UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM20-F

(Mark One)

or

For the fiscal year ended December 31, 20152016

or

For the transition period from                    to                    

or

Date of event requiring this shell company report                    

Commission file number001-15128

United Microelectronics Corporation

(Exact Name of Registrant as Specified in its Charter)

Taiwan, Republic of China

(Jurisdiction of Incorporation or Organization)

No. 3Li-Hsin Road II, Hsinchu Science Park,

Hsinchu City, Taiwan, Republic of China

(Address of Principal Executive Offices)

Chitung Liu, +886-2-2658-9168,+886-2-2658-9168,chitung_liu@umc.comchitungliu@umc.com,

8F, No. 68, Section 1, Neihu Road., Taipei 11493, Taiwan R.O.C.

(Name, Telephone,E-mail and/or Facsimile number and Address of Company Contact Person)

Securities registered or to be registered pursuant to Section 12(b) of the Act:

Securities registered or to be registered pursuant to Section 12(g) of the Act:

None

Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act:

None

Indicate the number of outstanding shares of each of the Issuer’s classes of capital or common stock as of the close of the period covered by the annual report.

12,758,132,91512,624,318,715 Common Shares of Registrant issued as of December 31, 20152016 (including 333,814,200400,000,000 treasury shares)

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes  x☒    No  ¨☐

If this report is an annual or transition report, indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934.    Yes  ¨☐    No  x☒

Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  x☒    No  ¨☐

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of RegulationS-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  ¨☐    No  ¨☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or anon-accelerated filer. See definition of “accelerated filer and large accelerated filer” in Rule12b-2 of the Exchange Act. (Check one):

Large accelerated filer  x☒                  Accelerated filer   ¨☐                 Non-accelerated filer  ¨☐

Indicate by check mark which basis of accounting the registrant has used to prepare the financial statements included in this filing:

If “Other” has been checked in response to the previous question, indicate by check mark which financial statement item the registrant has elected to follow. Item 17  ¨☐    Item 18  ¨☐

If this is an annual report, indicate by check mark whether the registrant is a shell company (as defined in Rule12b-2 of the Securities Exchange Act of 1934).    Yes  ¨☐    No  x☒

UNITED MICROELECTRONICS CORPORATION

FORM20-F ANNUAL REPORT

FISCAL YEAR ENDED DECEMBER 31, 20142016

Table of Contents

i

SUPPLEMENTAL INFORMATION

The references to “United Microelectronics”, “we”, “us”, “our”, “our company” and “the Company” in this annual report refer to United Microelectronics Corporation and its consolidated subsidiaries, unless the context suggests otherwise. The references to “Taiwan” and “R.O.C.” refer to Taiwan, Republic of China. The references to “China” and “PRC” refer to People’s Republic of China. The references to “shares” and “common shares” refer to our common shares, par value NT$10 per share, and “ADSs” refers to our American depositary shares, each representing five common shares. The ADSs are issued under the Deposit Agreement, dated as of October 21, 2009, as amended, supplemented or modified from time to time, among United Microelectronics, JPMorgan Chase Bank, N.A. and the holders and beneficial owners from time to time of American Depositary Receipts issued thereunder. The references to “TIFRSs” refers to the Taiwan International Financial Reporting Standards as issued by the Financial Supervisory Commission in the Republic of China, “IFRSs” refers to International Financial Reporting Standards as issued by the International Accounting Standards Board, or IASB, “R.O.C. GAAP” refers to the generally accepted accounting principles in the Republic of China, and “U.S. GAAP” refers to the generally accepted accounting principles in the United States. Any discrepancies in any table between totals and sums of the amounts listed are due to rounding.

We publish our financial statements in New Taiwan dollars, the lawful currency of the R.O.C. In this annual report, “NT$” and “NT dollars” mean New Taiwan dollars, “$”, “US$” and “U.S. dollars” mean United States dollars, “¥” means Japanese Yen, “RMB¥” means Renminbi and “€” means EURO.

