed.We rely heavily on trade secrets as well as invention assignment and confidentiality provisions that we have in contracts with our employees,consultants, collaborators and others to protect our algorithms and other aspects of our Zio service. We may not be able to prevent the unauthorizeddisclosure or use of our technical knowledge or other trade secrets by consultants, vendors or former or current employees, despite the existence generally ofthese confidentiality agreements and other contractual restrictions. These agreements may not provide meaningful protection for our trade secrets, know-how,or other proprietary information in the event of any unauthorized use, misappropriation, or disclosure of such trade secrets, know-how, or other proprietaryinformation. There can be no assurance that employees, consultants, vendors and clients have executed such agreements or have not breached or will notbreach their agreements with us, that we will have adequate remedies for any breach, or that our trade secrets will not otherwise become known orindependently developed by competitors. Despite the protections we do place on our intellectual property, monitoring unauthorized use and disclosure ofour intellectual property is difficult, and we do not know whether the steps we have taken to protect our intellectual property will be adequate. In addition,the laws of many foreign countries will not protect our intellectual property rights to the same extent as the laws of the United States. Consequently, we maybe unable to prevent our proprietary technology from being exploited abroad, which could affect our ability to expand to international markets or requirecostly efforts to protect our technology.We may also employ individuals who were previously or are concurrently employed at research institutions or other medical device companies,including our competitors or potential competitors. We may be subject to claims that these employees, or we, have inadvertently or otherwise used ordisclosed trade secrets or other proprietary information of their former or concurrent employers, or that patents and applications we have filed to protectinventions of these employees, even those related to one or more of our products, are rightfully owned by their former or concurrent employer. Litigation maybe necessary to defend against these claims. Even if we are successful in defending against these claims, litigation could result in substantial costs and be adistraction to management.To the extent our intellectual property protection is incomplete, we are exposed to a greater risk of direct competition. A third party could, withoutauthorization, copy or otherwise obtain and use our products or technology, or develop similar technology. Our competitors could purchase our products andattempt to replicate some or all of the competitive advantages we derive from our development efforts or design around our protected technology. Our failureto secure, protect and enforce our intellectual property rights could substantially harm the value of our Zio service, brand and business. The theft orunauthorized use or publication of our trade secrets and other confidential business information could reduce the differentiation of our products and harm ourbusiness, the value of our investment in development or business acquisitions could be reduced and third parties might make47 claims against us related to losses of their confidential or proprietary information. Any of the foregoing could materially and adversely affect our business.Further, it is possible that others will independently develop the same or similar technology or otherwise obtain access to our unpatented technology,and in such cases we could not assert any trade secret rights against such parties. Costly and time-consuming litigation could be necessary to enforce anddetermine the scope of our trade secret rights and related confidentiality and nondisclosure provisions. If we fail to obtain or maintain trade secret protection,or if our competitors obtain our trade secrets or independently develop technology similar to ours or competing technologies, our competitive marketposition could be materially and adversely affected. In addition, some courts inside and outside the United States are less willing or unwilling to protect tradesecrets and agreement terms that address non-competition are difficult to enforce in many jurisdictions and might not be enforceable in certain cases.If our trademarks and tradenames are not adequately protected, then we may not be able to build name recognition in our markets and our business maybe adversely affected.We rely on trademarks, service marks, tradenames and brand names, such as our registered trademark “ZIO,” to distinguish our products from theproducts of our competitors, and have registered or applied to register these trademarks. We cannot assure you that our trademark applications will beapproved. During trademark registration proceedings, we may receive rejections. Although we are given an opportunity to respond to those rejections, wemay be unable to overcome such rejections. In addition, in proceedings before the USPTO and in proceedings before comparable agencies in many foreignjurisdictions, third parties are given an opportunity to oppose pending trademark applications and to seek to cancel registered trademarks. Opposition orcancellation proceedings may be filed against our trademarks, and our trademarks may not survive such proceedings. In the event that our trademarks aresuccessfully challenged, we could be forced to rebrand our products, which could result in loss of brand recognition and could require us to devote resourcestowards advertising and marketing new brands. Further, we cannot assure you that competitors will not infringe our trademarks or that we will have adequateresources to enforce our trademarks. Additionally, we do not own any registered trademarks for the mark “IRHYTHM” and we are aware of at least one third-party that has registered the “IRHYTHM” mark in the United States, the European Union and Taiwan in connection with computer software for controllingand managing patient medical information, heart rate monitors, and heart rate monitors to be worn during moderate exercise, among other uses. We and thethird party are involved in adversary proceedings before the Trademark Offices in the United States and the European Union, and those proceedings couldimpact our ability to register the “IRHYTHM” mark in those jurisdictions. It is possible that the third-party could bring suit against us claiming infringementof the “IRHYTHM” mark, and if it did so and if there were a court determination against us, we might then be obligated to pay monetary damages, enter into alicense agreement, or cease use of the “IRHYTHM” name and mark, all of which could have a material adverse effect on our business, financial condition,results of operations and prospects.Changes in patent law could diminish the value of patents in general, thereby impairing our ability to protect our existing and future products.Recent patent reform legislation could increase the uncertainties and costs surrounding the prosecution of patent applications and the enforcement ordefense of issued patents. In 2011, the Leahy-Smith America Invents Act, or the Leahy-Smith Act, was signed into law. The Leahy-Smith Act includes anumber of significant changes to U.S. patent law. These include provisions that affect the way patent applications are prosecuted and also may affect patentlitigation. These also include provisions that switched the United States from a “first-to-invent” system to a “first-to-file” system, allow third-partysubmission of prior art to the USPTO during patent prosecution and set forth additional procedures to attack the validity of a patent by the USPTOadministered post grant proceedings. Under a first-to-file system, assuming the other requirements for patentability are met, the first inventor to file a patentapplication generally will be entitled to the patent on an invention regardless of whether another inventor had made the invention earlier. Under the new postgrant provisions of the Leahy-Smith Act, the USPTO introduced procedures that provide additional administrative pathways for third parties to challengeissued patents. Inter partes review, or IPR, is one of these procedures. The number of IPR challenges filed is increasing, and in many cases, the USPTO iscanceling or significantly narrowing issued patent claims. Accordingly, even if a patent is granted by the USPTO, there is risk that it may not withstand anIPR challenge. Accordingly, it is not clear what, if any, impact the Leahy-Smith Act will have on the operation of our business. The Leahy-Smith Act and itsimplementation could48 increase the uncertainties and costs surrounding the prosecution of our patent applications and the enforcement or defense of our issued patents, all of whichcould have a material adverse effect on our business, financial condition, results of operations and prospects.In addition, patent reform legislation may pass in the future that could lead to additional uncertainties and increased costs surrounding theprosecution, enforcement and defense of our patents and applications. Furthermore, the U.S. Supreme Court and the U.S. Court of Appeals for the FederalCircuit have made, and will likely continue to make, changes in how the patent laws of the United States are interpreted. Recent case law has increaseduncertainty regarding the availability of patent protection for certain technologies and the costs associated with obtaining patent protection for thosetechnologies. For example, the U.S. Supreme Court has ruled on several patent cases in recent years, either narrowing the scope of patent protection availablein certain circumstances or weakening the rights of patent owners in certain situations. In particular, the 2014 decision by the U.S. Supreme Court in AliceCorp. v. CLS Bank International has increased the difficultly of obtaining new software patents and enforcing existing software patents. Similarly, foreigncourts have made, and will likely continue to make, changes in how the patent laws in their respective jurisdictions are interpreted. We cannot predict futurechanges in the interpretation of patent laws or changes to patent laws that might be enacted into law by U.S. and foreign legislative bodies. Those changesmay materially affect our patents or patent applications and our ability to obtain additional patent protection in the future.Risks Related to Government RegulationChanges in the regulatory environment may constrain or require us to restructure our operations, which may harm our revenue and operating results.Healthcare laws and regulations change frequently and may change significantly in the future. We may not be able to adapt our operations to addressevery new regulation, and new regulations may adversely affect our business. We cannot assure you that a review of our business by courts or regulatoryauthorities would not result in a determination that adversely affects our revenue and operating results, or that the healthcare regulatory environment will notchange in a way that restricts our operations. In addition, there is risk that the U.S. Congress may implement changes in laws and regulations governinghealthcare service providers, including measures to control costs, or reductions in reimbursement levels, which may adversely affect our business and resultsof operations.Government payors, such as CMS, as well as insurers, have increased their efforts to control the cost, utilization and delivery of healthcare services.From time to time, the U.S. Congress has considered and implemented changes in the CMS fee schedules in conjunction with budgetary legislation. Furtherreductions of reimbursement by CMS for services or changes in policy regarding coverage of tests or other requirements for payment, such as priorauthorization or a physician or qualified practitioner’s signature on test requisitions, may be implemented from time to time. Reductions in thereimbursement rates and changes in payment policies of other third-party payors may occur as well. Similar changes in the past have resulted in reducedpayments as well as added costs and have added more complex regulatory and administrative requirements. Further changes in federal, state, local and third-party payor regulations or policies may have a material adverse impact on our business. Actions by agencies regulating insurance or changes in other laws,regulations, or policies may also have a material adverse effect on our business.49 If we fail to comply with healthcare and other governmental regulations, we could face substantial penalties and our business, results of operations andfinancial condition could be adversely affected.The products and services we offer are highly regulated, and there can be no assurance that the regulatory environment in which we operate will notchange significantly and adversely in the future. Our arrangements with physicians, hospitals and clinics may expose us to broadly applicable fraud andabuse and other laws and regulations that may restrict the financial arrangements and relationships through which we market, sell and distribute our productsand services. Our employees, consultants, and commercial partners may engage in misconduct or other improper activities, including non-compliance withregulatory standards and requirements. Federal and state healthcare laws and regulations that may affect our ability to conduct business, include, withoutlimitation: •federal and state laws and regulations regarding billing and claims payment applicable to our Zio service and regulatory agencies enforcingthose laws and regulations •the federal Anti-Kickback Statute, which prohibits, among other things, any person from knowingly and willfully offering, soliciting,receiving or providing remuneration, directly or indirectly, in exchange for or to induce either the referral of an individual for, or thepurchase, order or recommendation of, any good or service for which payment may be made under federal healthcare programs, such as theCMS programs •the federal False Claims Act, which prohibits, among other things, individuals or entities from knowingly presenting, or causing to bepresented, false claims, or knowingly using false statements, to obtain payment from the federal government •federal criminal laws that prohibit executing a scheme to defraud any healthcare benefit program or making false statements relating tohealthcare matters •the FCPA, the U.K. Bribery Act of 2010, and other local anti-corruption laws that apply to our international activities •the federal Physician Payment Sunshine Act, or Open Payments, created under the Affordable Care Act, and its implementing regulations,which requires manufacturers of drugs, medical devices, biologicals and medical supplies for which payment is available under Medicare,Medicaid, or the Children’s Health Insurance Program to report annually to the U.S. Department of Health and Human Services, or HHS,information related to payments or other transfers of value made to licensed physicians and teaching hospitals, as well as ownership andinvestment interests held by physicians and their immediate family members •HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act, and its implementing regulations, whichimpose certain requirements relating to the privacy, security and transmission of individually identifiable health information; HIPAA alsocreated criminal liability for knowingly and willfully falsifying or concealing a material fact or making a materially false statement inconnection with the delivery of or payment for healthcare benefits, items or services •the federal physician self-referral prohibition, commonly known as the Stark Law •state law equivalents of each of the above federal laws, such as anti-kickback and false claims laws which may apply to items or servicesreimbursed by any third-party payor, including commercial insurers, and state and foreign laws governing the privacy and security of healthinformation in certain circumstances, many of which differ from each other in significant ways and often are not preempted by HIPAA, thuscomplicating compliance effortsThe Affordable Care Act, was enacted in 2010. The Affordable Care Act, among other things, amends the intent requirement of the federal Anti-Kickback Statute and criminal healthcare fraud statutes. A person or entity no longer needs to have actual knowledge of this statute or specific intent toviolate it. In addition, the Affordable Care Act provides that the government may assert that a claim including items or services resulting from a violation ofthe federal Anti-Kickback Statute constitutes a false or fraudulent claim for purposes of the False Claims Act.Because of the breadth of these laws and the narrowness of available statutory and regulatory exemptions, it is possible that some of our activitiescould be subject to challenge under one or more of such laws. Any action50 brought against us for violations of these laws or regulations, even successfully defended, could cause us to incur significant legal expenses and divert ourmanagement’s attention from the operation of our business. We may be subject to private “qui tam” actions brought by individual whistleblowers on behalfof the federal or state governments, with potential liability under the federal False Claims Act including mandatory treble damages and significant per-claimpenalties, which were increased to $10,957 to $21,916 per false claim in 2017.Although we have adopted policies and procedures designed to comply with these laws and regulations and conduct internal reviews of ourcompliance with these laws, our compliance is also subject to governmental review. The growth of our business and sales organization and our expansionoutside of the United States may increase the potential of violating these laws or our internal policies and procedures. The risk of our being found inviolation of these or other laws and regulations is further increased by the fact that many have not been fully interpreted by the regulatory authorities or thecourts, and their provisions are open to a variety of interpretations. Any action brought against us for violation of these or other laws or regulations, even ifwe successfully defend against it, could cause us to incur significant legal expenses and divert our management’s attention from the operation of ourbusiness. If our operations are found to be in violation of any of the federal, state and foreign laws described above or any other current or future fraud andabuse or other healthcare laws and regulations that apply to us, we may be subject to penalties, including significant criminal, civil, and administrativepenalties, damages, fines, imprisonment, for individuals, exclusion from participation in government programs, such as Medicare and Medicaid, and wecould be required to curtail or cease our operations. Any of the foregoing consequences could seriously harm our business and our financial results.If we fail to obtain and maintain necessary regulatory clearances or approvals for the Zio XT and Zio AT monitors and Zio service, or if clearances orapprovals for future products and indications are delayed or not issued, our commercial operations would be harmed.The Zio monitors and Zio service are subject to extensive regulation by the FDA in the United States and by our Notified Body in the EuropeanUnion. Government regulations specific to medical devices are wide ranging and govern, among other things: •product design, development and manufacture •laboratory, preclinical and clinical testing, labeling, packaging, storage and distribution •premarketing clearance or approval •record keeping •product marketing, promotion and advertising, sales and distribution •post-marketing surveillance, including reporting of deaths or serious injuries and recalls and correction and removalsBefore a new medical device or service, or a new intended use for an existing product or service, can be marketed in the United States, a companymust first submit and receive either 510(k) clearance or premarketing approval from the FDA, unless an exemption applies. Either process can be expensive,lengthy and unpredictable. We may not be able to obtain the necessary clearances or approvals or may be unduly delayed in doing so, which could harm ourbusiness. Furthermore, even if we are granted regulatory clearances or approvals, they may include significant limitations on the indicated uses for theproduct, which may limit the market for the product. Although we have obtained 510(k) clearance to market the Zio XT and Zio AT monitors and the Zioservice, our clearance can be revoked if safety or efficacy problems develop.In addition, we are required to file various reports with the FDA, and European regulators, including reports required by the medical device reportingregulations, or MDRs, that require that we report to the regulatory authorities if our Zio service may have caused or contributed to a death or serious injury ormalfunctioned in a way that would likely cause or contribute to a death or serious injury if the malfunction were to recur. If these reports are not filed in atimely manner, regulators may impose sanctions and we may be subject to product liability or regulatory enforcement actions, all of which could harm ourbusiness.51 If we initiate a correction or removal for our Zio service to reduce a risk to health posed by the Zio service, we would be required to submit a publiclyavailable Correction and Removal report to the FDA and, in many cases, similar reports to other regulatory agencies. This report could be classified by theFDA as a device recall which could lead to increased scrutiny by the FDA, other international regulatory agencies and our customers regarding the qualityand safety of our Zio service. Furthermore, the submission of these reports could be used by competitors against us and cause physicians to delay or cancelprescriptions, which could harm our reputation.The FDA and the Federal Trade Commission, or FTC, also regulate the advertising and promotion of our products and services to ensure that theclaims we make are consistent with our regulatory clearances, that there is adequate and reasonable data to substantiate the claims and that our promotionallabeling and advertising is neither false nor misleading. If the FDA or FTC determines that any of our advertising or promotional claims are misleading, notsubstantiated or not permissible, we may be subject to enforcement actions, including warning letters, and we may be required to revise our promotionalclaims and make other corrections or restitutions.The FDA and state and international authorities have broad enforcement powers. Our failure to comply with applicable regulatory requirements couldresult in enforcement action any such agency, which may include any of the following sanctions: •adverse publicity, warning letters, fines, injunctions, consent decrees and civil penalties •repair, replacement, refunds, recall or seizure of our products •operating restrictions, partial suspension or total shutdown of production •denial of our requests for regulatory clearance or premarket approval of new products or services, new intended uses or modifications toexisting products or services •withdrawal of regulatory clearance or premarket approvals that have already been granted •criminal prosecutionIf any of these events were to occur, our business and financial condition could be harmed.Material modifications to the Zio XT or Zio AT monitors, labelling of the Zio XT or Zio AT monitors, or Zio service may require new 510(k) clearances,CE Marks or other premarket approvals or may require us to recall or cease marketing our products and services until clearances are obtained.Material modifications to the intended use or technological characteristics of the Zio monitors or Zio service will require new 510(k) clearances,premarket approvals or CE Mark grants, or require us to recall or cease marketing the modified devices until these clearances or approvals are obtained. Basedon FDA published guidelines, the FDA requires device manufacturers to initially make and document a determination of whether or not a modificationrequires a new approval, supplement or clearance; however, the FDA can review a manufacturer’s decision. Any modification to an FDA cleared device orservice that would significantly affect its safety or efficacy or that would constitute a major change in its intended use would require a new 510(k) clearanceor possibly a premarket approval. We may not be able to obtain additional 510(k) clearances or premarket approvals for new products or for modifications to,or additional indications for, the Zio monitors or Zio service in a timely fashion, or at all. Delays in obtaining required future clearances would harm ourability to introduce new or enhanced products in a timely manner, which in turn would harm our future growth. We have made modifications to the Ziomonitors and Zio service in the past that we believe do not require additional clearances or approvals, and we may make additional modifications in thefuture. If the FDA or an EU Notified Body disagrees and requires new clearances or approvals for any of these modifications, we may be required to recall andto stop selling or marketing the Zio monitors and Zio service as modified, which could harm our operating results and require us to redesign our products orservices. In these circumstances, we may be subject to significant enforcement actions.52 If we or our suppliers fail to comply with the FDA’s QSR or the European Union’s Medical Device Directive, our manufacturing or distribution operationscould be delayed or shut down and our revenue could suffer.Our manufacturing and design processes and those of our third-party suppliers are required to comply with the FDA’s Quality System Regulation, orQSR and the EU’s Medical Device Directive, or MDD, both of which cover procedures and documentation of the design, testing, production, control, qualityassurance, labeling, packaging, storage and shipping of Zio monitors. We are also subject to similar state requirements and licenses, and to ongoing ISOcompliance in all operations, including design, manufacturing, and service, to maintain our CE Mark. In addition, we must engage in extensiverecordkeeping and reporting and must make available our facilities and records for periodic unannounced inspections by governmental agencies, includingthe