ADTRAN
Annual Report 2016

Plain-text annual report

of Opportunities A MOSAIC OF OPPORTUNITIES 2016 ANNUAL REPORT ADTRAN is an ISO 9001, ISO 14001, and a TL 9000 certified supplier. ADTRAN, Inc. is an Equal Opportunity Employer committed to utilizing Minority Business Enterprises (MBE), Woman-Owned Business Enterprises (WBE) and Disabled Veteran Business Enterprises (DVBE) whenever possible and practical for procurements supporting ADTRAN and our customers. ADTRAN, NetVanta, Bluesocket, vWLAN and Total Access are registered trademarks of ADTRAN, Inc. ATLAS is a trademark of ADTRAN, Inc. All other trademarks and registered trademarks mentioned in this publication are the property of their respective owners. An Export License is required if these ADTRAN products are sold to a Government Entity outside of the EU+8 (Austria, Australia, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Japan, Latvia, Lithuania, Luxembourg, Malta, Netherlands, New Zealand, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, and the United Kingdom). This is per DOC/BIS ruling G030477 issued June 6, 2003. Copyright © 2017 ADTRAN, Inc. All rights reserved. Printed in USA. AD10404A ADTRAN 2016 Annual Report Information is a powerful tool. It can be used in so many ways to better the lives of those who seek it. Today, some 3.5 billion people have Internet access and these connections are positively affect- ing how they live, work and play. However, 3.9 billion people remain without connectivity, driving the need for broadband on a global basis. We depend on Internet access. It can be used to store and access information or as a means of communication between people and organizations. It is also a vast source of entertainment from games and books to movies and hobbies. Even more importantly, the Internet has redefined business. It is used as a primary means to pay bills, purchase commodi- ties, make bank transactions and purchase goods and services. ADTRAN is at the forefront of pushing the boundaries of Internet speed and access. New industries have emerged to support the promotion of businesses on the Internet. It is revolutionizing industries like education and healthcare, enabling distance learning, telehealth and much, much more. Because the Internet touches our everyday lives so much in today’s world, and with this influ- ence continuing to grow, having a connection is simply not enough. We want faster connections that will enable more interactivity and more collaboration. According to Broadbandtrends, in 2016 only six percent of subscribers had speeds of 100Mbps or greater. This is a long way from what people and businesses need. With an increasing number of over-the-top and stream- ing services, combined with mobile providers offering unlimited data, the need for high-speed ultra-broad- band services has no end in sight. In fact, Broadbandtrends projects that the number of subscribers receiving speeds of 100Mbps or greater will increase to 34 percent by 2020, with the strongest growth coming in the 500Mbps – 1Gbps segment. 3 Letter to ShareholdersADTRAN is at the forefront of pushing the boundaries of Inter- net speed and access. Everything we do is centered on enabling communities and connecting lives as we define the future network. We are enabling operators of all types around the globe to deploy services faster and more efficiently than ever before. We offer one of the most comprehensive broad- band product portfolios on the market with solutions leveraging fiber, copper, coax and wireless access networks. These solutions are enabling our customers to take advantage of the mosaic of oppor- tunities resulting from increasing network speed and agility. 4 Our focus remains on providing comprehensive access solutions with clear industry leadership in Gigabit fiber access and ultra-high speed broadband. ADTRAN 2016 Annual ReportOur focus remains on providing comprehensive access solutions with clear industry leadership in Gigabit fiber access and ultra-high speed broadband. This, combined with the world’s leading portfolio of virtualized access products, positions us to capitalize on the evo- lution in access as carriers around the world upgrade their infrastruc- ture to meet customer demand. During 2016, the telecom market experienced strong competition from Multi-Service Operators (MSOs) with the initial roll out of DOCSIS 3.1 promising ultra- broadband services to millions of customers. As a result, telecom carriers must quickly respond with faster technologies to remain competitive. Next-generation technologies like Super-Vectoring and G.fast have been proven to be cost-effective alternatives for the delivery of multi-hundred Mbps or Gigabit services for customer connections, requiring only a fraction of the cost and time needed for full fiber builds. Going forward, 10G capabilities will emerge in access networks as we realize multi-10G NG-PON2 and eventually 25G/40G/100G. Furthermore, the promise of wireless ubiquity, the introduction of 5G, and millimeter wave technologies will help drive the need for ever-present, low-latency, high-speed broadband services in the future. 5 Letter to ShareholdersSTRENGTHEN SOFTWARE CAPABILITIES KEY FOCUS 1 2 3 BROADBAND ACCESS INNOVATION GROWTH IN SERVICES & SUPPORT 6 ADTRAN 2016 Annual ReportThe Year in Review As we look back on 2016, the growing competition among U.S.- based service providers helped drive our domestic business up 20 percent year-over-year. This enabled us to finish the year strong at $637 million, up six percent over the previous year. We were also able to beat consensus revenue and earnings estimates all four quarters, further strengthening shareholder value. The second half of the year saw a resurgence in our international business, which contributed 21 percent of overall revenue for the year. As previously reported, we func- tionally realigned our business in mid-2015 with three goals in mind: ■ To strengthen our software capabilities and increase our position to address virtual- ized technologies spurred by Software Defined Networking (SDN) and Network Function Virtualization (NFV), ■ To position the company to address the resurgence in broadband spending with innovative solutions in areas like NG-PON and G.fast, and ■ To accelerate the growth in our services business by moving it into a separate segment with the ability to scale to meet the growing demand of our customers. These changes have enabled us to increase productivity and effi- ciency, preparing us for the mosaic of opportunities that lie ahead. 7 Letter to ShareholdersStrengthening our software capabilities and increasing our po- sition to address virtualized tech- nologies will be vitally important as we look to the future. As service providers continue to seek ways to deliver more bandwidth to their customers, the advantages of open, programmable and scalable net- works afforded through SDN and NFV are particularly attractive to larger Tier 1 customers. In fact, we have seen major barriers to market entry begin to erode as we move more features and functionality to software. We continue to place growing emphasis on our software development efforts moving for- ward as this enables us to provide an agile response to customer needs. Software & Virtualization 8 ADTRAN 2016 Annual ReportOur commitment to software development and virtualization was highlighted in 2016 through our introduction of Mosaic, the industry’s first truly open Soft- ware Defined Access (SD-Access) services architecture, the Mosaic Cloud Platform, Mosaic OS and our first Programmable Network Functions (PNFs). We believe we are the only access vendor with SDN controls, software modularity and application virtualization. Our solution is also media and platform agnostic, making it even more appealing to customers be- ginning the transition to virtual- ized multi-vendor networks. In less than one quarter after announcing these solutions, we had completed lab certification with a domestic Tier 1 provider and had begun work with other Tier 1 and 2 Communications Services Providers (CSPs) in the U.S., Europe, and the Middle East. By year end, this solution was selected for implementation by multiple Tier 1 carriers on a global basis and with additional lab trials underway. Our focus on software development highlights the importance of our Research and Development (R&D) efforts. R&D is the cornerstone of future opportunities for our customers and ADTRAN. We are committed to innovation, invest- ing approximately 20 percent of revenue in R&D on an annual basis. As a result of these efforts, we now proudly hold more than 500 active patents representing inventions in both the U.S. and abroad. ADTRAN Mosaic is the industry’s first truly open software defined (SD-Access) Services Architecture. 9 Letter to ShareholdersThe Resurgence of Broadband A supportive regulatory environ- ment has created a number of opportunities for us as we look to the year ahead. The resurgence in broadband spending spurred by the CAF and CAF II programs, along with increased demand for faster-speed services by both residential and business customers, has created a wealth of opportu- nities. Tier 1 and Tier 2 service providers have accepted $9 billion in price cap carrier CAF II funding beginning in 2016 that will run through 2020. ADTRAN’s network solutions are ideally suited for CAF build-outs. We believe that the enactment of CAF II rate of return carrier regulations, which provide over $5 billion in A-CAM support over a 10-year period to Tier 3 carriers, will also prove to be positive for us. G.fast and Vectoring/Super-Vec- toring technologies utilize existing copper plant to deliver speeds beyond 1Gbps. We bolstered our resources for G.fast development by almost 35 percent, resulting in increased customer momen- tum. As of year-end 2016, we had participated in more than 108 trials globally across six continents and, most importantly, celebrated customer awards in both the U.S. and Europe. Our G.fast product began shipping in late 2016 and we anticipate it will bring added momentum into the year ahead. 10 We have now shipped our 10 millionth vectoring-capable port, making vectoring the fastest-growing product in our company’s history. R E V O 100 G.FAST TRIALS ACROSS SIX CONTINENTS 10 GIGABIT PER SECOND WORLD’S MOST ADVANCED FIBER-ACCESS SOLUTIONS ADTRAN 2016 Annual ReportThe demand for our vectoring products remains strong. We extended our vectoring capabilities in 2016 with the first lab shipments of the world’s highest density Super-Vectoring product. We have now shipped our 10 millionth vectoring-capable port, making vectoring the fastest-growing product in our company’s history. We are a leader in the world’s largest vectoring project currently underway in Europe, and we have the dominant position in the larg- est vectoring project in the U.S., which began in 2016. We anticipate continued success with this product in the year ahead. As the demand for bandwidth continues to grow, so too does the fiber opportunity. PON continues to perform very well for us and represented the fast- est-growing product segment for us in 2016. This year marked the initial deployment of our XGS-PON platform, a technology ADTRAN pioneered that com- pleted standardization in June. It substantially changes the econom- ics of 10G PON deployment for wireless backhaul and business services. Our NG-PON2 initiatives continue to move forward as we bring to market the world’s most advanced fiber access solution using multi-wavelength TWDM- PON, Optical Network Terminals (ONTs) with tunable optics and SDN control. Our solution is unique in that it comprehensively addresses network growth by providing the easiest and most cost-effective way to support a common, converged fiber network delivering business, residential and wireless backhaul services. Like traditional Telcos, MSOs are fighting to win broadband cus- tomers, presenting an attractive opportunity for ADTRAN. We began increasing our focus on this space approximately two years ago and have experienced some traction in these accounts with our customer devices portfolio. In light of the sizable opportunity this market presents, we acquired CommScope’s active fiber access product lines in mid- 2016. This acquisition quickly opened up the addressable market and also provides us with a base of incumbency to leverage moving forward. We now offer multiple solutions for the MSO market ranging from business voice and customer premises equipment to Radio Frequency over Glass (RFoG) and Ethernet Passive Optical Networking (EPON) solutions for broadband services delivery. We also anticipate that Mosaic and our virtualized solu- tions will be beneficial as market penetration continues. 11 Letter to ShareholdersNow, in addition to acquiring our products, operators can purchase turnkey services enabling them to turn up services faster and more efficiently, speeding their time to market. 12 ADTRAN 2016 Annual ReportServices & Support SERVICES & SUPPORT RECORD REVENUE PERFORMANCE GROWTH 53% 17% SERVICES & SUPPORT COMPANY REVENUE Services & Support (S&S) holds great potential for the future. As part of our business realignment, we moved S&S into a separate segment, enabling us to scale to meet the needs of our customers and accelerate growth. The growing demand for ultra- broadband services has left many service providers turning to outside help for planning, engineering, implementation, and maintenance and support services. In turn, this has created a great opportunity for ADTRAN. Now, in addition to acquiring our products, operators can pur- chase turnkey services enabling them to turn up services faster and more efficiently, speeding their time to market. S&S set new revenue records in 2016, growing 53 percent and comprising 17 percent of company revenue. Demand is growing for our services at a healthy pace in both domestic markets and abroad, and we anticipate this trend to continue into the foreseeable future. 13 Letter to ShareholdersFinancial Highlights Company Financial Summary (Dollars In Millions, Except Per Share Amounts) $637M Annual Revenue Annual Earnings Per Share (Diluted) Gross Margin Operating Income 14 ADTRAN 2016 Annual Report Consolidated Statements of Income Data (In thousands, except per share amounts) 2016 2015 Total sales $636,781 $600,064 Income before provision for income taxes $46,895 $25,708 Net income $35,229 $18,646 Earnings per common share (Diluted) $0.72 $0.36 Consolidated Balance Sheet Data (In thousands) UNRESTRICTED CASH AND MARKETABLE SECURITIES TOTAL ASSETS STOCKHOLDERS’ EQUITY 2014 - $353,2071 2015 - $272,8482 2016 - $256,0213 2014 - $738,694 2015 - $632,904 2016 - $667,235 2014 - $549,013 2015 - $480,160 2016 - $479,517 1 Net of $81 million in stock repurchases and $20 million in dividend payments during 2014 2 Net of $66 million in stock repurchases and $18 million in dividend payments during 2015 3 Net of $26 million in stock repurchases and $18 million in dividend payments during 2016 Letter to Shareholders 15 Looking ahead, we are entering 2017 with renewed optimism about the opportunities before us. The appetite for infrastruc- ture development continues to grow. We believe the regulatory opportunities afforded by CAF II will continue to develop this year. Likewise, we look for our success in the technology and services areas mentioned above to continue to grow. We have a wealth of op- portunities before us, and we must now capitalize on them, growing revenue and shareholder equity. During the year ahead, we will work to capitalize on the many opportunities that lie before us and focus on our strategic goals, which include increasing market share in fixed-broadband access among our existing market seg- ments, positioning the company to realize growth in software and services revenue contribution as the industry shifts to software and outsourcing services functions, and leveraging adjacent market opportunities, enabling us to broaden our addressable markets. However, none of this will be attainable without our employees. I am continually amazed by the selfless devotion our employees display for our company. There is no challenge too large, and they continually strive for what is best for ADTRAN. We were proud to celebrate 30 years of success in 2016 – the result of the hard work and dedication of these individu- als. We now look forward to the next 30 years and the great things the future holds. Thank you for a job well done! Tom Stanton, Chairman & CEO ADTRAN, Inc. 2017 AND BEYOND 16 ADTRAN 2016 Annual Report Financial Results 18 Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities 19 Stock Performance Graph 20 Selected Financial Data 21 Management’s Discussion and Analysis of Financial Condition and Results of Operations Overview Critical Accounting Policies and Estimates Results of Operations 2016 Compared to 2015 2015 Compared to 2014 Liquidity and Capital Resources Recently Issued Accounting Pronouncements Subsequent Events 35 Quantitative and Qualitative Disclosures About Market Risk 36 Report of Independent Registered Public Accounting Firm 37 Financial Statements 42 Notes to Consolidated Financial Statements Note 1 – Nature of Business and Summary of Significant Accounting Policies Note 2 – Business Combinations Note 3 – Stock-Based Compensation Note 4 – Investments Note 5 – Derivative Instruments and Hedging Activities Note 6 – Inventory Note 7 – Property, Plant and Equipment Note 8 – Goodwill and Intangible Assets Note 9 – Alabama State Industrial Development Authority Financing and Economic Incentives Note 10 – Income Taxes Note 11 – Employee Benefit Plans Note 12 – Segment Information and Major Customers Note 13 – Commitments and Contingencies Note 14 – Earnings Per Share Note 15 – Summarized Quarterly Financial Data (Unaudited) Note 16 – Related Party Transactions Note 17 – Subsequent Events This annual report contains forward-looking statements which reflect management’s best judgment based on factors currently known. However, these statements involve risks and uncertainties, including the successful development and market acceptance of new products, the degree of competition in the market for such products, the product and channel mix, component costs, manufacturing efficiencies, and other risks detailed in our annual report on Form 10-K for the year ended December 31, 2016. These risks and uncertainties could cause actual results to differ materially from those in the forward-looking statements included in this annual report. 17 Financial ResultsMarket for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities ADTRAN’s common stock is traded on the NASDAQ Global Select Market under the symbol ADTN. As of February 2, 2017, ADTRAN had 187 stockholders of record and approximately 7,434 beneficial owners of shares held in street name. The following table shows the high and low closing prices per share for our common stock as reported by NASDAQ for the periods indicated. Common Stock Prices 2016 High Low 2015 High Low First Quarter Second Quarter Third Quarter Fourth Quarter $20.47 $16.60 $20.43 $17.14 $19.74 $17.81 $23.15 $17.90 First Quarter Second Quarter Third Quarter Fourth Quarter $23.38 $18.32 $19.27 $15.98 $17.28 $14.38 $17.52 $14.46 The following table shows the shareholder dividends paid in each quarter of 2016 and 2015. The Board of Directors presently anticipates that it will declare a regular quarterly dividend so long as the present tax treatment of dividends exists and adequate levels of liquidity are maintained. Dividends per Common Share 2016 2015 First Quarter Second Quarter Third Quarter Fourth Quarter $0.09 $0.09 $0.09 $0.09 First Quarter Second Quarter Third Quarter Fourth Quarter $0.09 $0.09 $0.09 $0.09 Stock Repurchases The following table sets forth repurchases of our common stock for the months indicated. Total Number of Shares Purchased Average Price Paid Per Share Total Number of Shares Purchased as Part of Publicly Announced Plans or Programs (1) Maximum Number of Shares That May Yet Be Purchased Under the Plans or Programs Period October 1, 2016 – October 31, 2016 November 1, 2016 – November 30, 2016 December 1, 2016 – December 31, 2016 37,082 124,414 — 17.81 18.00 — Total 161,496 37,082 124,414 — 161,496 4,539,322 4,414,908 4,414,908 (1) Since 1997, our Board of Directors has approved multiple share repurchase programs that have authorized open market repurchase transactions of up to 50.0 million shares of our common stock, which will be implemented through open market or private purchases from time to time as conditions warrant. 18 ADTRAN 2016 Annual ReportStock Performance Graph Our common stock began trading on the NASDAQ National Market on August 9, 1994. The price information reflected for our common stock in the following performance graph and accompanying table represents the closing sales prices of the common stock for the period from December 31, 2011 through December 31, 2016, on an annual basis. The graph and the accompanying table compare the cumulative total stockholders’ return on our common stock with the NASDAQ Telecommunications Index and the NASDAQ Composite Index. The calculations in the following graph and table assume that $100 was invested on December 31, 2011 in each of our common stock, the NASDAQ Telecommunications Index and the NASDAQ Composite Index and also assume dividend reinvestment. $250.00 $200.00 $150.00 $100.00 $50.00 $0.00 12/31/2011 12/31/2012 12/31/2013 12/31/2014 12/31/2015 12/31/2016 ADTRAN, Inc. NASDAQ Composite NASDAQ Telecommunications ADTRAN, Inc. NASDAQ Composite NASDAQ Telecommunications 12/31/11 12/31/12 12/31/13 12/31/14 12/31/15 12/31/16 $100.00 $100.00 $100.00 $65.79 $116.41 $102.78 $92.38 $165.47 $143.40 $75.77 $188.69 $149.42 $61.14 $200.32 $144.02 $80.92 $216.54 $153.88 19 Financial ResultsSelected Financial Data Income Statement Data (In thousands, except per share amounts) Year Ended December 31, 2016 2015 2014 2013 2012 Sales Cost of sales Gross profit Selling, general and administrative expenses Research and development expenses Operating income Interest and dividend income Interest expense Net realized investment gain Other income (expense), net Gain on bargain purchase of a business Income before provision for income taxes Provision for income taxes Net income $636,781 $600,064 $630,007 $641,744 $620,614 345,437 291,344 131,805 124,804 34,735 3,918 (572) 5,923 (651) 3,542 46,895 (11,666) $35,229 333,167 266,897 123,542 129,876 13,479 3,953 (596) 10,337 (1,465) — 318,680 311,327 131,958 132,258 47,111 5,019 (677) 7,278 1,175 — 332,858 308,886 129,366 131,055 48,465 7,012 (2,325) 8,614 (911) — 303,971 316,643 134,523 125,951 56,169 7,657 (2,347) 9,550 183 1,753 25,708 59,906 60,855 72,965 (7,062) (15,286) (15,061) (25,702) $18,646 $44,620 $45,794 $47,263 Weighted average shares outstanding – basic 48,724 51,145 55,120 59,001 63,259 Weighted average shares outstanding – assuming dilution (1) Earnings per common share – basic Earnings per common share – assuming dilution (1) Dividends declared and paid per common share 48,949 51,267 55,482 59,424 63,774 $0.72 $0.72 $0.36 $0.36 $0.36 $0.36 $0.81 $0.80 $0.36 $0.78 $0.77 $0.36 $0.75 $0.74 $0.36 Balance Sheet Data (In thousands) At December 31, Working capital (2) Total assets Total debt Stockholders’ equity 2016 $226,367 $667,235 $27,800 2015 $219,219 $632,904 $28,900 2014 $214,985 $738,694 $30,000 2013 $260,252 $789,898 $46,500 2012 $324,924 $883,656 $46,500 $479,517 $480,160 $549,013 $604,606 $692,406 (1) Assumes exercise of dilutive stock options calculated under the treasury method. See Notes 1 and 14 of Notes to Consolidated Financial Statements. (2) Working capital consists of current assets less current liabilities. Prior year amounts have been recast to conform to the current period’s presentation as a result of our early adoption of Accounting Standards Update 2015-17, Balance Sheet Classification of Deferred Taxes. See Note 1 of Notes to Consolidated Financial Statements. 