FORWARD-LOOKING STATEMENTS IN THIS ANNUAL REPORT MAY NOT BE REALIZED

Our disclosure and analysis in this annual report contain or incorporate by reference some forward-looking statements. Our forward-looking statements contain information regarding, among other things, our financial condition, future expansion plans and business strategy. We have based these forward-looking statements on our current expectations and projections about future events. You can identify these statements by the fact that they do not relate strictly to historical or current facts. Although we believe that these expectations and projections are reasonable, such forward-looking statements are inherently subject to risks, uncertainties and assumptions about us, including, among other things:

The words “may”, “will”, “is/are likely to”, “anticipate”, “believe”, “estimate”, “expect”, “intend”, “plan” and similar expressions are intended to identify a number of these forward-looking statements. We do not and will not undertake the obligation to update or revise any forward-looking statements contained in this annual report whether as a result of new information, future events or otherwise. In light of these risks, uncertainties and assumptions, the forward-looking events discussed in this annual report might not occur and our actual results could differ materially from those anticipated in these forward-looking statements.

GLOSSARY

Memory		A group of integrated circuits that a computer uses to store data and programs, such as ROM, RAM, DRAM and SRAM.

Micron		A unit of spatial measurement that isone-millionth of a meter.
Nanometer		A unit of spatial measurement that isone-billionth of a meter.
PC		Personal computer.
RAM		Random Access Memory. A type of volatile memory forming the main memory of a computer where applications and files are run.
ROM		Read-Only Memory. Memory that is programmed by the manufacturer and cannot be changed. Typically, ROM is used to providestart-up data when a computer is first turned on.
Scanner		A photolithography tool used in the production of semiconductor devices. This camera-likestep-and-scan tool projects the image of a circuit from a master image onto a photosensitized silicon wafer.
Semiconductor		A material with electrical conducting properties in between those of metals and insulators. Essentially, semiconductors transmit electricity only under certain circumstances, such as when given a positive or negative electric charge. Therefore, a semiconductor’s ability to conduct can be turned on or off by manipulating those charges and this allows the semiconductor to act as an electric switch. The most common semiconductor material is silicon, used as the base of most semiconductor chips today because it is relatively inexpensive and easy to create.
SoC		System-on-Chip. A chip that incorporates functions currently performed by several chips on a cost effective basis.
SOI		Silicon-On-Insulator. Silicon wafer consisting of a thin layer of oxide, on top of which semiconductor devices are built.
SRAM		Static Random Access Memory. A type of volatile memory product that is used in electronic systems to store data and program instructions. Unlike the more common DRAM, it does not need to be refreshed.
Transistor		Tri-terminal semiconductor device in which input signal (voltage or current depending on the type of transistor) controls output current. An individual circuit that can amplify or switch electric current. This is the building block of all integrated circuits.
Volatile memory		Memory products which lose their data content when the power supply is switched off.
Wafer		Thin, round, flat piece of silicon that is the base of most integrated circuits.
8-inch wafer equivalents		Standard unit describing the equivalent amount of8-inch wafers produced after conversion, used to quantify levels of wafer production for purposes of comparison. Figures of8-inch wafer equivalents are derived by converting the number of wafers of all dimensions (e.g., 6-inch, 8-inch6-inch,8-inch and12-inch) into their equivalent figures for8-inch wafers. 1006-inch wafers are equivalent to 56.258-inch wafers. 10012-inch wafers are equivalent to 2258-inch wafers.

PART II.

Not applicable.

Not applicable.

The selected consolidated balance sheets data as of December 31, 20142015 and 20152016 and the selected consolidated statements of comprehensive income data for the years ended December 31, 2013, 2014, 2015 and 20152016 are derived from our audited consolidated financial statements included elsewhere in this annual report. In accordance with the requirements of the Taiwan Financial Supervisory Commission, or FSC, beginning on January 1, 2013, we have adopted Taiwan-IFRSs, which is translated and published by Accounting Research and Development Foundation, or ARDF, referred to as “TIFRSs” for reporting our annual and interim consolidated financial statements in the R.O.C. At the same time, we have adopted IFRSs as issued by the IASB for our annual reports on Form20-F with the U.S. SEC beginning with the year ended December 31, 2013. However, since January 1, 2013, we only prepare our interim unaudited quarterly financial statements under TIFRSs, which are furnished to the SEC on Form6-K. The selected consolidated balance sheet data as of January 1, 2012, December 31, 2012, 2013 and 20132014 and the selected consolidated statements of comprehensive income data for the yearyears ended December 31, 2012 and 2013 are derived from our audited consolidated financial statements not included in this annual report.