FDA, state authorities, EU Notified Bodies and comparable agencies in other countries. If we fail a regulatory inspection, our operations could bedisrupted and our manufacturing interrupted. Failure to take adequate corrective action in response to an adverse regulatory inspection could result in,among other things, a shutdown of our manufacturing or product distribution operations, significant fines, suspension of marketing clearances and approvals,seizures or recalls of our device, operating restrictions and criminal prosecutions, any of which would cause our business to suffer. Furthermore, our keycomponent suppliers may not currently be or may not continue to be in compliance with applicable regulatory requirements, which may result inmanufacturing delays for our product and cause our revenue to decline.We are registered with the FDA as a medical device specifications developer and manufacturer. The FDA has broad post-market and regulatoryenforcement powers. We are subject to unannounced inspections by the FDA and the Food and Drug Branch of the California Department of Public Health, orCDPH, to determine our compliance with the QSR and other regulations at both our design and manufacturing facilities, and these inspections may includethe manufacturing facilities of our suppliers. Our design facilities in San Francisco, California were most recently audited by the FDA in June 2016 and noformal observations resulted. The most recent FDA audit of our manufacturing facility occurred in August 2017 and no formal observations resulted. Noadditional follow up with the FDA was required and we believe that we are in substantial compliance with the QSR.We are also registered with the EU as a medical device developer, manufacturer and service operator through the National Standard Authority ofIreland, or NSAI, our European Notified Body. Most recently, the NSAI conducted an ISO 13485 recertification audit of our design, manufacturing andservice operations in March, April and June 2017.We can provide no assurance that we will continue to remain in compliance with the QSR or MDD. If the FDA, CDPH or NSAI inspect any of ourfacilities and discover compliance problems, we may have to cease manufacturing and product distribution until we can take the appropriate remedial stepsto correct the audit findings. Taking corrective action may be expensive, time consuming and a distraction for management and if we experience a delay atour manufacturing facility we may be unable to produce Zio monitors, which would harm our business.Zio monitors may in the future be subject to product recalls that could harm our reputation.The FDA and similar governmental authorities in other countries have the authority to require the recall of commercialized products in the event ofmaterial regulatory deficiencies or defects in design or manufacture. A government mandated or voluntary recall by us could occur as a result of componentfailures, manufacturing errors or design or labeling defects. Recalls of Zio monitors would divert managerial attention, be expensive, harm our reputationwith customers and harm our financial condition and results of operations. A recall announcement would also negatively affect our stock price.Healthcare reform measures could hinder or prevent the Zio service’s commercial success.In the United States, there have been, and we expect there will continue to be, a number of legislative and regulatory changes to the healthcare system inways that could harm our future revenues and profitability and the demand for the Zio service. Federal and state lawmakers regularly propose and, at times,enact legislation that would result in significant changes to the healthcare system, some of which are intended to contain or reduce the costs of medicalproducts and services. The Affordable Care Act contains a number of provisions, including those governing enrollment in federal healthcare programs,reimbursement changes and fraud and abuse measures, all of which will53 impact existing government healthcare programs and will result in the development of new programs. The Affordable Care Act, among other things, imposedan excise tax of 2.3% on the sale of most medical devices, including ours, and any failure to pay this amount could result in the imposition of an injunctionon the sale of our products, fines and penalties. Although this tax has been suspended through 2019, it is expected to apply to sales of our products in 2020and thereafter. The current presidential administration and Congress may continue to attempt broad sweeping changes to the current health care laws. We faceuncertainties that might result from modifications or repeal of any of the provisions of the Affordable Care Act, including as a result of current and futureexecutive orders and legislative actions. The impact of those changes on us and potential effect on the medical device industry as a whole is currentlyunknown. Any changes to the Affordable Care Act are likely to have an impact on our results of operations, and may have a material adverse effect on ourresults of operations. We cannot predict what other health care programs and regulations will ultimately be implemented at the federal or state level or theeffect of any future legislation or regulation in the United States may have on our business.The continuing efforts of the government, insurance companies, managed care organizations and other payors of healthcare services to contain orreduce costs of healthcare may harm: •our ability to set a price that we believe is fair for our Zio service •our ability to generate revenue and achieve or maintain profitability •the availability of capitalCompliance with environmental laws and regulations could be expensive, and failure to comply with these laws and regulations could subject us tosignificant liability.Our research and development and manufacturing operations involve the use of hazardous substances and are subject to a variety of federal, state,local and foreign environmental laws and regulations relating to the storage, use, discharge, disposal, remediation of, and human exposure to, hazardoussubstances and the sale, labeling, collection, recycling, treatment and disposal of products containing hazardous substances. Liability under environmentallaws and regulations can be joint and several and without regard to fault or negligence. Compliance with environmental laws and regulations may beexpensive and noncompliance could result in substantial liabilities, fines and penalties, personal injury and third-party property damage claims andsubstantial investigation and remediation costs. Environmental laws and regulations could become more stringent over time, imposing greater compliancecosts and increasing risks and penalties associated with violations. We cannot assure you that violations of these laws and regulations will not occur in thefuture or have not occurred in the past as a result of human error, accidents, equipment failure or other causes. The expense associated with environmentalregulation and remediation could harm our financial condition and operating results.Risks Related to Our Common StockThe market price of our common stock may fluctuate substantially, and you could lose all or part of your investment.Our common stock became publicly traded in 2016, and we cannot be certain that an active trading market for our common stock will be sustained.The lack of an active market may impair the value of our common stock, or your ability to sell your shares at the time you wish to sell them or at a price thatyou consider reasonable. An inactive market may also impair our ability to raise capital to continue to fund operations by selling common stock and mayimpair our ability to acquire other companies or products by using our common stock as consideration. Although our common stock is listed on the NASDAQGlobal Select Market, if we fail to satisfy the continued listing standards of the NASDAQ Global Select Market, we could be de-listed, which wouldnegatively impact the price of our common stock.54 The market price of our common stock may fluctuate substantially in response to, among other things, the risk factors described in this AnnualReport on Form 10-K and other factors, many of which are beyond our control, including: •changes in analysts’ estimates, investors’ perceptions, recommendations by securities analysts or our failure to achieve analysts’ estimates •quarterly variations in our or our competitors’ results of operations •periodic fluctuations in our revenue, due in part to the way in which we recognize revenue •the financial projections we may provide to the public, any changes in these projections or our failure to meet these projections •general market conditions and other factors unrelated to our operating performance or the operating performance of our competitors •changes in reimbursement by current or potential payors •changes in operating performance and stock market valuations of other technology companies generally, or those in the medical deviceindustry in particular •actual or anticipated changes in regulatory oversight of our products •the results of our clinical trials •the loss of key personnel, including changes in our board of directors and management •legislation or regulation of our market •lawsuits threatened or filed against us •the announcement of new products or product enhancements by us or our competitors •announced or completed acquisitions of businesses or technologies by us or our competitors •announcements related to patents issued to us or our competitors and to litigation •developments in our industryIn addition, the market prices of the stock of many new issuers in the medical device industry and of other companies with smaller marketcapitalizations like us have been volatile and from time to time have experienced significant share price and trading volume changes unrelated ordisproportionate to the operating performance of those companies. Fluctuations in our stock price, volume of shares traded, and changes in our marketvaluations may make our stock less attractive to certain investors. In the past, stockholders have filed securities class action litigation following periods ofmarket volatility. If we were to become involved in securities litigation, it could subject us to substantial costs, divert resources and the attention ofmanagement from our business, and adversely affect our business, results of operations, financial condition, reputation and cash flows. These factors maymaterially and adversely affect the market price of our common stock.If securities or industry analysts do not publish research or reports about our business, or publish negative reports about our business, our share price andtrading volume could decline.The trading market for our common stock depends in part on the research and reports that securities or industry analysts publish about us or ourbusiness, our market and our competitors. We do not have any control over these analysts. If one or more of the analysts who cover us downgrade our sharesor change their opinion of our business, our share price would likely decline. If one or more of these analysts cease coverage of our company or fail toregularly publish reports on us, we could lose visibility in the financial markets, which could cause our share price or trading volume to decline.55 The requirements of being a public company may strain our resources, divert management’s attention and affect our ability to attract and retain executivemanagement and qualified board members.As a public company, we are subject to the reporting requirements of the Exchange Act, the Sarbanes-Oxley Act, the Dodd Frank Act, the listingrequirements of The NASDAQ Stock Market and other applicable securities laws, rules and regulations. Compliance with these laws, rules and regulationswill increase our legal and financial compliance costs, make some activities more difficult, time consuming or costly and increase demand on our systems andresources. The Exchange Act requires, among other things, that we file annual, quarterly and current reports with respect to our business and operating results.The Sarbanes-Oxley Act requires, among other things, that we maintain effective disclosure controls and procedures and internal control over financialreporting. In order to maintain and, if required, improve our disclosure controls and procedures and internal control over financial reporting to meet thisstandard, significant resources and management oversight may be required. As a result, our management and other personnel divert attention from operationaland other business matters to devote substantial time to these public company requirements. In particular, we will incur significant expenses and devotesubstantial management effort toward ensuring compliance with the requirements of Section 404, which has increased now that we will no longer be anemerging growth company under the JOBS Act. We continue to hire additional accounting and financial staff with appropriate public company experienceand technical accounting knowledge. We cannot predict or estimate the amount of additional costs we will incur in order to remain compliant with our publiccompany reporting requirements or the timing of such costs. Additional compensation costs and any future equity awards will increase our compensationexpense, which will increase our general and administrative expense and could adversely affect our profitability.In addition, changing laws, regulations and standards relating to corporate governance and public disclosure are creating uncertainty for publiccompanies, increasing legal and financial compliance costs and making some activities more time consuming. These laws, regulations and standards aresubject to varying interpretations, in many cases due to their lack of specificity and, as a result, their application in practice may evolve over time as newguidance is provided by regulatory and governing bodies. This could result in continuing uncertainty regarding compliance matters and higher costsnecessitated by ongoing revisions to disclosure and governance practices. We intend to invest resources to comply with evolving laws, regulations andstandards, and this investment may result in increased general and administrative expenses and a diversion of management’s time and attention from revenuegenerating activities to compliance activities. If our efforts to comply with new laws, regulations and standards differ from the activities intended byregulatory or governing bodies due to ambiguities related to their application and practice, regulatory authorities may initiate legal proceedings against usand our business may be harmed.We will incur additional compensation costs in the event that we decide to pay our executive officers cash compensation closer to that of executiveofficers of other public medical device companies, which would increase our general and administrative expense and could harm our profitability. Any futureequity awards will also increase our compensation expense. We also expect that being a public company and compliance with applicable rules andregulations will make it more expensive for us to obtain director and officer liability insurance, and we may be required to accept reduced coverage or incursubstantially higher costs to obtain coverage. These factors could also make it more difficult for us to attract and retain qualified executive officers andmembers of our board of directors, particularly to serve on our audit committee and compensation committee.As a result of disclosure of information in this filing and in other filings required of a public company, our business and financial condition is morevisible, which could be advantageous to our competitors and other third parties and could result in threatened or actual litigation. If such claims aresuccessful, our business and operating results could be harmed, and even if the claims are resolved in our favor, these claims, and the time and resourcesnecessary to resolve them, could divert the resources of our management and harm our business and operating results.56 Anti-takeover provisions in our amended and restated certificate of incorporation and bylaws, and Delaware law, could discourage a change in control ofour company or a change in our management.Our amended and restated certificate of incorporation and bylaws contain provisions that might enable our management to resist a takeover. Theseprovisions include: •a classified board of directors •advance notice requirements applicable to stockholders for matters to be brought before a meeting of stockholders and requirements as to theform and content of a stockholders’ notice •a supermajority stockholder vote requirement for amending certain provisions of our amended and restated certificate of incorporation andbylaws •the right to issue preferred stock without stockholder approval, which could be used to dilute the stock ownership of a potential hostileacquirer •allowing stockholders to remove directors only for cause •a requirement that the authorized number of directors may be changed only by resolution of the board of directors •allowing all vacancies, including newly created directorships, to be filled by the affirmative vote of a majority of directors then in office,even if less than a quorum, except as otherwise required by law •a requirement that our stockholders may only take action at annual or special meetings of our stockholders and not by written consent •limiting the forum to Delaware for certain litigation against us •limiting the persons that can call special meetings of our stockholders to our board of directors, the chairperson of our board of directors, thechief executive officer or the president (in the absence of a chief executive officer)These provisions might discourage, delay or prevent a change in control of our company or a change in our management. The existence of theseprovisions could adversely affect the voting power of holders of common stock and limit the price that investors might be willing to pay in the future forshares of our common stock. In addition, because we are incorporated in Delaware, we are governed by the provisions of Section 203 of the Delaware GeneralCorporation Law, which generally prohibits a Delaware corporation from engaging in any of a broad range of business combinations with any “interested”stockholder for a period of three years following the date on which the stockholder became an “interested” stockholder.Our amended and restated certificate of incorporation provides that the Court of Chancery of the State of Delaware will be the sole and exclusive forumfor substantially all disputes between us and our stockholders, which could limit our stockholders’ abilities to obtain a favorable judicial forum fordisputes with us or our directors, officers or employees.Our amended and restated certificate of incorporation provides that, unless we consent to the selection of an alternative forum, the Court of Chanceryof the State of Delaware is the sole and exclusive forum for (i) any derivative action or proceeding brought on our behalf, (ii) any action asserting a claim ofbreach of fiduciary duty owed by any of our directors, officers or other employees to us or to our stockholders, (iii) any action asserting a claim arisingpursuant to the Delaware General Corporation Law or our amended and restated certificate of incorporation or bylaws, (iv) any action to interpret, apply,enforce or determine the validity of our amended and restated certificate of incorporation or bylaws or (v) any action asserting a claim governed by theinternal affairs doctrine. The choice of forum provision may limit a stockholder’s ability to bring a claim in a judicial forum that it finds favorable fordisputes with us or our directors, officers or other employees, which may discourage such lawsuits against us and our directors, officers and other employees.Alternatively, if a court were to find the choice of forum provision contained in our amended and restated certificate of incorporation to be inapplicable orunenforceable in an action, we may incur additional costs associated with resolving such action in other jurisdictions, which could harm our business,financial condition and operating results.57 We have not paid dividends in the past and do not expect to pay dividends in the future, and, as a result, any return on investment may be limited to thevalue of our stock.We have never paid cash dividends and do not anticipate paying cash dividends in the foreseeable future. The payment of dividends will depend onour earnings, capital requirements, financial condition, prospects and other factors our board of directors may deem relevant. In addition, our loan agreementslimit our ability to, among other things, pay dividends or make other distributions or payments on account of our common stock, in each case subject tocertain exceptions. If we do not pay dividends, our stock may be less valuable because a return on your investment will only occur if you sell our commonstock after our stock price appreciates.Item 1B. Unresolved Staff Comments.Not applicable.Item 2. Properties.We lease 60,873 square feet for our corporate headquarters located in San Francisco, California under a lease agreement which will expire in February2020.We lease 41,500 square feet for our clinical center in Lincolnshire, Illinois under a lease agreement that expires in October 2019. We also lease20,276 square feet in Houston, Texas for another clinical center under a lease agreement that expires in September 2027.We lease 9,866 square feet for our manufacturing and distribution facilities in Cypress, California under an agreement that expires in September2020.We believe that these facilities are sufficient to meet our current and anticipated future needs.Item 3. Legal Proceedings.We are not currently a party to any material litigation or other material legal proceedings. From time to time we may be involved in legal proceedingsor investigations, which could have an adverse impact on our reputation, business and financial condition and divert the attention of our management fromthe operation of our business.Item 4. Mine Safety Disclosures.Not applicable.58 PART IIItem 5. Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities.Market InformationOur common stock began being traded on The NASDAQ Global Market under the symbol “IRTC” on October 20, 2016 and was subsequentlyupgraded to the NASDAQ Global Select Market. Prior to that date, there was no public trading market for our common stock. The following table sets forththe high and low sales price per share of our common stock as reported on The NASDAQ Global Select Market for the periods indicated: Year Ended December 31, 2016: High Low Fourth Quarter (from October 20, 2016) $30.94 $23.08 Year Ended December 31, 2017: First Quarter $39.84 $29.41 Second Quarter $42.92 $32.74 Third Quarter $51.88 $40.56 Fourth Quarter $57.68 $48.21Holders of Common StockAs of February 23, 2018, there were 27 holders of record of our common stock. Certain shares are held in “street” name and, accordingly, the numberof beneficial owners of such shares is not known or included in the foregoing number.Dividend PolicyWe have never declared or paid cash dividends on our capital stock. We intend to retain all available funds and any future earnings, if any, to fundthe development and expansion of our business and we do not anticipate paying any cash dividends in the foreseeable future. Any future determinationrelated to dividend policy will be made at the discretion of our board of directors.59 Performance GraphThis graph is not “soliciting material,” is not deemed “filed” with the SEC and is not to be incorporated by reference into any filing of iRhythmTechnologies, Inc. under the Securities Act or the Exchange Act, whether made before or after the date hereof and irrespective of any general incorporationlanguage in any such filing.The following graph shows the total stockholder return of an investment of $100 in cash at market close on October 20, 2016 (the first day of tradingof our common stock), through December 29, 2017 for (i) our common stock, (ii) the NASDAQ Composite Index (U.S.) and (iii) the NASDAQ BiotechnologyIndex. Pursuant to applicable Securities and Exchange Commission rules, all values assume reinvestment of the full amount of all dividends, however nodividends have been declared on our common stock to date. The stockholder return shown on the graph below is not necessarily indicative of futureperformance, and we do not make or endorse any predictions as to future stockholder returns. 10/20/2016 12/31/2016 3/31/2017 6/30/2017 9/30/2017 12/31/2017 iRhythm Technologies, Inc. $100 $115 $144 $163 $199 $215 NASDAQ Composite $100 $103 $113 $117 $124 $132 NASDAQ Biotechnology $100 $98 $109 $115 $124 $119 Recent Sales of Unregistered SecuritiesFrom January 1, 2016 through December 31, 2016, we sold and issued the following unregistered securities, which share numbers have beenadjusted, as appropriate, for the 5.882698-to-1 reverse stock split that occurred on October 5, 2016: 1.From January 1, 2016 through October 21, 2016 (the date of the filing of our registration statement on Form S-8, File No. 333-214203), we issuedand sold an aggregate of 44,702 shares of common stock to employees, directors and consultants for cash consideration in the aggregate amountof $84,000 upon the exercise of stock options. 