20 ADTRAN 2016 Annual ReportManagement’s Discussion and Analysis of Financial Condition and Results of Operations Overview ADTRAN, Inc. (ADTRAN) is a leading global provider of networking and communications equipment. Our solutions enable voice, data, video and Internet communications across a variety of network infrastructures. These solutions are deployed by many of the United States’ and the world’s largest CSPs, distributed enterprises and small and medium-sized businesses, public and private enterprises, and millions of individual users worldwide. Our success depends upon our ability to increase unit volume and market share through the introduction of new products and succeeding generations of products having lower selling prices and increased functionality as compared to both the prior generation of a product and to the products of competitors. An important part of our strategy is to reduce the cost of each suc- ceeding product generation and then lower the product’s selling price based on the cost savings achieved in order to gain market share and/or improve gross margins. As a part of this strategy, we seek in most instances to be a high-quality, low-cost provider of products in our markets. Our success to date is attributable in large measure to our ability to design our products initially with a view to their subsequent redesign, allowing both increased functionality and reduced manufacturing costs in each succeeding product generation. This strategy enables us to sell succeeding generations of products to existing customers, while increasing our market share by selling these enhanced products to new customers. In addition to reporting our Network Solutions and Services & Support segments, we report revenue across three categories— Access & Aggregation, Customer Devices, and Traditional & Other Products. Access & Aggregation solutions are used by CSPs to connect their network infrastructure to their subscribers. This category includes software and hardware-based products and services that aggregate and/or originate access technologies. The portfolio of ADTRAN solutions within this category includes a wide array of modular or fixed physical form factors designed to deliver the best technology and economic fit based on the target subscriber density and environmental conditions. The Access & Aggregation category includes product and service families such as: n Total Access 5000 Series Fiber to the Premises (FTTP) and Fiber to the Node (FTTN) Multi-Service Access Nodes (MSAN) n hiX 5600 Series fiber aggregation and FTTN MSAN n Fiber to the Distribution Point (FTTdp) Optical Network Units (ONU) n GPON, EPON and 10G PON Optical Line Terminals (OLT) n Optical Networking Edge (ONE) aggregation n IP Digital Subscriber Line Access Multiplexers (DSLAMs) n Cabinet and Outside-Plant (OSP) enclosures and services n Network Management and Cloud-based software platforms and applications n Pluggable optical transceivers (i.e., SFP, SFP+, XFP, QSFP), cables and other miscellaneous materials n Planning, engineering, program management, maintenance, installation and commissioning services to implement customer network solutions n Other products and services that are generally applicable to Access & Aggregation Customer Devices includes our products and services that provide end users access to CSP networks. Our Customer Devices portfolio includes a comprehensive array of service provider and enterprise hardware and software products and services. The Customer Devices category includes products and services such as: n Broadband customer premise solutions, including Passive Optical Network (PON) and point-to-point Ethernet Optical Network Terminals (ONTs) n Radio Frequency over Glass (RFoG) MicroNodes n Residential and business gateways n Wi-Fi access points and associated powering and switching infrastructure 21 Financial Resultsn Enterprise Session Border Controllers (eSBC) n Branch office and access routers n Carrier Ethernet services termination devices n VoIP media gateways n ProServices pre-sale and post-sale technical support n Planning, engineering, program management, maintenance, installation and commissioning services to implement the customer devices solutions into consumer, small business and enterprise locations n Other products and services that are generally applicable to customer devices Traditional & Other Products generally includes a mix of prior generation technologies’ products and services, as well as other products and services that do not fit within the Access & Aggregation or Customer Devices categories. The Traditional & Other Products category includes products and services such as: n Time Division Multiplexed (TDM) and Asynchronous Transfer Mode (ATM) based aggregation systems and customer devices n HDSL, ADSL and other mature technologies used to deliver business and residential services over the CSP access and customer networks n Other products and services that do not fit within the Access & Aggregation and Customer Devices categories Sales were $636.8 million in 2016, compared to $600.1 million in 2015 and $630.0 million in 2014. Our gross profit margin was 45.8% in 2016, compared to 44.5% in 2015 and 49.4% in 2014. Net income was $35.2 million in 2016, compared to $18.6 million in 2015 and $44.6 million in 2014. Earnings per share, assuming dilution, were $0.72 in 2016, compared to $0.36 in 2015 and $0.80 in 2014. Earnings per share in 2016, 2015 and 2014 include the effect of the repurchase of 1.4 million, 4.0 million and 3.7 million shares of our stock in those years, respectively. Our operating results have fluctuated on a quarterly basis in the past, and may vary significantly in future periods due to a number of factors, including customer order activity and backlog. Backlog levels vary because of seasonal trends, the timing of customer projects and other factors that affect customer order lead times. Many of our customers require prompt delivery of products. This requires us to maintain sufficient inventory levels to satisfy anticipated customer demand. If near-term demand for our products declines, or if potential sales in any quarter do not occur as anticipated, our financial results could be adversely affected. Operating expenses are relatively fixed in the short term; therefore, a shortfall in quarterly revenues could significantly impact our financial results in a given quarter. Our operating results may also fluctuate as a result of a number of other factors, including a decline in general economic and market conditions, foreign currency exchange rate movements, increased competition, customer order patterns, changes in product and services mix, timing differences between price decreases and product cost reductions, product warranty returns, expediting costs and announcements of new products by us or our competitors. Additionally, maintaining sufficient inventory levels to assure prompt delivery of our products increases the amount of inventory that may become obsolete and increases the risk that the obsolescence of this inventory may have an adverse effect on our business and operating results. Also, not maintain- ing sufficient inventory levels to assure prompt delivery of our products may cause us to incur expediting costs to meet customer delivery requirements, which may negatively impact our operating results in a given quarter. Accordingly, our historical financial performance is not necessarily a meaningful indicator of future results, and, in general, management expects that our financial results may vary from period to period. See Note 15 of Notes to Consolidated Financial Statements for additional information. For a discussion of risks associated with our operating results, see Item 1A of our Form 10-K for the year ended December 31, 2016. Critical Accounting Policies and Estimates An accounting policy is deemed to be critical if it requires an accounting estimate to be made based on assumptions about matters that are highly uncertain at the time the estimate is made, if different estimates reasonably could have been used, or if changes in the accounting estimate that are reasonably likely to occur could materially impact the results of financial operations. 22 ADTRAN 2016 Annual ReportWe believe the following critical accounting policies affect our more significant judgments and estimates used in the preparation of our consolidated financial statements. These policies have been consistently applied across our two reportable segments: (1) Network Solutions and (2) Services & Support. n Revenue is generally recognized when persuasive evidence of an arrangement exists, delivery has occurred, the product price is fixed or determinable, collection of the resulting receivable is reasonably assured, and product returns are reason- ably estimable. For product sales, revenue is generally recognized upon shipment of the product to our customer in accordance with the title transfer terms of the sales agreement, generally Ex Works, per International Commercial Terms. In the case of consigned inventory, revenue is recognized when the end customer assumes ownership of the product. Contracts that contain multiple deliverables are evaluated to determine the units of accounting, and the consideration from the arrangement is allocated to each unit of accounting based on the relative selling price and corresponding terms of the contract. We use vendor-specific objective evidence of selling price. When this evidence is not available, we are generally not able to determine third-party evidence of selling price because of the extent of customization among competing products or services from other companies. In these instances, we use best estimates to allocate consideration to each respective unit of accounting. These estimates include analysis of respective bills of material and review and analysis of similar product and service offerings. We record revenue associated with installation services when respec- tive contractual obligations are complete. In instances where customer acceptance is required, revenue is deferred until respective acceptance criteria have been met. Contracts that include both installation services and product sales are evaluated for revenue recognition in accordance with contract terms. As a result, installation services may be considered a separate deliverable or may be considered a combined single unit of accounting with the delivered product. Generally, either the purchaser, ADTRAN, or a third party can perform the installation of our products. Sales taxes invoiced to customers are included in revenue, and represent less than one percent of total revenues. The corresponding sales taxes paid are included in cost of goods sold. Value added taxes collected from customers in international jurisdictions are recorded in accrued expenses as a liability. Revenue is recorded net of discounts. Sales returns are recorded as a reduction of revenue and accrued based on historical sales return experience, which we believe provides a reasonable estimate of future returns. A significant portion of our products are sold in the United States through a non-exclusive distribution network of major technology distributors. These organizations then distribute or provide fulfillment services to an extensive network of VARs and SIs. VARs and SIs may be affiliated with us as a channel partner, or they may purchase from the distributor on an unaffiliated basis. Additionally, with certain limitations, our distributors may return unused and unopened product for stock-balancing purposes when these returns are accompanied by offsetting orders for products of equal or greater value. n We carry our inventory at the lower of cost or market, with cost being determined using the first-in, first-out method. We use standard costs for material, labor, and manufacturing overhead to value our inventory. Our standard costs are updated on at least a quarterly basis and any variances are expensed in the current period; therefore, our inventory costs approximate actual costs at the end of each reporting period. We write down our inventory for estimated obsolescence or unmarketable inventory by an amount equal to the difference between the cost of inventory and the estimated fair value based upon assumptions about future demand and market conditions. If actual future demand or market conditions are less favorable than those projected by management, we may be required to make additional inventory write-downs. Our reserve for excess and obsolete inventory was $25.2 million and $26.7 million at December 31, 2016 and 2015, respec- tively. Inventory disposals charged against the reserve were $4.7 million, $0.2 million and $2.1 million for the years ended December 31, 2016, 2015 and 2014, respectively. n For purposes of determining the estimated fair value of our stock option awards on the date of grant, we use the Black-Scholes Model. This model requires the input of certain assumptions that require subjective judgment. These assumptions include, but are not limited to, expected stock price volatility over the term of the awards and actual and projected employee stock option exercise behaviors. Because our stock option awards have characteristics significantly different from those of traded options, and because changes in the input assumptions can materially affect the fair value estimate, the existing model may not provide a reliable, single measure of the fair value of our stock option awards. For purposes of determining the estimated fair value of our performance-based performance stock unit (PSU) awards on the date of grant, we use a Monte Carlo Simulation valuation method. The PSUs are subject to a market condition based on the relative total shareholder return of ADTRAN against all of the companies in the NASDAQ Telecommunications 23 Financial ResultsIndex and vest at the end of a three-year performance period. The fair value of restricted stock and restricted stock units (RSUs) is equal to the closing price of our stock on the business day immediately preceding the grant date. Management will continue to assess the assumptions and methodologies used to calculate the estimated fair value of stock-based compensation. Circumstances may change and additional data may become available over time, which could result in changes to these assumptions and methodologies and thereby materially impact our fair value determination. If factors change in future periods, the compensation expense that we record may differ significantly from what we have recorded in the current period. n We estimate our income tax provision or benefit in each of the jurisdictions in which we operate, including estimating exposures related to examinations by taxing authorities. We also make judgments regarding the realization of deferred tax assets, and establish valuation allowances where we believe it is more likely than not that future taxable income in certain jurisdictions will be insufficient to realize these deferred tax assets. Our estimates regarding future taxable income and income tax provision or benefit may vary due to changes in market conditions, changes in tax laws, or other factors. If our assumptions, and consequently our estimates, change in the future, the valuation allowances we have established may be increased or decreased, impacting future income tax expense. At December 31, 2016 and 2015 respectively, the valuation allowance was $6.1 million and $7.3 million. As of December 31, 2016, we have state research tax credit carry-forwards of $3.9 million, which will expire between 2017 and 2030. These carry-forwards were caused by tax credits in excess of our annual tax liabilities to an individual state where we no longer generate sufficient state income. In addition, as of December 31, 2016, we have a deferred tax asset of $7.3 million relating to net operating loss carry-forwards which will expire between 2017 and 2030. These carry-forwards are the result of acquisitions in 2009 and in 2011. The acquired net operating losses are in excess of the amount of estimated earnings. We believe it is more likely than not that we will not realize the full benefits of our deferred tax asset arising from these credits and net operating losses, and accordingly, have provided a valuation allowance against that piece. We establish reserves to remove some or all of the tax benefit of any of our tax positions at the time we determine that the positions become uncertain. We adjust these reserves, including any impact on the related interest and penalties, as facts and circumstances change. n Our products generally include warranties of 90 days to five years for product defects. We accrue for warranty returns at the time revenue is recognized based on our estimate of the cost to repair or replace the defective products. We engage in extensive product quality programs and processes, including actively monitoring and evaluating the quality of our component suppliers. Our products continue to become more complex in both size and functionality as many of our product offerings migrate from line card applications to total systems. The increasing complexity of our products will cause warranty incidences, when they arise, to be more costly. Our estimates regarding future warranty obligations may change due to product failure rates, material usage, and other rework costs incurred in correcting a product failure. In addition, from time to time, specific warranty accruals may be recorded if unforeseen problems arise. Should our actual experience relative to these factors be worse than our estimates, we will be required to record additional warranty expense. Alternatively, if we provide for more reserves than we require, we will reverse a portion of such provisions in future periods. The liability for warranty obligations totaled $8.5 million and $8.7 million at December 31, 2016 and 2015, respectively. These liabilities are included in accrued expenses in the accompanying Consolidated Balance Sheets. n Pension benefit plan obligations are based on various assumptions used by our actuaries in calculating these amounts. These assumptions include discount rates, compensation rate increases, expected return on plan assets, retirement rates, and mortality rates. Actual results that differ from the assumptions and changes in assumptions could affect future expenses and obligations. Our net pension liability totaled $10.0 million and $7.6 million at December 31, 2016 and 2015, respectively. This liability is included in other non-current liabilities in the accompanying Consolidated Balance Sheets. n We evaluate the carrying value of goodwill during the fourth quarter of each year and between annual evaluations if events occur or circumstances change that would more likely than not reduce the fair value of the reporting unit below its carrying value. We have elected to first assess the qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit to which the goodwill is assigned is less than its carrying amount as a basis for determining whether it is necessary to perform the two-step impairment test. If we determine that it is more likely than not that its fair value is less than its carrying amount, then the two-step impairment test will be performed. Based on the results of our qualitative assessment in 2016, we concluded that it was not necessary to perform the two-step impairment test. There have been no impairment losses recognized since the acquisition in 2011. 24 ADTRAN 2016 Annual ReportResults of Operations The following table presents selected financial information derived from our consolidated statements of income expressed as a percentage of sales for the years indicated.. Year Ended December 31, 2016 2015 2014 Sales Products Services Total sales Cost of sales Products Services Gross profit Selling, general and administrative expenses Research and development expenses Operating income Interest and dividend income Interest expense Net realized investment gain Other income (expense), net Gain on bargain purchase of a business Income before provision for income taxes Provision for income taxes Net income 82.5% 17.5 100.0 42.5 11.7 45.8 20.7 19.6 5.5 0.6 (0.1) 0.9 (0.1) 0.6 7.4 (1.8) 5.5% 87.9% 12.1 100.0 49.0 6.6 44.5 20.6 21.6 2.2 0.7 (0.1) 1.7 (0.2) — 4.3 (1.2) 3.1% 88.8% 11.2 100.0 45.7 4.9 49.4 20.9 21.0 7.5 0.8 (0.1) 1.2 0.2 — 9.5 (2.4) 7.1% 25 Financial Results 2016 Compared to 2015 Sales Our sales increased 6.1% from $600.1 million in 2015 to $636.8 million in 2016. The increase in sales is primarily attributable to a $38.6 million increase in Services & Support sales, partially offset by a $1.9 million decrease in Network Solutions sales. Network Solutions sales decreased 0.4% from $527.4 million in 2015 to $525.5 million in 2016. The decrease in sales in 2016 is primarily attributable to a decrease in sales of our Access & Aggregation products and Traditional & Other products, partially offset by an increase in sales of our Customer Devices products. The decrease in sales of our Access & Aggregation products is primarily attributable to a decrease in international hiX product sales, partially offset by an increase in OSP DSLAM sales. The increase in sales of our Customer Devices products is primarily attributable to increased sales of our FTTP ONT products. While we expect that revenues from Traditional & Other products will continue to decline over time, these revenues may fluctu- ate and continue for years because of the time required for our customers to transition to newer technologies. Services & Support sales increased 53.2% from $72.6 million in 2015 to $111.3 million in 2016. The increase in sales in 2016 is primarily attributable to an increase in network installation services for Access & Aggregation products. International sales, which are included in the Network Solutions and Services & Support amounts discussed above, decreased 25.0% from $180.7 million in 2015 to $135.4 million in 2016. International sales, as a percentage of total sales, decreased from 30.1% in 2015 to 21.3% in 2016. Our international revenues are affected to a great extent by the timing of network upgrade proj- ects at our larger European and Latin American customers and by changes in foreign exchange rates in territories in which we sell our products and services. Throughout 2016, our largest European customer focused on completing network upgrade activi- ties in regions outside of our footprint with them. However, we expect that once current projects are completed, future network upgrades will resume in the second half of 2017 within our geographic footprint with this customer. Additionally, after reaching a cyclical high in the second quarter of 2014, the value of the Euro currency relative to the U.S. dollar declined significantly throughout the second half of 2014 and in 2015. Though the Euro-USD exchange rate appears to have stabilized since reaching a low in the fourth quarter of 2015, it remains approximately 20% below the highs of 2014. This decline in the value of the Euro throughout 2015 and into 2016 significantly reduced the U.S. dollar value of revenue from our European sales. Cost of Sales As a percentage of sales, cost of sales decreased from 55.5% in 2015 to 54.2% in 2016. The decrease is primarily attributable to a regional revenue shift and customer and product mix, partially offset by a change in services mix, restructuring expenses and an increase in warranty expense related to a product recall caused by a defect in a part provided by a third party supplier. Network Solutions cost of sales, as a percent of that segment’s sales, decreased from 55.7% of sales in 2015 to 51.5% of sales in 2016. The decrease in Network Solutions cost of sales as a percentage of that segment’s sales is primarily attributable to a regional revenue shift and customer and product mix, partially offset by restructuring expenses and an increase in warranty expense related to a product recall caused by a defect in a part provided by a third party supplier. Services & Support cost of sales, as a percent of that segment’s sales, increased from 54.1% of sales in 2015 to 67.2% of sales in 2016. The increase in Services & Support cost of sales as a percentage of that segment’s sales is primarily attributable to an increase in network installation services, which have higher costs than maintenance and support services, and in restructuring expenses. An important part of our strategy is to reduce the product cost of each succeeding product generation and then to lower the product’s price based on the cost savings achieved. This may cause variations in our gross profit percentage due to timing differ- ences between the recognition of cost reductions and the lowering of product selling prices. Selling, General and Administrative Expenses Selling, general and administrative expenses increased 6.7% from $123.5 million in 2015 to $131.8 million in 2016. Selling, gen- eral and administrative expenses include personnel costs for administration, finance, information systems, human resources, sales and marketing, and general management, as well as rent, utilities, legal and accounting expenses, bad debt expense, adver- tising, promotional material, trade show expenses, and related travel costs. The increase in selling, general and administrative expenses is primarily attributable to an increase in variable incentive compensation expense and use tax expense, partially offset by a decrease in professional services. Selling, general and administrative expenses as a percentage of sales increased from 20.6% for the year ended December 31, 2015 to 20.7% for the year ended December 31, 2016. Selling, general and administrative expenses as a percentage of sales will gener- ally fluctuate whenever there is a significant fluctuation in revenues for the periods being compared. 