In accordance with rule amendments adopted by the U.S. SEC for foreign private issuers reporting under IFRSs, we are not required to provide reconciliations to U.S. GAAP in this annual report following our adoption of IFRSs.

The selected financial data set forth below should be read in conjunction with “Item 5. Operating and Financial Review and Prospects” and our consolidated financial statements and the notes to those statements included in this annual report.

Currency Translations and Exchange Rates

In portions of this annual report, we have translated New Taiwan dollar amounts into U.S. dollars for the convenience of readers. The rate we used for the translations was NT$32.79 =32.40 to US$1.00, which was the noon buyingforeign exchange rate on December 30, 2016 as certified for customs purposesreleased by the Board of Governors of the Federal Reserve Bank of New York on December 31, 2015.System. The translation does not mean that New Taiwan dollars could actually be converted into U.S. dollars at that rate. The following table shows the noon buying rates for New Taiwan dollars expressed in New Taiwan dollar per US$1.00. On April 8, 2016,7, 2017, the noon buying rate was NT$32.4030.56 to US$1.00.

Source: Federal Reserve Statistical Release, the Board of Governors of the Federal Reserve System.

Not applicable.

Not applicable.

Our business and operations are subject to various risks, many of which are beyond our control. If any of the risks described below actually occurs, our business, financial condition or results of operations could be seriously harmed.

Risks Related to Our Business and Financial Condition

Any global systemic political, economic and financial crisis or catastrophic natural disasters (as well as the indirect effects flowing therefrom) could negatively affect our business, results of operations, and financial condition.

In recent times, several major systemic economic and financial crises and natural disasters negatively affected global business, banking and financial sectors, including the semiconductor industry and markets. These types of crises cause turmoil in global markets that often result in declines in electronic products sales from which we generate our income through our goods and services. In addition, these crises may cause a number of indirect effects such as undermining the ability of our customers to remain competitive when faced with the financial and economic challenges created by insolvent countries and companies still struggling to survive in the wake of these crises. For example, there could be in the futureknock-on effects from these types of crises on our business, including significant decreases in orders from our customers; insolvency of key suppliers resulting in product delays; inability of customers to obtain credit to finance purchases of our products; customer insolvencies; and counterparty failures negatively impacting our treasury operations. Any future systemic political, economic or financial crises or catastrophic natural disasters (as well as the indirect effects flowing from these crises or disasters) could cause revenues for the semiconductor industry as a whole to decline dramatically, and if the economic conditions or financial condition of our customers were to deteriorate, additional accounting related allowances may be required in the future and such additional allowances could increase our operating expenses and therefore reduce our operating income and net income. Thus, any future global economic crisis or catastrophic natural disaster (and their indirect effects) could materially and adversely affect our results of operations.

In 2009, we established a 100% owned subsidiary, UMC New Business Investment Corporation, or NBI, to focus on investments in the solar energy, and light emitting diodes, or LED, light source module design, epi wafer manufacturing, and packaging. In recent years, the growth of solar energy and LED industries is adversely affected by the on-going anti-subsidy and anti-dumping investigations from various regions, the combination of an increase in supply coupled with a decrease in the availability of government subsidies and the decrease in the price of international crude oil resulted in an excess of supply in the solar energy and LED industries and negative pressure on the pricing. As a result,Historically, we recognized impairment for our investments in thesesolar energy and LED industries made through our subsidiary, namely UMC New Business Investment Corporation, or NBI. If the solar energy and LED industries continue to encounter significant downturns or significant reductions of government subsidies, our investments made through NBI will be adversely affected which could adversely affect our results of operations.

The seasonality and cyclical nature of the semiconductor industry and periodic overcapacity make us particularly vulnerable to significant and sometimes prolonged economic downturns.