60 2.From January 1, 2016 through October 21, 2016 (the date of the filing of our registration statement on Form S-8, File No. 333-214203), wegranted stock options and stock awards to employees, directors and consultants under our 2006 Stock Incentive Plan and our 2016 EquityIncentive Plan covering an aggregate of 339,758 shares of common stock, at an average exercise price of $14.98 per share. Of these, optionscovering an aggregate of 1,952 shares were cancelled without being exercised.We deemed the grants and exercises of stock options described above to be exempt from registration under the Securities Act in reliance on Rule701 of the Securities Act as offers and sales of securities under compensatory benefit plans and contracts relating to compensation in compliance with Rule701. Each of the recipients of securities in any transaction exempt from registration either received or had adequate access, through employment, business orother relationships, to information about us.Use of ProceedsOn October 25, 2016, we closed our initial public offering, or IPO, of 7,238,235 shares of common stock (inclusive of 944,117 shares of commonstock from the full exercise of the overallotment option of shares granted to the underwriters). The offer and sale of all of the shares in the initial publicoffering were registered under the Securities Act pursuant to a registration statement on Form S-1 (File Nos. 333-213773 and 333-214179), which wasdeclared effective by the SEC on October 19, 2016. J.P. Morgan Securities LLC, Morgan Stanley Securities LLC & Co. LLC, Canaccord Genuity Inc. andBTIG, LLC acted as the underwriters. The public offering price of the shares sold in the offering was $17.00 per share. The total gross proceeds from theoffering were $123.0 million.After deducting underwriting discounts and commissions of $8.6 million and offering expenses paid or payable by us of approximately $3.7 million,the net proceeds from the offering were approximately $110.7 million.There has been no material change in the planned use of proceeds from our IPO as described in our final IPO prospectus filed with the SEC onOctober 20, 2016 pursuant to rule 424(b) of the Securities Act. We invested the funds received in short-term and long-term, interest-bearing investment-gradesecurities and government securities.Issuer Purchases of Equity SecuritiesNone61 Item 6. Selected Consolidated Financial Data.The information set forth below should be read in conjunction with "Item 7. Management's Discussion and Analysis of Financial Condition andResults of Operations" and our financial statements and related notes included elsewhere in this Annual Report on Form 10-K. The selected consolidatedfinancial data in this section are not intended to replace our financial statements and are qualified in their entirety by the financial statements and relatednotes included elsewhere in this Annual Report on Form 10-K. The selected consolidated balance sheet data at December 31, 2017, 2016, 2015 and 2014 andthe selected consolidated statements of operations data for each of the years ended December 31, 2017, 2016, 2015 and 2014 have been derived from ouraudited consolidated financial statements. The financial data included in this report are historical and are not necessarily indicative of results to be expectedin any future period. Year Ended December 31,(in thousands, except share and per share data) 2017 2016 2015 2014 Consolidated Statements of Operation Data: Revenue $98,509 $64,072 $36,140 $21,749 Cost of revenue(1) 27,708 20,883 14,700 10,591 Gross profit 70,801 43,189 21,440 11,158 Operating expenses: Research and development(1) 13,335 7,150 6,349 5,698 Selling, general and administrative(1) 84,737 51,621 36,722 20,225 Total operating expenses(1) 98,072 58,771 43,071 25,923 Loss from operations (27,271) (15,582) (21,631) (14,765)Interest expense (3,386) (3,248) (1,059) (774)Other expense, net 1,237 (2,073) (109) (293)Net loss $(29,420) $(20,903) $(22,799) $(15,832)Net loss per common share, basic and diluted $(1.30) $(3.95) $(16.57) $(12.05)Shares used in computing net loss per common share, basic and diluted 22,627,327 5,285,847 1,376,106 1,314,294 (1)Includes employee stock-based compensation as follows: Year Ended December 31, 2017 2016 2015 2014 Cost of revenue $163 $17 $17 $15 Research and development 1,733 203 165 80 Selling, general and administrative 8,227 1,651 1,228 733 Total stock-based compensation $10,123 $1,871 $1,410 $828 As of December 31, 2017 2016 2015 2014 Consolidated Balance Sheets Data: Cash and cash equivalents $8,671 $51,643 $25,208 $8,618 Working capital 98,663 105,393 24,054 10,672 Total assets 133,123 138,156 37,872 18,509 Notes payable 33,978 32,227 30,552 6,255 Convertible preferred stock — — 97,096 85,014 Accumulated deficit (156,589) (127,169) (106,266) (83,467)Total stockholders' equity (deficit) $79,553 $92,562 $(101,624) $(80,544) 62 Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.You should read the following discussion and analysis of our financial condition and results of operations together with the financial statementsand related notes included elsewhere in Item 8 of Part II of this Annual Report on Form 10-K. This discussion and other parts of this Annual Report on Form10-K contain forward-looking statements that involve risks and uncertainties, such as statements of our plans, objectives, expectations and intentions. Ouractual results could differ materially from those discussed in these forward-looking statements. Factors that could cause or contribute to such differencesinclude, but are not limited to, those discussed in the section of this Annual Report on Form 10-K entitled “Risk Factors.”OverviewWe are a commercial-stage digital healthcare company redefining the way cardiac arrhythmias are clinically diagnosed by combining our wearablebiosensing technology with cloud-based data analytics and machine-learning capabilities. Our goal is to be the leading provider of first-line ambulatoryelectrocardiogram, or ECG, monitoring for patients at risk for arrhythmias. We have created a unique platform, called the Zio service, which combines aneasy-to-wear and unobtrusive biosensor that can be worn for up to 14 days with powerful proprietary algorithms that distill data from millions of heartbeatsinto clinically actionable information.The Zio service consists of: •a wearable patch-based biosensor, which continuously records and stores ECG data from every patient heartbeat for up to 14 days •a cloud-based analysis of the recorded cardiac rhythms using our proprietary machine-learned algorithms •a final quality assessment review of the data by our certified cardiac technicians •the easy-to-read Zio Report, a curated summary of findings that includes high quality and clinically-actionable information, which is sentdirectly to a patient’s physician and can be integrated into a patient’s electronic health recordWe receive revenue for the Zio service primarily from two sources: third-party payors and institutions. Third-party payors, which accounted forapproximately 82%, 74% and 62% of our revenue for the years ended December 31, 2017, 2016 and 2015, respectively, consist of commercial payors andgovernment agencies, such as the Centers for Medicare & Medicaid Services, or CMS, and the Veterans Administration, or VA. A significant portion of ourrevenue in the third-party commercial payor category is contracted, which means we have entered into pricing contracts with these payors. Approximately37%, 40% and 41% of our total revenue for the years ended December 31, 2017, 2016 and 2015, respectively, is received from federal government agenciesunder established reimbursement codes. A small portion of this revenue is received from patients in accordance with their insurance co-payments anddeductibles. Institutions, which are typically hospitals, clinics, or private physician practices accounted for approximately 18%, 26% and 38% of our revenuefor the years ended December 31, 2017, 2016, and 2015 respectively. We bill these organizations directly for our services and they are responsible for payingthose invoices and seeking reimbursement from third-party payors where applicable. In addition, a small percentage of patients whose physicians prescribethe Zio service pay us directly. Typically, we bill institutional customers and rely on a third-party billing partner, XIFIN, Inc., to submit patient claims andcollect from commercial payors and certain government agencies.Since our Zio service was cleared by the U.S. Food and Drug Administration, or FDA, in 2009, we have provided the Zio service to over one millionpatients and have collected over 250 million hours of curated heartbeat data. We believe the Zio service is well-positioned to disrupt an already-established$1.4 billion U.S. ambulatory cardiac monitoring market by offering a user-friendly device to patients, actionable information to physicians and value topayors.63 We market our Zio service in the United States and the United Kingdom to physicians, hospitals and clinics through a direct sales organizationcomprised of sales management, field billing specialists, and quota-carrying sales representatives. Our sales representatives focus on initial introduction intonew customers, penetration across a sales region, driving adoption within existing accounts and conveying our message of clinical and economic value toservice line managers and hospital administrators and departments. We expect to continue to increase the size of our sales organization to expand the currentcustomer account base and increase utilization of our monitoring solution. In addition, we will continue to explore new opportunities to expand our sales andmarketing efforts in international geographies using both direct and distribution channels.Components of Results of OperationsRevenueSubstantially all of our revenue is derived from sales of our Zio service in the United States. We earn revenue from the provision of our Zio serviceprimarily from two sources, third-party payors and institutions; however, a small percentage of our revenue is derived directly from patient payments. For theyears ended December 31, 2017, 2016 and 2015, we recognized approximately 89%, 83% and 90%, respectively, of our revenue on an accrual basis forinstances where we have a predictable history of collections, which consists primarily of revenue from contracted payors and institutions. We recognizerevenue based on the billing rate less contractual and other adjustments to arrive at the amount we expect to collect from third-party payors with anestablished billing rate. We determine the amount we expect to collect based on a per-payor or agreement basis, after analyzing payment history. When we donot have a contract or agreement, or have an insufficient or unpredictable history of collections, we recognize revenue only upon the earlier of notification ofthe payor benefits allowed or when payment is received. We expect our revenue to increase as we increase the number of covered and contracted lives for ourZio service, expand our sales and marketing infrastructure, increase awareness of our product offerings, expand the range of indications for our Zio serviceand develop new products and services. We are subject to seasonality similar to other companies in our field, as vacations by physicians and patients tend toaffect enrollment in the Zio service more during the summer months and during the end of year holidays compared to other times of the year. To date, theeffect of these seasonal fluctuations on our quarterly results has been obscured by the growth of our business.Cost of Revenue and Gross MarginCost of revenue is expensed as incurred and includes direct labor, material costs, equipment and infrastructure expenses, amortization of internal-usesoftware, allocated overhead, and shipping and handling. Direct labor includes personnel involved in manufacturing and data analysis. Material costsinclude both the disposable materials costs of the Zio XT monitors and amortization of the re-usable printed circuit board assemblies, or PCBAs. Each Zio XTmonitor includes a PCBA, the cost of which is amortized over the anticipated number of uses of the board. We expect cost of revenue to increase in absolutedollars to the extent our revenue grows.We calculate gross margin as gross profit divided by revenue. Our gross margin has been and will continue to be affected by a variety of factors,including increased contracting with third-party payors and institutional providers. Historically, we have increased our average selling price by entering intocontracts with third-party commercial payors at rates that were higher than amounts typically collected from payors without contracts or from institutionalcustomers. We have in the past been able to increase our pricing as third-party payors become more familiar with the benefits of the Zio service and move tocontracted pricing arrangements. We believe we will be able to continue to achieve pricing increases as more payors contract with us due to the benefits theZio service provides compared to other available products. We expect to continue to decrease the cost of service per device by obtaining volume purchasediscounts for our material costs and implementing scan time algorithm improvements and software-driven workflow enhancements to reduce labor costs. Weexpect further decreases in the cost of service as we spread the fixed portion of our manufacturing overhead costs over a larger number of units produced,which will result in a decrease in our per unit manufacturing costs.64 Research and Development ExpensesWe expense research and development costs as they are incurred. Research and development expenses include payroll and personnel-related costsincluding stock-based compensation, consulting services, clinical studies, laboratory supplies and an allocation of facility overhead costs. We expect ourresearch and development costs to increase in absolute dollars as we hire additional personnel to develop new product and service offerings and productenhancements.Selling, General and Administrative ExpensesOur sales and marketing expenses consist of payroll and personnel-related costs, including stock-based compensation, sales commissions, travelexpenses, consulting, public relations costs, direct marketing, tradeshow and promotional expenses and allocated facility overhead costs. We expect our salesand marketing expenses to increase in absolute dollars as we hire additional sales personnel and increase our sales support infrastructure in order to furtherpenetrate the U.S. market and expand into international markets. Our general and administrative expenses consist primarily of compensation for executive,finance, legal and administrative personnel, including stock-based compensation. Other significant expenses include professional fees for legal andaccounting services, consulting fees, recruiting fees, bad debt expense, third-party patient claims processing fees and travel expenses.Interest ExpenseInterest expense consists of cash and non-cash components. The cash component of interest expense is attributable to borrowings under our loanagreements and amounts owed under the promissory note issued to California HealthCare Foundation. The non-cash component consists of interest expenserecognized from the amortization of debt discounts derived from the issuance of warrants and debt issuance costs capitalized on our balance sheets, and“paid-in-kind” interest when debt payments are interest only and are added back to the debt balance.Other Income (Expense), NetOther income (expense), net consists primarily of the change in fair value of our convertible preferred stock warrant liabilities and interest income.Our convertible preferred stock warrants were exercisable for shares that were contingently redeemable and as such, were classified as a liability on ourbalance sheets at their estimated fair value. Upon completion of our IPO, all convertible preferred stock warrants converted into warrants to purchase commonstock. Interest income consists primarily of interest received on our cash, cash equivalents and investments balances.65 Results of OperationsComparison of the Years Ended December 31, 2017 and 2016 Years Ended December 31, 2017 2016 $ Change % Change (dollars in thousands) Revenue $98,509 $64,072 $34,437 54%Cost of revenue 27,708 20,883 6,825 33%Gross profit 70,801 43,189 27,612 64%Gross margin 72% 67% Operating expenses: Research and development 13,335 7,150 6,185 87%Selling, general and administrative 84,737 51,621 33,116 64%Total operating expenses 98,072 58,771 39,301 67%Loss from operations (27,271) (15,582) (11,689) 75%Interest expense (3,386) (3,248) (138) 4%Other income (expense), net 1,237 (2,073) 3,310 (160)%Net loss $(29,420) $(20,903) $(8,517) 41% Revenue Revenue increased $34.4 million, or 54%, to $98.5 million during the year ended December 31, 2017 from $64.1 million during the year endedDecember 31, 2016. The increase in revenue was primarily attributable to the increase in volume of the Zio service performed as a result of the expansion ofcoverage and the increase in the number of payors under contract, increasing physician acceptance and expansion of our sales force as we continue to gainmarket acceptance for our Zio service. Cost of Revenue and Gross Margin Cost of revenue increased $6.8 million, or 33%, to $27.7 million during the year ended December 31, 2017 from $20.9 million during the year endedDecember 31, 2016. The increase in cost of revenue was primarily due to increased Zio service volume in 2017. This increase was partially offset by thereduction in costs to provide the Zio service, which was achieved through manufacturing efficiencies in the production of our device and reductions incardiac technician labor costs through algorithm improvements and software driven workflow enhancements. Gross margin for the year ended December 31, 2017 increased to 72%, compared to 67% for the year ended December 31, 2016. The increase wasdriven primarily by the reduction in the cost of the Zio service due to our continued efforts to lower manufacturing costs, fixed costs absorption and reducedlabor costs per device through our algorithm improvements and software-driven workflow enhancements. In addition, we experienced some mix shift drivenby the success of our contracting efforts, which also improved our gross margin during the year ended December 31, 2017. Research and Development Expenses Research and development expenses increased $6.2 million, or 87%, to $13.3 million during the year ended December 31, 2017 from $7.2 millionduring the year ended December 31, 2016. The increase was primarily attributable to a $4.4 million increase for payroll and personnel-related expenses as aresult of increased headcount to support the growth in our operations, and a $1.4 million increase in facility-related expenses. Selling, General and Administrative Expenses Selling, general and administrative expenses increased $33.1 million, or 64%, to $84.7 million during the year ended December 31, 2017 from $51.6million during the year ended December 31, 2016. The increase was primarily attributable to a $18.7 million increase in payroll and personnel-relatedexpenses as a result of increased headcount to support the growth in our operations, a $6.0 million increase in professional services expenses, primarily as a66 result of an increase in accounting, legal and recruiting services expenses, a $1.8 million increase in facility-related expenses, and a $1.7 million increase inbad-debt expense primarily due to the overall increase in accounts receivable. Interest Expense Interest expense increased $0.2 million to $3.4 million during the year ended December 31, 2017 from $3.2 million during the year ended December31, 2017 due to increased principal balance of our December 2015 debt financing as a result of paid-in-kind interest. Other Income (Expense), Net Other income (expense), net increased $3.3 million to income of $1.2 million during the year ended December 31, 2017 from expense of $2.1 millionduring the year ended December 31, 2016. The change was primarily related to an increase of $1.2 million of interest income from our investments and$2.1 million decrease from the fair value re-measurement of preferred stock warrant liabilities at each balance sheet date, which concluded upon theconversion to common warrants upon the IPO in October 2016. Comparison of the Year Ended December 31, 2016 and 2015 Year Ended December 31, 2016 2015 $ Change % Change (dollars in thousands) Revenue $64,072 $36,140 $27,932 77%Cost of revenue 20,883 14,700 6,183 42 Gross profit 43,189 21,440 21,749 101 Gross margin 67% 59% Operating expenses: Research and development 7,150 6,349 801 13 Selling, general and administrative 51,621 36,722 14,899 41 Total operating expenses 58,771 43,071 15,700 36 Loss from operations (15,582) (21,631) 6,049 28 Interest expense (3,248) (1,059) (2,189) 207 Other expense, net (2,073) (109) (1,964) 1,802 Net loss $(20,903) $(22,799) $1,896 (8)% Revenue Revenue increased $27.9 million, or 77%, to $64.1 million during the year ended December 31, 2016 from $36.1 million during the year endedDecember 31, 2015. The increase in revenue was primarily attributable to the increase in volume of the Zio service performed as a result of the expansion ofcoverage and the increase in the number of payors under contract, increasing physician acceptance and expansion of our sales force as we continued to gainmarket acceptance for our Zio service. To a lesser extent, increases in contracted rates contributed to the revenue increase.Cost of Revenue and Gross MarginCost of revenue increased $6.2 million, or 42%, to $20.9 million during the year ended December 31, 2016 from $14.7 million during the yearended December 31, 2015. The increase in cost of revenue was primarily due to increased Zio service volume in 2016. This increase was partially offset bythe reduction in costs to provide the Zio service, which was achieved through manufacturing efficiencies in the production of our device and reductions incardiac technician labor costs through algorithm improvements and software driven workflow enhancements.Gross margin for the year ended December 31, 2016 increased to 67%, compared to 59% for the year ended December 31, 2015. The increase wasdriven primarily by the reduction in the cost of the Zio service due to our continued efforts to lower manufacturing costs, fixed costs absorption and reducedlabor costs per device through67 our algorithm improvements and software-driven workflow enhancements. In addition, we experienced some mix shift driven by the success of ourcontracting efforts, which also improved our gross margin during the year ended December 31, 2016. Research and Development Expenses Research and development expenses increased $0.8 million, or 13%, to $7.2 million during the year ended December 31, 2016 from $6.3 millionduring the year ended December 31, 2015. The increase was primarily attributable to a $0.9 million increase for payroll and personnel-related expenses, and a$0.7 million increase in facility-related expenses, partially offset by decreases of $0.4 million for professional service fees and $0.4 million for clinical trials. Selling, General and Administrative ExpensesSelling, general and administrative expenses increased $14.9 million, or 41%, to $51.6 million during the year ended December 31, 2016 from$36.7 million during the year ended December 31, 2015. The increase was primarily attributable to a $7.7 million increase in payroll and personnel-relatedexpenses as a result of increased headcount to support the growth in our operations, a $3.3 million increase in professional services expenses, primarily as aresult of an increase in accounting, legal and recruiting services expenses, a $2.8 million increase in facility-related expenses, a $0.9 million increase in bad-debt expense due to the overall increase in accounts receivable, and an $0.8 million increase in travel and other expenses. These increases were partiallyoffset by a $0.5 million decrease in commissions as a result of increased sales quotas that were not achieved. Interest ExpenseInterest expense increased $2.2 million to $3.2 million during the year ended December 31, 2016 from $1.1 million during the year endedDecember 31, 2015 primarily due to our debt financing in December 2015.Other Expense, NetOther expense, net increased $2.0 million to $2.1 million during the year ended December 31, 2016 from $0.1 million during the year endedDecember 31, 2015. The change was primarily related to the fair value re-measurement of warrant liabilities at each balance sheet date and the final re-measurement upon the IPO in October 2016 when the preferred stock warrants converted to common stock warrants. Liquidity and Capital Expenditures Overview As of December 31, 2017, we had cash and cash equivalents of $8.7 million, short-term investments of $93.7 million, long-term investments of $3.0million and an accumulated deficit of $156.6 million. In connection with our IPO that closed in October 2016, we received net cash proceeds of $110.7million, net of underwriters’ discounts and commissions and expenses paid by us. Prior to the IPO we financed our operations primarily through sales of ourprivate securities, sales of our products and services and debt financings.Our expected future capital requirements may depend on many factors including expanding our customer base, the expansion of our salesforce, andthe timing and extent of spending on the development of our technology to increase our product offerings. If we raise additional funds by issuing equitysecurities, our stockholders may experience dilution. Any future debt financing into which we enter may impose upon us additional covenants that restrictour operations, including limitations on our ability to incur liens or additional debt, pay dividends, repurchase our common stock, make certain investmentsand engage in certain merger, consolidation or asset sale transactions. Any debt financing or additional equity that we raise may contain terms that are notfavorable to us or our stockholders.68 Cash FlowsThe following table summarizes our cash flows for the periods indicated (in thousands): Year Ended December 31, 2017 2016 2015 Net cash (used in) provided by: Operating activities $(14,911) $(16,651) $(18,005)Investing activities (34,593) (68,166) (1,787)Financing activities 6,532 111,252 36,382 Net increase (decrease) in cash and cash equivalents $(42,972) $26,435 $16,590 Cash Used in Operating ActivitiesDuring the year ended December 31, 2017, cash used in operating activities was $14.9 million, which consisted of a net loss of $29.4 million,adjusted by non-cash charges of $22.6 million and a net change of $8.1 million in our net operating assets and liabilities. The non-cash charges are primarilycomprised of an increase in stock-based compensation expense of $10.1 million, as well as a change in allowance for doubtful accounts and contractualallowance of $9.4 million. The change in our net operating assets and liabilities was primarily due to an increase of $13.0 million in the change in accountsreceivable as a result of the increase in our revenue, and a decrease of $5.4 million in accrued liabilities, primarily related to increased accrued payroll andrelated compensation accruals.During the year ended December 31, 2016, cash used in operating activities was $16.7 million, which consisted of a net loss of $20.9 million,adjusted by non-cash charges of $11.0 million and a net change of $6.7 million in our net operating assets and liabilities. The non-cash charges are primarilycomprised of an increase in