26 ADTRAN 2016 Annual ReportResearch and Development Expenses Research and development expenses decreased 3.9% from $129.9 million in 2015 to $124.8 million in 2016. The decrease in research and development expenses is primarily attributable to a decrease in compensation expense, lease expense and testing expense, partially offset by an increase in contract services. The decrease in compensation expense and lease expense in 2016 was primarily attributable to the consolidation of engineering resources that occurred during the second quarter of 2015. Research and development expenses as a percentage of sales decreased from 21.6% for the year ended December 31, 2015 to 19.6% for the year ended December 31, 2016. Research and development expenses as a percentage of sales will fluctuate whenev- er there are incremental product development activities or a significant fluctuation in revenues for the periods being compared. We expect to continue to incur research and development expenses in connection with our new and existing products and our expansion into international markets. We continually evaluate new product opportunities and engage in intensive research and product development efforts which provide for new product development, enhancement of existing products and product cost reductions. We may incur significant research and development expenses prior to the receipt of revenues from a major new product group. Interest and Dividend Income Interest and dividend income remained constant at $3.95 million in 2015 and $3.92 million in 2016. Interest Expense Interest expense, which is primarily related to our taxable revenue bond, remained consistent at $0.6 million in 2015 and 2016, as we had no substantial change in our fixed-rate borrowing. See “Financing Activities” in “Liquidity and Capital Resources” below for additional information on our taxable revenue bond. Net Realized Investment Gain Net realized investment gain decreased from $10.3 million in 2015 to $5.9 million in 2016. The decrease in realized investment gains is primarily attributable to fewer gains from the sale of equity securities in 2016. See “Investing Activities” in “Liquidity and Capital Resources” below for additional information. Other Income (Expense), net Other income (expense), net, comprised primarily of miscellaneous income, gains and losses resulting from foreign currency exchange rate movements, and investment account management fees, decreased from $1.5 million of expense in 2015 to $0.7 million of expense in 2016. The change is primarily attributable to gains on forward currency contracts during the fourth quarter of 2016. Gain on Bargain Purchase of a Business Gain on bargain purchase of a business is related to our acquisition of key fiber access products, technologies and service re- lationships from a third party on September 13, 2016. See note 2 of Notes to Consolidated Financial Statements for additional information. Income Taxes Our effective tax rate decreased from 27.5% in 2015 to 24.9% in 2016. The decrease in the effective tax rate between the two periods is primarily attributable to the benefit associated with the bargain purchase gain. Net Income As a result of the above factors, net income increased from $18.6 million in 2015 to $35.2 million in 2016. As a percentage of sales, net income increased from 3.1% in 2015 to 5.5% in 2016. 2015 Compared to 2014 Sales Our sales decreased 4.8% from $630.0 million in 2014 to $600.1 million in 2015. The decrease in sales is primarily attributable to a $32.1 million decrease in Network Solutions sales, partially offset by a $2.2 million increase in Services & Support sales. Network Solutions sales decreased 5.7% from $559.5 million in 2014 to $527.4 million in 2015. The decrease in sales in 2015 is primarily attributable to a decrease in sales of our Customer Devices products and Traditional & Other products. The decrease in sales of our Customer Devices products is primarily attributable to weakness in sales of IP gateway products to the CLEC and MSO markets. While we expect that revenues from Traditional & Other products will continue to decline over time, these rev- 27 Financial Resultsenues may fluctuate and continue for years because of the time required for our customers to transition to newer technologies. Network Solutions sales were also negatively impacted by the impact of the strengthening U.S. dollar against the Euro. Services & Support sales increased 3.1% from $70.5 million in 2014 to $72.6 million in 2015. The increase in sales in 2015 is primarily attributable to an increase in network installation services for Access & Aggregation products. International sales, which are included in the Network Solutions and Services & Support amounts discussed above, decreased 27.3% from $248.6 million in 2014 to $180.7 million in 2015. International sales, as a percentage of total sales, decreased from 39.5% in 2014 to 30.1% in 2015. Our international revenues are affected to a great extent by the timing of network upgrade proj- ects at our larger European and Latin American customers and by changes in foreign exchange rates in territories in which we sell or products and services. After reaching a cyclical high in the second quarter of 2014, the value of the Euro currency relative to the U.S. dollar declined significantly throughout the second half of 2014 and in 2015. This decline in the value of the Euro throughout 2015 significantly reduced the U.S. dollar value of revenue from our European sales. Cost of Sales As a percentage of sales, cost of sales increased from 50.6% in 2014 to 55.5% in 2015. The increase is primarily attributable to the strengthening of the U.S. dollar against the Euro, growth in our service-related material sales in the U.S. market, and customer and product mix. Network Solutions cost of sales, as a percent of that segment’s sales, increased from 51.5% of sales in 2014 to 55.7% of sales in 2015. The increase in Network Solutions cost of sales as a percentage of that segment’s sales is primarily attributable to the strengthening of the U.S. dollar against the Euro, and customer and product mix. Services & Support cost of sales, as a percent of that segment’s sales, increased from 43.5% of sales in 2014 to 54.1% of sales in 2015. The increase in Services & Support cost of sales as a percentage of that segment’s sales is primarily attributable to an increase in network installation services, which have higher costs, versus a greater mix of maintenance and support services in the prior period. An important part of our strategy is to reduce the product cost of each succeeding product generation and then to lower the product’s price based on the cost savings achieved. This may cause variations in our gross profit percentage due to timing differ- ences between the recognition of cost reductions and the lowering of product selling prices. Selling, General and Administrative Expenses Selling, general and administrative expenses decreased 6.4% from $132.0 million in 2014 to $123.5 million in 2015. Selling, gen- eral and administrative expenses include personnel costs for administration, finance, information systems, human resources, sales and marketing, and general management, as well as rent, utilities, legal and accounting expenses, bad debt expense, adver- tising, promotional material, trade show expenses, and related travel costs. The decrease in selling, general and administrative expenses is primarily attributable to decreases in compensation expense, travel expense, and independent contractor expense, partially offset by an increase in professional services and restructuring charges. Selling, general and administrative expenses as a percentage of sales decreased from 20.9% for the year ended December 31, 2014 to 20.6% for the year ended December 31, 2015. Selling, general and administrative expenses as a percentage of sales will generally fluctuate whenever there is a significant fluctuation in revenues for the periods being compared. Research and Development Expenses Research and development expenses decreased 1.8% from $132.3 million in 2014 to $129.9 million in 2015. The decrease in re- search and development expenses is primarily attributable to decreases in compensation expense and independent contractors, partially offset by an increase in engineering and testing expense and restructuring charges. Research and development expenses as a percentage of sales increased from 21.0% for the year ended December 31, 2014 to 21.6% for the year ended December 31, 2015. Research and development expenses as a percentage of sales will fluctuate whenev- er there are incremental product development activities or a significant fluctuation in revenues for the periods being compared. We expect to continue to incur research and development expenses in connection with our new and existing products and our expansion into international markets. We continually evaluate new product opportunities and engage in intensive research and product development efforts which provide for new product development, enhancement of existing products and product cost reductions. We may incur significant research and development expenses prior to the receipt of revenues from a major new product group. 28 ADTRAN 2016 Annual ReportInterest and Dividend Income Interest and dividend income decreased from $5.0 million in 2014 to $4.0 million in 2015. The decrease in interest and dividend income is primarily attributable to a reduction in the average rate of return on our investments, as well as a decrease in our aver- age investment balances. Interest Expense Interest expense, which is primarily related to our taxable revenue bond, decreased from $0.7 million in 2014 to $0.6 million in 2015. The decrease is primarily attributable to a reduction in the principal and the impact of an interest rate reduction, which occurred during the first quarter of 2014. See “Financing Activities” in “Liquidity and Capital Resources” below for additional information on our taxable revenue bond. Net Realized Investment Gain Net realized investment gain increased from $7.3 million in 2014 to $10.3 million in 2015. The increase in realized investment gains is primarily attributable to larger gains from the sale of equity securities in 2015. See “Investing Activities” in “Liquidity and Capital Resources” below for additional information. Other Income (Expense), net Other income (expense), net, comprised primarily of miscellaneous income, gains and losses resulting from foreign currency exchange rate movements, and investment account management fees, changed from $1.2 million of income in 2014 to $1.5 million of expense in 2015. The change is primarily attributable to a $2.4 million gain recorded in the fourth quarter of 2014 related to the settlement of working capital items from an acquisition transaction that closed in 2012. Income Taxes Our effective tax rate increased from 25.5% in 2014 to 27.5% in 2015. The increase in the effective tax rate between the two periods is primarily attributable to a foreign tax benefit from the elimination of a valuation allowance in 2014, partially offset by a benefit from the closure of an audit and a higher R&D credit in 2015. Net Income As a result of the above factors, net income decreased from $44.6 million in 2014 to $18.6 million in 2015. As a percentage of sales, net income decreased from 7.1% in 2014 to 3.1% in 2015. Liquidity and Capital Resources Liquidity We intend to finance our operations with cash flow from operations. We have used, and expect to continue to use, the cash generated from operations for working capital, purchases of treasury stock, shareholder dividends, and other general corporate purposes, including (i) product development activities to enhance our existing products and develop new products and (ii) expansion of sales and marketing activities. We believe our cash and cash equivalents, investments and cash generated from operations to be adequate to meet our operating and capital needs for at least the next 12 months. At December 31, 2016, cash on hand was $79.9 million and short-term investments were $43.2 million, which resulted in avail- able short-term liquidity of $123.1 million, of which $42.1 million was held by our foreign subsidiaries. At December 31, 2015, cash on hand was $84.6 million and short-term investments were $34.4 million, which resulted in available short-term liquidity of $118.9 million, of which $38.9 million was held by our foreign subsidiaries. The increase in short-term liquidity from Decem- ber 31, 2015 to December 31, 2016 is primarily attributable to shifts among available investment option tenures to provide funds for our short-term cash needs. Operating Activities Our working capital, which consists of current assets less current liabilities, increased 3.3% from $219.2 million as of December 31, 2015 to $226.4 million as of December 31, 2016. The increase in our working capital is primarily attributable to an increase in accounts receivable and inventory, partially offset by an increase in accounts payable and accrued wages and benefits. The quick ratio, defined as cash and cash equivalents, short-term investments, and net accounts receivable, divided by current liabilities, decreased from 2.06 as of December 31, 2015 to 1.70 as of December 31, 2016. The decrease in the quick ratio is primarily at- tributable to an increase in accounts payable and accrued wages and benefits, partially offset by an increase in accounts receiv- able. The current ratio, defined as current assets divided by current liabilities, decreased from 3.37 as of December 31, 2015 to 29 Financial Results2.79 as of December 31, 2016. The decrease in the current ratio is primarily attributable to an increase in accounts payable and accrued wages and benefits, partially offset by an increase in accounts receivable and inventory. The increase in accrued wages and benefits was primarily attributable to an increase in accrued variable incentive compensation. Net accounts receivable increased 28.4% from $71.9 million at December 31, 2015 to $92.3 million at December 31, 2016. Our allowance for doubtful accounts was $19 thousand at December 31, 2015 and nil at December 31, 2016. Quarterly accounts receivable DSO increased from 48 days as of December 31, 2015 to 52 days as of December 31, 2016. The change in net accounts receivable and DSO is due to changes in customer mix and the timing of sales and collections during the quarter. Certain inter- national customers can have longer payment terms than U.S. customers. Annual inventory turnover decreased from 3.75 turns as of December 31, 2015 to 3.51 turns as of December 31, 2016. Inventory increased 14.8% from $91.5 million at December 31, 2015 to $105.1 million at December 31, 2016. We expect inventory levels to fluctuate as we attempt to maintain sufficient inventory in response to seasonal cycles of our business ensuring competitive lead times while managing the risk of inventory obsolescence that may occur due to rapidly changing technology and customer demand. Accounts payable increased 58.9% from $48.7 million at December 31, 2015 to $77.3 million at December 31, 2016. Accounts payable will fluctuate due to variations in the timing of the receipt of supplies, inventory and services and our subsequent pay- ments for these purchases. Investing Activities Capital expenditures totaled approximately $21.4 million, $11.8 million and $11.3 million for the years ended December 31, 2016, 2015 and 2014, respectively. These expenditures were primarily used to purchase computer hardware, software, manufac- turing and test equipment, and building improvements. Our combined short-term and long-term investments decreased $13.1 million from $232.4 million at December 31, 2015 to $219.3 million at December 31, 2016. This decrease reflects the impact of our cash needs for share repurchases, shareholder divi- dends, equipment acquisitions, as well as net realized and unrealized losses, and amortization of net premiums on our combined investments, partially offset by additional funds available for investment provided by our operating activities and stock option exercises by our employees. We invest all available cash not required for immediate use in operations primarily in securities that we believe bear minimal risk of loss. At December 31, 2016, these investments included corporate bonds of $66.4 million, municipal fixed-rate bonds of $11.8 million, asset-backed bonds of $10.2 million, mortgage/agency-backed bonds of $13.0 million, U.S. government bonds of $29.8 million, foreign government bonds of $3.7 million, and variable rate demand notes of $11.9 million. At December 31, 2015, these investments included corporate bonds of $57.6 million, municipal fixed-rate bonds of $26.4 million, asset- backed bonds of $19.2 million, mortgage/agency-backed bonds of $15.4 million and government bonds of $35.4 million. As of December 31, 2016, our corporate bonds, municipal fixed-rate bonds, asset-backed bonds, mortgage/agency-backed bonds, U.S. government bonds, foreign government bonds, and municipal variable rate demand notes were classified as available-for- sale and had a combined duration of 1.15 years with an average credit rating of A+. Because our bond portfolio has a high qual- ity rating and contractual maturities of a short duration, we are able to obtain prices for these bonds derived from observable market inputs, or for similar securities traded in an active market, on a daily basis. Our long-term investments decreased 11.1% from $198.0 million at December 31, 2015 to $176.1 million at December 31, 2016. Long-term investments at December 31, 2016 and December 31, 2015 included an investment in a certificate of deposit of $27.8 million and $30.0 million, respectively, which serves as collateral for our revenue bond, as discussed below. We have invest- ments in various marketable equity securities classified as long-term investments at a cost of $30.6 million and $31.6 million, and with a fair value of $29.4 million and $34.3 million, at December 31, 2016 and December 31, 2015, respectively. Long-term investments at December 31, 2016 and 2015 also included $14.6 million and $12.8 million, respectively, related to our deferred compensation plan, and $0.8 million and $1.3 million, respectively, of other investments, consisting of interests in two private equity funds and an investment in a privately held telecommunications equipment manufacturer. We review our investment portfolio for potential “other-than-temporary” declines in value on an individual investment basis. We assess, on a quarterly basis, significant declines in value which may be considered other-than-temporary and, if necessary, recognize and record the appropriate charge to write-down the carrying value of such investments. In making this assessment, we take into consideration qualitative and quantitative information, including but not limited to the following: the magnitude 30 ADTRAN 2016 Annual Reportand duration of historical declines in market prices, credit rating activity, assessments of liquidity, public filings, and statements made by the issuer. We generally begin our identification of potential other-than-temporary impairments by reviewing any security with a fair value that has declined from its original or adjusted cost basis by 25% or more for six or more consecutive months. We then evaluate the individual security based on the previously identified factors to determine the amount of the write-down, if any. For the years ended December 31, 2016, 2015, and 2014, we recorded charges of $0.8 million, $0.2 million and $0.1 million, respectively, related to the other-than-temporary impairment of certain publicly traded equity securities, our deferred compensation plan assets, and our investments in two private equity funds. Financing Activities In conjunction with an expansion of our Huntsville, Alabama, facility, we were approved for participation in an incentive pro- gram offered by the State of Alabama Industrial Development Authority (the “Authority”). Pursuant to the program, on January 13, 1995, the Authority issued $20.0 million of its taxable revenue bonds and loaned the proceeds from the sale of the bonds to ADTRAN. The bonds were originally purchased by AmSouth Bank of Alabama, Birmingham, Alabama (the “Bank”). Wachovia Bank, N.A., Nashville, Tennessee (formerly First Union National Bank of Tennessee) (the “Bondholder”), which was acquired by Wells Fargo & Company on December 31, 2008, purchased the original bonds from the Bank and made further advances to the Authority, bringing the total amount outstanding to $50.0 million. An Amended and Restated Taxable Revenue Bond (“Amended and Restated Bond”) was issued and the original financing agreement was amended. The Amended and Restated Bond bears interest, payable monthly. The interest rate is 2% per annum. The Amended and Restated Bond matures on January 1, 2020, and is currently outstanding in the aggregate principal amount of $27.8 million. The estimated fair value of the bond using a level 2 valuation technique at December 31, 2016 was approximately $28.1 million, based on a debt security with a comparable interest rate and maturity and a Standard & Poor’s credit rating of AAA. We are required to make payments to the Authority in amounts necessary to pay the interest on the Amended and Restated Bond. Included in long-term investments at December 31, 2016 is $27.8 million which is invested in a restricted certificate of deposit. These funds serve as a collateral deposit against the principal of this bond, and we have the right to set-off the balance of the Bond with the collateral deposit in order to reduce the balance of the indebtedness. In conjunction with this program, we are eligible to receive certain economic incentives from the state of Alabama that reduce the amount of payroll withholdings that we are required to remit to the state for those employment positions that qualify under the program. We realized economic incentives related to payroll withholdings totaling $1.3 million for each of the years ended December 31, 2016, 2015 and 2014. We made principal payments of $1.1 million for the years ended December 31, 2016 and 2015, respectively, and we anticipate making a principal payment in 2017. At December 31, 2016, $1.0 million of the bond debt was classified as a current liability in accounts payable in the Consolidated Balance Sheets. Dividends During 2016, 2015 and 2014, we paid shareholder dividends totaling $17.6 million, $18.4 million and $19.9 million, respectively. The Board of Directors presently anticipates that it will declare a regular quarterly dividend so long as the present tax treatment of dividends exists and adequate levels of liquidity are maintained. The following table shows dividends paid to our shareholders in each quarter of 2016, 2015 and 2014. Dividends per Common Share 2016 2015 2014 First Quarter Second Quarter Third Quarter Fourth Quarter $0.09 $0.09 $0.09 $0.09 First Quarter Second Quarter Third Quarter Fourth Quarter $0.09 $0.09 $0.09 $0.09 First Quarter Second Quarter Third Quarter Fourth Quarter $0.09 $0.09 $0.09 $0.09 31 Financial ResultsStock Repurchase Program Since 1997, our Board of Directors has approved multiple share repurchase programs that have authorized open market re- purchase transactions of up to 50.0 million shares of our common stock, which will be implemented through open market or private purchases from time to time as conditions warrant. For the years 2016, 2015 and 2014, we repurchased 1.4 million shares, 4.0 million shares and 3.7 million shares, respectively, for a cost of $25.8 million, $66.2 million and $80.6 million, respectively, at an average price of $18.29, $16.68 and $21.96 per share, respectively. We currently have the authority to purchase an additional 4.4 million shares of our common stock under the current plans approved by the Board of Directors. Stock Option Exercises To accommodate employee stock option exercises, we issued 0.3 million shares of treasury stock for $4.7 million during the year ended December 31, 2016, 0.1 million shares of treasury stock for $1.0 million during the year ended December 31, 2015, and 0.1 million shares of treasury stock for $2.8 million during the year ended December 31, 2014. Off-Balance Sheet Arrangements and Contractual Obligations We do not have off-balance sheet financing arrangements and have not engaged in any related party transactions or arrange- ments with unconsolidated entities or other persons that are reasonably likely to materially affect liquidity or the availability of or requirements for capital resources. We have various contractual obligations and commercial commitments. The following table sets forth, in millions, the annual payments we are required to make under contractual cash obligations and other commercial commitments at December 31, 2016. Contractual Obligations (In millions) Long-term debt Interest on long-term debt Purchase obligations Operating lease obligations Total $27.8 1.5 184.5 10.5 2017 $1.0 0.5 183.4 3.8 Totals $224.3 $188.7 2018 $— 0.5 0.8 2.0 $3.3 2019 $— 0.5 0.3 0.8 $1.6 2020 $26.8 — — 0.7 $27.5 After 2020 $— — — 3.2 $3.2 We are required to make payments necessary to pay the interest on the Amended and Restated Bond, currently outstanding in the aggregate principal amount of $27.8 million. The bond matures on January 1, 2020, and bears interest at the rate of 2% per annum. Included in long-term investments are $27.8 million of restricted funds, which is a collateral deposit against the prin- cipal amount of this bond. We made principal payments of $1.1 million for the years ended December 31, 2016 and 2015. We anticipate making a principal payment in 2017. At December 31, 2016 and 2015, $1.0 million of the bond debt was classified as a current liability in accounts payable in the Consolidated Balance Sheets. See Note 9 of Notes to Consolidated Financial State- ments for additional information. Purchase obligations primarily relate to open purchase orders to our contract manufacturers, component suppliers, service partners, and other vendors. We have committed to invest up to an aggregate of $7.9 million in two private equity funds, and we have contributed $8.4 million as of December 31, 2016, of which $7.7 million has been applied to these commitments. The additional $0.2 million commit- ment has been excluded from the table above due to uncertainty of when it will be applied. We also have obligations related to uncertain income tax positions that have been excluded from the table above due to the uncertainty of when the related expense will be recognized. See Note 10 of Notes to Consolidated Financial Statements for ad- ditional information. 