The semiconductor industry has historically been highly cyclical and, at various times, has experienced significant downturns. Since most of our customers operate in semiconductor-related industries, variations in order levels from our customers can result in volatility in our revenues and earnings. Because our business is, and will continue to be, largely dependent on the requirements of semiconductor companies for our services, downturns in the semiconductor industry will lead to reduced demand for our services.

Our net operating revenues are also typically affected by seasonal variations in market conditions that contribute to the fluctuations of the average selling price of semiconductor services and products. The seasonal sales trends for semiconductor services and products closely mirror those for consumer electronics, communication and computer sales. We generally experience seasonal lows in the demand for semiconductor services and products during the first half of the year, primarily as a result of inventory correction by our customers. Any change in the general seasonal variations, which we cannot anticipate, may result in materially adverse effects on our revenues, operations and businesses.

Our operating results fluctuate from quarter to quarter, which makes it difficult to predict our future performance.

Our revenues, expenses and results of operations have varied significantly in the past and may fluctuate significantly from quarter to quarter in the future due to a number of factors, many of which are beyond our control. Our business and operations have at times in the past been negatively affected by, and are expected to continue to be subject to the risk of the following factors:

Due to the factors noted above and other risks discussed in this section, many of which are beyond our control, you should not rely onquarter-to-quarter comparisons to predict our future performance. Unfavorable changes in any of the above factors may seriously harm our business, financial condition and results of operations. In addition, our operating results may be below the expectations of public market analysts and investors in some future periods. In this event, the price of the common shares or ADSs may underperform or fall.

A decrease in demand for or selling prices of communication devices, consumer electronics and computer goods may decrease the demand for our services and reduce our margins.

Our customers generally use the semiconductors produced in our fabs in a wide variety of applications. We derive a significant percentage of our operating revenues from customers who use our manufacturing services to make semiconductors for communication devices, consumer electronics, PCs and other computers. The semiconductor industry experienced several downturns due to recent major financial crises and natural disasters. These downturns resulted in a reduced demand for our services and hence decreased our revenues and earnings. Any significant decrease in the demand for communication devices, consumer electronics, PCs or other computers may further decrease the demand for our services. In addition, if the average selling price of communication devices, consumer electronics, PCs or other computers decline significantly, we will be pressured to further reduce our selling prices, which may reduce our revenues and, therefore, reduce our margins significantly. As demonstrated by downturns in demand for high technology products in the past, market conditions can change rapidly, without apparent warning or advance notice. In such instances, our customers will experience inventory buildup and/or difficulties in selling their products and, in turn, will reduce or cancel orders for wafers from us. The timing, severity and recovery of these downturns cannot be predicted accurately or at all. When they occur, our business, profitability and price of the common shares and ADSs are likely to suffer.

Overcapacity in the semiconductor industry may reduce our revenues, earnings and margins.

The prices that we can charge our customers for our services are significantly related to the overall worldwide supply of integrated circuits and semiconductor products. The overall supply of semiconductor products is based in part on the capacity of other companies, which is outside of our control. For example, in light of the current market conditions, some companies, including our largest competitors, have announced plans to increase capacity expenditures significantly. We believe such plans, if carried out as planned, will increase the industry-wide capacity and are likely to result in overcapacity in the future. In periods of overcapacity, if we are unable to offset the adverse effects of overcapacity through, among other things, our technology and product mix, we may have to lower the prices we charge our customers for our services and/or we may have to operate at significantly less than full capacity. Such actions could reduce our margin and weaken our financial condition and results of operations. We cannot give any assurance that an increase in the demand for foundry services in the future will not lead to overcapacity in the near future, which could materially adversely affect our revenues, earnings and margins.

Any problem in the semiconductor outsourcing infrastructure can adversely affect our net operating revenues and profitability.

Many of our customers depend on third parties to provide mask tooling, assembly and test services. If these customers cannot timely obtain these services on reasonable terms, they may not order any foundry services from us. This may significantly reduce our net operating revenues and negatively affect our profitability.

We may be unable to implement new technologies as they become available, which may result in the decrease of our profitability and the loss of customers and market share.