allowance for doubtful accounts and contractual allowance of $4.7 million, a change in value of warrant liability of $2.1 million,stock based compensation of $1.9 million, depreciation and amortization of $0.6 million and $0.3 million related to amortization of debt discounts. Thechange in our net operating assets and liabilities was primarily due to an increase of $6.5 million in accounts receivable as a result of the increase in ourrevenue, an increase of $1.2 million in other assets primarily related to the purchase of the Zio XT monitor PCBAs to support the growth in volume of Zioservice performed and an increase of $0.9 million in prepaid expenses and other current assets. This change was partially offset by a $4.9 million increase inaccrued liabilities primarily related to increased accrued payroll and related compensation accruals and a $0.4 million increase in deferred revenue.During the year ended December 31, 2015, cash used in operating activities was $18.0 million, which consisted of a net loss of $22.8 million,adjusted by non-cash charges of $3.6 million and a net change of $1.2 million in our net operating assets and liabilities. The non-cash charges are primarilycomprised of stock-based compensation of $1.4 million, change in allowance for doubtful accounts and contractual allowance of $1.6 million anddepreciation and amortization of $0.5 million. The change in our net operating assets and liabilities was primarily due to a $3.5 million increase in accruedliabilities, primarily related to accrued payroll and related compensation accruals as a result of increased headcount. This increase was partially offset by a$1.2 million increase in accounts receivable due to an increase in revenue, a $0.5 million increase in prepaid expenses and other assets, primarily due to thetiming of annual insurance fees and certain software contracts and a $0.5 million increase in other assets primarily related to the purchase of PCBAs tosupport the growth in volumeCash Used in Investing ActivitiesCash used in investing activities during the year ended December 31, 2017 was $34.6 million, which consisted of $129.8 million in purchases ofinvestments and $3.6 million of capital expenditures to purchase property and equipment, partially offset by maturities of available for sale investments of$98.7 million.Cash used in investing activities during the year ended December 31, 2016 was $68.2 million, which consisted of $65.4 million in purchases ofinvestments and $2.8 million of capital expenditures to purchase property and equipment.69 Cash used in investing activities during the year ended December 31, 2015 was $1.8 million, which consisted of capital expenditures to purchaseproperty and equipment.Cash Provided by Financing ActivitiesDuring the year ended December 31, 2017, cash provided by financing activities was $6.5 million, consisting primarily of net proceeds of $6.4 fromthe issuance of common stock related to employee equity incentive plans. During the year ended December 31, 2016, cash provided by financing activities was $111.3 million, consisting primarily of net proceeds of $110.9million from the IPO completed in October 2016, which is net of bankers fees, commissions and offering costs. During the year ended December 31, 2015, cash provided by financing activities was $36.4 million, primarily consisting of net proceeds from bankdebt of $29.0 million and net proceeds of $12.1 million from the issuance of convertible preferred stock, partially offset by $4.9 million in payments on bankdebt. Indebtedness Pharmakon Loan AgreementIn December 2015, we entered into a Loan Agreement with Pharmakon. The Pharmakon Loan Agreement provides for up to $55.0 million in termloans split into two tranches as follows: (i) Tranche A Loans of $30.0 million in term loans, and (ii) Tranche B Loans are up to $25.0 million in term loans.The Tranche A Loans were drawn on December 4, 2015. The Tranche B Loans were available to be drawn prior to December 4, 2016. No additional draw wastaken.During the first four years, payments are interest only and for the first two years 50% of the interest will be “paid-in-kind.” We are subject to afinancial covenant related to minimum trailing revenue targets that begins in June 2017, and is tested on a semi-annual basis. The minimum net revenuecovenant ranges from $44.7 million for the period ended June 30, 2017 to $102.6 million for the period ended December 31, 2021. The minimum net revenuefinancial covenant has a 45-day equity cure period following required delivery date of the financial statements. Pursuant to this equity cure provision, wemay cure a revenue covenant default by raising additional funds from the sale of equity. The loan matures in December 2021. As of December 31, 2017,$32.5 million was outstanding under the Pharmakon Loan Agreement.The Tranche A Loans bear interest at a fixed rate equal to 9.50% per annum, which is due and payable quarterly in arrears. During the first eightcalendar quarters, 50% of the interest due and payable shall be added to the then-outstanding principal.The Pharmakon Loan Agreement requires us to maintain a minimum liquidity and minimum net sales during the term of the loan facility andcontains customary affirmative and negative covenants and event of default provisions that could result in the acceleration of the repayment obligationsunder the loan facility. Upon a change in control of our company, Pharmakon has the option to demand payment in full of the outstanding loans togetherwith the prepayment premium. The obligations under the Pharmakon Loan Agreement are secured by a security interest in substantially all of our assetspursuant to the Pharmakon Guaranty and Security Agreement, and this security interest is governed by an intercreditor agreement between Pharmakon andSVB.70 SVB Loan and Security AgreementIn December 2015, we entered into a Second Amended and Restated Loan and Security Agreement with SVB, or the SVB Loan Agreement. Under theSVB Loan Agreement we may borrow, repay and reborrow under a revolving credit line, but not in excess of the maximum loan amount of $15.0 million,until December 4, 2018, when all outstanding principal and accrued interest becomes due and payable. Any principal amount outstanding under the SVBrevolving credit line bears interest at a floating rate per annum equal to the rate published by The Wall Street Journal as the “Prime Rate” plus 0.25%. Thecredit line is subject to financial covenants tied to our trailing twelve-month net sales. We may borrow up to 80% of our eligible accounts receivable, up tothe maximum of $15.0 million. In August 2016, we obtained a $3.1 million standby letter of credit pursuant to the SVB revolving credit facility inconnection with a new lease. As of December 31, 2017, we were eligible to borrow up to $3.3 million and no amount was outstanding under the SVBrevolving credit line.The SVB Loan Agreement requires us to maintain a minimum consolidated liquidity and minimum net sales during the term of the loan facility. Inaddition, the SVB Loan Agreement contains customary affirmative and negative covenants and events of default. The obligations under the SVB LoanAgreement are secured by a security interest in substantially all of our assets, and this security interest is governed by an intercreditor agreement betweenPharmakon and SVB.CHCF NoteIn November 2012, we entered into a Note Purchase Agreement and Promissory Note with the California HealthCare Foundation, or the CHCF Note,through which we borrowed $1.5 million. The CHCF Note accrues simple interest of 2.0%. The accrued interest and the principal was set to mature inNovember 2016. In June 2015, we amended the CHCF Note to extend the maturity date to May 2018. The CHCF Note is subordinate to other bank debt.Critical Accounting Policies and EstimatesOur management’s discussion and analysis of our financial condition and results of operations is based on our financial statements, which have beenprepared in accordance with United States generally accepted accounting principles, or U.S. GAAP. The preparation of these financial statements requires ourmanagement to make judgments and estimates that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilitiesat the date of the financial statements, as well as the reported revenue generated and expenses incurred during the reporting periods. Our estimates are basedon our historical experience and on various other factors that we believe are reasonable under the circumstances, the results of which form the basis formaking judgments about the carrying value of assets and liabilities that are not readily apparent from other sources. Actual results may differ from thesejudgments and estimates under different assumptions or conditions and any such differences may be material. We believe that the accounting policiesdiscussed below are critical to understanding our historical and future performance, as these policies relate to the more significant areas involvingmanagement’s judgments and estimates.Revenue RecognitionOur Zio XT monitor, a wearable biosensor, is worn by patients for a monitoring period up to 14 days. The Zio XT monitor is returned to ourmonitoring facility and the heartbeat data is curated and analyzed by our proprietary algorithms and reviewed by our certified cardiac technicians. The finalstep in the Zio service is the delivery of an electronic Zio Report to the prescribing physician with a summary of findings. Our Zio service is generallybillable when the Zio Report is issued to the physician. For all Zio services performed, we consider whether or not the following revenue recognition criteriaare met: persuasive evidence of an arrangement exists and delivery has occurred or services have been rendered. For services performed for customers whichwe invoice directly, additional revenue recognition criteria include that the price is fixed and determinable and collectability is reasonably assured; forcustomers for which we submit claims to third party commercial and governmental payors for reimbursement, we recognize revenue only when a reasonableestimate of reimbursement can be made.71 The assessment of whether a reasonable estimate of reimbursement can be made requires significant judgment. If all revenue recognition criteria aremet, revenue is recognized upon delivery of the ZIO Report. To date, we have not been able to estimate revenue for third-party payors for which we do nothave a contracted rate and therefore revenue has been recognized on the earlier of notification or when payment is received. Some patients have out-of-pocket costs for amounts not covered by their insurance carrier, and we may bill patients directly for these amounts in the form of co-payments and co-insurance in accordance with their insurance carrier and health plans. Some payors may not cover our Zio service under their reimbursement policies. In theabsence of contracted reimbursement coverage or the ability to reasonably estimate reimbursement, we recognize revenue only upon the earlier ofnotification of payment or when payment is received.We recognize revenue related to billings for Centers for Medicare & Medicaid Services, or CMS, and commercial payors on an accrual basis, net ofcontractual adjustments, when a reasonable estimate of reimbursement can be made. These contractual adjustments represent the difference between the listprice (the billing rate) and the reimbursement rate for each payor. Upon ultimate collection from CMS and commercial payors, the amount is compared to theprevious estimates and the contractual allowance is adjusted accordingly. Until a contract has been negotiated with a commercial payor, our services may ormay not be covered by these entities’ existing reimbursement policies. In addition, patients do not enter into direct agreements with us that commit them topay any portion of the cost of the Zio service in the event that their insurance declines to reimburse us. In the absence of an agreement with the patient orother clearly enforceable legal right to demand payment from the patient, the related revenue is recognized only upon the earlier of notification of paymentor when payment is received. Costs associated with providing the Zio service are recorded as the service is provided regardless of whether or when revenue isrecognized.Allowance for Doubtful Accounts and Contractual AllowanceWe establish an allowance for doubtful accounts for estimated uncollectible receivables based on our historical collections, review of specificoutstanding claims, consideration of relevant qualitative factors and an established allowance percentage by aging category. We write off outstandingaccounts against the allowance for doubtful accounts when they are deemed to be uncollectible. Increases and decreases in the allowance for doubtfulaccounts are included as a component of general and administrative expenses. We record reductions in revenue for estimated uncollectible amounts ascontractual allowances.We review and update our estimates for the allowance for doubtful accounts and the contractual allowance periodically to reflect our experienceregarding historical collections. If we were to make different judgments or utilize different estimates in the allowance for doubtful accounts and thecontractual allowance, differences in both the amount of reported general and administrative expenses and revenue could result.Estimated Usage of the Printed Circuit Board AssemblyWe use a printed circuit board assembly, or PCBA, in each wearable device and it is reused numerous times in multiple patients. Each time the PCBAis used in a wearable Zio XT monitor, a portion of the cost of the PCBA is recorded as a cost of revenue. We have based our estimates of how many times aPCBA can be used on testing in research and development, loss rates, product obsolescence, and the amount of time it takes the device to go through themanufacturing, shipping, customer shelf and patient wear time and upload process. We periodically evaluate the use estimate.Stock-Based CompensationWe recognize compensation costs related to stock option grants, restricted stock unit grants, or RSUs, and shares under the employee stock purchaseprogram, or ESPP, based on the estimated fair value of the awards on the date of grant, net of estimated forfeitures. We estimate the grant date fair value, andthe resulting stock-based compensation expense for options and shares under the ESPP, using the Black-Scholes option pricing model. The RSU grant datefair value is based on the closing price on the date of the grant. The grant date fair value of stock-based awards is expensed on a straight-line basis over theperiod during which the employee is required to provide service in exchange for the award (generally the vesting period).72 We estimate the fair value of our stock-based awards using the Black-Scholes option-pricing model, which requires the input of highly subjectiveassumptions. Our assumptions are as follows: •Expected term. The expected term represents the period that the stock-based awards are expected to be outstanding. We use the simplifiedmethod to determine the expected term, which is calculated as the average of the time to vesting and the contractual life of the options. •Expected volatility. As our common stock has been publicly traded for a limited time, the expected volatility is derived from the averagehistorical volatilities of publicly traded companies within our industry that we consider to be comparable to our business over a periodapproximately equal to the expected term for employees’ options and the remaining contractual life for nonemployees’ options. •Risk-free interest rate. The risk-free interest rate is based on the U.S. Treasury yield with a maturity equal to the expected term of the optionin effect at the time of grant. •Dividend yield. The expected dividend is assumed to be zero as we have never paid dividends and have no current plans to pay anydividends on our common stock.In addition to the assumptions used in the Black-Scholes option-pricing model, we also estimate a forfeiture rate to calculate the stock-basedcompensation for our equity awards. We will continue to use judgment in evaluating the expected volatility, expected terms and forfeiture rates utilized forour stock-based compensation calculations on a prospective basis.Stock-based compensation expense for options granted to non-employees as consideration for services received is measured on the date ofperformance at the fair value of the consideration received or the fair value of the equity instruments issued, using the Black-Scholes option-pricing model,whichever can be more reliably measured. Stock-based compensation expense for options granted to non-employees is periodically re-measured as theunderlying options vest.We recognize compensation expense related to restricted stock units based on the grant date fair value on a straight-line basis over the period duringwhich the employee is required to provide service in exchange for the award (generally the vesting period). We recognize compensation expense related to the Employee Stock Purchase Program (“ESPP”) based on the estimated fair value of the options onthe date of grant, net of estimated forfeitures. We estimate the grant date fair value, and the resulting stock-based compensation expense, using the Black-Scholes option pricing model for each purchase period. The grant date fair value is expensed on a straight-line basis over the offering period. We recorded stock-based compensation expense of $10.1 million, $1.9 million and $1.4 million for the years ended December 31, 2017, 2016 and2015, respectively. We expect to continue to grant stock options and other equity-based awards in the future, and to the extent that we do, our stock-basedcompensation expense recognized in future periods will likely increase. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”), issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue fromContracts with Customers (Topic 606). Areas of revenue recognition that will be affected include, but are not limited to, transfer of control, variableconsideration, allocation of transfer pricing, licenses, time value of money, contract costs and disclosures. The core principle of ASU 2014-09 is to recognizerevenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for thosegoods or services. ASU 2014-09 defines a five-step process to achieve this core principle and, in doing so, it is possible more judgment and estimates may berequired within the revenue recognition process than are required under existing GAAP. In addition, Topic 606 requires more detailed disclosures to enableusers of financial statements to understand the nature, timing and uncertainty of revenue and cash flows arising from a review of historical accountingpolicies and practices to identify potential differences in applying Topic 606. 73 The Company adopted this standard on January 1, 2018 and used the modified retrospective approach. Upon adoption, the Company recognized thecumulative effect of adopting the new revenue standard as an adjustment to the opening balance of the Company’s accumulated deficit. This adjustment didnot have a material impact on the Company’s consolidated financial statements. Prior periods will not be retrospectively adjusted. The adoption results in achange to net revenue primarily due to the change in classification of bad debt expense related to the patient responsibility of both contracted and non-contracted claims as a reduction of gross revenue rather than as a component of selling, general and administrative expenses. As a result, starting on January1, 2018, the Company will be presenting revenue net of this bad debt expense. To a lesser extent, revenue will be impacted due to timing differences in itsrecognition of revenue related to non-contracted third-party payor claims as a result of changing from recognition based on the earlier of notification of thepayor benefits allowed or when payment is received to the accrual basis based on historical experience. In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation (Topic 718). This ASU was issued as part of the FASB’ssimplification initiative and affects all entities that issue share-based payment awards to their employees. This standard covers accounting for income taxes,forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. As a result of adopting ASU No. 2016‑09 onJanuary 1, 2017, the Company has made an accounting policy election to continue to estimate forfeitures. The adoption of ASU No. 2016‑09 also requiresexcess tax benefits and tax deficiencies be recorded in the income statement as opposed to additional paid‑in capital when the awards vest or are settled, andhas been applied on a prospective basis with no impact on the consolidated financial statements as of and for the year ended December 31, 2017. As a resultof the adoption, the Company increased its total NOLs by $0.1 million on January 1, 2017 related to deferred tax assets that arose directly from taxdeductions related to equity compensation greater than compensation recognized for financial reporting purposes. This amount is fully offset by thevaluation allowance. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which requires lessees to recognize lease liabilities and correspondingright-of-use assets for all leases with lease terms of greater than 12 months. It also changes the definition of a lease and expands the disclosure requirements oflease arrangements. Currently, the new guidance must be adopted using the modified retrospective approach, including a number of optional practicalexpedients that entities may elect to apply, with the cumulative effect of applying the new guidance recognized as an adjustment to the opening retainedearnings balance in the earliest period presented. In January 2018, the FASB issued an exposure draft that, if adopted, would allow for recognition of thecumulative effect of applying the new guidance as an adjustment to the opening retained earnings balance in the year of adoption, among other changes. TheCompany will adopt the new guidance in the first quarter of fiscal 2019 and is in the process of determining the effects the adoption will have on itsconsolidated financial statements. In November 2016, the FASB issued ASU No. 2016-18 Statement of Cash Flow: Restricted Cash (Topic 230), which provides guidance on theclassification of restricted cash to be included with cash and cash equivalents when reconciling the beginning of period and end of period total amounts onthe statement of cash flows. The amendments of this ASU are effective for interim and annual periods beginning after December 15, 2017. The standard mustbe applied retrospectively to all periods presented. The adoption of this standard will not have a material impact on the cash flow activity presented on theCompany's Consolidated Statements of Cash Flows. In May 2017, the FASB issued ASU 2017-09, Scope of Modification Accounting, which amends the scope of modification accounting for share-based payment arrangements, provides guidance on the types of changes to the terms or conditions of share-based payment awards to which an entity wouldbe required to apply modification accounting under ASC 718. This ASU is effective for annual reporting periods, including interim periods within thoseannual reporting periods, beginning after December 15, 2017. The Company is currently evaluating the impact of adoption of this standard.Off-Balance Sheet ArrangementsWe have not entered into any off-balance sheet arrangements and do not have any holdings in variable interest entities.74 Contractual ObligationsThe following summarized our contractual obligations as of December 31, 2017 (in thousands): Payments Due by Period Less Than1 Year 1 to 3Years 3 to 5Years More Than5 Years Total Debt including interest $4,858 $39,925 $— $— $44,783 Operating leases 5,260 6,894 417 2,125 14,696 Total contractual obligations $10,118 $46,819 $417 $2,125 $59,479 The table above does not include approximately $3.7 million in non-cancelable purchase orders related to inventory and printed circuit boardassemblies entered into in the normal course of operations, which we expect to be paid in less than one year. The table excludes unrecognized tax benefits of$0.9 million as of December 31, 2017 because these uncertain tax positions, if recognized, would be an adjustment to our net deferred tax assets. Item 7A. Quantitative and Qualitative Disclosures About Market Risk. We are exposed to market risks in the ordinary course of our business. These risks primarily include risk related to interest rate sensitivities andforeign currency exchange rate sensitivity. Interest Rate Sensitivity We had cash, cash equivalents and investments of $105.4 million as of December 31, 2017; which consisted of bank deposits, money market fundsand U.S. government securities, corporate notes, and commercial paper. Such interest-earning instruments carry a degree of interest rate risk; however,historical fluctuations in interest income have not been significant.We do not enter into investments for trading or speculative purposes and have not used any derivative financial instruments to manage our interestrate risk exposure. We have not been exposed nor do we anticipate being exposed to material risks due to changes in interest rates. A hypothetical 10%change in interest rates during any of the periods presented would not have had a material impact on our consolidated financial statements. We had total outstanding debt of $34.0 million and $32.2 million, which is net of debt discount and debt issuance costs, as of December 31, 2017and 2016, respectively. The interest rates on our bank debt and CHCF Note carry fixed interest rates. A hypothetical 10% change in interest rates during anyof the periods presented would not have had a material impact on our consolidated financial statements.Foreign Currency Exchange Rate SensitivityWe face foreign exchange risk as a result of entering into transactions denominated in currencies other than U.S. dollars, particularly in British PoundSterling. As of December 31, 2017, we do not consider this risk to be material. We do not utilize any forward foreign exchange contracts. All foreigntransactions settle on the applicable spot exchange basis at the time such payments are made.75 Item 8. Financial Statements and Supplementary Data.IRHYTHM TECHNOLOGIES, INC.Index to Financial Statements Report of Independent Registered Public Accounting Firm 77Financial Statements Consolidated Balance Sheets 79Consolidated