32 ADTRAN 2016 Annual ReportRecently Issued Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) (ASU 2014-09), which supersedes the revenue recognition requirements in Topic 605, Revenue Recognition, including most industry-specific revenue recognition guidance throughout the Industry Topics of the Codification. The core principle of ASU 2014-09 is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. In August 2015, the FASB issued ASU 2015-14, which deferred the effective date of ASU 2014-09 to fiscal years beginning after December 31, 2017, and interim periods within those fiscal years, with early adoption permitted for reporting periods beginning after December 15, 2016. Subsequently, the FASB issued ASUs in 2016 containing implementation guidance related to ASU 2014-09, including: ASU 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Report- ing Revenue Gross versus Net), which is intended to improve the operability and understandability of the implementation guid- ance on principal versus agent considerations; ASU 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing, which is intended to clarify two aspects of Topic 606: identifying performance obliga- tions and the licensing implementation guidance; ASU 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow- Scope Improvements and Practical Expedients, which contains certain provisions and practical expedients in response to identi- fied implementation issues; and ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers, which is intended to clarify the Codification or to correct unintended application of guidance. ASU 2014-09 allows for either full retrospective or modified retrospective adoption. We plan to adopt ASU 2014-09 and the related ASUs on January 1, 2018, and we are currently evaluating the transition method that will be elected. We are continuing to evaluate the po- tential impact of these ASUs, and we believe the most significant potential impact relates to our accounting for software license and installation services revenues. We do not believe there will be a significant impact to product or maintenance revenues. In July 2015, the FASB issued Accounting Standards Update No. 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory (ASU 2015-11). Currently, Topic 330, Inventory, requires an entity to measure inventory at the lower of cost or mar- ket. Market could be replacement cost, net realizable value, or net realizable value less an approximately normal profit margin. ASU 2015-11 does not apply to inventory that is measured using last-in, first-out (LIFO) or the retail inventory method. The amendments apply to all other inventory, which includes inventory that is measured using first-in, first-out (FIFO) or average cost. ASU 2015-11 requires an entity to measure in scope inventory at the lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. ASU 2015-11 is effective for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. The amendments should be applied prospectively with earlier application permitted as of the beginning of an interim or annual reporting period. We adopted ASU 2015-05 in the first quarter of 2017, and there was no material impact on our financial position, results of operations and cash flows. In February 2016, the FASB issued Accounting Standards Update No. 2016-02, Leases (Topic 842) (ASU 2016-02). ASU 2016-02 requires an entity to recognize lease assets and lease liabilities on the balance sheet and to disclose key information about the entity’s leasing arrangements. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. A modified retrospective approach is required. We anticipate the adoption of ASU 2016-02 will have a material impact on our financial position; however, we do not believe adoption will have a material impact on our results of operations. We believe the most significant impact relates to our accounting for operating leases for office space and equipment. In March 2016, the FASB issued Accounting Standards Update No. 2016-09, Compensation – Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (ASU 2016-09). ASU 2016-09 simplifies several aspects of ac- counting for share-based compensation arrangements, including income tax effects, the classification of tax-related cash flows on the statement of cash flows, and accounting for forfeitures. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016, including interim periods within those years. We adopted ASU 2016-09 in the first quarter of 2017, and there was no material impact on our financial position, results of operations and cash flows. In January 2017, the FASB issued Accounting Standards Update No. 2017-04, Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment (ASU 2017-04). ASU 2017-04 simplifies the measurement of goodwill by elimi- nating step 2 of the goodwill impairment test. Under ASU 2017-04, entities will be required to compare the fair value of a report- ing unit to its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. ASU 2017-04 is effective for annual or interim impairment tests performed in fiscal years beginning after December 15, 2019, with early adoption permitted for annual or interim impairment tests performed on testing dates after January 1, 2017. The amendments should be applied prospectively. We do not expect the adoption of ASU 2017-04 will have a material impact on our financial position, results of operations or cash flows. 33 Financial ResultsDuring 2016, we adopted the following accounting standards, which had no material effect on our financial position, results of operations or cash flows: In April 2015, the FASB issued Accounting Standards Update No. 2015-05, Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement (ASU 2015-05), which provides guidance on accounting for fees paid by a customer in a cloud computing arrangement. If a cloud computing ar- rangement includes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. ASU 2015-05 is effective for annual reporting periods beginning after December 15, 2015, including interim periods within that reporting period. The amendments may be applied either prospectively to all arrangements entered into or materially modified after the effective date or retrospectively. We adopted ASU 2015-05 during the first quarter of 2016 and will apply the new standard prospectively. The adoption of ASU 2015-05 did not have a material impact on our financial position, results of operations and cash flows. In November 2015, the FASB issued Accounting Standards Update No. 2015-17, Balance Sheet Classification of Deferred Taxes (ASU 2015-17). ASU 2015-17 amends the existing guidance on income taxes to require the classification of all deferred tax assets and liabilities as non-current on the balance sheet. ASU 2015-17 is effective for fiscal years beginning after December 15, 2016, including interim periods within those years. Early adoption is permitted. The guidance may be applied either prospectively, for all deferred tax assets and liabilities, or retrospectively to all periods presented. We elected to early adopt ASU 2015-17 during the fourth quarter of 2016, and we applied the guidance retrospectively to all periods presented. As a result, $17.3 million and $18.9 million were reclassified from current deferred tax assets to non-current deferred tax assets at December 31, 2016 and 2015, respectively. Subsequent Events On January 17, 2017, the Board declared a quarterly cash dividend of $0.09 per common share to be paid to shareholders of record at the close of business on February 2, 2017. The quarterly dividend payment was $4.4 million and was paid on February 16, 2017. In July 2003, our Board of Directors elected to begin declaring quarterly dividends on our common stock considering the tax treatment of dividends and adequate levels of Company liquidity. During the first quarter and as of February 24, 2017, we have repurchased 0.2 million shares of our common stock through open market purchases at an average cost of $21.46 per share. We currently have the authority to purchase an additional 4.2 million shares of our common stock under the current plan approved by the Board of Directors. 34 ADTRAN 2016 Annual ReportQuantitative and Qualitative Disclosures About Market Risk We are exposed to financial market risks, including changes in interest rates, foreign currency rates and prices of marketable eq- uity and fixed-income securities. The primary objective of the large majority of our investment activities is to preserve principal while at the same time achieving appropriate yields without significantly increasing risk. To achieve this objective, a majority of our marketable securities are investment grade, fixed-rate bonds, and municipal money market instruments denominated in U.S. dollars. Our investment policy provides limitations for issuer concentration, which limits, at the time of purchase, the concentration in any one issuer to 5% of the market value of our total investment portfolio. We maintain depository investments with certain financial institutions. Although these depository investments may exceed government insured depository limits, we have evaluated the credit worthiness of these financial institutions, and determined the risk of material financial loss due to exposure of such credit risk to be minimal. As of December 31, 2016, $77.9 million of our cash and cash equivalents, primarily certain domestic money market funds and foreign depository accounts, were in excess of government provided insured depository limits. As of December 31, 2016, approximately $166.7 million of our cash and investments may be directly affected by changes in interest rates. We have performed a hypothetical sensitivity analysis assuming market interest rates increase or decrease by 50 basis points (bps) for an entire year, while all other variables remain constant. At December 31, 2016, we held $67.8 million of cash and variable-rate investments where a change in interest rates would impact our interest income. A hypothetical 50 bps decline in interest rates as of December 31, 2016 would reduce annualized interest income on our cash and investments by ap- proximately $0.3 million. In addition, we held $98.9 million of fixed-rate bonds whose fair values may be directly affected by a change in interest rates. A hypothetical 50 bps increase in interest rates as of December 31, 2016 would reduce the fair value of our fixed-rate bonds by approximately $0.6 million. As of December 31, 2015, interest income on approximately $169.6 million of our cash and investments was subject to being directly affected by changes in interest rates. We performed a hypothetical sensitivity analysis assuming market interest rates in- crease or decrease by 50 bps for an entire year, while all other variables remain constant. A hypothetical 50 bps decline in interest rates as of December 31, 2015 would have reduced annualized interest income on our cash, money market instruments, float- ing rate corporate bonds and municipal variable rate demand notes by approximately $0.3 million. In addition, a hypothetical 50 bps increase in interest rates as of December 31, 2015 would have reduced the fair value of our municipal and corporate bonds by approximately $0.8 million. We are exposed to changes in foreign currency exchange rates to the extent that such changes affect our revenue and gross mar- gin on revenue derived from some international customers, expenses, and assets and liabilities held in non-functional currencies related to our foreign subsidiaries. Our primary exposures to foreign currency exchange rate movements are with our German subsidiary, whose functional currency is the Euro, our Australian subsidiary, whose functional currency is the Australian dol- lar, and our Mexican subsidiary, whose functional currency is the U.S. dollar. We are exposed to changes in foreign currency exchange rates to the extent of our German subsidiary’s use of contract manufacturers and raw material suppliers whom we predominately pay in U.S. dollars. As a result, changes in currency exchange rates could cause variations in gross margin in the products that we sell in the EMEA region. We have certain international customers who are invoiced or pay in a non-functional currency. Changes in the monetary ex- change rates used to invoice such customers versus the functional currency of the entity billing such customers may adversely affect our results of operations and financial condition. To manage the volatility relating to these typical business exposures, we may enter into various derivative transactions, when appropriate. We do not hold or issue derivative instruments for trad- ing or other speculative purposes. All non-functional currencies billed would result in a combined hypothetical gain or loss of $0.3 million if the U.S. dollar weakened or strengthened 10% against the billing currencies. Any gain or loss would be partially mitigated by these derivative instruments. As of December 31, 2016, we had no material contracts subject to currency revaluation, other than accounts receivable, accounts payable, and loans to a subsidiary, denominated in foreign currencies. As of December 31, 2016, we had forward contracts out- standing with notional amounts totaling €5.5 million ($5.8 million), which mature in the first quarter of 2017. The fair value of these forward contracts was a net asset of approximately $0.2 million as of December 31, 2016. For further information about the fair value of our available-for-sale investments and our derivative and hedging activities as of December 31, 2016, see Notes 4 and 5 of Notes to Consolidated Financial Statements. 35 Financial ResultsReport of Independent Registered Public Accounting Firm To Board of Directors and Stockholders of ADTRAN, Inc.: In our opinion, the consolidated financial statements listed in the accompanying index present fairly, in all material respects, the financial position of ADTRAN, Inc. and its subsidiaries at December 31, 2016 and December 31, 2015 and the results of their operations and their cash flows for each of the three years in the period ended December 31, 2016 in conformity with account- ing principles generally accepted in the United States of America. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2016, based on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). The Company’s management is responsible for these financial statements, for maintaining effective internal control over financial reporting and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying Management’s Report On Internal Control Over Financial Reporting. Our responsibility is to express opinions on these financial statements and on the Company’s internal control over financial reporting based on our integrated audits. We conducted our audits in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the financial state- ments are free of material misstatement and whether effective internal control over financial reporting was maintained in all material respects. Our audits of the financial statements included examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by manage- ment, and evaluating the overall financial statement presentation. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also in- cluded performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions. As discussed in Note 1 to the consolidated financial statements, the Company changed the manner in which it accounts for deferred income taxes in 2016. A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reli- ability of financial reporting and the preparation of financial statements for external purposes in accordance with generally ac- cepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (i) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (iii) provide reasonable assurance regarding prevention or timely detection of 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, pro- jections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate. PricewaterhouseCoopers LLP Birmingham, Alabama February 24, 2017 36 ADTRAN 2016 Annual ReportFinancial Statements ADTRAN, INC. Consolidated Balance Sheets December 31, 2016 and 2015 (In thousands, except per share amounts) Assets Current Assets Cash and cash equivalents Short-term investments Accounts receivable, less allowance for doubtful accounts of $— and $19 at December 31, 2016 and 2015, respectively Other receivables Income tax receivable, net Inventory, net Prepaid expenses and other current assets Total Current Assets Property, plant and equipment, net Deferred tax assets, net Goodwill Other assets Long-term investments Total Assets Liabilities and Stockholders’ Equity Current Liabilities Accounts payable Unearned revenue Accrued expenses Accrued wages and benefits Income tax payable, net Total Current Liabilities Non-current unearned revenue Other non-current liabilities Bonds payable Total Liabilities Commitments and contingencies (see Note 13) Stockholders' Equity Common stock, par value $0.01 per share; 200,000 shares authorized; 79,652 shares issued and 48,472 shares outstanding at December 31, 2016 and 79,652 shares issued and 49,558 shares outstanding at December 31, 2015 Additional paid-in capital Accumulated other comprehensive loss Retained earnings Less treasury stock at cost: 31,180 and 30,094 shares at December 31, 2016 and 2015, respectively Total Stockholders' Equity Total Liabilities and Stockholders' Equity See notes to consolidated financial statements. 2016 2015 $79,895 43,188 92,346 15,137 760 105,117 16,459 352,902 84,469 38,036 3,492 12,234 176,102 $667,235 $77,342 16,326 12,434 20,433 — 126,535 6,333 28,050 26,800 187,718 797 252,957 (12,188) 921,942 (683,991) 479,517 $667,235 $84,550 34,396 71,917 19,321 — 91,533 10,145 311,862 73,233 37,015 3,492 9,276 198,026 $632,904 $48,668 16,615 12,108 12,857 2,395 92,643 7,965 24,236 27,900 152,744 797 246,879 (8,969) 906,772 (665,319) 480,160 $632,904 37 Financial Results ADTRAN, INC. Consolidated Statements of Income Years ended December 31, 2016, 2015 and 2014 (In thousands, except per share amounts) 2016 2015 2014 Sales Products Services Total Sales Cost of Sales Products Services Total Cost of Sales Gross Profit Selling, general and administrative expenses Research and development expenses Operating Income Interest and dividend income Interest expense Net realized investment gain Other income (expense), net Gain on bargain purchase of a business Income before provision for income taxes Provision for income taxes Net Income Weighted average shares outstanding—basic Weighted average shares outstanding—diluted Earnings per common share—basic Earnings per common share—diluted See notes to consolidated financial statements. $525,502 111,279 636,781 $527,422 72,642 600,064 $559,532 70,475 630,007 270,695 74,742 345,437 291,344 131,805 124,804 34,735 3,918 (572) 5,923 (651) 3,542 46,895 (11,666) $35,229 48,724 48,949 $0.72 $0.72 293,843 39,324 333,167 266,897 123,542 129,876 13,479 3,953 (596) 10,337 (1,465) — 25,708 (7,062) $18,646 51,145 51,267 $0.36 $0.36 288,015 30,665 318,680 311,327 131,958 132,258 47,111 5,019 (677) 7,278 1,175 — 59,906 (15,286) $44,620 55,120 55,482 $0.81 $0.80 38 ADTRAN 2016 Annual Report ADTRAN, INC. Consolidated Statements of Comprehensive Income Years ended December 31, 2016, 2015 and 2014 (In thousands) Net Income Other Comprehensive Loss, net of tax: Net unrealized losses on available-for-sale securities Defined benefit plan adjustments Foreign currency translation Other Comprehensive Loss, net of tax Comprehensive Income, net of tax See notes to consolidated financial statements. 2016 $35,229 (1,528) (1,122) (569) (3,219) $32,010 2015 $18,646 (7,032) 1,862 (3,724) (8,894) $9,752 2014 $44,620 (1,773) (4,866) (4,189) (10,828) $33,792 39 Financial ResultsADTRAN, INC. Consolidated Statements of Changes in Stockholders’ Equity Years ended December 31, 2016, 2015 and 2014 Common Shares Common Stock Additional Paid-In Capital Retained Earnings Treasury Stock Accumulated Other Comprehensive Income Total Stockholders’ Equity 79,652 $797 $233,511 $884,451 $(524,906) $10,753 $604,606 (In thousands) Balance, December 31, 2013 Net income Other comprehensive loss, net of tax Dividend payments Dividends accrued for unvested restricted stock units Stock options exercised: 147 shares PSUs and restricted stock vested: 35 shares Purchase of treasury stock: 3,669 shares Income tax effect of stock compensation arrangements Stock-based compensation expense (10,828) 44,620 (19,947) (19) (558) (796) 3,397 796 (80,576) (326) 81 8,563 Balance, December 31, 2014 79,652 797 241,829 907,751 (601,289) (75) Net income Other comprehensive loss, net of tax Dividend payments Dividends accrued for unvested restricted stock units Stock options exercised: 60 shares PSUs and restricted stock vested: 34 shares Purchase of treasury stock: 3,967 shares Income tax effect of stock compensation arrangements Stock-based compensation expense (8,894) 18,646 (18,449) (7) (402) (767) 1,363 767 (66,160) (69) (1,593) 6,712 Balance, December 31, 2015 79,652 797 246,879 906,772 (665,319) (8,969) Net income Other comprehensive loss, net of tax Dividend payments Dividends accrued for unvested restricted stock units Stock options exercised: 283 shares PSUs and restricted stock vested: 42 shares Purchase of treasury stock: 1,411 shares Income tax effect of stock compensation arrangements Stock-based compensation expense (3,219) 35,229 (17,583) (48) (1,499) 6,216 (142) (929) 929 (25,817) (475) 6,695 44,620 (10,828) (19,947) (19) 2,839 (326) (80,576) 81 8,563 549,013 18,646 (8,894) (18,449) (7) 961 (69) (66,160) (1,593) 6,712 480,160 35,229 (3,219) (17,583) (48) 4,717 (142) (25,817) (475) 6,695 Balance, December 31, 2016 79,652 $797 $252,957 $921,942 $(683,991) $(12,188) $479,517 See notes to consolidated financial statements. 40 ADTRAN 2016 Annual ReportADTRAN, INC. Consolidated Statements of Cash Flows Years ended December 31, 2016, 2015 and 2014 (In thousands) Cash flows from operating activities Net income Adjustments to reconcile net income to net cash provided by operating activities: Depreciation and amortization Amortization of net premium on available-for-sale investments Net realized gain on long-term investments Net loss on disposal of property, plant and equipment Gain on bargain purchase of a business Stock-based compensation expense Deferred income taxes Tax impact of stock option exercises Excess tax benefits from stock-based compensation arrangements Change in operating assets and liabilities: Accounts receivable, net Other receivables Inventory Prepaid expenses and other assets Accounts payable Accrued expenses and other liabilities Income taxes payable, net Net cash provided by operating activities Cash flows from investing activities Purchases of property, plant and equipment Proceeds from disposals of property, plant and equipment 2016 2015 2014 $35,229 $18,646 $44,620 14,407 643 (5,923) 22 (3,542) 6,695 (2,685) — (2) (21,302) 4,101 (10,887) (7,108) 26,722 8,792 (3,162) 42,000 14,245 2,402 (10,337) 644 — 6,712 (692) (40) (3) 14,918 11,704 (6,877) (5,070) (5,826) (10,289) (11,590) 18,547 14,845 4,360 (7,278) 142 — 8,563 (5,526) 81 (63) (3,910) (19,298) 2,144 (3,818) 9,973 (166) 11,168 55,837 (21,441) (11,753) (11,256) — 183 1 Proceeds from sales and maturities of available-for-sale investments 225,075 280,435 230,019 Purchases of available-for-sale investments (209,172) (188,921) (142,695) Acquisition of business Net cash provided by (used in) investing activities Cash flows from financing activities Proceeds from stock option exercises Purchases of treasury stock Dividend payments Payments on long-term debt Excess tax benefits from stock-based compensation arrangements Net cash used in financing activities Net increase (decrease) in cash and cash equivalents Effect of exchange rate changes Cash and cash equivalents, beginning of year Cash and cash equivalents, end of year Supplemental disclosure of cash flow information Cash paid during the year for interest Cash paid during the year for income taxes Supplemental disclosure of non-cash investing activities (943) (6,481) 4,717 (25,817) (17,583) (1,100) 2 (39,781) (4,262) (393) 84,550 $79,895 $575 $18,689 — 79,944 961 (66,160) (18,449) (1,100) 3 — 76,069 2,839 (80,576) (19,947) (16,500) 63 (84,745) (114,121) 13,746 (2,635) 73,439 17,785 (2,644) 58,298 $84,550 $73,439 $598 $20,139 $758 $9,856 Purchases of property, plant and equipment included in accounts payable $2,103 $598 $467 See notes to consolidated financial statements. 41 Financial ResultsNotes to Consolidated Financial Statements 1 Nature of Business and Summary of Significant Accounting Policies ADTRAN, Inc. is a leading global provider of networking and communications equipment. Our solutions enable voice, data, video and Internet communications across a variety of network infrastructures. These solutions are deployed by many of the United States’ and the world’s largest CSPs, distributed enterprises and small and medium-sized businesses, public and private enterprises, and millions of individual users worldwide. Principles of Consolidation Our consolidated financial statements include ADTRAN and its wholly owned subsidiaries. All inter-company accounts and transactions have been eliminated in consolidation. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and ex- pense during the reporting period. Our more significant estimates include the obsolete and excess inventory reserves, warranty reserves, customer rebates, determination of the deferred revenue components of multiple element sales agreements, estimated costs to complete obligations associated with deferred revenues and network installations, estimated income tax provision and income tax contingencies, the fair value of stock- based compensation, impairment of goodwill, valuation and estimated lives of intangible assets, estimated pension liability, fair value of investments, and the evaluation of other-than-temporary declines in the value of investments. Actual amounts could differ significantly from these estimates. Cash and Cash Equivalents Cash and cash equivalents represent demand deposits, money market funds, and short-term investments classified as available- for-sale with original maturities of three months or less. We maintain depository investments with certain financial institutions. Although these depository investments may exceed government insured depository limits, we have evaluated the credit worthi- ness of these applicable financial institutions, and determined the risk of material financial loss due to the exposure of such credit risk to be minimal. As of December 31, 2016, $77.9 million of our cash and cash equivalents, primarily certain domestic money market funds and foreign depository accounts, were in excess of government provided insured depository limits. Financial Instruments The carrying amounts reported in the consolidated balance sheets for cash and cash equivalents, accounts receivable, and ac- counts payable approximate fair value due to the immediate or short-term maturity of these financial instruments. The carrying amount reported for bonds payable was $27.8 million, compared to an estimated fair value of $28.1 million, based on a debt security with a comparable interest rate and maturity and a Standard & Poor’s credit rating of AAA. Investments with contractual maturities beyond one year, such as our variable rate demand notes, may be classified as short- term based on their highly liquid nature and because such marketable securities represent the investment of cash that is avail- able for current operations. Despite the long-term nature of their stated contractual maturities, we routinely buy and sell these securities and we believe we have the ability to quickly sell them to the remarketing agent, tender agent, or issuer at par value plus accrued interest in the event we decide to liquidate our investment in a particular variable rate demand note. All income generated from these investments was recorded as interest income. We have not been required to record any losses relating to variable rate demand notes. 42 ADTRAN 2016 Annual ReportLong-term investments represent a restricted certificate of deposit held at cost, deferred compensation plan assets, corporate bonds, municipal fixed-rate bonds, asset-backed bonds, mortgage/agency backed bonds, U.S. and foreign government bonds, variable rate demand notes, marketable equity securities, and other equity investments. Marketable equity securities are report- ed at fair value as determined by the most recently traded price of the securities at the balance sheet date, although the securities may not be readily marketable due to the size of the available market. Unrealized gains and losses, net of tax, are reported as a separate component of stockholders’ equity. Realized gains and losses on sales of securities are computed under the specific iden- tification method and are included in current income. We review our investment portfolio quarterly for investments considered to have sustained an other-than-temporary decline in value. Impairment charges for other-than-temporary declines in value are recorded as realized losses in the accompanying consolidated statements of income. All of our investments at December 31, 2016 and 2015 are classified as available-for-sale securities. See Note 4 of Notes to Consolidated Financial Statements for additional information. Accounts Receivable We record accounts receivable at net realizable value. Prior to establishing payment terms for a new customer, we evaluate the credit risk of the customer. Credit limits and payment terms established for new customers are re-evaluated periodically based on customer collection experience and other financial factors. At December 31, 2016, three customers accounted for 63.3% of our total accounts receivable. At December 31, 2015, three customers accounted for 37.3% of our total accounts receivable. We maintain an allowance for doubtful accounts for losses resulting from the inability of our customers to make required pay- ments. We regularly review the allowance for doubtful accounts and consider factors such as the age of accounts receivable bal- ances, the current economic conditions that may affect a customer’s ability to pay, significant one-time events and our historical experience. If the financial condition of a customer deteriorates, resulting in an impairment of their ability to make payments, we may be required to record an allowance for doubtful accounts. If circumstances change with regard to individual receivable balances that have previously been determined to be uncollectible (and for which a specific reserve has been established), a re- duction in our allowance for doubtful accounts may be required. Our allowance for doubtful accounts was nil and $19 thousand at December 31, 2016 and December 31, 2015, respectively. Other Receivables Other receivables are comprised primarily of amounts due from subcontract manufacturers for product component transfers, accrued interest on investments and on a restricted certificate of deposit, amounts due from various jurisdictions for value- added tax, and amounts due from employee stock option exercises. Inventory Inventory is carried at the lower of cost or market, with cost being determined using the first-in, first-out method. Standard costs for material, labor and manufacturing overhead are used to value inventory. Standard costs are updated at least quarterly; there- fore, inventory costs approximate actual costs at the end of each reporting period. We establish reserves for estimated excess, obsolete or unmarketable inventory equal to the difference between the cost of the inventory and the estimated fair value of the inventory based upon assumptions about future demand, market conditions and age. When we dispose of excess and obsolete inventories, the related disposals are charged against the inventory reserve. See Note 6 of Notes to Consolidated Financial State- ments for additional information. Property, Plant and Equipment Property, plant and equipment, which is stated at cost, is depreciated using the straight-line method over the estimated useful lives of the assets. We depreciate building and land improvements from five to 39 years, office machinery and equipment from three to seven years, engineering machinery and equipment from three to seven years, and computer software from three to five years. Expenditures for repairs and maintenance are charged to expense as incurred. Betterments that materially prolong the lives of the assets are capitalized. Gains and losses on the disposal of property, plant and equipment are recorded in operating income. See Note 7 of Notes to Consolidated Financial Statements for additional information. 43 Financial ResultsLiability for Warranty Our products generally include warranties of 90 days to five years for product defects. We accrue for warranty returns at the time revenue is recognized based on our estimate of the cost to repair or replace the defective products. We engage in extensive product quality programs and processes, including actively monitoring and evaluating the quality of our component suppliers. Our products continue to become more complex in both size and functionality as many of our product offerings migrate from line card applications to total systems. The increasing complexity of our products will cause warranty incidences, when they arise, to be more costly. Our estimates regarding future warranty obligations may change due to product failure rates, material usage, and other rework costs incurred in correcting a product failure. In addition, from time to time, specific warranty accruals may be recorded if unforeseen problems arise. Should our actual experience relative to these factors be worse than our estimates, we will be required to record additional warranty expense. Alternatively, if we provide for more reserves than we require, we will reverse a portion of such provisions in future periods. During 2016, we incurred an increase in warranty expense related to a product recall caused by a defect in a part provided by a third party supplier. The liability for warranty obligations totaled $8.5 million and $8.7 million at December 31, 2016 and 2015, respectively. These liabilities are included in accrued expenses in the accompanying consolidated balance sheets. A summary of warranty expense and write-off activity for the years ended December 31, 2016, 2015 and 2014 is as follows: (In thousands) Year Ended December 31, Balance at beginning of period Plus: Amounts charged to cost and expenses Less: Deductions Balance at end of period 2016 $8,739 8,561 (8,752) $8,548 2015 $8,415 2,998 (2,674) $8,739 2014 $8,977 3,103 (3,665) $8,415 Pension Benefit Plan Obligations We maintain a defined benefit pension plan covering employees in certain foreign countries. Pension benefit plan obligations are based on various assumptions used by our actuaries in calculating these amounts. These assumptions include discount rates, compensation rate increases, expected return on plan assets, retirement rates and mortality rates. Actual results that differ from the assumptions and changes in assumptions could affect future expenses and obligations. Stock-Based Compensation We have two Board and stockholder approved stock incentive plans from which stock options and other awards are available for grant to employees and directors. All employee and director stock options granted under our stock option plans have an exercise price equal to the fair market value of the award, as defined in the plan, of the underlying common stock on the grant date. There are currently no vesting provisions tied to performance or market conditions for any stock awards. Vesting for all outstanding award grants is based only on continued service as an employee or director of ADTRAN. All of our outstanding stock option awards are classified as equity awards. Under the provisions of our approved plans, we made grants of performance stock units to certain of our executive officers in 2016, 2015, and 2014. The performance stock units are subject to a market condition based on the relative total shareholder return of ADTRAN against all the companies in the NASDAQ Telecommunications Index and vest at the end of a three-year performance period. The performance stock units are converted into shares of common stock upon vesting. Depending on the relative total shareholder return over the performance period, the executive officers may earn from 0% to 150% of the number of restricted stock units granted. The fair value of the award is based on the market price of our common stock on the date of grant, adjusted for the expected outcome of the impact of market conditions using a Monte Carlo Simulation valuation method. The recipients of the performance stock units also earn dividend credits during the performance period, which are paid in cash upon the issuance of common stock for the restricted stock units. Stock-based compensation expense recognized in 2016, 2015 and 2014 was approximately $6.7 million, $6.7 million and $8.6 million, respectively. As of December 31, 2016, total compensation cost related to non-vested stock options, restricted stock units, performance stock units and restricted stock not yet recognized was approximately $16.4 million, which is expected to be recognized over an average remaining recognition period of 2.9 years. See Note 3 of Notes to Consolidated Financial Statements for additional information. 44 ADTRAN 2016 Annual ReportImpairment of Long-Lived Assets We review long-lived assets used in operations for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable and the undiscounted cash flows estimated to be generated by the asset are less than the asset’s carrying value. An impairment loss would be recognized in the amount by which the recorded value of the asset exceeds the fair value of the asset, measured by the quoted market price of an asset or an estimate based on the best infor- mation available in the circumstances. There were no impairment losses recognized during 2016, 2015 or 2014. Goodwill and Purchased Intangible Assets We evaluate the carrying value of goodwill during the fourth quarter of each year and between annual evaluations if events occur or circumstances change that would more likely than not reduce the fair value of the reporting unit below its carrying amount. We have elected to first assess the qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit to which the goodwill is assigned is less than its carrying amount as a basis for determining whether it is necessary to perform the two-step impairment test. If we determine that it is more likely than not that its fair value is less than its carrying amount, then the two-step impairment test will be performed. Based on the results of our qualitative assessment in 2016, we concluded that it was not necessary to perform the two-step impairment test. There have been no impairment losses recognized since the acquisition in 2011. Purchased intangible assets with finite lives are carried at cost, less accumulated amortization. Amortization is recorded over the estimated useful lives of the respective assets, which is 9 months to 14 years. Research and Development Costs Research and development costs include compensation for engineers and support personnel, outside contracted services, de- preciation and material costs associated with new product development, the enhancement of current products, and product cost reductions. We continually evaluate new product opportunities and engage in intensive research and product development efforts. Research and development costs totaled $124.8 million, $129.9 million and $132.3 million for the years ended December 31, 2016, 2015 and 2014, respectively. Other Comprehensive Income Other comprehensive income consists of unrealized gains (losses) on available-for-sale securities, reclassification adjustments for amounts included in net income related to impairments of available-for-sale securities and realized gains (losses) on avail- able-for-sale securities, defined benefit plan adjustments and foreign currency translation adjustments. The following table presents changes in accumulated other comprehensive income, net of tax, by component for the years ended December 31, 2014, 2015 and 2016: (In thousands) Balance at December 31, 2013 Other comprehensive income (loss) before reclassifications Amounts reclassified from accumulated other comprehensive income Balance at December 31, 2014 Other comprehensive income (loss) before reclassifications Amounts reclassified from accumulated other comprehensive income Balance at December 31, 2015 Other comprehensive income (loss) before reclassifications Amounts reclassified from accumulated other comprehensive income Balance at December 31, 2016 Unrealized Gains (Losses) on Available-for-Sale Securities Defined Benefit Plan Adjustments Foreign Currency Adjustments $(891) (4,866) — (5,757) 1,589 273 (3,895) (1,229) $907 Total $10,753 (4,189) (6,692) — (4,136) (3,282) (3,724) — (7,006) (569) (75) (2,979) (5,915) (8,969) (283) $10,737 2,363 (4,136) 8,964 (844) (6,188) 1,932 1,515 (3,043) $404 107 — (2,936) $(5,017) $(7,575) $(12,188) 45 Financial ResultsThe following tables present the details of reclassifications out of accumulated other comprehensive income for the years ended December 31, 2016, 2015 and 2014: (In thousands) 2016 Details about Accumulated Other Comprehensive Income Components Unrealized gains (losses) on available-for-sale securities: Net realized gain on sales of securities Impairment expense Defined benefit plan adjustments – actuarial losses Total reclassifications for the period, before tax Tax (expense) benefit Total reclassifications for the period, net of tax Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Statement Where Net Income Is Presented $5,408 Net realized investment gain (419) Net realized investment gain (156) (1) 4,833 (1,897) $2,936 (1) Included in the computation of net periodic pension cost. See Note 11 of Notes to Consolidated Financial Statements. (In thousands) 2015 Details about Accumulated Other Comprehensive Income Components Unrealized gains (losses) on available-for-sale securities: Net realized gain on sales of securities Impairment expense Defined benefit plan adjustments – actuarial losses Total reclassifications for the period, before tax Tax (expense) benefit Total reclassifications for the period, net of tax Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Statement Where Net Income Is Presented $10,348 Net realized investment gain (203) Net realized investment gain (396) (1) 9,749 (3,834) $5,915 (1) Included in the computation of net periodic pension cost. See Note 11 of Notes to Consolidated Financial Statements. (In thousands) 2014 Details about Accumulated Other Comprehensive Income Components Unrealized gains (losses) on available-for-sale securities: Net realized gain on sales of securities Impairment expense Total reclassifications for the period, before tax Tax (expense) benefit Total reclassifications for the period, net of tax Amount Reclassified from Accumulated Other Comprehensive Income Affected Line Item in the Statement Where Net Income Is Presented $6,895 Net realized investment gain (115) Net realized investment gain 6,780 (2,644) $4,136 46 ADTRAN 2016 Annual ReportThe following tables present the tax effects related to the change in each component of other comprehensive income for the years ended December 31, 2016, 2015 and 2014: (In thousands) Unrealized gains (losses) on available-for-sale securities Reclassification adjustment for amounts related to available-for-sale investments Defined benefit plan adjustments Reclassification adjustment for amounts related to defined benefit plan adjustments included in net income Foreign currency translation adjustment Total Other Comprehensive Income (Loss) (In thousands) Unrealized gains (losses) on available-for-sale securities Reclassification adjustment for amounts related to available-for-sale investments Defined benefit plan adjustments Reclassification adjustment for amounts related to defined benefit plan adjustments included in net income Foreign currency translation adjustment Total Other Comprehensive Income (Loss) Before-Tax Amount 2016 Tax (Expense) Benefit Net-of-Tax Amount $2,484 (4,989) (1,782) 156 (569) $(4,700) $(969) 1,946 553 (49) — $1,481 $1,515 (3,043) (1,229) 107 (569) $(3,219) Before-Tax Amount 2015 Tax (Expense) Benefit Net-of-Tax Amount $(1,384) (10,145) 2,303 396 (3,724) $(12,554) $540 3,957 (714) (123) — $3,660 $(844) (6,188) 1,589 273 (3,724) $(8,894) (In thousands) Unrealized gains (losses) on available-for-sale securities Reclassification adjustment for amounts related to available-for-sale investments Defined benefit plan adjustments Foreign currency translation adjustment Total Other Comprehensive Income (Loss) Before-Tax Amount 2014 Tax (Expense) Benefit Net-of-Tax Amount $3,874 (6,780) (7,052) (4,189) $(14,147) $(1,511) 2,644 2,186 — $3,319 $2,363 (4,136) (4,866) (4,189) $(10,828) Income Taxes The provision for income taxes has been determined using the asset and liability approach of accounting for income taxes. Un- der this approach, deferred taxes represent the future tax consequences expected to occur when the reported amounts of assets and liabilities are recovered or paid. The provision for income taxes represents income taxes paid or payable for the current year plus the change in deferred taxes during the year. Deferred taxes result from the difference between financial and tax bases of our assets and liabilities and are adjusted for changes in tax rates and tax laws when such changes are enacted. Valuation allowances are recorded to reduce deferred tax assets when it is more likely than not that a tax benefit will not be realized. We establish reserves to remove some or all of the tax benefit of any of our tax positions at the time we determine that the positions become uncertain. We adjust these reserves, including any impact on the related interest and penalties, as facts and circumstances change. 47 Financial ResultsForeign Currency We record transactions denominated in foreign currencies on a monthly basis using exchange rates from throughout the year. Assets and liabilities denominated in foreign currencies are translated at the balance sheet dates using the closing rates of ex- change between those foreign currencies and the functional currency with any transaction gains or losses reported in other income (expense). Our primary exposures to foreign currency exchange rate movements are with our German subsidiary, whose functional currency is the Euro, our Australian subsidiary, whose functional currency is the Australian dollar, and our Mexican subsidiary, whose functional currency is the U.S. dollar. Adjustments resulting from translating financial statements of international subsidiaries are recorded as a component of accumulated other comprehensive income (loss). Revenue Recognition Revenue is generally recognized when persuasive evidence of an arrangement exists, delivery has occurred, the product price is fixed or determinable, collection of the resulting receivable is reasonably assured, and product returns are reasonably esti- mable. For product sales, revenue is generally recognized upon shipment of the product to our customer in accordance with the title transfer terms of the sales agreement, generally Ex Works, per International Commercial Terms. In the case of consigned inventory, revenue is recognized when the end customer assumes ownership of the product. Contracts that contain multiple deliverables are evaluated to determine the units of accounting, and the consideration from the arrangement is allocated to each unit of accounting based on the relative selling price and corresponding terms of the contract. We use vendor-specific objec- tive evidence of selling price. When this evidence is not available, we are generally not able to determine third-party evidence of selling price because of the extent of customization among competing products or services from other companies. In these instances, we use best estimates to allocate consideration to each respective unit of accounting. These estimates include analysis of respective bills of material and review and analysis of similar product and service offerings. We record revenue associated with installation services when respective contractual obligations are complete. In instances where customer acceptance is required, revenue is deferred until respective acceptance criteria have been met. Contracts that include both installation services and product sales are evaluated for revenue recognition in accordance with contract terms. As a result, installation services may be considered a separate deliverable or may be considered a combined single unit of accounting with the delivered product. Gener- ally, either the purchaser, ADTRAN, or a third party can perform the installation of our products. Shipping fees are recorded as revenue and the related cost is included in cost of sales. Sales taxes invoiced to customers are included in revenues, and represent less than one percent of total revenues. The corresponding sales taxes paid are included in cost of goods sold. Value added taxes collected from customers in international jurisdictions are recorded in accrued expenses as a liability. Revenue is recorded net of discounts. Sales returns are recorded as a reduction of revenue and accrued based on historical sales return experience, which we believe provides a reasonable estimate of future returns. A portion of our products are sold to a non-exclusive distribution network of major technology distributors in the United States. These large organizations then distribute or provide fulfillment services to an extensive network of VARs and SIs. VARs and SIs may be affiliated with us as a channel partner, or they may purchase from the distributor in an unaffiliated fashion. Additionally, with certain limitations our distributors may return unused and unopened product for stock-balancing purposes when such returns are accompanied by offsetting orders for products of equal or greater value. We participate in cooperative advertising and market development programs with certain customers. We use these programs to reimburse customers for certain forms of advertising, and in general, to allow our customers credits up to a specified percent- age of their net purchases. Our costs associated with these programs are estimated and included in marketing expenses in our consolidated statements of income. We also participate in rebate programs to provide sales incentives for certain products. Our costs associated with these programs are estimated and accrued at the time of sale, and are recorded as a reduction of sales in our consolidated statements of income. 