The semiconductor industry is developing rapidly and the related technology is constantly evolving. If we do not anticipate the technology evolution and rapidly adopt new and innovative technology, we may not be able to produce sufficiently advanced services at competitive prices. There is a risk that our competitors may adopt new technology before we do, resulting in our loss of market share. If we are unable to begin offering advanced services and processes on a competitive and timely basis, we may lose customers to our competitors providing similar technologies, which may cause our net operating revenues to decline unless we can replace lost customers with new customers. In addition, the market prices for advanced technology and services tend to fall over time. As a result, if we are unable to offer new advanced services and processes on a competitive and timely basis, we need to decrease the prices that we set for our existing services and processes, which would have a negative effect on our profitability. We also depend upon the introduction of new technologies on a timely basis in order to benefit from the relatively higher prices such new technologies offer in the earlier stages of their life cycles. If we are unable to introduce new technologies on a timely and competitive basis, we may not be able to benefit from the relatively higher prices for new technologies, and our average selling price and profits would decrease accordingly.

We may be unable to provide leading technology to our customers if we lose the support of our technology partners.

Enhancing our manufacturing process technologies is critical to our ability to provide services for our customers. We intend to continue to advance our process technologies through internal research and development and alliances with other companies. Although we have an internal research and development team focused on developing new and improved semiconductor manufacturing process technologies, we are also dependent on some of our technology partners to advance certain process technology portfolios. In addition, we currently have patent cross-licensing agreements with several companies, including International Business Machines Corporation, or IBM. Some mask and equipment vendors also supply our technology development teams with masks and equipment needed to develop more advanced processing technologies. If we are unable to continue any of our joint development arrangements, patent cross-licensing agreements and other agreements, on mutually beneficial economic terms, if were-evaluate the technological and economic benefits of such relationships, if we are unable to enter into new technology alliances and arrangements with other leading and specialty semiconductor companies, or if we fail to secure masks and equipment from our vendors in a timely manner sufficient to support our ongoing technology development, we may be unable to continue providing our customers with leading edge mass-producible process technologies and may, as a result, lose important customers, which would have a materially adverse effect on our businesses, results of operations and financial condition.

In addition, some of our customers rely upon third-party vendors, or intellectual property vendors, for the intellectual property they embed into their designs. Although we work and collaborate with intellectual property vendors with respect to such matters, there can be no guarantee that we will be successful or that the vendors will deliver according to our requirements or the needs of our customers. Failures to meet the targets or to deliver on a timely basis could cause customers to cancel orders and/or shift capacity to other suppliers.

Our business may suffer if we cannot compete successfully in our industry.

The worldwide semiconductor foundry industry is highly competitive. We compete with dedicated foundry service providers such as Taiwan Semiconductor Manufacturing Company Limited, Semiconductor Manufacturing International (Shanghai) Corporation and Globalfoundries Inc., as well as the foundry operation services of some integrated device manufacturers, such as IBM, Intel, Samsung Electronics, or Samsung, and Toshiba Corporation, or Toshiba. Integrated device manufacturers principally manufacture and sell their own proprietary semiconductor products, but may also offer foundry services. Other competitors such as DongbuAnam Semiconductor, Grace Semiconductor Manufacturing Corp.,X-FAB Semiconductors Foundries AG and Silterra Malaysia Sdn. Bhd. have initiated efforts to expand and develop substantial additional foundry capacity. New entrants and consolidations in the foundry business, such as the acquisition of Chartered Semiconductor by Globalfoundries in 2009, are likely to initiate a trend of competitive pricing and create potential overcapacity in legacy technology. Some of our competitors have greater access to capital and substantially greater production, research and development, marketing and other resources than we do. As a result, these companies may be able to compete more aggressively over a longer period of time than we can.

The principal elements of competition in the wafer foundry market include:

Our ability to compete successfully also depends on factors partially outside of our control, including product availability, intellectual property, including cell libraries that our customers embed in their product designs, and industry and general economic trends.

We may not be able to implement our planned growth if we are unable to obtain the financing necessary to fund the substantial capital expenditures we expect to incur.