Statements of Operations 80Consolidated Statements of Comprehensive Loss 81Consolidated Statements of Convertible Preferred Stock and Stockholders’ Equity (Deficit) 82Consolidated Statements of Cash Flows 83Notes to the Consolidated Financial Statements 84 76 Report of Independent Registered Public Accounting FirmTo the Board of Directors and Stockholders ofiRhythm Technologies, Inc.Opinions on the Financial Statements and Internal Control over Financial ReportingWe have audited the accompanying consolidated balance sheets of iRhythm Technologies, Inc. and its subsidiary as of December 31, 2017 and 2016, and therelated consolidated statements of operations, of comprehensive loss, of convertible preferred stock and stockholders’ equity (deficit) and of cash flows foreach of the three years in the period ended December 31, 2017, including the related notes (collectively referred to as the “consolidated financialstatements”). We also have audited the Company's internal control over financial reporting as of December 31, 2017, based on criteria established in InternalControl - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO).In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of the Company as ofDecember 31, 2017 and 2016, and the results of their operations and their cash flows for each of the three years in the period ended December 31, 2017 inconformity with accounting principles generally accepted in the United States of America. Also in our opinion, the Company maintained, in all materialrespects, effective internal control over financial reporting as of December 31, 2017, based on criteria established in Internal Control - Integrated Framework(2013) issued by the COSO.Basis for OpinionsThe Company's management is responsible for these consolidated financial statements, for maintaining effective internal control over financial reporting, andfor its assessment of the effectiveness of internal control over financial reporting, included in Management’s Report on Internal Control over FinancialReporting appearing under item 9A. Our responsibility is to express opinions on the Company’s consolidated financial statements and on the Company'sinternal control over financial reporting based on our audits. We are a public accounting firm registered with the Public Company Accounting OversightBoard (United States) ("PCAOB") and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and theapplicable rules and regulations of the Securities and Exchange Commission and the PCAOB.We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtain reasonableassurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud, and whether effective internalcontrol over financial reporting was maintained in all material respects.Our audits of the consolidated financial statements included performing procedures to assess the risks of material misstatement of the consolidated financialstatements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis,evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles usedand significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. Our audit of internalcontrol over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weaknessexists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performingsuch other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions. Definition and Limitations of Internal Control over Financial Reporting A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reportingand the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal controlover financial reporting77 includes those policies and procedures that (i) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactionsand dispositions of the assets of the company; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financialstatements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only inaccordance with authorizations of management and directors of the company; and (iii) provide reasonable assurance regarding prevention or timely detectionof unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements. Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation ofeffectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliancewith the policies or procedures may deteriorate. /s/ PricewaterhouseCoopers LLPSan Jose, CaliforniaMarch 1, 2018 We have served as the Company’s auditor since 2009. 78 IRHYTHM TECHNOLOGIES, INC.Consolidated Balance Sheets(In thousands, except share and per share data) December 31, 2017 2016 Assets Current assets: Cash and cash equivalents $8,671 $51,643 Short-term investments 93,692 54,407 Accounts receivable, net 12,953 9,406 Inventory 1,683 1,390 Prepaid expenses and other current assets 2,582 1,671 Restricted cash — 91 Total current assets 119,581 118,608 Investments, long-term 2,994 10,981 Property and equipment, net 6,221 4,653 Goodwill 862 862 Other assets 3,465 3,052 Total assets $133,123 $138,156 Liabilities, and Stockholders’ Equity Current liabilities: Accounts payable $2,395 $2,103 Accrued liabilities 15,644 10,165 Deferred revenue 1,238 947 Accrued interest, current portion 154 — Debt, current portion 1,487 — Total current liabilities 20,918 13,215 Debt 32,491 32,227 Deferred rent, noncurrent portion 161 26 Accrued interest, net of current portion — 126 Total liabilities 53,570 45,594 Commitments and contingencies (Note 6) Stockholders’ equity: Preferred stock, $0.001 par value – 5,000,000 shares authorized at December 31, 2017 and 2016, respectively; and none issued and outstanding at December 31, 2017 and 2016, respectively — — Common stock, $0.001 par value – 100,000,000 shares authorized at December 31, 2017 and 2016, respectively; 23,377,315 and 22,139,346 shares issued and outstanding at December 31, 2017 and 2016, respectively 23 22 Additional paid-in capital 236,184 219,718 Accumulated other comprehensive loss (65) (9)Accumulated deficit (156,589) (127,169)Total stockholders’ equity 79,553 92,562 Total liabilities, preferred stock and stockholders’ equity $133,123 $138,156 The accompanying notes are an integral part of these consolidated financial statements.79 IRHYTHM TECHNOLOGIES, INC.Consolidated Statements of Operations(In thousands, except share and per share data) Year Ended December 31, 2017 2016 2015 Revenue $98,509 $64,072 $36,140 Cost of revenue 27,708 20,883 14,700 Gross profit 70,801 43,189 21,440 Operating expenses: Research and development 13,335 7,150 6,349 Selling, general and administrative 84,737 51,621 36,722 Total operating expenses 98,072 58,771 43,071 Loss from operations (27,271) (15,582) (21,631)Interest expense (3,386) (3,248) (1,059)Other income (expense), net 1,237 (2,073) (109)Net loss $(29,420) $(20,903) $(22,799)Net loss per common share, basic and diluted $(1.30) $(3.95) $(16.57)Weighted-average shares used to compute net loss per common share, basic and diluted 22,627,327 5,285,847 1,376,106 The accompanying notes are an integral part of these consolidated financial statements. 80 IRHYTHM TECHNOLOGIES, INC.Consolidated Statements of Comprehensive Loss(In thousands) Year Ended December 31, 2017 2016 2015 Net Loss $(29,420) $(20,903) $(22,799)Other comprehensive loss: Net change in unrealized losses on available-for-sale securities (56) (9) — Comprehensive loss $(29,476) $(20,912) $(22,799) The accompanying notes are an integral part of these consolidated financial statements.81 IRHYTHM TECHNOLOGIES, INC.Consolidated Statements of Convertible Preferred Stock and Stockholders’ Equity (Deficit)(In thousands, except share and per share data) Accumulated Total Convertible Additional Other Stockholders’ Preferred Stock Common Stock Paid-In Accumulated Comprehensive Equity Shares Amount Shares Amount Capital Deficit Loss (Deficit) Balance at December 31, 2014 9,657,867 $85,014 1,326,636 $1 $2,922 $(83,467) $— $(80,544)Issuance of Series E convertible preferred stock for cash at $8.77 per share, net of issuance costs of $92 1,388,279 12,082 — — — — — — Issuance of common stock upon the exercise of options, net of repurchases — — 83,929 — 309 — — 309 Stock-based compensation expense — — — — 1,410 — — 1,410 Net loss — — — — — (22,799) — (22,799)Balance at December 31, 2015 11,046,146 97,096 1,410,565 1 4,641 (106,266) — (101,624)Issuance of common stock upon the exercise of options, net of repurchases — — 56,827 1 131 — — 132 Issuance of preferred stock upon exercise of warrants 31,359 457 — — — — — — Issuance of common stock in connection with initial public offering, net of offering costs — — 7,238,235 7 110,714 — — 110,721 Conversion of convertible preferred stock to common stock in connection with initial public offering (11,077,505) (97,553) 13,375,333 13 97,540 — — 97,553 Conversion of convertible preferred stock warrants to common stock warrants in connection with initial public offering — — — — 4,821 — — 4,821 Issuance of common stock upon net exercise of warrants — — 58,386 — — — — — Stock-based compensation expense — — — — 1,871 — — 1,871 Net loss — — — — — (20,903) — (20,903)Net unrealized loss on investments — — — — — — (9) (9)Balance at December 31, 2016 — — 22,139,346 22 219,718 (127,169) (9) 92,562 Issuance of common stock upon in connection with employee equity incentive plans, net — — 1,027,595 1 6,389 — — 6,390 Issuance of common stock upon net exercise of warrants — — 210,374 — — — — — Tax withholding upon vesting of restricted stock awards — — — — (46) — — (46)Stock-based compensation expense — — — — 10,123 — — 10,123 Net loss — — — — — (29,420) — (29,420)Net unrealized loss on investments — — — — — — (56) (56)Balance at December 31, 2017 — $— 23,377,315 $23 $236,184 $(156,589) $(65) $79,553 The accompanying notes are an integral part of these consolidated financial statements.82 IRHYTHM TECHNOLOGIES, INC.Consolidated Statements of Cash Flows(In thousands) Year EndedDecember 31, 2017 2016 2015 Cash flows from operating activities Net loss $(29,420) $(20,903) $(22,799)Adjustments to reconcile net loss to net cash used in operating activities: Depreciation and amortization 1,597 568 492 Stock-based compensation 10,123 1,871 1,410 Amortization of debt discount and issuance costs 260 251 116 Amortization (accretion) on investments (352) 6 — Loss on disposal of assets 9 — 10 Change in accrued interest — — (64)Provision for bad debt and contractual allowance 9,403 4,686 1,557 Change in fair value of preferred stock warrant liabilities — 2,123 111 Non-cash interest expense 1,550 1,481 — Changes in operating assets and liabilities: Accounts receivable (12,950) (8,515) (1,281)Inventory (293) (245) (327)Prepaid expenses and other current assets (795) (863) (506)Other assets (467) (1,235) (491)Accounts payable 634 305 132 Accrued liabilities 5,364 3,380 3,522 Deferred rent 135 (2) 28 Deferred revenue 291 441 85 Net cash used in operating activities (14,911) (16,651) (18,005)Cash flows from investing activities Purchases of property and equipment (3,562) (2,763) (1,787)Purchases of available-for-sale investments (129,829) (65,403) — Maturities of available-for-sale investments 98,707 — — Restricted cash 91 — — Net cash used in investing activities (34,593) (68,166) (1,787)Cash flows from financing activities Proceeds from issuance of common stock upon exercise of stock options, net of repurchases 6,390 132 309 Proceeds from issuance of common stock upon exercise of warrants — 206 — Tax withholding upon vesting of restricted stock awards (46) — — Proceeds from issuance of convertible preferred stock, net of issuance costs — — 12,134 Payments of deferred offering costs 188 (3,522) (5)Proceeds from long-term debt, net of debt discount and issuance costs — — 29,018 Repayments of long-term debt — — (4,905)Payments of issuance costs for revolving line of credit — — (169)Proceeds of issuance of common stock upon initial public offering — 114,436 — Net cash provided by financing activities 6,532 111,252 36,382 Net increase (decrease) in cash and cash equivalents (42,972) 26,435 16,590 Cash and cash equivalents, beginning of year 51,643 25,208 8,618 Cash and cash equivalents, end of year $8,671 $51,643 $25,208 Supplemental disclosures of cash flow information Interest paid $1,550 $1,591 $343 Non-cash investing and financing activities Issuance of warrants to purchase preferred stock $— $— $44 Series E convertible preferred stock issuance costs included in accrued liabilities $— $— $52 Property and equipment included in accounts payable $35 $423 $— Deferred offering costs included in accounts payable and accrued liabilities $— $188 $265 Conversion of preferred stock to common stock $— $97,553 $— Conversion of preferred stock warrants to common stock warrants $— $4,821 $—The accompanying notes are an integral part of these consolidated financial statements.83 IRHYTHM TECHNOLOGIES, INC.Notes to Consolidated Financial Statements1. Organization and Description of BusinessiRhythm Technologies, Inc. (the “Company”) was incorporated in the state of Delaware in September 2006. The Company is a commercial-stagedigital healthcare company redefining the way cardiac arrhythmias are clinically diagnosed by combining wearable biosensing technology with cloud-baseddata analytics and machine-learning capabilities. The Company commenced commercial introduction of its products in the United States in 2009 followingclearance by the U.S. Food and Drug Administration.The Company’s headquarters is based in San Francisco, California, and is also a clinical center. The Company has additional clinical centers inLincolnshire, Illinois and Houston, Texas and a manufacturing facility in Cypress, California. In March 2016, the Company formed a wholly-ownedsubsidiary in the United Kingdom. The Company manages its operations as a single operating segment. Substantially all of the Company’s assets aremaintained in the United States. The Company derives substantially all of its revenue from sales to customers in the United States.Reverse Stock SplitOn October 4, 2016, the Company’s board of directors approved an amendment to the Company’s amended and restated certificate of incorporationto effect a reverse split of the Company’s issued and outstanding common stock at a 1-for- 5.882698 ratio, which was effected on October 5, 2016. The parvalue and authorized shares of common stock and convertible preferred stock were not adjusted as a result of the reverse split. All issued and outstandingcommon stock, options to purchase common stock and per share amounts contained in these consolidated financial statements have been retroactivelyadjusted to reflect the reverse stock split for all periods presented.Initial Public OfferingThe Company’s initial public offering (“IPO”) of 7,238,235 shares of common stock was effected through a registration statement on Form S-1(Registration Nos. 333-213773 and 333-214179), which was declared effective on October 19, 2016. The initial public offering closed on October 25, 2016and resulted in net proceeds of approximately $110.7 million, after deducting underwriting discounts and commissions of $8.6 million and other expenses of$3.7 million.In October 2016, immediately upon the Company’s sale of its common stock in the initial public offering, all outstanding shares of convertiblepreferred stock converted into 13,375,333 shares of common stock with the related carrying value of $97.6 million reclassified to common stock andadditional paid-in capital. In addition, all convertible preferred stock warrants were also thereby converted into common stock warrants.2. Summary of Significant Accounting PoliciesBasis of PresentationThe accompanying consolidated financial statements for the years ended December, 31, 2017, 2016, and 2015 are prepared in accordance with U.S.generally accepted accounting principles and include the accounts of iRhythm Technologies, Inc. and its wholly-owned subsidiary, iRhythm TechnologiesLtd., established in March 2016. All intercompany accounts and transactions have been eliminated. The financial statements of iRhythm Technologies Ltd.use the U.S. dollar as the functional currency. For all non-functional currency balances, the remeasurement of such balances to functional currency results in aforeign exchange transaction gain or loss, which is recorded in the consolidated statements of operations.Use of EstimatesThe preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions thataffect the reported amounts of assets and liabilities and disclosure of84 contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Onan ongoing basis, management evaluates its estimates, including those related to revenue recognition, contractual allowances for revenue, allowance fordoubtful accounts, the useful lives of property and equipment, the recoverability of long-lived assets including the estimated usage of the printed circuitboard assemblies (“PCBAs”), accounting for income taxes, the fair value of the Company’s common stock and stock-based compensation. The Companybases these estimates on historical and anticipated results, trends, and various other assumptions that the Company believes are reasonable under thecircumstances, including assumptions as to future events. Actual results may differ from those estimates.Fair Value of Financial InstrumentsThe carrying amounts of certain of the Company’s financial instruments, which include cash equivalents, short-term investments, long-terminvestments, accounts receivable, accounts payable and accrued liabilities, approximate fair value due to their short maturities.Cash EquivalentsCash equivalents consist of short-term, highly liquid investments with original maturities of three months or less from the date of purchase.InvestmentsShort-term investments consist of debt securities classified as available-for-sale and have maturities greater than 90 days, but less than one year as ofthe balance sheet date. Long-term investments have maturities greater than one year as of the balance sheet date. All investments are carried at fair valuebased upon quoted market prices. Unrealized gains and losses on available-for-sale securities are excluded from earnings and are reported as a component ofaccumulated other comprehensive loss. The cost of available-for-sale securities sold is based on the specific-identification method. Realized gains and lossesare included in earnings, and are derived for specific-identification method for determining the costs of investments sold.Restricted CashRestricted cash consisted of certificates of deposit held with a financial institution as security deposits for building leases, and is included in short-term assets on the Company’s consolidated balance sheets.Accounts Receivable, Allowance for Doubtful Accounts and Contractual AllowanceAccounts receivable consists of amounts due to the Company from institutions and third-party government and commercial payors and their relatedpatients, as a result of the Company’s normal business activities. Accounts receivable is reported on the balance sheets net of an estimated allowance fordoubtful accounts and contractual allowance.The Company establishes an allowance for doubtful accounts for estimated uncollectible receivables based on its historical experience, andrecognizes the provision as a component of selling, general and administrative expenses. The Company establishes a contractual allowance, which is areduction in revenue, for estimated uncollectible amounts from Centers for Medicare & Medicaid Services (“CMS”), and contracted third-party commercialpayors.85 The following table presents the changes in the allowance for doubtful accounts (in thousands): December 31, December 31, 2017 2016 Balance, beginning of period $1,792 $1,125 Add: provision for doubtful accounts 3,640 1,960 Less: write-offs, net of recoveries and other adjustments (1,864) (1,293)Balance, end of period $3,568 $1,792 The following table presents the changes in the contractual allowance (in thousands): December 31, December 31, 2017 2016 Balance, beginning of period $2,340 $338 Add: contractual allowances 5,763 2,726 Less: write-offs, net of recoveries and other adjustments (659) (724)Balance, end of period $7,444 $2,340 Management reviews and updates its estimates for the allowances for doubtful accounts and contractual allowance periodically to reflect itsexperience regarding historical collections. If management were to make different judgments or utilize different estimates in the allowances for doubtfulaccounts and contractual allowance, differences in the amount of reported selling, general and administrative expenses and revenue could result,respectively.Concentrations of RiskCredit RiskFinancial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash and cash equivalents,investments and accounts receivable. Cash, cash equivalents, and investments are deposited in financial institutions which, at times, such deposits may be inexcess of federally insured limits. Cash equivalents are invested in highly rated money market funds. The Company invests in a variety of financialinstruments, such as, but not limited to, United States Government securities, corporate notes, commercial paper and, by policy, limits the amount of creditexposure with any one financial institution or commercial issuer. The Company has not experienced any material losses on its deposits of cash and cashequivalents or investments.Concentrations of credit risk with respect to accounts receivable are limited due to the large number of customers comprising the Company’scustomer base and their dispersion across many geographies. The Company does not require collateral. The Company records an allowance for doubtfulaccounts when it becomes probable that a receivable will not be collected. Federal government agencies, including CMS and the Veterans Administration,accounted for approximately 37%, 40% and 41% of the Company’s revenue for the years ended December 31, 2017, 2016 and 2015, respectively. Accountsreceivable related to federal government agencies accounted for 27% and 27% at December 31, 2017 and 2016, respectively.Supply RiskWhile the Company has not experienced manufacturing supply disruptions to date, the Company relies on single-source vendors for the supply of itsdisposable housings, instruments and other materials used to manufacture the Zio XT monitor and the adhesive that binds the Zio XT monitor to a patient’sbody. These components and materials are critical, and there could be a considerable delay in finding alternative sources of supply.86 InventoryInventory is stated at the lower of cost or net realizable value, cost being determined on a standard cost basis for material costs and on actual costbasis for labor and overhead, which approximates actual cost on a first in, first out (“FIFO”) basis, and market being determined as the lower of cost or netrealizable value. The Company records write-downs of inventory that is obsolete or in excess of anticipated demand or market value based on considerationof product lifecycle stage, technology trends, product development plans and assumptions about future demand and market conditions. Actual demand maydiffer from forecasted demand, and such differences may have a material effect on recorded inventory values. Inventory write-downs are charged to cost ofrevenue and establish a new cost basis for the inventory.Property and EquipmentProperty and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization is computed using thestraight-line method over the estimated useful lives of the assets, ranging from three to five years. Leasehold improvements are amortized over the shorter ofthe lease term or the estimated useful lives of the assets. Maintenance and repairs are charged to expense as incurred, and improvements and betterments arecapitalized.Internal-Use SoftwareThe Company capitalizes costs related to internal-use software during the application development stage. Costs related to planning and postimplementation activities are expensed as incurred. Capitalized internal-use software is amortized, and recognized as cost of revenue, on a straight-line basisover the estimated useful life, which is up to five years. The Company evaluates the useful lives of these assets on an annual basis, and tests for impairmentwhenever events or changes in circumstances occur that could impact the recoverability of these assets. Capitalized internal-use software costs are classifiedas a component of property and equipment.GoodwillGoodwill represents the excess of the purchase price paid over the fair value of tangible and identifiable intangible net assets acquired in businesscombinations. Goodwill is tested for impairment on an annual basis and at any other time if events occur or circumstances indicate that the carrying amountof goodwill may not be recoverable. Such events or circumstances may include significant adverse changes in the general business climate, among otherthings. The impairment test is performed by determining the enterprise fair value of the Company, which is primarily based on the Company’s marketcapitalization. If the Company’s carrying value, as a one reporting unit entity, is less than its fair value, then the fair value is allocated to all of its assets andliabilities (including any unrecognized intangible assets) as if the fair value was the purchase price to acquire the Company. The excess of the fair value overthe amounts assigned to the Company’s assets and liabilities is the implied fair value of the goodwill. If the carrying amount of goodwill exceeds the impliedfair value of that goodwill, an impairment loss is recognized in an amount equal to that excess. The Company performs its annual evaluation of goodwillduring the fourth quarter of each fiscal year. The Company did not record any charges related to goodwill impairment in any of the periods presented in theseconsolidated financial statements.Impairment of Long-Lived AssetsThe Company annually reviews long-lived assets for impairment or whenever events or changes in circumstances indicate that the carrying amountof an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future net cash flows which the assets areexpected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amountof the assets exceeds the projected discounted future net cash flows arising from the asset. To date, there have been no such impairments of long-lived assets.87 Other AssetsIncluded in the other assets are printed circuit board assemblies (“PCBAs”) totaling $3.3 million and $2.8 million as of December 31, 2017 and 2016,respectively. The Company uses a PCBA in each wearable Zio XT monitor which is used numerous times and has a useful life beyond one year. Each time thePCBA is used in a wearable Zio XT monitor, a portion of the