48 ADTRAN 2016 Annual ReportUnearned Revenue Unearned revenue primarily represents customer billings on our maintenance service programs and unearned revenues relat- ing to multiple element contracts where we still have contractual obligations to our customers. We currently offer maintenance contracts ranging from one to five years. Revenue attributable to maintenance contracts is recognized on a straight-line basis over the related contract term. In addition, we provide software maintenance and a variety of hardware maintenance services to customers under contracts with terms up to ten years. When we defer revenue related to multiple-element contracts where we still have contractual obligations, we also defer the related costs. Deferred costs are included in prepaid expenses and other assets and totaled $10.7 million and $5.2 million at December 31, 2016 and 2015, respectively. Other Income (Expense), Net Other income (expense), net, is comprised primarily of miscellaneous income and expense, gains and losses on foreign currency transactions, and investment account management fees. For the year ended December 31, 2014, other income (expense), net in- cluded a $2.4 million gain related to the settlement of working capital items from an acquisition transaction that closed in 2012. Earnings per Share Earnings per common share, and earnings per common share assuming dilution, are based on the weighted average number of common shares and, when dilutive, common equivalent shares outstanding during the year. See Note 14 of Notes to Consoli- dated Financial Statements for additional information. Dividends During 2016, 2015 and 2014, we paid shareholder dividends totaling $17.6 million, $18.4 million and $19.9 million, respectively. The Board of Directors presently anticipates that it will declare a regular quarterly dividend so long as the present tax treatment of dividends exists and adequate levels of liquidity are maintained. The following table shows dividends paid to our shareholders in each quarter of 2016, 2015 and 2014. Dividends per Common Share 2016 First Quarter Second Quarter Third Quarter Fourth Quarter 2015 2014 $0.09 $0.09 $0.09 $0.09 First Quarter Second Quarter Third Quarter Fourth Quarter $0.09 $0.09 $0.09 $0.09 First Quarter Second Quarter Third Quarter Fourth Quarter $0.09 $0.09 $0.09 $0.09 On January 17, 2017, the Board of Directors declared a quarterly cash dividend of $0.09 per common share to be paid to share- holders of record at the close of business on February 2, 2017. The ex-dividend date was January 31, 2017 and the payment date was February 16, 2017. The quarterly dividend payment was $4.4 million. Business Combinations We use the acquisition method to account for business combinations. Under the acquisition method of accounting, we recog- nize the assets acquired and liabilities assumed at their fair value on the acquisition date. Goodwill is measured as the excess of the consideration transferred over the net assets acquired. Costs incurred to complete the business combination, such as legal, accounting or other professional fees, are charged to general and administrative expenses as they are incurred. 49 Financial ResultsRecently Issued Accounting Standards In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers (Topic 606) (ASU 2014-09), which supersedes the revenue recognition requirements in Topic 605, Revenue Recognition, including most industry-specific revenue recognition guidance throughout the Industry Topics of the Codification. The core principle of ASU 2014-09 is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. In August 2015, the FASB issued ASU 2015-14, which deferred the effective date of ASU 2014-09 to fiscal years beginning after December 31, 2017, and interim periods within those fiscal years, with early adoption permitted for reporting periods beginning after December 15, 2016. Subsequently, the FASB issued ASUs in 2016 containing implementation guidance related to ASU 2014-09, including: ASU 2016-08, Revenue from Contracts with Customers (Topic 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net), which is intended to improve the operability and understandability of the implementation guidance on principal versus agent considerations; ASU 2016-10, Revenue from Contracts with Customers (Topic 606): Identifying Per- formance Obligations and Licensing, which is intended to clarify two aspects of Topic 606: identifying performance obligations and the licensing implementation guidance; ASU 2016-12, Revenue from Contracts with Customers (Topic 606): Narrow-Scope Improvements and Practical Expedients, which contains certain provisions and practical expedients in response to identified implementation issues; and ASU 2016-20, Technical Corrections and Improvements to Topic 606, Revenue from Contracts with Customers, which is intended to clarify the Codification or to correct unintended application of guidance. ASU 2014-09 allows for either full retrospective or modified retrospective adoption. We plan to adopt ASU 2014-09 and the related ASUs on January 1, 2018, and we are currently evaluating the transition method that will be elected. We are continuing to evaluate the potential impact of these ASUs, and we believe the most significant potential impact relates to our accounting for software license and installation services revenues. We do not believe there will be a significant impact to product or maintenance revenues. In July 2015, the FASB issued Accounting Standards Update No. 2015-11, Inventory (Topic 330): Simplifying the Measurement of Inventory (ASU 2015-11). Currently, Topic 330, Inventory, requires an entity to measure inventory at the lower of cost or mar- ket. Market could be replacement cost, net realizable value, or net realizable value less an approximately normal profit margin. ASU 2015-11 does not apply to inventory that is measured using last-in, first-out (LIFO) or the retail inventory method. The amendments apply to all other inventory, which includes inventory that is measured using first-in, first-out (FIFO) or average cost. ASU 2015-11 requires an entity to measure in scope inventory at the lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. ASU 2015-11 is effective for annual reporting periods beginning after December 15, 2016, including interim periods within that reporting period. The amendments should be applied prospectively with earlier application permitted as of the beginning of an interim or annual reporting period. We adopted ASU 2015-05 in the first quarter of 2017, and there was no material impact on our financial position, results of operations and cash flows. In February 2016, the FASB issued Accounting Standards Update No. 2016-02, Leases (Topic 842) (ASU 2016-02). ASU 2016-02 requires an entity to recognize lease assets and lease liabilities on the balance sheet and to disclose key information about the entity’s leasing arrangements. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. A modified retrospective approach is required. We anticipate the adoption of ASU 2016-02 will have a material impact on our financial position; however, we do not believe adoption will have a material impact on our results of operations. We believe the most significant impact relates to our accounting for operating leases for office space and equipment. In March 2016, the FASB issued Accounting Standards Update No. 2016-09, Compensation – Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting (ASU 2016-09). ASU 2016-09 simplifies several aspects of account- ing for share-based compensation arrangements, including income tax effects, the classification of tax-related cash flows on the statement of cash flows, and accounting for forfeitures. ASU 2016-09 is effective for fiscal years beginning after December 15, 2016, including interim periods within those years. We adopted ASU 2016-09 in the first quarter of 2017, and there was no material impact on our financial position, results of operations and cash flows. 50 ADTRAN 2016 Annual ReportIn January 2017, the FASB issued Accounting Standards Update No. 2017-04, Intangibles – Goodwill and Other (Topic 350): Sim- plifying the Test for Goodwill Impairment (ASU 2017-04). ASU 2017-04 simplifies the measurement of goodwill by eliminating step 2 of the goodwill impairment test. Under ASU 2017-04, entities will be required to compare the fair value of a reporting unit to its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. ASU 2017-04 is effective for annual or interim impairment tests performed in fiscal years beginning after December 15, 2019, with early adoption permitted for annual or interim impairment tests performed on testing dates after January 1, 2017. The amendments should be applied prospectively. We do not expect the adoption of ASU 2017-04 will have a material impact on our financial position, results of operations or cash flows. During 2016, we adopted the following accounting standards, which had no material effect on our financial position, results of operations or cash flows: In April 2015, the FASB issued Accounting Standards Update No. 2015-05, Intangibles – Goodwill and Other – Internal-Use Soft- ware (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement (ASU 2015-05), which provides guidance on accounting for fees paid by a customer in a cloud computing arrangement. If a cloud computing arrangement in- cludes a software license, then the customer should account for the software license element of the arrangement consistent with the acquisition of other software licenses. If a cloud computing arrangement does not include a software license, the customer should account for the arrangement as a service contract. ASU 2015-05 is effective for annual reporting periods beginning after December 15, 2015, including interim periods within that reporting period. The amendments may be applied either prospec- tively to all arrangements entered into or materially modified after the effective date or retrospectively. We adopted ASU 2015- 05 during the first quarter of 2016 and will apply the new standard prospectively. The adoption of ASU 2015-05 did not have a material impact on our financial position, results of operations and cash flows. In November 2015, the FASB issued Accounting Standards Update No. 2015-17, Balance Sheet Classification of Deferred Taxes (ASU 2015-17). ASU 2015-17 amends the existing guidance on income taxes to require the classification of all deferred tax assets and liabilities as non-current on the balance sheet. ASU 2015-17 is effective for fiscal years beginning after December 15, 2016, including interim periods within those years. Early adoption is permitted. The guidance may be applied either prospectively, for all deferred tax assets and liabilities, or retrospectively to all periods presented. We elected to early adopt ASU 2015-17 during the fourth quarter of 2016, and we applied the guidance retrospectively to all periods presented. As a result, $17.3 million and $18.9 million were reclassified from current deferred tax assets to non-current deferred tax assets at December 31, 2016 and 2015, respectively. 51 Financial Results2 Business Combinations On September 13, 2016, we acquired key fiber access products, technologies and service relationships from subsidiaries of Com- mScope, Inc. for $0.9 million in cash. This acquisition will enhance our solutions for the cable MSO industry and will provide cable operators with the scalable solutions, services and support they require to compete in the multi-gigabit service delivery market. This transaction was accounted for as a business combination. We have included the financial results of this acquisition in our consolidated financial statements since the date of acquisition. These revenues are included in the Network Solutions reportable segment, and in the Access & Aggregation and Customer Devices categories. We recorded a bargain purchase gain of $3.5 million, net of income taxes, subject to customary working capital adjustments between the parties. The bargain purchase gain represents the excess fair value of the net assets acquired over the consideration exchanged. We have assessed the recognition and measurement of the assets acquired and liabilities assumed based on historical and pro forma data for future periods and have concluded that our valuation procedures and resulting measures were appro- priate. The gain is included in the line item “Gain on bargain purchase of a business” in the 2016 Consolidated Statements of Income. The allocation of the purchase price to the estimated fair value of the assets acquired and liabilities assumed at the acquisition date, subject to working capital adjustments, is as follows: (In thousands) Assets Inventory Property, plant and equipment Intangible assets Total assets acquired Liabilities Accounts payable Warranty payable Accrued wages and benefits Deferred income taxes Total liabilities assumed Total net assets Gain on bargain purchase of a business, net of tax Total purchase price The details of the acquired intangible assets are as follows: (In thousands) Supply agreement Customer relationships Developed technology License Patent Non-compete Trade name Total 52 $3,131 352 4,700 8,183 (1,250) (61) (122) (2,265) (3,698) 4,485 (3,542) $943 Life (years) 0.8 6.0 10.0 1.3 7.3 2.3 2.0 Value $1,400 1,200 800 500 500 200 100 $4,700 ADTRAN 2016 Annual Report The actual revenue and net loss included in our Consolidated Statements of Income for the period September 13, 2016 to December 31, 2016 are as follows: (In thousands) Revenue Net loss September 13 to December 31, 2016 $2,768 $(805) The following supplemental unaudited pro forma information presents the financial results as if the acquisition had occurred on January 1, 2015. This supplemental unaudited pro forma information does not purport to be indicative of what would have occurred had the acquisition been completed on January 1, 2015, nor is it indicative of any future results. Aside from revising the 2015 net income for the effect of the bargain purchase gain, there were no material, non-recurring adjustments to this unaudited pro forma information. (In thousands) Pro forma revenue Pro forma net income 2016 $641,170 $31,212 2015 $603,923 $22,945 For the year ended December 31, 2016, we incurred acquisition and integration related expenses and amortization of acquired intangibles of $1.0 million related to this acquisition. 3 Stock-Based Compensation Stock Incentive Program Descriptions On January 23, 2006, the Board of Directors adopted the ADTRAN, Inc. 2006 Employee Stock Incentive Plan (2006 Plan), which authorized 13.0 million shares of common stock for issuance to certain employees and officers through incentive stock options and non-qualified stock options, stock appreciation rights, restricted stock and restricted stock units (RSUs). The 2006 Plan was adopted by stockholder approval at our annual meeting of stockholders held on May 9, 2006. Options granted under the 2006 Plan typically become exercisable beginning after one year of continued employment, normally pursuant to a four-year vesting schedule beginning on the first anniversary of the grant date, and have a ten-year contractual term. The 2006 Plan was replaced on May 13, 2015 by the ADTRAN, Inc. 2015 Employee Stock Incentive Plan (2015 Plan). Expiration dates of options outstanding at December 31, 2016 under the 2006 Plan range from 2017 to 2024. Our stockholders approved the 2010 Directors Stock Plan (2010 Directors Plan) on May 5, 2010, under which 0.5 million shares of common stock have been reserved. This plan replaces the 2005 Directors Stock Option Plan. Under the 2010 Directors Plan, the Company may issue stock options, restricted stock and RSUs to our non-employee directors. Stock awards issued under the 2010 Directors Plan normally become vested in full on the first anniversary of the grant date. Options issued under the 2010 Directors Plan have a ten-year contractual term. Expiration dates of options outstanding at December 31, 2016 under the 2010 Directors Plan range from 2017 to 2019. On January 20, 2015, the Board of Directors adopted the ADTRAN, Inc. 2015 Employee Stock Incentive Plan (2015 Plan), which authorizes 7.7 million shares of common stock for issuance to certain employees and officers through incentive stock op- tions and non-qualified stock options, stock appreciation rights, performance stock units (PSUs), restricted stock and RSUs. The 2015 Plan was adopted by stockholder approval at our annual meeting of stockholders held on May 13, 2015. PSUs, restricted stock and RSUs granted under the 2015 Plan reduce the shares authorized for issuance under the 2015 Plan by 2.5 shares of com- mon stock for each share underlying the award. Options granted under the 2015 Plan typically become exercisable beginning after one year of continued employment, normally pursuant to a four-year vesting schedule beginning on the first anniversary of the grant date, and have a ten-year contractual term. Expiration dates of options outstanding at December 31, 2015 under the 2015 Plan range from 2025 to 2026. 53 Financial Results The following table summarizes stock-based compensation expense related to stock options, PSUs, restricted stock and RSUs for the years ended December 31, 2016, 2015 and 2014, which was recognized as follows: (In thousands) Stock-based compensation expense included in cost of sales Selling, general and administrative expense Research and development expense Stock-based compensation expense included in operating expenses Total stock-based compensation expense Tax benefit for expense associated with non-qualified options Total stock-based compensation expense, net of tax 2016 $389 3,341 2,965 6,306 6,695 (963) $5,732 2015 $280 3,261 3,171 6,432 6,712 (862) $5,850 2014 $479 4,185 3,899 8,084 8,563 (1,157) $7,406 Stock-based compensation expense recognized in our Consolidated Statements of Income for the years ended December 31, 2016, 2015 and 2014 is based on stock options, PSUs, restricted stock and RSUs ultimately expected to vest, and has been re- duced for estimated forfeitures. Estimates for forfeiture rates are based upon historical experience and are evaluated quarterly. We expect our forfeiture rate for stock options and RSUs to be approximately 3.7% annually. We estimated a 0% forfeiture rate for our PSUs and restricted stock due to the limited number of recipients and historical experience for these awards. Stock Options The following table is a summary of our stock options outstanding as of December 31, 2015 and 2016 and the changes that occurred during 2016: (In thousands, except per share amounts) Options outstanding, December 31, 2015 Options granted Options exercised Options forfeited Options expired Options outstanding, December 31, 2016 Options vested and expected to vest, December 31, 2016 Options exercisable, December 31, 2016 Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Life in Years Aggregate Intrinsic Value 7,108 19 (283) (93) (413) 6,338 6,276 4,757 $21.97 $18.24 $16.66 $17.90 $23.96 $22.14 $22.20 $23.67 6.42 $3,284 5.63 5.60 4.73 $16,972 $16,606 $9,137 At December 31, 2016, total compensation cost related to non-vested stock options not yet recognized was approximately $7.5 million, which is expected to be recognized over an average remaining recognition period of 2.1 years. All of the options above were issued at exercise prices that approximated fair market value at the date of grant. At December 31, 2016, 5.6 million options were available for grant under the shareholder approved plans. The aggregate intrinsic values in the table above represent the total pre-tax intrinsic value (the difference between ADTRAN’s closing stock price on the last trading day of 2016 and the exercise price, multiplied by the number of in-the-money options) that would have been received by the option holders had all option holders exercised their options on December 31, 2016. The amount of aggregate intrinsic value will change based on the fair market value of ADTRAN’s stock. 54 ADTRAN 2016 Annual Report The total pre-tax intrinsic value of options exercised during 2016, 2015 and 2014 was $1.1 million, $0.1 million and $0.7 million, respectively. The fair value of options fully vesting during 2016, 2015 and 2014 was $5.7 million, $6.6 million and $7.7 million, respectively. The following table further describes our stock options outstanding as of December 31, 2016: Range of Exercise Prices $14.88 – 18.96 $18.97 – 23.45 $23.46 – 30.35 $30.36 – 41.92 Options Outstanding Options Outstanding at 12/31/16 (in thousands) Weighted Avg. Remaining Contractual Life in Years 2,101 1,380 1,491 1,366 6,338 6.78 5.79 5.08 4.29 Weighted Average Exercise Price $15.82 $20.17 $23.89 $31.94 Options Exercisable Options Exercisable at 12/31/16 (in thousands) Weighted Average Exercise Price 1,217 881 1,293 1,366 4,757 $16.14 $20.84 $23.92 $31.94 PSUs, restricted stock and RSUs Under the 2015 Plan, awards other than stock options, including PSUs, restricted stock and RSUs, may be granted to certain employees and officers. Under our PSU program, the number of shares of common stock earned by a recipient pursuant to the PSUs is subject to a market condition based on ADTRAN’s relative total shareholder return against all companies in the NASDAQ Telecommunications Index at the end of a three-year performance period. Depending on the relative total share- holder return over the performance period, the recipient may earn from 0% to 150% of the shares underlying the PSUs, with the shares earned distributed upon the vesting of the PSUs at the end of the three-year performance period. The fair value of the award is based on the market price of our common stock on the date of grant, adjusted for the expected outcome of the impact of market conditions using a Monte Carlo Simulation valuation method. A portion of the granted PSUs also vest and the underly- ing shares become deliverable upon the death or disability of the recipient or upon a change of control of ADTRAN, as defined by the 2015 Plan. The recipients of the PSUs receive dividend credits based on the shares of common stock underlying the PSUs. The dividend credits are vested and earned in the same manner as the PSUs and are paid in cash upon the issuance of common stock for the PSUs. The fair value of restricted stock and RSUs is equal to the closing price of our stock on the business day im- mediately preceding the grant date. Restricted stock and RSUs vest ratably over one year and four year periods, respectively. The following table is a summary of our PSUs, restricted stock and RSUs outstanding as of December 31, 2015 and 2016 and the changes that occurred during 2016: (In thousands except per share amounts) Unvested PSUs, restricted stock and RSUs outstanding, December 31, 2015 PSUs, restricted stock and RSUs granted PSUs, restricted stock and RSUs vested PSUs, restricted stock and RSUs forfeited Unvested RSUs and restricted stock outstanding, December 31, 2016 Number of Shares Weighted Average Grant Date Fair Value 106 460 (46) (1) 519 $21.09 $20.63 $22.50 $20.00 $20.51 At December 31, 2016, total compensation cost related to the non-vested portion of PSUs, restricted stock and RSUs not yet recognized was approximately $8.9 million, which is expected to be recognized over an average remaining recognition period of 3.6 years. 