cost of the PCBA is recorded as a cost of revenue. The Company has based its estimates of howmany times a PCBA can be used on testing in research and development, loss rates, product obsolescence, and the amount of time it takes the device to gothrough the manufacturing, shipping, customer shelf and patient wear time and upload process. The Company periodically evaluates the use estimate.Comprehensive LossComprehensive loss represents all changes in stockholders’ equity during the period from non-owner sources. The Company’s unrealized gains andlosses on available-for-sale securities represent the only component of other comprehensive loss that are excluded from the reported net loss and that arepresented in the consolidated statements of comprehensive loss.Revenue RecognitionThe Company’s devices, cardiac rhythm monitors, have a wear period for up to 14 days for the Zio XT service or 30 days for the Zio Event Card. TheCompany’s services, consisting of the delivery of reports containing analysis of data captured by the physical device to the prescribing physician, aregenerally billable at the start of the wear period or when reports are issued to physicians, depending on the service provided. For the Zio XT service, theCompany recognizes the revenue at the time that a report is delivered to a physician. For the Zio Event Card, the Company recognizes revenue on a straight-line basis over the applicable wear period, as the event monitoring results are delivered to physicians. For all services performed, the Company considerswhether or not the following revenue recognition criteria are met: persuasive evidence of an arrangement exists and delivery has occurred or services havebeen rendered. For services performed for customers which the Company invoices directly, additional revenue recognition criteria include that the price isfixed and determinable and collectability is reasonably assured; for customers in which the Company submits claims to third-party commercial andgovernmental payors for reimbursement, the Company recognizes revenue only when a reasonable estimate of reimbursement can be made.The assessment of whether a reasonable estimate of reimbursement can be made requires significant judgment by management. Where management’sjudgment indicates a reasonable estimate of reimbursement can be made, revenue is recognized upon delivery of the patient report for the Zio XT service andstraight-line for the Zio Event Card. Some patients have out-of-pocket costs for amounts not covered by their insurance carrier, and the Company bills thepatient directly for these amounts in the form of co-payments and co-insurance in accordance with their insurance carrier and health plans. Some payors maynot cover the Company’s service as ordered by the prescribing physician under their reimbursement policies. In the absence of an agreement with the patientor other clearly enforceable legal right to demand payment from the patient, the related revenue is recognized upon the earlier of notification of the payorbenefits allowed or when payment is received, until the Company has the ability to make a reasonable estimate. Once a reasonable estimate can be made,revenue is recognized upon delivery of the service. During 2017, the Company recognized revenue on an accrual basis from certain non-contracted payors asa reasonable estimate was able to be made, primarily based on the consistency of historical payments.The Company recognizes revenue related to billings for CMS and commercial payors on an accrual basis, net of contractual allowances, when areasonable estimate of reimbursement can be made. These contractual allowances represent the difference between the list price (the billing rate) and thereimbursement rate for each payor. Upon ultimate collection from CMS and commercial payors, the amount is compared to the previous estimates and thecontractual allowance is adjusted accordingly. Until a contract has been negotiated with a commercial payor, the Company’s services may or may not becovered by these entities’ existing reimbursement policies. In addition, patients do not enter into direct agreements with the Company that commit them topay any portion of the cost of the service in the event that their insurance declines to reimburse the Company. In the absence of an agreement with the patientor other clearly enforceable legal right to demand payment from the patient, the related revenue is recognized only upon the earlier of notification of thepayor benefits allowed or when payment is received, until the Company has the ability to make a reasonable estimate. Revenue related to non-contractedclaims was $11.3 million,88 $11.2 million, and $3.5 million for the years ended December 31, 2017, 2016 and 2015, respectively. Contracted revenue recognized on an accrual basis was$87.2 million, $52.9 million, and $32.6 million for the years ended December 31, 2017, 2016 and 2015, respectively.Certain of the Company’s customers pay the Company directly for the Zio XT service upon shipment of devices. Such advance payments arerecorded as deferred revenue on the consolidated balance sheets and revenue is recognized when reports are delivered to physicians.Cost of RevenueCost of revenue is expensed as incurred, and includes direct labor, material costs, equipment and infrastructure expenses, amortization of internal-usesoftware, allocated overhead, and shipping and handling. Material costs include both the disposable costs of the device and amortization of the PCBAs. Eachtime the PCBA is used in a wearable Zio XT monitor, a portion of the cost of the PCBA is recorded as a cost of revenue.Research and DevelopmentThe Company’s research and development costs are expensed as incurred. Research and development costs include, but are not limited to, payrolland personnel-related expenses, laboratory supplies, consulting costs and overhead charges.Income TaxesThe Company uses the asset and liability method to account for income taxes in accordance with the authoritative guidance for income taxes. Underthis method, deferred tax assets and liabilities are determined based on future tax consequences attributable to differences between the financial statementcarrying amounts of existing assets and liabilities and their respective tax bases, and tax loss and credit carryforwards. Deferred tax assets and liabilities aremeasured using enacted tax rates applied to taxable income in the years in which those temporary differences are expected to be recovered or settled. Theeffect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuationallowance is established when necessary to reduce deferred tax assets to the amount expected to be realized.The Tax Cuts and Jobs Act (“2017 Tax Act”) was enacted on December 22, 2017 and introduces significant changes to U.S. income tax law. Effectivein 2018, the Tax Act reduces the U.S. statutory tax rate from 35% to 21% among other significant changes. In addition, in 2017 the Company is subject to aone-time transition tax on accumulated foreign subsidiary earnings not previously subject to U.S. income tax. Accounting for the income tax effects of theTax Act requires significant judgments and estimates in the interpretation and calculations of the provisions of the Tax Act.On December 22, 2017, the SEC staff issued Staff Accounting Bulletin No. 118 (“SAB 118”), which provides guidance for the tax effect of the 2017Tax Act. SAB 118 provides a measurement period that should not extend beyond one year from the 2017 Tax Act’s enactment date for companies tocomplete the accounting under Accounting Standards Codification Topic 740, Income Taxes (“ASC 740”). In accordance with SAB 118, the Company mustreflect the income tax effects of those aspects of the 2017 Tax Act for which the accounting under ASC 740 is complete. To the extent that our accounting forcertain income tax effects of the Tax Act is incomplete, but we are able to determine a reasonable estimate, we must record a provisional estimate in ourconsolidated financial statements. If we cannot determine a provisional estimate to be included in our consolidated financial statements, we should continueto apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the Tax Act. The amounts of the taxeffects related to the Tax Act described in the paragraphs above represent our reasonable estimates and are provisional amounts within the meaning of SAB118. Also, it is expected that the U.S. Treasury will issue regulations and other guidance on the application of certain provisions of the 2017 Tax Act. Insubsequent periods, but within the measurement period, we will analyze that guidance and other necessary information to refine our estimates and completeour accounting for the tax effects of the 2017 Tax Act as necessary.Due to the timing of the enactment and the complexity involved in applying the provisions of the 2017 Tax Act, the Company made reasonableestimates of the effects and recorded provisional amounts in its financial89 statements for the year ended December 31, 2017. As the Company collects and prepares necessary data, and interprets any additional guidance issued by theU.S. Department of the Treasury or other standard-setting bodies, the Company may make adjustments to the provisional amounts.The Company recognizes the effect of income tax positions only if those positions are more likely than not of being sustained. Recognized incometax positions are measured at the largest amount that has a greater than 50% likelihood of being realized. Changes in recognition or measurement arereflected in the period in which the change in judgment occurs. The Company records interest and penalties related to unrecognized tax benefits in incometax expense. To date, there have been no interest or penalties charged in relation to the unrecognized tax benefits. Stock-based Compensation The Company measures its stock-based awards made to employees based on the estimated fair values of the awards as of the grant date. The fair valueof stock options is determined using the Black-Scholes option pricing model. Stock-based compensation expense is recognized over the requisite serviceperiod using the straight-line method and is based on the value of the portion of stock-based payment awards that is ultimately expected to vest. As such, theCompany’s stock-based compensation is reduced for the estimated forfeitures at the date of grant and revised, if necessary, in subsequent periods if actualforfeitures differ from those estimates. For restricted stock, the compensation cost for these awards is based on the closing price of the Company’s commonstock on the date of grant, and recognized as compensation expense on a straight-line basis over the requisite service period. The Company recognizes compensation expense related to the Employee Stock Purchase Program (“ESPP”) based on the estimated fair value of theoptions on the date of grant, net of estimated forfeitures. The Company estimates the grant date fair value, and the resulting stock-based compensationexpense, using the Black-Scholes option pricing model for each purchase period. The grant date fair value is expensed on a straight-line basis over theoffering period. Net Loss per Common Share Basic net loss per common share is calculated by dividing the net loss by the weighted average number of shares of common stock outstandingduring the period, without consideration of potentially dilutive securities. Diluted net loss per common share is the same as basic net loss per common sharefor all periods presented, since the effect of potentially dilutive securities are anti-dilutive. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”), issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue fromContracts with Customers (Topic 606). Areas of revenue recognition that will be affected include, but are not limited to, transfer of control, variableconsideration, allocation of transfer pricing, licenses, time value of money, contract costs and disclosures. The core principle of ASU 2014-09 is to recognizerevenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for thosegoods or services. ASU 2014-09 defines a five-step process to achieve this core principle and, in doing so, it is possible more judgment and estimates may berequired within the revenue recognition process than are required under existing GAAP. In addition, Topic 606 requires more detailed disclosures to enableusers of financial statements to understand the nature, timing and uncertainty of revenue and cash flows arising from a review of historical accountingpolicies and practices to identify potential differences in applying Topic 606. The Company adopted this standard on January 1, 2018 and used the modified retrospective approach. Upon adoption, the Company recognized thecumulative effect of adopting the new revenue standard as an adjustment to the opening balance of the Company’s accumulated deficit. This adjustment didnot have a material impact on the Company’s consolidated financial statements. Prior periods will not be retrospectively adjusted. The adoption results in achange to net revenue primarily due to the change in classification of bad debt expense related to the patient responsibility of both contracted and non-contracted claims as a reduction of gross revenue rather than as a component of selling, general and administrative expenses. As a result, starting on January1, 2018, the Company90 will be presenting revenue net of this bad debt expense. To a lesser extent, revenue will be impacted due to timing differences in its recognition of revenuerelated to non-contracted third-party payor claims as a result of changing from recognition based on the earlier of notification of the payor benefits allowed orwhen payment is received to the accrual basis based on historical experience. In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation (Topic 718). This ASU was issued as part of the FASB’ssimplification initiative and affects all entities that issue share-based payment awards to their employees. This standard covers accounting for income taxes,forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. As a result of adopting ASU No. 2016‑09 onJanuary 1, 2017, the Company has made an accounting policy election to continue to estimate forfeitures. The adoption of ASU No. 2016‑09 also requiresexcess tax benefits and tax deficiencies be recorded in the income statement as opposed to additional paid‑in capital when the awards vest or are settled, andhas been applied on a prospective basis with no impact on the consolidated financial statements as of and for the year ended December 31, 2017. As a resultof the adoption, the Company increased its total NOLs by $0.1 million on January 1, 2017 related to deferred tax assets that arose directly from taxdeductions related to equity compensation greater than compensation recognized for financial reporting purposes. This amount is fully offset by thevaluation allowance. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which requires lessees to recognize lease liabilities and correspondingright-of-use assets for all leases with lease terms of greater than 12 months. It also changes the definition of a lease and expands the disclosure requirements oflease arrangements. Currently, the new guidance must be adopted using the modified retrospective approach, including a number of optional practicalexpedients that entities may elect to apply, with the cumulative effect of applying the new guidance recognized as an adjustment to the opening retainedearnings balance in the earliest period presented. In January 2018, the FASB issued an exposure draft that, if adopted, would allow for recognition of thecumulative effect of applying the new guidance as an adjustment to the opening retained earnings balance in the year of adoption, among other changes. TheCompany will adopt the new guidance in the first quarter of fiscal 2019 and is in the process of determining the effects the adoption will have on itsconsolidated financial statements. In November 2016, the FASB issued ASU No. 2016-18 Statement of Cash Flow: Restricted Cash (Topic 230), which provides guidance on theclassification of restricted cash to be included with cash and cash equivalents when reconciling the beginning of period and end of period total amounts onthe statement of cash flows. The amendments of this ASU are effective for interim and annual periods beginning after December 15, 2017. The standard mustbe applied retrospectively to all periods presented. The adoption of this standard will not have a material impact on the cash flow activity presented on theCompany's Consolidated Statements of Cash Flows. In May 2017, the FASB issued ASU 2017-09, Scope of Modification Accounting, which amends the scope of modification accounting for share-based payment arrangements, provides guidance on the types of changes to the terms or conditions of share-based payment awards to which an entity wouldbe required to apply modification accounting under ASC 718. This ASU is effective for annual reporting periods, including interim periods within thoseannual reporting periods, beginning after December 15, 2017. The Company is currently evaluating the impact of adoption of this standard. 91 3. Cash Equivalents and Investments The fair value of securities, not including cash at December 31, 2017 and 2016 were as follows (in thousands): December 31, 2017 Amortized Gross Unrealized Estimated Cost Gains Losses Fair Value Money market funds $5,574 $— $— $5,574 U.S. government securities 24,969 — (29) 24,940 Corporate notes 24,539 — (36) 24,503 Commercial paper 47,243 — — 47,243 Total available-for-sale securities $102,325 $— $(65) $102,260 Classified as: Cash equivalents $5,574 Short-term investments 93,692 Long-term investments 2,994 Total $102,260 December 31, 2016 Amortized Gross Unrealized Estimated Cost Gains Losses Fair Value Money market funds $45,937 $— $— $45,937 U.S. government securities 16,479 11 — 16,490 Corporate notes 23,947 — (20) 23,927 Commercial paper 24,971 — — 24,971 Total available-for-sale securities $111,334 $11 $(20) $111,325 Classified as: Cash equivalents $45,937 Short-term investments 54,407 Long-term investments 10,981 Total $111,325 Available-for-sale securities held as of December 31, 2017 had a weighted average days to maturity of 143 days. As of December 31, 2017, theCompany had 17 investments in an unrealized loss position. There have been no material realized gains or realized losses on available-for-sale securities forthe periods presented.As the carrying value approximates the fair value for the Company’s cash equivalents, short-term and long-term marketable securities shown in thetables above, the following table summarizes the fair value of the Company’s cash equivalents, short-term and long-term marketable securities classified bymaturity as of December 31, 2017 and 2016 (in thousands): December 31, 2017 2016 Due within one year $99,266 $100,344 Due after one year through three years 2,994 10,981 Total available-for-sale marketable debt securities $102,260 $111,325 92 4. Fair Value MeasurementsThe Company discloses and recognizes the fair value of its assets and liabilities using a hierarchy that prioritizes the inputs to valuation techniquesused to measure fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderlytransaction between market participants at the reporting date. The hierarchy gives the highest priority to valuations based upon unadjusted quoted prices inactive markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to valuations based upon unobservable inputs that aresignificant to the valuation (Level 3 measurements). The guidance establishes three levels of the fair value hierarchy as follows:Level 1—Inputs are unadjusted quoted prices in active markets for identical assets or liabilities at the measurement date.Level 2—Inputs (other than quoted market prices included in Level 1) are either directly or indirectly observable for the asset or liability throughcorrelation with market data at the measurement date and for the duration of the instrument’s anticipated life.Level 3—Inputs reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date.Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model.Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair valuemeasurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to makejudgments and consider factors specific to the asset or liability. The corporate notes, commercial paper and government bonds are classified as Level 2 asthey were valued based upon quoted market prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets thatare not active and model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observablemarket data for substantially the full term of the assets.The fair value of the Company’s outstanding interest-bearing obligations is estimated using the net present value of the payments, discounted at aninterest rate that is consistent with market interest rates, which is a Level 2 input. The carrying amount and the estimated fair value of the Company’soutstanding interest-bearing obligations at December 31, 2017 are $34.0 million and $38.6 million, respectively. The carrying amount and the estimated fairvalue of the Company’s outstanding interest-bearing obligations at December 31, 2016 were $32.2 million and $32.2 million, respectively. The following table presents the fair value of the Company’s financial assets and liabilities determined using the inputs defined above (inthousands). December 31, 2017 Level 1 Level 2 Level 3 Total Assets Money market funds $5,574 $— $— $5,574 U.S. government securities — 24,940 — 24,940 Corporate notes — 24,503 — 24,503 Commercial paper — 47,243 — 47,243 Total $5,574 $96,686 $— $102,260 December 31, 2016 Level 1 Level 2 Level 3 Total Assets Money market funds $45,937 $— $— $45,937 U.S. government securities — 16,490 — 16,490 Corporate notes — 23,927 — 23,927 Commercial paper — 24,971 — 24,971 Total $45,937 $65,388 $— $111,325 93 The following table sets forth a summary of the changes in the fair value of the preferred stock warrants which are classified as Level 3 in the fairvalue hierarchy. All preferred stock warrants were converted in 2016, and no additional charges were recorded in 2017. There were no transfers into or out ofLevel 3 during the periods (in thousands): Year Ended December31, 2016 Beginning balance $2,949 Exercise of preferred stock warrants (251)Total change in fair value recorded as other expense, net 2,123 Reclassification of warrant liability to additional paid-in capital (4,821)Ending balance $— The valuation of the preferred stock warrant liabilities is discussed in Note 10.5. Balance Sheet ComponentsInventory and PCBAsInventory and PCBAs consisted of the following (in thousands): December 31, 2017 2016 Raw materials $1,103 $839 Finished goods 3,830 3,324 Total $4,933 $4,163 December 31, 2017 2016 Reported on the consolidated balance sheet as: Inventory $1,683 $1,390 Other assets 3,250 2,773 Total $4,933 $4,163 Amounts reported as other assets are comprised of the PCBA costs that are included in both raw materials and finished goods totals above.Property and Equipment, NetProperty and equipment, net consisted of the following (in thousands): December 31, 2017 2016 Laboratory and manufacturing equipment $1,994 $1,509 Computer equipment and software 1,015 736 Furniture and fixtures 953 657 Leasehold improvements 726 502 Internal-use software 4,598 2,900 Total property and equipment, gross 9,286 6,304 Less: accumulated depreciation and amortization (3,065) (1,651)Total property and equipment, net $6,221 $4,65394 Depreciation and amortization expense for the years ended December 31, 2017, 2016 and 2015 was $1.6 million, $0.6, million and $0.5 millionrespectively.Accrued LiabilitiesAccrued liabilities consisted of the following (in thousands): December 31, 2017 2016 Accrued vacation $2,081 $1,642 Accrued payroll and related expenses 9,361 6,179 Accrued professional services fees 1,041 636 Claims payable 1,375 257 Other 1,786 1,451 Total accrued liabilities $15,644 $10,165 6. Commitments and ContingenciesLease ArrangementsThe Company leases office and manufacturing space under non-cancelable operating leases which expire on various dates through 2027. Theseleases generally contain scheduled rent increases or escalation clauses and renewal options. The Company recognizes rent expense on a straight-line basisover the lease period.The following table summarizes the Company’s future minimum lease payments as of December 31, 2017 (in thousands): Period Ending December 31: 2018 $5,260 2019 5,294 2020 1,194 2021 406 2022 417 Thereafter 2,125 Total $14,696 The Company’s rent expense was $5.1 million, $3.1 million and $1.6 million for the years ended December 31, 2017, 2016 and 2015, respectively.Legal ProceedingsFrom time to time, the Company may become involved in legal proceedings arising from the ordinary course of its business. Management is currentlynot aware of any matters that could have a material adverse effect on the financial position, results of operations or cash flows of the Company.IndemnificationsIn the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements,the Company may indemnify, hold harmless and defend an indemnified party for losses suffered or incurred by the indemnified party. Some of the provisionswill limit losses to those arising from third-party actions. In some cases, the indemnification will continue after the termination of the agreement. Themaximum potential amount of future payments the Company could be required to make under these provisions is not determinable. The Company has alsoentered into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilitiesthat may arise by95 reason of their status or service as directors or officers to the fullest extent permitted by California corporate law. The Company currently has directors’ andofficers’ insurance. The Company has never incurred material costs to defend lawsuits or settle claims related to these indemnification provisions, andbelieves that the estimated fair value of these indemnification obligations is not material and it has not accrued any amounts for these obligations.7. DebtPharmakon Loan AgreementIn December 2015, the Company entered into a Loan Agreement with Biopharma Secured Investments III Holdings Cayman LP, or Pharmakon (the“Pharmakon Loan Agreement”). The Pharmakon Loan Agreement provides for up to $55.0 million in term loans split into two tranches as follows: (i) theTranche A Loans are $30.0 million in term loans, and (ii) the Tranche B Loans are up to $25.0 