55 Financial ResultsValuation and Expense Information We use the Black-Scholes option pricing model (Black-Scholes Model) for the purpose of determining the estimated fair value of stock option awards on the date of grant. The Black-Scholes Model requires the input of certain assumptions that involve judg- ment. Because our stock options have characteristics significantly different from those of traded options, and because changes in the input assumptions can materially affect the fair value estimate, existing models may not provide reliable measures of fair value of our stock options. We use a Monte Carlo Simulation valuation method to value our performance-based PSUs. The fair value of RSUs and restricted stock issued is equal to the closing price of our stock on the date of grant. We will continue to assess the assumptions and methodologies used to calculate the estimated fair value of stock-based compensation. If circumstances change, and additional data becomes available over time, we may change our assumptions and methodologies, which may ma- terially impact our fair value determination. The stock option pricing model requires the use of several assumptions that impact the fair value estimate. These variables include, but are not limited to, the volatility of our stock price and employee exercise behaviors. There were no changes made during 2016 to the methodology used to determine our assumptions. The weighted-average estimated fair value of stock options granted to employees during the years ended December 31, 2016, 2015 and 2014 was $5.22 per share, $4.28 per share and $6.31 per share, respectively, with the following weighted-average as- sumptions: Expected volatility Risk-free interest rate Expected dividend yield Expected life (in years) 2016 34.79% 1.36% 1.98% 6.25 2015 34.57% 1.81% 2.35% 6.23 2014 39.05% 1.79% 1.90% 6.33 We based our estimate of expected volatility for the years ended December 31, 2016, 2015 and 2014 on the sequential historical daily trading data of our common stock for a period equal to the expected life of the options granted. The selection of the his- torical volatility method was based on available data indicating our historical volatility is as equally representative of our future stock price trends as is our implied volatility. We have no reason to believe the future volatility of our stock price is likely to differ from its past volatility. The risk-free interest rate assumption is based upon implied yields of U.S. Treasury zero-coupon bonds on the date of grant having a remaining term equal to the expected life of the options granted. The dividend yield is based on our historical and expected dividend payouts. The expected life of our stock options is based upon historical exercise and forfeiture activity of our previous stock-based grants with a ten-year contractual term. The PSU pricing model also requires the use of several significant assumptions that impact the fair value estimate. The estimated fair value of the PSUs granted to employees during the years ended December 31, 2016, 2015 and 2014 was $23.50 per share, $17.64 per share and $22.11 per share, respectively, with the following assumptions: Expected volatility Risk-free interest rate Expected dividend yield 2016 29.79% 1.17% 1.80% 2015 31.34% 1.20% 2.35% 2014 36.40% 0.96% 1.89% 56 ADTRAN 2016 Annual ReportInvestments 4 At December 31, 2016, we held the following securities and investments, recorded at either fair value or cost: Available-for-sale securities held at fair value $190,146 Restricted investment held at cost Other investments Total carrying value of available-for-sale investments At December 31, 2015, we held the following securities and investments, recorded at either fair value or cost: (In thousands) Deferred compensation plan assets Corporate bonds Municipal fixed-rate bonds Asset-backed bonds Mortgage/Agency-backed bonds U.S. government bonds Foreign government bonds Variable rate demand notes Marketable equity securities (In thousands) Deferred compensation plan assets Corporate bonds Municipal fixed-rate bonds Asset-backed bonds Mortgage/Agency-backed bonds Government bonds Marketable equity securities Amortized Cost $12,367 Gross Unrealized Gains $2,271 66,522 11,799 10,201 13,080 30,022 3,729 11,855 30,571 58,328 26,414 19,281 15,463 35,646 31,643 64 12 19 15 15 2 — 311 $2,709 20 28 2 1 — 4,301 $5,927 Amortized Cost $11,325 Gross Unrealized Gains $1,575 Gross Unrealized Losses $(42) (174) (37) (14) (91) (270) (1) — (1,503) $(2,132) Gross Unrealized Losses $(66) (734) (18) (44) (91) (248) (1,693) Fair Value/ Carrying Value $14,596 66,412 11,774 10,206 13,004 29,767 3,730 11,855 29,379 $190,723 27,800 767 $219,290 Fair Value/ Carrying Value $12,834 57,614 26,424 19,239 15,373 35,398 34,251 $(2,894) $201,133 30,000 1,289 $232,422 Available-for-sale securities held at fair value $198,100 Restricted investment held at cost Other investments held at cost Total carrying value of available-for-sale investments As of December 31, 2016, corporate bonds, municipal fixed-rate bonds, asset-backed bonds, mortgage/agency-backed bonds, U.S. government bonds, and foreign government bonds had the following contractual maturities: (In thousands) Less than one year One to two years Two to three years Three to five years Five to ten years More than ten years Total Corporate bonds Municipal fixed-rate bonds Asset- backed bonds Mortgage/ Agency- backed bonds U.S. government bonds Foreign government bonds $18,912 32,497 11,486 3,517 — — $8,321 1,703 351 1,399 — — $— 635 2,415 5,402 1,600 154 $— 976 980 — 2,060 8,988 $1,701 4,903 13,072 10,091 — — $2,400 1,330 — — — — $66,412 $11,774 $10,206 $13,004 $29,767 $3,730 57 Financial ResultsOur investment policy provides limitations for issuer concentration, which limits, at the time of purchase, the concentration in any one issuer to 5% of the market value of our total investment portfolio. We review our investment portfolio for potential “other-than-temporary” declines in value on an individual investment basis. We assess, on a quarterly basis, significant declines in value which may be considered other-than-temporary and, if necessary, recognize and record the appropriate charge to write-down the carrying value of such investments. In making this assessment, we take into consideration qualitative and quantitative information, including but not limited to the following: the magnitude and duration of historical declines in market prices, credit rating activity, assessments of liquidity, public filings, and statements made by the issuer. We generally begin our identification of potential other-than-temporary impairments by reviewing any security with a fair value that has declined from its original or adjusted cost basis by 25% or more for six or more consecu- tive months. We then evaluate the individual security based on the previously identified factors to determine the amount of the write-down, if any. For each of the years ended December 31, 2016, 2015 and 2014, we recorded a charge of $0.8 million, $0.2 million and $0.1 million, respectively, related to the other-than-temporary impairment of certain marketable equity securi- ties and our deferred compensation plan assets. Realized gains and losses on sales of securities are computed under the specific identification method. The following table pres- ents gross realized gains and losses related to our investments for the years ended December 31, 2016, 2015 and 2014: (In thousands) Year Ended December 31, Gross realized gains Gross realized losses 2016 $7,530 2015 $10,906 $(1,607) $(569) 2014 $7,586 $(308) The following table presents the breakdown of investments with unrealized losses at December 31, 2016: (In thousands) Continuous Unrealized Loss Position for Less than 12 Months Continuous Unrealized Loss Position for 12 Months or Greater Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Deferred compensation plan assets Corporate bonds Municipal fixed-rate bonds Asset-backed bonds Mortgage/Agency-backed bonds U.S. government bonds Foreign government bonds Marketable equity securities Total $294 32,562 8,936 2,986 7,842 26,449 924 21,607 $101,600 $(12) (166) (37) (14) (81) (270) (1) (1,200) $(1,781) $245 2,722 — — 1,239 — — 1,495 $5,701 $(30) (8) — — (10) — — (303) $(351) $539 35,284 8,936 2,986 9,081 26,449 924 23,102 $107,301 $(42) (174) (37) (14) (91) (270) (1) (1,503) $(2,132) The following table presents the breakdown of investments with unrealized losses at December 31, 2015: (In thousands) Continuous Unrealized Loss Position for Less than 12 Months Continuous Unrealized Loss Position for 12 Months or Greater Total Fair Value Unrealized Losses Fair Value Unrealized Losses Fair Value Unrealized Losses Deferred compensation plan assets Corporate bonds Municipal fixed-rate bonds Asset-backed bonds Mortgage/Agency-backed bonds Government bonds Marketable equity securities Total $1,243 35,952 9,160 16,857 15,216 35,397 14,364 $128,189 $(53) (566) (18) (44) (91) (248) (1,564) $(2,584) $92 3,042 — — — — 374 $3,508 $(13) (168) — — — — (129) $(310) $1,335 38,994 9,160 16,857 15,216 35,397 14,738 $131,697 $(66) (734) (18) (44) (91) (248) (1,693) $(2,894) 58 ADTRAN 2016 Annual ReportThe decrease in unrealized losses during 2016, as reflected in the table above, results from changes in market positions associated with our fixed income and equity investment portfolio. At December 31, 2016, a total of 293 of our marketable equity securities were in an unrealized loss position. We have categorized our cash equivalents and our investments held at fair value into a three-level fair value hierarchy based on the priority of the inputs to the valuation technique for the cash equivalents and investments as follows: Level 1 - Values based on unadjusted quoted prices for identical assets or liabilities in an active market; Level 2 - Values based on quoted prices in markets that are not active or model inputs that are observable either directly or indirectly; Level 3 - Values based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These inputs could include information supplied by investees. Fair Value Measurements at December 31, 2016 Using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fair Value (In thousands) Cash equivalents Money market funds Commercial paper Cash equivalents Available-for-sale securities Deferred compensation plan assets Available-for-sale debt securities Corporate bonds Municipal fixed-rate bonds Asset-backed bonds Mortgage/Agency-backed bonds U.S. government bonds Foreign government bonds Variable rate demand notes $6,878 17,222 24,100 14,596 66,412 11,774 10,206 13,004 29,767 3,730 11,855 Available-for-sale marketable equity securities Marketable equity securities— technology industry Marketable equity securities—other Available-for-sale securities Total 3,374 26,005 190,723 $214,823 $6,878 — 6,878 14,596 — — — — 29,767 — — 3,374 26,005 73,742 $80,620 $— 17,222 17,222 — 66,412 11,774 10,206 13,004 — 3,730 11,855 — — 116,981 $134,203 $— — — — — — — — — — — — — — $— 59 Financial ResultsFair Value Measurements at December 31, 2015 Using (In thousands) Cash equivalents Money market funds Commercial paper Cash equivalents Available-for-sale securities Deferred compensation plan assets Available-for-sale debt securities Corporate bonds Municipal fixed-rate bonds Asset-backed bonds Mortgage/Agency-backed bonds Government bonds $1,271 11,696 12,967 12,834 57,614 26,424 19,239 15,373 35,398 Available-for-sale marketable equity securities Marketable equity securities— technology industry Marketable equity securities—other Available-for-sale securities Total 5,384 28,867 201,133 $214,100 Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Fair Value $1,271 — 1,271 12,834 — — — — 35,398 5,384 28,867 82,483 $83,754 $— 11,696 11,696 — 57,614 26,424 19,239 15,373 — — — 118,650 $130,346 $— — — — — — — — — — — — $— The fair value of our Level 2 securities is calculated using a weighted average market price for each security. Market prices are obtained from a variety of industry standard data providers, security master files from large financial institutions, and other third-party sources. These multiple market prices are used as inputs into a distribution-curve-based algorithm to determine the daily market value of each security. Our municipal variable rate demand notes have a structure that implies a standard expected market price. The frequent interest rate resets make it reasonable to expect the price to stay at par. These securities are priced at the expected market price. 5 Derivative Instruments and Hedging Activities We have certain customers and suppliers who are invoiced or pay in a non-functional currency. Changes in the monetary exchange rates may adversely affect our results of operations and financial condition, as these are remeasured to the functional currency through profit and loss. When appropriate, we enter into various derivative transactions to enhance our ability to manage the volatility relating to these typical business exposures. We do not hold or issue derivative instruments for trading or other speculative purposes. Our derivative instruments are recorded in the Consolidated Balance Sheets at their fair values. Our derivative instruments do not qualify for hedge accounting, and accordingly, all changes in the fair value of the instruments are recognized as other income (expense) in the Consolidated Statements of Income. Our derivative instruments are not subject to master netting arrangements and are not offset in the Consolidated Balance Sheets. As of December 31, 2016, we had forward contracts outstanding with notional amounts totaling €5.5 million ($5.8 million), which mature in the first quarter of in 2017. 60 ADTRAN 2016 Annual ReportThe fair values of our derivative instruments recorded in the Consolidated Balance Sheet as of December 31, 2016 and 2015 were as follows: (In thousands) Balance Sheet Location Derivatives Not Designated as Hedging Instruments (Level 2): Foreign exchange contracts – asset derivatives Other receivables 2016 $159 2015 — The change in the fair values of our derivative instruments recorded in the Consolidated Statements of Income during the years ended December 31, 2016, 2015 and 2014 were as follows: (In thousands) Income Statement Location Derivatives Not Designated as Hedging Instruments: Foreign exchange contracts Other income (expense) 2016 $724 2015 $511 2014 $1,852 Inventory 6 At December 31, 2016 and 2015, inventory was comprised of the following: (In thousands) Raw materials Work in process Finished goods Total Inventory, net 2016 $40,461 4,003 60,653 $105,117 2015 $34,223 2,893 54,417 $91,533 We establish reserves for estimated excess, obsolete, or unmarketable inventory equal to the difference between the cost of the inventory and the estimated fair value of the inventory based upon assumptions about future demand and market conditions. At December 31, 2016 and 2015, raw materials reserves totaled $14.6 million and $17.5 million, respectively, and finished goods inventory reserves totaled $10.6 million and $9.2 million, respectively. 7 Property, Plant and Equipment At December 31, 2016 and 2015, property, plant and equipment were comprised of the following: (In thousands) Land Building and land improvements Building Furniture and fixtures Computer hardware and software Engineering and other equipment Total Property, Plant and Equipment Less accumulated depreciation Total Property, Plant and Equipment, net 2016 $4,575 29,229 68,301 18,477 87,655 118,746 326,983 (242,514) $84,469 2015 $4,575 25,667 68,301 17,347 76,389 112,132 304,411 (231,178) $73,233 Depreciation expense was $12.0 million, $12.3 million and $12.5 million in 2016, 2015, and 2014, respectively. 61 Financial Results8 Goodwill and Intangible Assets Goodwill was $3.5 million at December 31, 2016 and 2015, and was previously recorded in our Enterprise Networks reportable segment. As a result of our new reporting structure adopted in the first quarter of 2016, which is discussed further in Note 12, we reallocated goodwill from our Enterprise Networks reportable segment to our two, new reportable segments – Network So- lutions and Services & Support. As a result, goodwill of $3.1 million and $0.4 million was reallocated to our Network Solutions and Services & Support reportable segments, respectively. We evaluate the carrying value of goodwill during the fourth quarter of each year and between annual evaluations if events occur or circumstances change that would more likely than not reduce the fair value of the reporting unit below its carrying amount. We have elected to first assess the qualitative factors to determine whether it is more likely than not that the fair value of the reporting unit to which the goodwill is assigned is less than its carrying amount as a basis for determining whether it is necessary to perform the two-step impairment test. If we determine that it is more likely than not that its fair value is less than its carrying amount, then the two-step impairment test will be performed. Based on the results of our qualitative assessment in 2016, we concluded that it was not necessary to perform the two-step impairment test. There have been no impairment losses recognized since the acquisition in 2011. Intangible assets are included in other assets in the accompanying Consolidated Balance Sheets. The following table presents our intangible assets as of December 31, 2016 and 2015: (In thousands) Customer relationships Developed technology Intellectual property Supply agreement License Patent Trade names Non-compete Total 2016 Accumulated Amortization Gross Value $6,899 6,444 2,340 1,400 500 500 370 200 $(3,208) (5,061) (2,129) (544) (113) (20) (285) (26) 2015 Accumulated Amortization Gross Value $5,828 5,720 2,340 — — — 270 11 $(2,627) (4,329) (1,854) — — — (265) (11) Net Value $3,691 1,383 211 856 387 480 85 174 Net Value $3,201 1,391 486 — — — 5 — $18,653 $(11,386) $7,267 $14,169 $(9,086) $5,083 Amortization expense was $2.5 million, $1.9 million and $2.3 million for the years ended December 31, 2016, 2015 and 2014, respectively. As of December 31, 2016, the estimated future amortization expense of intangible assets is as follows: (In thousands) 2017 2018 2019 2020 2021 Thereafter Total 62 Amount $2,867 1,168 655 621 568 1,388 $7,267 ADTRAN 2016 Annual Report9 Alabama State Industrial Development Authority Financing and Economic Incentives In conjunction with an expansion of our Huntsville, Alabama, facility, we were approved for participation in an incentive pro- gram offered by the State of Alabama Industrial Development Authority (the “Authority”). Pursuant to the program, on January 13, 1995, the Authority issued $20.0 million of its taxable revenue bonds and loaned the proceeds from the sale of the bonds to ADTRAN. The bonds were originally purchased by AmSouth Bank of Alabama, Birmingham, Alabama (the “Bank”). Wachovia Bank, N.A., Nashville, Tennessee (formerly First Union National Bank of Tennessee) (the “Bondholder”), which was acquired by Wells Fargo & Company on December 31, 2008, purchased the original bonds from the Bank and made further advances to the Authority, bringing the total amount outstanding to $50.0 million. An Amended and Restated Taxable Revenue Bond (“Amended and Restated Bond”) was issued and the original financing agreement was amended. The Amended and Restated Bond bears interest, payable monthly. The interest rate is 2% per annum. The Amended and Restated Bond matures on January 1, 2020, and is currently outstanding in the aggregate principal amount of $27.8 million. The estimated fair value of the bond using a level 2 valuation technique at December 31, 2016 was approximately $28.1 million, based on a debt security with a comparable interest rate and maturity and a Standard & Poor’s credit rating of AAA. We are required to make payments to the Authority in amounts necessary to pay the interest on the Amended and Restated Bond. Included in long-term investments at December 31, 2016 is $27.8 million which is invested in a restricted certificate of deposit. These funds serve as a collateral deposit against the principal of this bond, and we have the right to set-off the balance of the Bond with the collateral deposit in order to reduce the balance of the indebtedness. In conjunction with this program, we are eligible to receive certain economic incentives from the state of Alabama that reduce the amount of payroll withholdings that we are required to remit to the state for those employment positions that qualify under the program. We realized economic incentives related to payroll withholdings totaling $1.3 million for each of the years ended December 31, 2016, 2015 and 2014. We made principal payments of $1.1 million for the years ended December 31, 2016 and 2015, respectively, and anticipate making a principal payment in 2017. At December 31, 2016, $1.0 million of the bond debt was classified as a current liability in accounts payable in the Consolidated Balance Sheets. 10 Income Taxes A summary of the components of the provision for income taxes for the years ended December 31, 2016, 2015 and 2014 is as follows: (In thousands) Current Federal State International Total Current Deferred Federal State International Total Deferred Total Provision for Income Taxes 2016 2015 2014 $12,733 1,141 477 14,351 647 73 (3,405) (2,685) $11,666 $7,504 279 (29) 7,754 (585) (66) (41) (692) $7,626 599 12,587 20,812 (1,083) (123) (4,320) (5,526) $7,062 $15,286 63 Financial ResultsOur effective income tax rate differs from the federal statutory rate due to the following: Tax provision computed at the federal statutory rate State income tax provision, net of federal benefit Federal research credits Foreign taxes Tax-exempt income State tax incentives Stock-based compensation Domestic production activity deduction Bargain purchase Other, net Effective Tax Rate 2016 35.00% 3.93 (8.15) (0.34) (0.53) (2.77) 2.53 (2.23) (2.64) 0.08 2015 35.00% 4.86 (12.55) 2.10 (1.94) (5.04) 6.91 (3.17) — 1.30 2014 35.00% 2.69 (4.05) (7.26) (1.25) (2.21) 3.06 (1.15) — 0.69 24.88% 27.47% 25.52% Income before provision for income taxes for the years ended December 31, 2016, 2015 and 2014 is as follows: (In thousands) U.S. entities International entities Total 2016 $54,077 (7,182) $46,895 2015 $27,400 (1,692) $25,708 2014 $23,812 36,094 $59,906 Income before provision for income taxes for international entities reflects income based on statutory transfer pricing agree- ments. This amount does not correlate to consolidated international revenues, many of which occur from our U.S. entity. Deferred income taxes on the balance sheet result from temporary differences between the amount of assets and liabilities rec- ognized for financial reporting and tax purposes. The principal components of our current and non-current deferred taxes are as follows: (In thousands) Deferred tax assets Accounts receivable Inventory Accrued expenses Investments Deferred compensation Stock-based compensation Uncertain tax positions related to state taxes and related interest Pensions Foreign losses State losses and credit carry-forwards Federal loss and research carry-forwards Valuation allowance Total Deferred Tax Assets Deferred tax liabilities Property, plant and equipment Accrued expenses Intellectual property Investments Total Deferred Tax Liabilities Net Deferred Tax Assets 64 2016 2015 $— 12,020 5,551 1,062 5,751 4,724 762 4,273 6,486 4,021 5,886 (6,149) 44,387 (4,433) — (1,918) — (6,351) $38,036 $ 7 12,558 6,359 — 5,072 4,704 1,026 5,729 5,389 4,187 5,886 (7,250) 43,667 (3,315) (2,791) (476) (70) (6,652) $37,015 ADTRAN 2016 Annual ReportAt December 31, 2016 and 2015, non-current deferred taxes related to our investments and our defined benefit pension plan, reflect deferred taxes on the net unrealized gains on available-for-sale investments and deferred taxes on unrealized losses in our pension plan. The net change in non-current deferred taxes associated with these items, a deferred tax benefit of $1.5 million and $3.7 million in 2016 and 2015, respectively, is recorded as an adjustment to other comprehensive income, presented in the Consolidated Statements of Comprehensive Income. Based upon our results of operations in 2016 and expected profitability in future years in a certain international jurisdiction, we concluded that it is more likely than not certain foreign deferred tax assets will be realized. As of December 31, 2016, the remain- ing valuation allowance primarily relates to deferred tax assets related to state credit carry-forwards from tax credits in excess of our annual tax liability to an individual state where we do not generate sufficient state income to offset the credit and net operat- ing losses in foreign jurisdictions. We believe it is more likely than not that we will not realize the full benefits of the deferred tax assets arising from these losses and credits, and accordingly, we have provided a valuation allowance against these deferred tax assets. The deferred tax assets for foreign and domestic carry-forwards, unamortized research and development costs, and state credit carry-forwards of $16.4 million will expire between 2017 and 2030. The loss carry-forwards were acquired through acquisitions in 2009 and 2011. We will continue to assess the realization of our deferred tax assets and related valuations allow- ances. We do not provide for U.S. income tax on undistributed earnings of our foreign operations, whose earnings are intended to be permanently reinvested. These earnings are not required to service debt or fund our U.S. operations. It is impracticable to determine the amount of any unrecognized deferred tax liability for temporary differences related to investments in foreign subsidiaries. The net change in our valuation allowance from December 31, 2015 to December 31, 2016 was $1.1 million. As of December 31, 2016 and 2015, respectively, our cash and cash equivalents were $79.9 million and $84.6 million and short- term investments were $43.2 million and $34.4 million, which provided an available short-term liquidity of $123.1 million and $118.9 million. Of these amounts, our foreign subsidiaries held cash of $42.1 million and $38.9 million, respectively, represent- ing approximately 34.2% and 32.7% of available short-term liquidity, which is used to fund on-going liquidity needs of these subsidiaries. We intend to permanently reinvest these funds outside the U.S. and our current business plans do not indicate a need to repatriate to fund domestic operations. However, if these funds were repatriated to the U.S. or used for U.S. opera- tions, certain amounts related to the earnings and profits of foreign subsidiaries could be subject to U.S. tax for the incremental amount in excess of the foreign tax paid. Due to the timing and circumstances of repatriation of such earnings, if any, it is not practical to determine the amount of funds subject to repatriation or the associated unrecognized deferred tax liability related to the amount. During 2016, 2015 and 2014, we recorded an income tax benefit (expense) of nil, $(40) thousand and $0.1 million, respectively, as an adjustment to equity. This is calculated on the difference between the exercise price of stock option exercises and the mar- ket price of the underlying common stock upon exercise. The change in the unrecognized income tax benefits for the years ended December 31, 2016, 2015 and 2014 is reconciled below: (In thousands) Balance at beginning of period Increases for tax position related to: Prior years Current year Decreases for tax positions related to: Prior years Settlements with taxing authorities Expiration of applicable statute of limitations Balance at end of period 2016 $2,537 95 428 — — (834) $2,226 2015 $3,334 — 280 (29) (103) (945) $2,537 2014 $3,240 — 522 — — (428) $3,334 As of December 31, 2016, 2015, and 2014, our total liability for unrecognized tax benefits was $2.2 million, $2.5 million, and $3.3 million, respectively, of which $1.7 million, $1.8 million, and $2.6 million, respectively, would reduce our effective tax rate if we were successful in upholding all of the uncertain positions and recognized the amounts recorded. We classify interest and penalties recognized on the liability for unrecognized tax benefits as income tax expense. As of December 31, 2016, 2015 and 2014, the balances of accrued interest and penalties were $0.8 million, $0.9 million and $1.0 million, respectively. We do not anticipate a single tax position generating a significant increase or decrease in our liability for unrecognized tax ben- efits within 12 months of this reporting date. We file income tax returns in the U.S. federal and various state jurisdictions and several foreign jurisdictions. We are not currently under audit by the Internal Revenue Service. Generally, we are not subject to changes in income taxes by any taxing jurisdiction for the years prior to 2013. 65 Financial Results11 Employee Benefit Plans Pension Benefit Plan We maintain a defined benefit pension plan covering employees in certain foreign countries. The pension benefit plan obligations and funded status at December 31, 2016 and 2015, are as follows: (In thousands) Change in projected benefit obligation: Projected benefit obligation at beginning of period Service cost Interest cost Actuarial gain (loss) - experience Actuarial gain (loss) - assumptions Benefit payments Effects of foreign currency exchange rate changes Projected benefit obligation at end of period Change in plan assets: Fair value of plan assets at beginning of period Actual return on plan assets Effects of foreign currency exchange rate changes Fair value of plan assets at end of period Funded (unfunded) status at end of period 2016 2015 $(26,851) (1,211) (720) 431 (2,628) 52 916 $(30,507) (1,314) (615) 247 2,078 81 3,179 (30,011) (26,851) 19,213 1,494 (662) 20,045 $(9,966) 20,338 988 (2,113) 19,213 $(7,638) The accumulated benefit obligation was $28.7 million and $25.1 million at December 31, 2016 and 2015, respectively. The in- crease in the accumulated benefit obligation and the change in actuarial gain (loss) is primarily attributable to a decrease in the discount rate used in 2016 to determine the accumulated benefit obligation. The net amounts recognized in the balance sheet for the unfunded pension liability as of December 31, 2016 and 2015 are as follows: (In thousands) Current liability Non-current liability Total 2016 $— (9,966) $(9,966) 2015 $— (7,638) $(7,638) The components of net periodic pension cost and amounts recognized in other comprehensive income for the years ended December 31, 2016, 2015 and 2014 are as follows: (In thousands) Net periodic benefit cost: Service cost Interest cost Expected return on plan assets Amortization of actuarial losses Net periodic benefit cost Other changes in plan assets and benefit obligations recognized in other comprehensive income: Net actuarial (gain) loss Amortization of actuarial losses Amount recognized in other comprehensive income Total recognized in net periodic benefit cost and other comprehensive income 2016 $1,211 720 (1,057) 175 1,049 1,782 (156) 1,626 $2,675 2015 $1,314 615 (1,011) 407 1,325 (2,303) (396) (2,699) $(1,374) 2014 $1,189 836 (1,086) — 939 7,052 — 7,052 $7,991 66 ADTRAN 2016 Annual ReportThe amounts recognized in accumulated other comprehensive income as of December 31, 2016 and 2015 are as follows: (In thousands) Net actuarial loss 2016 $6,871 2015 $5,245 The defined benefit pension plan is accounted for on an actuarial basis, which requires the selection of various assumptions, including an expected rate of return on plan assets and a discount rate. The expected return on our German plan assets that is utilized in determining the benefit obligation and net periodic benefit cost is derived from periodic studies, which include a review of asset allocation strategies, anticipated future long-term performance of individual asset classes, risks using standard deviations and correlations of returns among the asset classes that comprise the plans’ asset mix. While the studies give appro- priate consideration to recent plan performance and historical returns, the assumptions are primarily long-term, prospective rates of return. Another key assumption in determining net pension expense is the assumed discount rate to be used to discount plan obliga- tions. The discount rate has been derived from the returns of high-quality, corporate bonds denominated in Euro currency with durations close to the duration of our pension obligations. The weighted-average assumptions that were used to determine the net periodic benefit cost for the years ended December 31, 2016, 2015 and 2014 are as follows: Discount rates Rate of compensation increase Expected long-term rates of return 2016 2.64% 2.00% 5.40% 2015 2.20% 2.25% 5.40% The weighted-average assumptions that were used to determine the benefit obligation at December 31, 2016 and 2015: Discount rates Rate of compensation increase 2016 1.90% 2.00% 2014 3.70% 2.25% 5.40% 2015 2.64% 2.25% Actuarial gains and losses are recorded in accumulated other comprehensive income. To the extent unamortized gains and losses exceed 10% of the higher of the market-related value of assets or the projected benefit obligation, the excess is amor- tized as a component of net periodic pension cost over the remaining service period of active participants. We estimate that $0.3 million will be amortized from accumulated other comprehensive income into net periodic pension cost in 2017 for the net actuarial loss. We do not anticipate making a contribution to this pension plan in 2017. The following pension benefit payments, which reflect expected future service, as appropriate, are expected to be paid to participants: (In thousands) 2017 2018 2019 2020 2021 2022 – 2026 Total $348 515 699 964 1,079 5,156 $8,761 67 Financial ResultsWe have categorized our cash equivalents and our investments held at fair value into a three-level fair value hierarchy based on the priority of the inputs to the valuation technique for the cash equivalents and investments as follows: Level 1 - Values based on unadjusted quoted prices for identical assets or liabilities in an active market; Level 2 - Values based on quoted prices in markets that are not active or model inputs that are observable either directly or indirectly; Level 3 - Values based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These inputs include information supplied by investees. Fair Value Measurements at December 31, 2016 Using (In thousands) Cash and cash equivalents Available-for-sale securities Bond funds: Corporate bonds Government bonds Equity funds: Large cap blend Large cap value Balanced fund Available-for-sale securities Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) $6 $— $— Fair Value $6 12,546 2,037 4,462 249 745 20,039 $20,045 12,546 2,037 4,462 249 745 20,039 $20,045 — — — — — — $— — — — — — — $— Fair Value Measurements at December 31, 2015 Using (In thousands) Cash and cash equivalents Available-for-sale securities Bond funds: Corporate bonds Government bonds Equity funds: Large cap blend Large cap value Balanced fund Available-for-sale securities Total Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) $3 $— $— Fair Value $3 11,633 1,960 4,604 258 755 19,210 $19,213 11,633 1,960 4,604 258 755 19,210 $19,213 — — — — — — $— — — — — — — $— Our investment policy includes various guidelines and procedures designed to ensure assets are invested in a manner neces- sary to meet expected future benefits earned by participants, and consider a broad range of economic conditions. Central to the policy are target allocation ranges by asset class, which is currently 75% for bond funds and 25% for equity funds. The objectives of the target allocations are to maintain investment portfolios that diversify risk through prudent asset allocation parameters, achieve asset returns that meet or exceed the plans’ actuarial assumptions, and achieve asset returns that are com- petitive with like institutions employing similar investment strategies. The investment policy is periodically reviewed by us and a designated third-party fiduciary for investment matters. The policy is established and administered in a manner that is compliant at all times with applicable government regulations. 68 ADTRAN 2016 Annual Report 401(k) Savings Plan We maintain the ADTRAN, Inc. 401(k) Retirement Plan (Savings Plan) for the benefit of our eligible employees. The Savings Plan is intended to qualify under Sections 401(a) and 401(k) of the Internal Revenue Code of 1986, as amended (Code), and is intended to be a “safe harbor” 401(k) plan under Code Section 401(k)(12). The Savings Plan allows employees to save for retirement by contributing part of their compensation to the plan on a tax-deferred basis. The Savings Plan also requires us to contribute a “safe harbor” amount each year. We match up to 4% of employee contributions (100% of an employee’s first 3% of contributions and 50% of their next 2% of contributions), beginning on the employee’s one year anniversary date. In calculating our matching contribution, we only use compensation up to the statutory maximum under the Code ($265 thousand for 2016). All contributions under the Savings Plan are 100% vested. Expenses recorded for employer contributions and plan administra- tion costs for the Savings Plan amounted to approximately $4.1 million, $4.7 million and $4.5 million in 2016, 2015 and 2014, respectively. Deferred Compensation Plans We maintain four deferred compensation programs for certain executive management employees and our Board of Directors. For our executive management employees, the ADTRAN, Inc. Deferred Compensation Program for Employees is offered as a supplement to our tax-qualified 401(k) plan and is available to certain executive management employees who have been desig- nated by our Board of Directors. This deferred compensation plan allows participants to defer all or a portion of certain specified bonuses and up to 25% of remaining cash compensation, and permits us to make matching contributions on a discretionary basis, without the limitations that apply to the 401(k) plan. To date, we have not made any matching contributions under this plan. We also maintain the ADTRAN, Inc. Equity Deferral Program for Employees. Under this plan, participants may elect to defer all or a portion of their vested PSUs to the Plan. Such deferrals shall continue to be held and deemed to be invested in shares of ADTRAN stock unless and until the amounts are distributed or such deferrals are moved to another deemed investment pursuant to an election made by the Participant. For our Board of Directors, we maintain the ADTRAN, Inc. Deferred Compensation Program for Directors. This program al- lows our Board of Directors to defer all or a portion of monetary remuneration paid to the Director, including, but not limited to, meeting fees and annual retainers. We also maintain the ADTRAN, Inc. Equity Deferral Program for Directors. Under this plan, participants may elect to defer all or a portion of their vested restricted stock awards. Such deferrals shall continue to be held and deemed to be invested in shares of ADTRAN stock unless and until the amounts are distributed or such deferrals are moved to another deemed investment pursuant to an election made by the Director. We have set aside the plan assets for all plans in a rabbi trust (Trust) and all contributions are credited to bookkeeping accounts for the participants. The Trust assets are subject to the claims of our creditors in the event of bankruptcy or insolvency. The as- sets of the Trust are deemed to be invested in pre-approved mutual funds as directed by each participant, and the participant’s bookkeeping account is credited with the earnings and losses attributable to those investments. Benefits are scheduled to be distributed six months after termination of employment in a single lump sum payment or annual installments paid over a three or ten year term. Distributions will be made on a pro rata basis from each of the hypothetical investments of the Participant’s account in cash. Any whole shares of ADTRAN, Inc. common stock that are distributed will be distributed in-kind. Assets of the Trust are deemed invested in mutual funds that cover an investment spectrum ranging from equities to money market instruments. These mutual funds are publicly quoted and reported at fair value. The fair value of the assets held by the Trust and the amounts payable to the plan participants at December 31, 2016 and 2015 are as follows: (In thousands) Fair Value of Plan Assets Long-term Investments Total Fair Value of Plan Assets Amounts Payable to Plan Participants Non-current Liabilities Total Amounts Payable to Plan Participants 2016 2015 $14,596 $14,596 $14,596 $14,596 $12,834 $12,834 $12,834 $12,834 69 Financial Results Interest and dividend income of the Trust have been included in interest and dividend income in the accompanying 2016, 2015 and 2014 Consolidated Statements of Income. Changes in the fair value of the plan assets held by the Trust have been included in accumulated other comprehensive income in the accompanying 2016 and 2015 Consolidated Balance Sheets. Changes in the fair value of the deferred compensation liability are included as selling, general and administrative expense in the accompanying 2016, 2015 and 2014 Consolidated Statements of Income. Based on the changes in the total fair value of the Trust’s assets, we recorded deferred compensation income (expense) in 2016, 2015 and 2014 of $(1.3) million, $0.3 million and $(0.7) million, respectively. Retiree Medical Coverage We provide medical, dental and prescription drug coverage to one retired former officer and his spouse, for his life, on the same terms as provided to our active officers, and to the spouse of a former deceased officer for up to 30 years. At December 31, 2016 and 2015, this liability totaled $0.2 million. 12 Segment Information and Major Customers In 2015, we realigned our organizational structure to better match our market opportunities, technological development initia- tives, and improve efficiencies. During the first quarter of 2016, our chief operating decision maker requested changes in the information that he regularly reviews for purposes of allocating resources and assessing performance. As a result, beginning with the quarter ended March 31, 2016, we began reporting our financial performance based on two, new reportable segments— Network Solutions and Services & Support. Network Solutions includes hardware products and next-generation virtualized solutions used in service provider or business networks, as well as prior-generation products. Services & Support includes our suite of ProCloud managed services, network installation, engineering and maintenance services, and fee-based technical sup- port and equipment repair/replacement plans. We evaluate the performance of our new segments based on gross profit; therefore, selling, general and administrative expenses, research and development expenses, interest and dividend income, interest expense, net realized investment gain/loss, other income/expense and provision for taxes are reported on a company-wide, functional basis only. Historical financial information by reportable segment and category, as discussed below, has been recast to conform to our new reporting structure. There are no inter-segment revenues. The following table presents information about the reported sales and gross profit of our reportable segments for each of the years ended December 31, 2016, 2015 and 2014. Asset information by reportable segment is not reported, since we do not pro- duce such information internally. (In thousands) Sales and Gross Profit by Market Segment Network Solutions Services & Support Total 2016 2015 2014 Sales Gross Profit Sales Gross Profit Sales Gross Profit $525,502 111,279 $636,781 $254,807 $527,422 $233,579 $559,532 36,537 72,642 33,318 70,475 $291,344 $600,064 $266,897 $630,007 $271,517 39,810 $311,327 Sales by Category In addition to our new reporting segments, we will also report revenue for the following three categories—Access & Aggrega- tion, Customer Devices, and Traditional & Other Products. The table below presents sales information by product category for the years ended December 31, 2016, 2015 and 2014: (In thousands) Access & Aggregation Customer Devices Traditional & Other Products Total 2016 $436,372 137,608 62,801 $636,781 2015 $405,698 125,565 68,801 $600,064 2014 $401,769 138,051 90,187 $630,007 70 ADTRAN 2016 Annual ReportThe following table presents sales information by geographic area for the years ended December 31, 2016, 2015 and 2014. Inter- national sales correlate to shipments with a non-U.S. destination. (In thousands) United States Germany Other international Total 2016 $501,337 85,780 49,664 $636,781 2015 $419,366 111,666 69,032 $600,064 2014 $381,382 150,987 97,638 $630,007 Customers comprising more than 10% of revenue can change from year to year. Single customers comprising more than 10% of our revenue in 2016 included three customers at 24%, 19% and 12%. Single customers comprising more than 10% of our revenue in 2015 included three customers at 20%, 17% and 14%. Single customers comprising more than 10% of our revenue in 2014 included two customers at 21% and 14%. No other customer accounted for 10% or more of our sales in 2016, 2015 or 2014. Our five largest customers, other than those with more than 10 percent of revenues disclosed above, can change from year to year. These customers represented 13%, 14%, and 22% of total revenue in 2016, 2015 and 2014, respectively. Revenues in this disclosure do not include distributor agents, who predominately provide fulfillment services to end users. In such cases where known, that revenue is associated with the end user. Additional Segment Information As of December 31, 2016, long-lived assets, net totaled $84.5 million, which includes $79.9 million held in the United States and $4.6 million held outside the United States. As of December 31, 2015, long-lived assets, net totaled $73.2 million, which includes $68.8 million held in the United States and $4.4 million held outside the United States. 13 Commitments and Contingencies In the ordinary course of business, we may be subject to various legal proceedings and claims, including employment disputes, patent claims, disputes over contract agreements and other commercial disputes. In some cases, claimants seek damages or other relief, such as royalty payments related to patents, which, if granted, could require significant expenditures. Although the outcome of any claim or litigation can never be certain, it is our opinion that the outcome of all contingencies of which we are currently aware will not materially affect our business, operations, financial condition or cash flows. We have committed to invest up to an aggregate of $7.9 million in two private equity funds, and we have contributed $8.4 million as of December 31, 2016, of which $7.7 million has been applied to these commitments. We lease office space and equipment under operating leases which expire at various dates through 2025. As of December 31, 2016, future minimum rental payments under non-cancelable operating leases with original maturities of greater than 12 months are as follows: (In thousands) 2017 2018 2019 2020 Thereafter Total $3,788 2,043 847 741 3,243 $10,662 Rental expense was $4.2 million, $4.9 million and $4.7 million for the years ended December 31, 2016, 2015 and 2014, respec- tively. 71 Financial Results14 Earnings per Share A summary of the calculation of basic and diluted earnings per share (EPS) for the years ended December 31, 2016, 2015 and 2014 is as follows: (In thousands, except for per share amounts) 2016 2015 2014 Numerator Net Income Denominator $35,229 $18,646 $44,620 Weighted average number of shares—basic 48,724 51,145 55,120 Effect of dilutive securities: Stock options Restricted stock and restricted stock units Weighted average number of shares—diluted Net income per share—basic Net income per share—diluted 170 55 48,949 $0.72 $0.72 81 41 51,267 $0.36 $0.36 304 58 55,482 $0.81 $0.80 For each of the years ended December 31, 2016, 2015 and 2014, 4.6 million, 6.1 million and 4.4 million stock options were out- standing but were not included in the computation of that year’s diluted EPS because the options’ exercise prices were greater than the average market price of the common shares, therefore making them anti-dilutive under the treasury stock method. 15 Summarized Quarterly Financial Data (Unaudited) The following table presents unaudited quarterly operating results for each of our last eight fiscal quarters. This information has been prepared on a basis consistent with our audited financial statements and includes all adjustments, consisting only of normal recurring adjustments, considered necessary for a fair presentation of the data. Unaudited Quarterly Operating Results (In thousands, except for per share amounts) Three Months Ended March 31, 2016 Net sales Gross profit Operating income Net income Earnings per common share Earnings per common share assuming dilution (1) $142,204 $65,794 $5,521 $5,014 $0.10 $0.10 June 30, 2016 September 30, 2016 December 31, 2016 $162,701 $78,955 $14,812 $10,228 $0.21 $0.21 $168,890 $75,808 $10,130 $12,415 $0.26 $0.26 $162,986 $70,787 $4,272 $7,572 $0.16 $0.16 Three Months Ended March 31, 2015 June 30, 2015 September 30, 2015 December 31, 2015 Net sales Gross profit Operating income Net income Earnings per common share Earnings per common share assuming dilution (1) $142,835 $65,563 $1,963 $3,317 $0.06 $0.06 $160,138 $68,246 $644 $2,544 $0.05 $0.05 $158,078 $70,649 $8,072 $7,067 $0.14 $0.14 $139,013 $62,439 $2,800 $5,718 $0.12 $0.12 (1) Assumes exercise of dilutive stock options calculated under the treasury stock method. 72 ADTRAN 2016 Annual Report 16 Related Party Transactions We employed the law firm of our director emeritus for legal services. All bills for services rendered by this firm were reviewed and approved by our Chief Financial Officer. We believe that the fees for such services are comparable to those charged by other firms for services rendered to us. The services of our director emeritus ended with his death on September 7, 2014. For the year ended 2014, we incurred fees of $0.1 million for these legal services. 17 Subsequent Events On January 17, 2017, the Board declared a quarterly cash dividend of $0.09 per common share to be paid to shareholders of record at the close of business on February 2, 2017. The quarterly dividend payment was $4.4 million and was paid on February 16, 2017. In July 2003, our Board of Directors elected to begin declaring quarterly dividends on our common stock considering the tax treatment of dividends and adequate levels of Company liquidity. During the first quarter and as of February 24, 2017, we have repurchased 0.2 million shares of our common stock through open market purchases at an average cost of $21.46 per share. We currently have the authority to purchase an additional 4.2 million shares of our common stock under the current plan approved by the Board of Directors. 73 Financial ResultsDirectors and Executive Officers Thomas R. Stanton Chairman and Chief Executive Officer H. Fenwick Huss Director of the Company Willem Kooyker Dean of the Zicklin School of Business at Baruch College William L. Marks Director of the Company Former Chairman of the Board and Chief Executive Officer of Whitney Holding Corp. (the holding company for Whitney National Bank of New Orleans) Anthony J. Melone Director of the Company Former Executive Vice President and Chief Technology Officer for Verizon Communications Balan Nair Director of the Company Executive Vice President and Chief Technology Officer of Liberty Global, Inc. Roy J. Nichols Director Emeritus Founder and former President of Nichols Research Corporation Jacqueline H. Rice Executive Vice President and Chief Risk and Compliance Officer for Target Corporation Kathryn A. Walker Director of the Company Managing Director for OpenAir Equity Partners Michael K. Foliano Senior Vice President Global Operations Kevin P. Heering Senior Vice President Quality and Administration Roger D. Shannon Senior Vice President of Finance, Chief Financial Officer, Corporate Secretary and Treasurer Raymond R. Schansman Senior Vice President Global Services & Support Eduard Scheiterer Senior Vice President Engineering and Development James D. Wilson, Jr. Senior Vice President Technology and Strategy Transfer Agent American Stock Transfer and Trust Company New York, NY Independent Registered Public Accounting Firm PricewaterhouseCoopers LLP Birmingham, Alabama Special Counsel Dentons US LLP Atlanta, Georgia Form 10-K ADTRAN’s 2016 Annual Report on Form 10-K (without exhibits) as filed with the Securities and Exchange Commission is available to stockholders without charge upon written request to: Investor Relations ADTRAN, Inc. 901 Explorer Blvd. P.O. Box 140000 Huntsville, Alabama 35814-4000 256 963-8220 or 256 963-7600 investorrelations@adtran.com (email) Annual Meeting The 2017 Annual Meeting of Stockholders will be held at ADTRAN corporate headquarters, 901 Explorer Boulevard, Huntsville, Alabama, on Wednesday, May 10, 2017, at 10:30 a.m. Central time. 74 ADTRAN 2016 Annual ReportCorporate Headquarters ADTRAN, Inc. 901 Explorer Boulevard Huntsville, AL 35806 USA P.O. Box 140000 Huntsville, AL 35814-4000 1 800 9ADTRAN 1 256 963-8000 1 256 963-8004 fax investorrelations@adtran.com www.adtran.com International Offices ADTRAN Networks Pty. Ltd. Melbourne, Australia ADTRAN Singapore Pte. Ltd. Singapore ADTRAN Europe Limited Basingstoke, Hampshire and Ipswich, Suffolk, United Kingdom ADTRAN Canada, Inc. Montreal and Mississauga, Canada ADTRAN Networks S.A. de C.V. Mexico City, Mexico ADTRAN Networks & Services S. de R.L. de C.V. Mexico City, Mexico ADTRAN Peru S.R.L. Lima, Peru ADTRAN GmbH Berlin, Bruchsal, Greifswald, Leipzig, and Munich, Germany ADTRAN Oy Helsinki, Finland ADTRAN M.E.P.E. Athens, Greece ADTRAN Networks India Private Limited Hyderabad, India ADTRAN Holdings Ltd. Tel Aviv, Israel ADTRAN S.R.L. Milan, Italy ADTRAN Sp. z.o.o. Warsaw, Poland ADTRAN s.r.o. Bratislava, Slovakia ADTRAN Switzerland GmbH Zurich, Switzerland Saudi Arabian Branch of ADTRAN International, Inc. Riyadh, Saudi Arabia ADTRAN GmbH Permanent Establishment Tunis, Tunisia 

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