million in term loans. The Tranche A Loans were drawn onDecember 4, 2015. The Tranche B Loans were available to be drawn prior to December 4, 2016. No additional draw was made. During the first full eight quarters, payments are interest only and for the first two years 50% of the interest will be “paid-in-kind.” The Company issubject to a financial covenant related to minimum trailing revenue targets that begins in June 2017, and is tested on a semi-annual basis. The minimum netrevenue covenant ranges from $44.7 million for the period ended June 30, 2017 to $102.6 million for the period ended December 31, 2021. To date allminimum revenue targets have been achieved. The minimum net revenues financial covenant has a 45-day equity cure period following required deliverydate of the financial statements. Pursuant to this equity cure provision, the Company may cure a revenue covenant default by raising additional funds fromthe sale of equity. The Company was in compliance with loan covenants as of December 31, 2017. The loan matures December 2021. The Tranche A Loans bear interest at a fixed rate equal to 9.50% per annum that is due and payable quarterly in arrears. During the first eight calendarquarters, 50% of the interest due and payable shall be added to the then outstanding principal. The Pharmakon Loan Agreement requires the Company to maintain a minimum consolidated liquidity and minimum net revenue during the term ofthe loan facility and contains customary affirmative and negative covenants and event of default provisions that could result in the acceleration of therepayment obligations under the loan facility. Upon a change in control of the Company, Pharmakon has the option to demand payment in full of theoutstanding loans together with any prepayment premium. The obligations under the Pharmakon Loan Agreement are secured by a security interest in substantially all of the Company’s assets pursuant to thePharmakon Guaranty and Security Agreement and this security interest is governed by an intercreditor agreement between Pharmakon and Silicon ValleyBank (“SVB”). In December 2015, the Company used the proceeds from the Pharmakon Loan Agreement to repay $4.9 million of bank debt to SVB. The issuancecosts and debt discount have been netted against the borrowed funds on the balance sheet. The debt balance as of December 31, 2017 and 2016, was $32.5million and $30.8 million, respectively.Bank DebtIn December 2015, the Company entered into a Second Amended and Restated Loan and Security Agreement with SVB, (the “SVB LoanAgreement”). Under the SVB Loan Agreement the Company may borrow, repay and reborrow under a revolving credit line, but not in excess of the maximumloan amount of $15.0 million, until December 4, 2018, when all outstanding principal and accrued interest becomes due and payable. Any principal amountoutstanding under the SVB revolving credit line shall bear interest at a floating rate per annum equal to the rate published by The Wall Street Journal as the“Prime Rate” plus 0.25%. The Company may borrow up to 80% of its eligible accounts receivable, up to the maximum of $15.0 million.96 In August 2016, the Company obtained a $3.1 million standby letter of credit pursuant to the SVB Loan Agreement in connection with a lease for itsSan Francisco office. As of December 31, 2017 and 2016, the Company was eligible to borrow up to $3.3 million and $2.5 million, respectively, under theSVB revolving credit line.The SVB Loan Agreement requires the Company to maintain a minimum consolidated liquidity and minimum net sales during the term of the loanfacility. In addition, the SVB Loan Agreement contains customary affirmative and negative covenants and events of default. The Company was incompliance with loan covenants as of December 31, 2017. The obligations under the SVB Loan Agreement are collaterialized by substantially all assets ofthe Company and this security interest is governed by an intercreditor agreement between Pharmakon and SVB.California HealthCare Foundation NoteIn November 2012, the Company entered into a Note Purchase Agreement and Promissory Note with the California HealthCare Foundation (the“CHCF Note”), through which the Company borrowed $1.5 million. The CHCF Note accrues simple interest of 2.0%. The accrued interest and the principalwas to mature in November 2016. In partial consideration for the issuance of the CHCF Note, the Company issued warrants to purchase 22,807 shares of theCompany’s Series D convertible preferred stock.In June 2015, the Company amended the CHCF Note to extend the maturity date to May 2018. In partial consideration for the amendment, theCompany issued 8,552 warrants at $6.58 exercise price per share for shares of the Company’s Series D convertible preferred stock.The CHCF note is subordinate to other debt. The debt balance, net of debt discount, as of December 31, 2017 and 2016 was $1.5 million and $1.5million, respectively.Future minimum paymentsFuture minimum payments under the CHCF Note and Pharmakon Loan at December 31, 2017 are as follows (in thousands): 2017 Year Ending December 31: 2018 $4,858 2019 3,192 2020 19,169 2021 17,564 Total 44,783 Less: Amount representing interest (10,143)Less: Amount representing debt discount and issuance costs (662)Present value of minimum payments $33,978 Reported as: Short-term debt $1,487 Long-term debt 32,491 Total $33,978 8. Income Taxes In December 2017, the Tax Cuts and Jobs Act (the “2017 Tax Act”) was enacted. The 2017 Tax Act includes a number of changes to existing U.S. taxlaws that impact the company, most notably a reduction of the U.S. corporate income tax rate from 35 percent to 21 percent for tax years beginning afterDecember 31, 2017. The 2017 Tax Act also provides for a one-time transition tax on certain foreign earnings and the acceleration of depreciation97 for certain assets placed into service after September 27, 2017 as well as prospective changes beginning in 2018, including repeal of the domesticmanufacturing deduction, acceleration of tax revenue recognition, capitalization of research and development expenditures, additional limitations onexecutive compensation and limitations on the deductibility of interest.On December 22, 2017, the SEC staff issued Staff Accounting Bulletin No. 118 (“SAB 118”), which provides guidance for the tax effect of the 2017Tax Act. SAB 118 provides a measurement period that should not extend beyond one year from the 2017 Tax Act’s enactment date for companies tocomplete the accounting under Accounting Standards Codification Topic 740, Income Taxes (“ASC 740”). In accordance with SAB 118, the Company mustreflect the income tax effects of those aspects of the 2017 Tax Act for which the accounting under ASC 740 is complete. To the extent that our accounting forcertain income tax effects of the Tax Act is incomplete, but we are able to determine a reasonable estimate, we must record a provisional estimate in ourconsolidated financial statements. If we cannot determine a provisional estimate to be included in our consolidated financial statements, we should continueto apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the Tax Act. The amounts of the taxeffects related to the Tax Act described in the paragraphs above represent our reasonable estimates and are provisional amounts within the meaning of SAB118. Also, it is expected that the U.S. Treasury will issue regulations and other guidance on the application of certain provisions of the 2017 Tax Act. Insubsequent periods, but within the measurement period, we will analyze that guidance and other necessary information to refine our estimates and completeour accounting for the tax effects of the 2017 Tax Act as necessary.Due to the timing of the enactment and the complexity involved in applying the provisions of the Tax Act, the Company has made reasonableestimates of the effects and recorded provisional amounts in the consolidated financial statements as of December 31, 2017. As the Company collects andprepares necessary data, and interprets the Tax Act and any additional guidance issued by the U.S. Department of Treasury and other standard-setting bodies,the Company may make adjustments to the provisional amounts.Provisional amounts for the following income tax effects of the Tax Act have been recorded as of December 31, 2017 and are subject to changeduring 2018.One-time transition taxThe Tax Act requires the Company to pay U.S. income taxes on accumulated foreign subsidiary earnings not previously subject to U.S. income tax ata rate of 15.5% to the extent of foreign cash and certain other net current assets and 8% on the remaining earnings. The Company recorded a provisionalimmaterial amount for a one-time transitional tax liability which was fully offset by utilization of its net operating loss. Deferred tax effectsThe Tax Act reduces the U.S. statutory tax rate from 35% to 21% for years after 2017. Accordingly, the Company remeasured its deferred taxes as ofDecember 31, 2017 to reflect the reduced rate that will apply in future periods when these deferred taxes are settled or realized. The Company recognized theremeasurement of deferred taxes with an offset to the valuation allowance of $20.7 million. Although the tax rate reduction is known, the analysis of theeffect of the Tax Act on the underlying deferred taxes are considered to be provisional.98 The Company operates in the United States for tax reporting purposes. The Company did not record a provision or benefit for income taxes duringthe years ended December 31, 2017, 2016 and 2015, as it reported losses in each period which are not more likely than not to be realized. Due to theuncertainties surrounding the realization of deferred tax assets through future taxable income, the Company has provided a full valuation allowance and,therefore, no benefit has been recognized for the net operating loss carryforwards and other deferred tax assets.The following table presents a reconciliation of the tax expense computed at the statutory federal rate and the Company’s tax expense for the periodpresented (in thousands): Year Ended December 31, 2017 2016 2015 Tax at statutory federal rate (10,034) $(7,107) $(7,752)Stock-based compensation (7,634) 255 251 Other 53 916 (128)Tax credits (644) (139) (178)2017 Tax Act 21,928 — — Change in valuation allowance (3,669) 6,075 7,807 Provision for income taxes $— $— $— 99 Deferred income taxes reflect the net effects of temporary differences between the carrying amounts of assets and liabilities for financial reportingpurposes and the amounts used for income tax purposes. The Company recorded a provisional adjustment to the U.S. deferred income taxes as of December31, 2017 to reflect the reduction in the U.S. corporate income tax rate from 35% to 21% resulting from the 2017 Tax Act. Significant components of ourdeferred tax assets and liabilities are as follows (in thousands): December 31, 2017 2016 Deferred tax assets: Net operating loss carryforwards $35,338 $38,694 Tax credit carryforwards 2,642 1,587 Allowances and other 6,682 4,787 Depreciation and amortization (414) (207)Total deferred tax assets 44,248 44,861 Valuation allowance (44,248) (44,861)Net deferred tax assets $— $— Due to the uncertainties surrounding the realization of deferred tax assets through future taxable income, the Company has provided a full valuationallowance and, therefore, no benefit has been recognized for the net operating loss carryforwards and other deferred tax assets. The valuation allowancedecreased by $0.6 million and increased by $6.3 million for the years ended December 31, 2017 and December 31, 2016, respectively. The current yearchange in the valuation allowance is primarily related to the increase in net operating loss carryforwards generated during the year and offset by a decrease inthe deferred taxes assets related to the reduction of the U.S. corporate income tax rate from the 2017 Tax Act.As of December 31, 2017, the Company had approximately $143.1 million of federal and $82.4 million of state net operating loss carryforwardsavailable to offset future taxable income which expires in varying amounts beginning in 2027 and 2018, respectively.As of December 31, 2017, the Company had tax credit carryforwards of approximately $2.1 million, and $1.8 million available to reduce futuretaxable income, if any, for both federal and state purposes, respectively. The federal tax credit carryforwards expire beginning in 2028 and the state taxcredits can be carried forward indefinitely.Section 382 of the Internal Revenue Code, and similar state provisions, limits the use of net operating loss and tax credit carryforwards in certainsituations where equity transactions result in a change of ownership as defined by Internal Revenue Code Section 382. In the event the Company shouldexperience an ownership change, as defined, utilization of its net operating loss carryforwards and tax credits could be limited.A reconciliation of the Company’s unrecognized tax benefit amount is as follows (in thousands): Year Ended December 31, 2017 2016 2015 Balance at beginning of year $616 $570 $460 Additions for tax positions taken in current year 328 75 110 Decreases in balances related to prior year tax position (1) (29) — Balance at end of year $943 $616 $570 The total amount of gross unrecognized tax benefits was $0.9 million, $0.6 million, and $0.6 million as of December 31, 2017, 2016, and 2015respectively, all of which , if recognized, would affect the effective tax rate. The Company does not anticipate the total amounts of unrecognized tax benefitswill significantly increase or decrease in the next 12 months.100 The Company’s policy is to include interest and penalties related to unrecognized tax benefits within the provision for taxes. Managementdetermined that no accrual for interest or penalties was required as of December 31, 2017 and 2016.The Company files income tax returns in the U.S. and UK jurisdictions. All of the Company's tax years are open to examination by the US federal,state and foreign tax authorities.9. Stockholders’ EquityCommon stockThe Company’s amended and restated certificate of incorporation dated October 25, 2016, authorizes the Company to issue 100,000,000 shares ofcommon stock with a par value of $0.001 per share and 5,000,000 shares of preferred stock with a par value of $0.001 per share. The holders of common stockare entitled to receive dividends whenever funds and assets are legally available and when declared by the board of directors, subject to the prior rights ofholders of all series of convertible preferred stock outstanding. No dividends were declared through December 31, 2017.The Company had reserved shares of common stock for issuance as follows: December 31, 2017 2016 Options issued and outstanding 2,601,181 2,977,218 Unvested restricted stock units 468,426 105,529 Common stock warrants issued and outstanding 4,857 217,245 Shares available for grant under future stock plans 4,650,669 4,226,068 7,725,133 7,526,060 10. Common Stock Warrant LiabilitiesIn November 2012, in connection with borrowings under a convertible note, the Company issued warrants to purchase shares of Series C or NewPreferred. The warrants were only exercisable if the Convertible Notes were converted into Series C or New Preferred. The warrants’ exercise price is $0.001per share and they have a seven year term. On March 27, 2013 the Company closed the Series D financing. The warrants were converted into warrants topurchase 207,177 shares of Series D convertible preferred stock. The Company recognized a charge of $1,199,000, and income of $42,000 related to thechange in the fair value of the warrants for the years ended December 31, 2016 and 2015, respectively. Upon the IPO, the Series D preferred stock warrantsconverted into common stock warrants and were reclassified to additional paid-in-capital in the Company's balance sheet. As a result, the warrants are nolonger subject to fair value remeasurement. As of December 31, 2017 and December 31, 2016, warrants outstanding were 4,857, and 217,245, respectively.In June 2014, in connection with borrowings under the Second Amendment (See Note 7), the Company issued warrants to purchase 20,136 shares ofSeries D Preferred Stock at $7.31 per share that expire June 2024. The fair value of the warrants was determined by using an option pricing model prepared bya third-party based on an allocation of the Company’s aggregate value to the outstanding equity instruments, applying a 30% discount to the warrant valuefor lack of marketability. The fair value of the warrants, $0.1 million, was recorded as a debt discount and is being amortized over the loan repayment periodto interest expense. The Company recognized a charge of $237,000, and a charge of $14,000 related to change in the fair value of the warrants for the yearsended December 31, 2016 and 2015, respectively. The warrants were converted into warrants to purchase common stock upon the completion of the IPO in2016, and were reclassified to additional paid-in-capital in the Company's balance sheet. One of the warrants for 10,068 shares was exercised through acashless exercise on October 26, 2016 resulting in the issuance of a net 7,310 shares of the Company's common stock, and the other warrant for 10,068 was101 exercised through a cashless exercise on May 2, 2017 resulting in the issuance of a net 8,077 shares of the Company’s common stock. 11. Stock Incentive Plans2006 PlanIn October 2006, the Company adopted the 2006 Equity Incentive Plan, as amended, (the “2006 Plan”). The Plan provided for the granting of stockoptions to employees and non-employees of the Company. Options granted under the Plan were either incentive stock options or nonqualified stock options.Incentive stock options (“ISO”) were granted only to employees (including officers and directors who are also employees). Nonqualified stock options(“NSO”) may be granted to employees and non-employees. The board of directors had the authority to determine to whom options will be granted, thenumber of options, the term and the exercise price.Options under the Plan were granted for periods of up to ten years and at the fair value of the shares on the date of grant as determined by the board ofdirectors. In general, options become exercisable at a rate of 25% after the first anniversary of the grant and then monthly vesting for an additional three yearsfrom date of grant. The term for options is no longer than five years for ISOs for which the grantee owns greater than 10% of the voting power of all classes ofstock and no longer than ten years for all other options. The Company issues new shares upon the exercise of options.2016 PlanIn October 2016, the Company adopted the 2016 Equity Incentive Plan, (the “2016 Plan”). The 2016 Plan was subsequently approved by theCompany’s stockholders and became effective on October 19, 2016, immediately before the effective date of the IPO. Following the effectiveness of the 2016Plan, no additional options will be granted under the 2006 Plan. In addition, to the extent that any awards outstanding or subject to vesting restrictions underthe 2006 Plan are subsequently forfeited or terminated for any reason before being exercised or settled, the shares of common stock reserved for issuancepursuant to such awards as of the closing of the IPO will become available for issuance under the 2016 Plan. The remaining shares available for grant underthe 2006 Plan became available for issuance under the 2016 Plan upon the closing of the IPO. On the first day of each year beginning with 2017, the 2016Plan authorizes an annual increase of the least of 3,865,000 shares, 5% of outstanding shares on the last day of the immediately preceding fiscal year or anamount as determined by the Company's Board of Directors. As of December 31, 2017, the Company has reserved 4,971,966 shares of common stock forissuance under the 2016 Plan.Pursuant to the 2016 Plan, stock options, restricted shares, stock units, including restricted stock units and stock appreciation rights may be grantedto employees, consultants, and outside directors of the Company. Options granted may be either ISOs or NSOs.Stock options are governed by stock option agreements between the Company and recipients of stock options. ISOs and NSOs may be granted underthe 2016 Plan at an exercise price of not less than 100% of the fair market value of the common stock on the date of grant, determined by the CompensationCommittee of the Board of Directors. Options become exercisable and expire as determined by the Compensation Committee, provided that the term of ISOsmay not exceed ten years from the date of grant.Employee Stock Purchase Program (“ESPP”)In October 2016, the Company’s Board of Directors and stockholders approved the Employee Stock Purchase Plan (the “ESPP”). Under the ESPP, theCompany initially reserved 483,031 shares of common stock for issuance as of its effective date of October 19, 2016. On the first day of each calendar year,beginning in 2017, the number of shares in the reserve will increase by the least of 966,062 shares, 1.5% of the shares of the Company’s common stockoutstanding on the last day of the immediately preceding fiscal year, or an amount as determined by the Company’s Board of Directors. The ESPP allowseligible employees to purchase shares of the Company’s common102 stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan limitations. The ESPP provides for twelve-month offering periods that each contain two six-month purchase periods. At the end of each purchase period, employees are able to purchase shares at 85%of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last day of the purchase period.As of December 31, 2017, 198,604 shares of common stock have been issued to employees participating in the ESPP and 616,517 shares wereavailable for issuance under the ESPP.The Company used the following assumptions to estimate the fair value of the ESPP offered for the year ended December 31, 2017: expected term of0.5 – 1.12 years, volatility of 42.18% - 57.69 %, risk-free interest rate of 0.52% - 1.62% and expected dividend yield of zero.Equity Incentive Plan ActivityA summary of share-based awards available for grant is as follows: Shares Availablefor Grant Balance at December 31, 2014 347,814 Additional options authorized 781,954 Awards granted (915,080)Awards forfeited 117,250 Balance at December 31, 2015 331,938 Additional options authorized 3,865,000 Awards granted (466,914)Awards forfeited 13,013 Balance at December 31, 2016 3,743,037 Additional awards authorized 1,106,966 Awards granted (837,436)Awards forfeited 21,585 Balance at December 31, 2017 4,034,152103 The following table summarizes stock option activity under the 2006 and 2016 Plans, including grants to nonemployees: Options Outstanding OptionsOutstanding Weighted-AverageExercisePrice PerShare Weighted-AverageRemainingContractualLife (years) AggregateIntrinsicValue(in thousands) Balance at December 31, 2014 1,972,383 $3.70 7.86 $4,191 Options granted 915,080 $3.98 Options exercised (84,300) $3.71 Options forfeited (117,250) $3.94 Balance at December 31, 2015 2,685,913 $4.81 7.63 $11,589 Options granted 361,385 $15.65 Options exercised (57,067) $2.33 Options forfeited (13,013) $6.92 Balances at December 31, 2016 2,977,218 $6.16 6.93 $70,979 Options granted 465,271 $36.76 Options exercised (827,556) $4.11 Options forfeited (13,752) $14.43 Balance at December 31, 2017 2,601,181 $12.24 7.17 113,958 Options exercisable – December 31, 2017 1,580,121 $5.82 6.29 79,376 Options vested and expected to vest – December 31, 2017 2,544,782 $11.95 7.13 112,225 The aggregate intrinsic values of options outstanding, exercisable, vested and expected to vest were calculated as the difference between the exerciseprice of the options and the closing price of the Company’s common stock.During the years ended December 31, 2017, 2016 and 2015, the Company granted options with a weighted-average grant date fair value of $18.69,$8.76 and $4.08 per share, respectively.The aggregate intrinsic value of options exercised was $32.5 million $0.7 million and $0.2 million for the years ended December 31, 2017, 2016 and2015, respectively. The total estimated grant date fair value of options vested during the period was $2.4 million, $1.8 million and $1.1 million for the yearsended December 31, 2017, 2016 and 2015, respectively.The fair value of nonvested restricted stock units (“RSUs”) is based on our closing stock price on the date of grant. A summary for the yearended December 31, 2017, is as follows: SharesUnderlyingRSUs WeightedAverageGrant DateFair Value WeightedRemainingVestingPeriod(in years) AggregateIntrinsicValue(in thousands) Nonvested as of December 31, 2016 105,529 $27.39 2.12 $3,166 Granted 372,165 $39.57 Vested and released (1,435) $25.82 Forfeited (7,833) $34.89 Nonvested as of December 31, 2017 468,426 $36.96 2.54 $26,255 104 12. Stock-Based CompensationEmployee Stock-Based CompensationThe Company estimates the fair value of stock options using the Black-Scholes option valuation model. The fair value of employee stock options isbeing amortized on a straight-line basis over the requisite service period of the awards. The fair value of employee stock options was estimated using theweighted average assumptions below. Each of these inputs is subjective and its determination generally requires significant judgment. Year EndedDecember 31 2017 2016 2015 Expected term (in years) 6.1 6.1 6.1 Expected volatility 51.9% 60.0% 60.0%Risk-free interest rate 2.07% 1.42% 1.76%Dividend yield 0.0% 0.0% 0.0% Fair Value of Common Stock— Prior to the completion of the Company’s IPO, the fair value of the shares of the Company’s common stock underlyingthe stock options had historically been determined by the Company’s board of directors. Because there had been no public market for the Company’scommon stock, its board of directors determined the fair value of the Company’s common stock at the time of grant of the option by considering anumber of objective and subjective factors, including valuations of comparable companies, sales of the Company’s convertible preferred stock, theCompany’s operating and financial performance, the lack of liquidity of the Company’s capital stock, and the general and industry-specific economicoutlooks. For stock options granted after the completion of the IPO, the Company’s Board of Directors determined the fair value of each share ofunderlying common stock based on the closing price of the Company’s common stock as reported on the date of grant.Expected Term—The expected term represents the period that the share-based awards are expected to be outstanding. As the Company has very limitedhistorical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock-option grants the Company has elected to use the “simplified method” as prescribed by authoritative guidance to compute expected term.Expected Volatility—Since the Company does not have trading history for its common stock, the expected volatility was estimated based on the averagevolatility for comparable publicly traded companies over a period equal to the expected term of the stock option grants. When selecting comparablepublicly traded companies in a similar industry on which it has based its expected stock price volatility, the Company selected companies withcomparable characteristics to it, including enterprise value, risk profiles, position within the industry, and with historical share price informationsufficient to meet the expected life of the stock-based awards. The Company will continue to apply this process until a sufficient amount of historicalinformation regarding the volatility of its own stock price becomes available.Risk-Free Interest Rate—The risk-free interest rate is based on the U.S. Treasury yield curve in effect on the date of grant for zero coupon U.S. Treasurynotes with maturities approximately equal to expected term of the option award.Expected Dividend Yield—The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock.Therefore, the Company used an expected dividend yield of zero.In addition to the assumptions used in the Black-Scholes option-pricing model, the Company also estimates a forfeiture rate to calculate the stock-based compensation for the Company’s equity awards. The Company will continue to use judgment in evaluating the expected volatility, expected terms andforfeiture rates utilized for the Company’s stock-based compensation calculations on a prospective basis.105 The following table summarizes the total stock-based compensation expense for options, RSUs and ESPP included in the consolidated statements ofoperations for all periods presented (in thousands): Year EndedDecember 31 2017 2016 2015 Cost of revenue $163 $17 $17 Research and development 1,733 203 165 Selling, general and administrative 8,227 1,651 1,228 Total stock-based compensation expense $10,123 $1,871 $1,410 As of December 31, 2017, there was total unamortized compensation costs of $9.5 million, net of estimated forfeitures, related to unvested stockoptions which the Company expects to recognize over a period of approximately 2.4 years, $12.1 million, net of estimated forfeitures, related tounrecognized RSU expense, which the Company expects to recognize over a period of 2.5 years, and $1.3 million unrecognized ESPP expense, which theCompany will recognize over 1.0 years.Non-Employee Stock-Based CompensationStock based compensation expense related to stock options granted to nonemployees is recognized as the stock options are earned. The measurementof stock based compensation for non-employees is subject to periodic adjustment as the underlying equity instruments vest, and the related compensationexpense is based on the estimated fair value of the equity instruments using the Black Scholes option pricing model. The Company believes that theestimated fair value of the stock options is more readily measurable than the fair value of the services received. Such expense was not material for the yearsended December 31, 2017, 2016 and 2015.13. Net Loss Per Common ShareAs the Company had net losses for the years ended December 31, 2017, 2016 and 2015, all potential common shares were determined to be anti-dilutive. The following table sets forth the computation of the basic and diluted net loss per share during the years ended December 31, 2017, 2016 and 2015attributable to common stock holders (in thousands, except share and per share data): Year Ended December 31, 2017 2016 2015 Numerator: Net loss $(29,420) $(20,903) $(22,799)Denominator: Weighted-average shares used to compute net loss per common share, basic and diluted 22,627,327 5,285,847 1,376,106 Net loss per common share, basic and diluted $(1.30) $(3.95) $(16.57) 106 The following outstanding shares of potentially dilutive securities have been excluded from diluted net loss per common share for the years endedDecember 31, 2017, 2016, and 2015 because their inclusion would be anti-dilutive: Year Ended December 31, 2017 2016 2015 Convertible preferred stock on an as-if converted basis — — 13,343,981 Options to purchase common stock 2,601,181 2,977,218 2,685,913 RSUs issued and unvested 468,426 105,529 — Warrants to purchase convertible preferred stock on an as-ifconverted basis — — 328,114 Warrants to purchase common stock 4,857 217,245 — Total 3,074,464 3,299,992 16,358,008 14. Selected Quarterly Financial Data (unaudited)The following table presents selected unaudited financial data for each of the eight quarters in the two-year period ended December 31, 2017. TheCompany believes this information reflects all recurring adjustments necessary to fairly state this information when read in conjunction with the Company'sfinancial statements and the related notes. Net loss per common share, basic and diluted, for the four quarters of each fiscal year may not sum to the total forthe fiscal year because of the different number of shares outstanding during each period. The results of operations for any quarter are not necessarilyindicative of the results to be expected for any future period (in thousands of dollars, except for share and per share data): Quarter Ended March 31 June 30 September 30 December 31 2017: Total revenues $21,437 $23,854 $25,035 $28,183 Gross profit 15,100 17,110 18,115 20,476 Net loss (5,303) (6,444) (6,524) (11,149)Net loss per common share, basic and diluted $(0.24) $(0.29) $(0.29) $(0.48)2016: Total revenues $12,854 $15,734 $16,780 $18,704 Gross profit 8,195 10,578 11,498 12,918 Net loss (6,126) (4,436) (4,075) (6,266)Net loss per common share, basic and diluted $(4.34) $(3.12) $(2.80) $(0.37) 107 Item 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure.None. Item 9A. Controls and Procedures. Evaluation of Disclosure Controls and Procedures Our management, with the participation of our Chief Executive Officer and our Chief Financial Officer, has evaluated the effectiveness of ourdisclosure controls and procedures as of the end of the period covered by this Annual Report on Form 10-K. The term “disclosure controls and procedures,” asdefined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), means controls and other proceduresof a company that are designed to ensure that information required to be disclosed by a company in the reports that it files or submits under the Exchange Actis recorded, processed, summarized and reported, within the time periods specified in the SEC’s rules and forms. Disclosure controls and procedures include,without limitation, controls and procedures designed to ensure that information required to be disclosed by a company in the reports that it files or submitsunder the Exchange Act is accumulated and communicated to the company’s management, including its principal executive and principal financial officers,or persons performing similar functions, as appropriate to allow timely decisions regarding required disclosure. Management recognizes that any controls andprocedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives and management necessarilyapplies its judgment in evaluating the cost-benefit relationship of possible controls and procedures. The design of disclosure controls and procedures andinternal control over financial reporting must reflect the fact that there are resource constraints and that management is required to apply judgment inevaluating the benefits of possible controls and procedures relative to their costs. Based on such evaluation, our Chief Executive Officer and Chief FinancialOfficer have concluded that, as of December 31, 2017, our disclosure controls and procedures were effective at the reasonable assurance level. Changes in Internal Controls over Financial Reporting There were no changes in our internal control over financial reporting as defined in Exchange Act Rule 13a-15(f) and 15d-15(f) that occurred duringour most recently completed fiscal quarter ended December 31, 2017 that have materially affected, or are reasonably likely to materially affect, our internalcontrol over financial reporting. Management’s Report on Internal Control over Financial Reporting Our management is responsible for establishing and maintaining adequate internal control over financial reporting (as defined in Rules 13a-15(f) and15d-15(f) under the Exchange Act). Our management conducted an assessment of the effectiveness of our internal control over financial reporting based onthe criteria established in “Internal Control - Integrated Framework” (2013) issued by the Committee of Sponsoring Organizations of the TreadwayCommission (“COSO”). Based on that assessment, our management has concluded that our internal control over financial reporting was effective as ofDecember 31, 2017. The effectiveness of the Company’s internal control over financial reporting as of December 31, 2017 has been audited byPricewaterhouseCoopers LLP, an independent registered public accounting firm, as stated in their report which appears herein. Item 9B. Other Information.None.108 PART IIIItem 10. Directors, Executive Officers and Corporate Governance.The information required by this item is incorporated by reference from our definitive Proxy Statement to be filed with the SEC in connection withour 2018 Annual Meeting of Stockholders within 120 days after the end of the fiscal year ended December 31, 2017.Item 11. Executive Compensation.The information required by this item is incorporated by reference from our definitive Proxy Statement to be filed with the SEC in connection withour 2018 Annual Meeting of Stockholders within 120 days after the end of the fiscal year ended December 31, 2017.Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters.The information required by this item is incorporated by reference from our definitive Proxy Statement to be filed with the SEC in connection withour 2018 Annual Meeting of Stockholders within 120 days after the end of the fiscal year ended December 31, 2017.Item 13. Certain Relationships and Related Transactions, and Director Independence.The information required by this item is incorporated by reference from our definitive Proxy Statement to be filed with the SEC in connection withour 2018 Annual Meeting of Stockholders within 120 days after the end of the fiscal year ended December 31, 2017. Item 14. Principal Accounting Fees and Services.The information required by this item is incorporated by reference from our definitive Proxy Statement to be filed with the SEC in connection withour 2018 Annual Meeting of Stockholders within 120 days after the end of the fiscal year ended December 31, 2017.109 PART IVItem 15. Exhibits, Financial Statement Schedules. (a)List the following documents filed as a part of this Annual Report on Form 10-K: (1)All financial statements; (2)Those financial statement schedules required to be filed by Item 8 of this form, and by paragraph (b) below. All financial statementschedules are omitted because they are not applicable or the amounts are immaterial or the required information is presented in theconsolidated financial statements and notes thereto in Part II, Item 8 above. (3)Those exhibits required by Item 601 of Regulation S-K (§ 229.601 of this chapter) and by paragraph (b) below. Identify in the listeach management contract or compensatory plan or arrangement required to be filed as an exhibit to this form pursuant to Item 15(b)of this report. (b)Registrants shall file, as exhibits to this form, the exhibits required by Item 601 of Regulation S-K (§ 229.601 of this chapter). (c)Registrants shall file, as financial statement schedules to this form, the financial statements required by Regulation S-X (17 CFR 210) whichare excluded from the annual report to shareholders by Rule 14a-3(b) including (1) separate financial statements of subsidiaries notconsolidated and fifty percent or less owned persons; (2) separate financial statements of affiliates whose securities are pledged as collateral;and (3) schedules. 110 Exhibit Index Exhibit Incorporated by ReferenceNumber Exhibit Title Form File No. Exhibit Filing Date3.1 Amended and Restated Certificate of Incorporation of the Registrant. 8-K 001-37918 3.1 October 26, 20163.2 Amended and Restated Bylaws of the Registrant. 8-K 001-37918 3.2 October 26, 20164.1 Specimen Common Stock Certificate of the Registrant. S-1 333-213773 4.1 September 23, 20164.2 Amended and Restated Investors’ Rights Agreement dated May 16, 2014 by andamong the Registrant and certain stockholders. S-1/A 333-213773 4.2 October 7, 20164.8 Warrant to Purchase Stock issued to Life Science Loans, LLC dated as of June 3,2014. S-1 333-213773 4.8 September 23, 201610.1+ Form of Indemnification Agreement for directors and executive officers. S-1 333-213773 10.1 September 23, 201610.2+ 2006 Stock Plan, as amended, and Form of Option Agreement thereunder. S-1 333-213773 10.2 September 23, 201610.3+ 2016 Equity Incentive Plan and related form agreements. S-1/A 333-213773 10.3 October 7, 201610.4+ 2016 Employee Stock Purchase Plan and related form agreements. S-1/A 333-213773 10.4 October 7, 201610.5+ Executive Incentive Compensation Plan. S-1/A 333-213773 10.5 October 7, 201610.6 Manufacturing Services Agreement dated March 1, 2009 between the Registrant andJabil Circuit, Inc. S-1 333-213773 10.6 September 23, 201610.7 Memorandum of Understanding dated February 16, 2015 between the Registrantand Jabil Circuit, Inc. S-1 333-213773 10.7 September 23, 201610.8 Warland Business Park Lease dated April 20, 2015 between the Registrant andWarland Investments Company. S-1 333-213773 10.8 September 23, 201610.9 Office Lease dated April 30, 2008 between the Registrant and 650 TownsendAssociates, LLC. S-1/A 333-213773 10.9 October 7, 201610.10 First Amendment to Lease dated February 26, 2010 between the Registrant and 650Townsend Associates, LLC. S-1 333-213773 10.10 September 23, 201610.11 Second Amendment to Lease dated December 19, 2011 between the Registrant and650 Townsend Associates, LLC. S-1 333-213773 10.11 September 23, 201610.12 Third Amendment to Lease dated January 8, 2014 between the Registrant and BigDog Holdings, LLC, as successor in interest to 650 Townsend Associates LLC. S-1 333-213773 10.12 September 23, 201610.13 Fourth Amendment to Lease dated April 22, 2015 between the Registrant and BigDog Holdings, LLC, as successor in interest to 650 Townsend Associates LLC. S-1 333-213773 10.13 September 23, 201610.14 Fifth Amendment to Lease dated November 20, 2015 between the Registrant andBig Dog Holdings, LLC, as successor in interest to 650 Townsend Associates LLC. S-1 333-213773 10.14 September 23, 201610.15 Sixth Amendment to Lease dated August 10, 2016 between the Registrant and BigDog Holdings, LLC, as successor in interest to 650 Townsend Associates LLC. S-1 333-213773 10.15 September 23, 201610.16 Sublease dated October 29, 2009 between the Registrant and Freedomroads, LLC. S-1/A 333-213773 10.16 October 7, 201610.17 First Amendment to Sublease dated June 1, 2010 between the Registrant andFreedomroads, LLC. S-1/A 333-213773 10.17 October 7, 2016  Exhibit Incorporated by ReferenceNumber Exhibit Title Form File No. Exhibit Filing Date10.18 Second Amendment to Sublease dated September 24, 2013 between the Registrant,Freedomroads, LLC and FRHP Lincolnshire, LLC. S-1 333-213773 10.18 September 23, 201610.19 Sublease dated April 15, 2014 between the Registrant and Lone Star R.S. Platou,Inc. S-1 333-213773 10.19 September 23, 201610.20± Services Agreement dated December 24, 2013 between the Registrant and XIFIN,Inc. S-1 333-213773 10.20 September 23, 201610.21 Second Amended and Restated Loan and Security Agreement dated December 4,2015 between the Registrant and Silicon Valley Bank. S-1/A 333-213773 10.21 October 7, 201610.22 Loan Agreement dated December 4, 2015 between the Registrant and BiopharmaSecured Investments III Holdings Cayman LP. S-1 333-213773 10.22 September 23, 201610.23 Guaranty and Security Agreement dated December 4, 2015 by the Registrant andeach other grantor from time to time party thereto in favor of Biopharma SecuredInvestments III Holdings Cayman LP. S-1 333-213773 10.23 September 23, 201610.24 Note Purchase Agreement dated November 16, 2012, as amended, by and betweenthe Registrant and California HealthCare Foundation, exhibits related thereto andrelated Promissory Note. S-1/A 333-213773 10.24 October 7, 201610.25+ Employment Letter to Kevin M. King dated July 23, 2012 between the Registrantand Kevin M. King. S-1 333-213773 10.25 September 23, 201610.26+ Employment Letter to David A. Vort dated November 22, 2013 between theRegistrant and David A. Vort. S-1 333-213773 10.26 September 23, 201610.27+ Employment Letter to Derrick Sung dated March 24, 2015 between the Registrantand Derrick Sung. S-1 333-213773 10.27 September 23, 201610.28+ Employment Letter to Matthew C. Garrett dated December 2, 2012 between theRegistrant and Matthew C. Garrett. S-1 333-213773 10.28 September 23, 201610.29 Form of Change of Control and Severance Agreement to be effective upon theclosing of the offering. 10-Q 333-213773 10.29 November 14, 201710.30 Office Lease (Suite 500) dated August 9, 2016 between the Registrant and Big DogHoldings, LLC. S-1 333-213773 10.30 September 23, 201610.31 Note and Warrant Purchase Agreement dated November 1, 2012, by and among theRegistrant and the persons and entities listed on the Schedule of Investors attachedthereto as Exhibit A and exhibits related thereto. S-1/A 333-213773 10.31 October 7, 201610.32 Office Lease dated May 1, 2017 between the Registrant and Radler LimitedPartnership 10-Q 333-213773 10.32 August 7, 201721.1 List of Subsidiaries of Registrant. S-1 333-213773 21.1 September 23, 201623.1 Consent of Independent Registered Public Accounting Firm 31.1 Certification of Principal Executive Officer Pursuant to Rules 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934, as Adopted Pursuant to Section302 of the Sarbanes-Oxley Act of 2002. 31.2 Certification of Principal Financial Officer Pursuant to Rules 13a-14(a) and 15d-14(a) under the Securities Exchange Act of 1934, as Adopted Pursuant to Section302 of the Sarbanes-Oxley Act of 2002.  Exhibit Incorporated by ReferenceNumber Exhibit Title Form File No. Exhibit Filing Date32.1† Certification of Principal Executive Officer and Principal Financial Officer Pursuantto 18 U.S.C. Section 1350, as Adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. 101.INS XBRL Instance Document 101.SCH XBRL Taxonomy Extension Schema Document 101.CAL XBRL Taxonomy Extension Calculation Linkbase Document 101.DEF XBRL Taxonomy Extension Definition Linkbase Document 101.LAB XBRL Taxonomy Extension Label Linkbase Document 101.PRE XBRL Taxonomy Extension Presentation Linkbase Document †The certifications attached as Exhibit 32.1 and 32.2 that accompany this Annual Report on Form 10-K, are deemed furnished and not filed with the Securities andExchange Commission and are not to be incorporated by reference into any filing of iRhythm Technologies, Inc. under the Securities Act of 1933, as amended, or theSecurities Exchange Act of 1934, as amended, whether made before or after the date of this Annual Report on Form 10-K, irrespective of any general incorporationlanguage contained in such filing.+Indicates management contract or compensatory plan.±Confidential treatment has been requested for portions of this exhibit. These portions have been omitted and have been filed separately with the Securities and ExchangeCommission.  SIGNATURESPursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, as amended, the Registrant has duly caused this Report tobe signed on its behalf by the undersigned, thereunto duly authorized. Company Name Date: March 1, 2018 By:/s/ Kevin M. King Kevin M. King President and Chief Executive Officer(Principal Executive Officer) Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, this Report has been signed below by the following persons onbehalf of the Registrant in the capacities and on the dates indicated. Name Title Date /s/ Kevin M. King President, Chief Executive Officer and Director(Principal Executive Officer) March 1, 2018Kevin M. King /s/ Matthew C. Garrett Chief Financial Officer(Principal Financial Officer) March 1, 2018Matthew C. Garrett /s/ Bruce G. Bodaken Director March 1, 2018Bruce G. Bodaken /s/ Ralph Snyderman M.D. Director March 1, 2018Ralph Snyderman M.D. /s/ Vijay K. Lathi Director March 1, 2018Vijay K. Lathi /s/ Mark J. Rubash Director March 1, 2018Mark J. Rubash /s/ Raymond W. Scott Director March 1, 2018Raymond W. Scott /s/ Abhijit Y. Talwalkar Director and Chairman of the Board March 1, 2018Abhijit Y. Talwalkar  Exhibit 23.1CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRMWe hereby consent to the incorporation by reference in the Registration Statements on Form S-8 (Nos. 333-214203 and 333-217077) of iRhythmTechnologies, Inc. of our report dated March 1, 2018 relating to the consolidated financial statements and the effectiveness of internal control over financialreporting, which appears in this Form 10‑K./s/ PricewaterhouseCoopers LLPSan Jose, CaliforniaMarch 1, 2018  Exhibit 31.1CERTIFICATION PURSUANT TORULES 13a-14(a) AND 15d-14(a) UNDER THE SECURITIES EXCHANGE ACT OF 1934,AS ADOPTED PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002I, Kevin M. King, certify that:1.I have reviewed this Annual Report on Form 10-K of iRhythm Technologies, Inc.;2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make thestatements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by thisreport;3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects thefinancial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;4.The registrant's other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined inExchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have: (a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision,to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others withinthose entities, particularly during the period in which this report is being prepared; (b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under oursupervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements forexternal purposes in accordance with generally accepted accounting principles; (c)Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about theeffectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and (d)Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recentfiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely tomaterially affect, the registrant's internal control over financial reporting; and5.The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to theregistrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions): (a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which arereasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and (b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internalcontrol over financial reporting. Date: March 1, 2018 By: /s/ Kevin M. King Kevin M. King President and Chief Executive Officer(Principal Executive Officer) Exhibit 31.2CERTIFICATION PURSUANT TORULES 13a-14(a) AND 15d-14(a) UNDER THE SECURITIES EXCHANGE ACT OF 1934,AS ADOPTED PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002I, Matthew C. Garrett, certify that:1.I have reviewed this Annual Report on Form 10-K of iRhythm Technologies, Inc.;2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make thestatements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by thisreport;3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects thefinancial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;4.The registrant's other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined inExchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have: (a)Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision,to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others withinthose entities, particularly during the period in which this report is being prepared; (b)Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under oursupervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements forexternal purposes in accordance with generally accepted accounting principles; (c)Evaluated the effectiveness of the registrant's disclosure controls and procedures and presented in this report our conclusions about theeffectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and (d)Disclosed in this report any change in the registrant's internal control over financial reporting that occurred during the registrant's most recentfiscal quarter (the registrant's fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely tomaterially affect, the registrant's internal control over financial reporting; and5.The registrant's other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to theregistrant's auditors and the audit committee of the registrant's board of directors (or persons performing the equivalent functions): (a)All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which arereasonably likely to adversely affect the registrant's ability to record, process, summarize and report financial information; and (b)Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant's internalcontrol over financial reporting. Date: March 1, 2018 By: /s/ Matthew C. Garrett Matthew C. Garrett Chief Financial Officer Exhibit 32.1CERTIFICATION PURSUANT TO18 U.S.C. SECTION 1350, AS ADOPTED PURSUANT TOSECTION 906 OF THE SARBANES-OXLEY ACT OF 2002In connection with the Annual Report of iRhythm Technologies, Inc. (the “Company”) on Form 10-K for the period ending December 31, 2017 asfiled with the Securities and Exchange Commission on the date hereof (the “Report”), I certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 906 ofthe Sarbanes-Oxley Act of 2002, that: (1)The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and (2)The information contained in the Report fairly presents, in all material respects, the financial condition and result of operations of theCompany. Date: March 1, 2018 By:/s/ Kevin M. King Kevin M. King President and Chief Executive Officer(Principal Executive Officer) By:/s/ Matthew C. Garrett Matthew C. Garrett Chief Financial Officer (Principal Financial Officer and Chief Accounting Officer) 

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