Our business and the nature of our industry require us to make substantial capital expenditures leading to a high level of fixed costs. The costs of facilities, tools and equipment to make semiconductors with advanced technology continue to rise, with each generation typically significantly more expensive than thelarger-in-size more mature technologies which preceded. We expect to incur significant capital expenditures in connection with our growth plans. These capital expenditures will be made in advance of any additional sales to be generated by new or upgraded fabs as a result of these expenditures. Given the fixed-cost nature of our business, we have in the past incurred, and may in the future incur, operating losses if our revenues do not adequately offset our capital expenditures. Additionally, our actual expenditures may exceed our planned expenditures for a variety of reasons, including changes in:

We cannot assure you that additional financing will be available on satisfactory terms, if at all. If adequate funds are not available on satisfactory terms, we may be forced to curtail our expansion plans or delay the deployment of our services, which could result in a loss of customers and limit the growth of our business.

We depend on a small number of customers for a significant portion of our net operating revenues and any loss of these customers would result in significant declines in our net operating revenues.

We have been largely dependent on a small number of customers for a substantial portion of our business. In 2015,2016, our top ten customers accounted for 57.3%60.2% of our net operating revenues. We expect that we will continue to depend upon a relatively limited number of customers for a significant portion of our net operating revenues. We cannot assure you that our net operating revenues generated from these customers, individually or in the aggregate, will reach or exceed historical levels in any future period. Loss or cancellation of business from significant changes in scheduled deliveries to, or decreases in the prices of services sold to any of these customers could significantly reduce our net operating revenues.

Our customers generally do not place purchase orders far in advance, which makes it difficult for us to predict our future revenues, adjust production costs and allocate capacity efficiently on a timely basis. In addition, due to the cyclical nature of the semiconductor industry, our customers’ purchase orders have varied significantly from period to period. As a result, we do not typically operate with any significant backlog, except in periods of extreme capacity shortage such as that experienced in late 2009 and early 2010.shortage. The lack of significant backlog and the unpredictable length and timing of semiconductor cycles make it difficult for us to forecast our revenues in future periods. Moreover, our expense levels are based in part on our expectations of future revenues, and we may be unable to adjust costs in a timely manner to compensate for revenue shortfalls. We expect that in the future our net operating revenues in any quarter will continue to be substantially dependent upon purchase orders received in that quarter.

Moreover, the increasing trend in mergers and acquisitions activities in the semiconductor industry could decrease total available customer base, which could potentially result in a loss of customers.

Our inability to obtain, preserve and defend intellectual property rights could harm our competitive position.

Our ability to compete successfully and achieve future growth will depend, in part, on our ability to protect our proprietary technology and to secure critical processing technology that we do not own at commercially reasonable terms. We cannot assure you that in the future we will be able to independently develop, or secure from any third party, the technology required for upgrading our production facilities or for meeting our customer needs. Our failure to successfully obtain such technology may seriously harm our competitive position.

Our ability to compete successfully also depends on our ability to operate without infringing on the proprietary rights of others. We have no means of knowing what patent applications have been filed in the United States or in certain other countries until months after they are filed. The semiconductor industry, because of the complexity of the technology used and the multitude of patents, copyrights and other overlapping intellectual property rights, is characterized by frequent litigation regarding patent, trade secret and other intellectual property rights. It is common for patent owners to assert their patents against semiconductor manufacturers. We have received from time to time communications from third parties asserting patents that cover certain of our technologies and alleging infringement of intellectual property rights of others, and we expect to continue to receive such communications in the future. See “Item 4. Information on the Company—B. Business Overview—Litigation” for more details of our ongoing litigation. In the event any third party was to make a valid claim against us or against our customers, we could be required to:

Any one of these developments could place substantial financial and administrative burdens on us and hinder our business. Litigation, which could result in substantial expenses for us and diversion of our resources, may also be necessary to enforce our patents or other intellectual property rights or to defend us or our customers against claimed infringement of the rights of others. If we fail to obtain necessary licenses or if litigation relating to patent infringement or other intellectual property matters occurs, it could hurt our reputation as a technology leader in our industry and prevent us from manufacturing particular products or applying particular technologies, which could reduce opportunities to generate revenues.

Our operations and business will suffer if we lose one or more of our key personnel without adequate replacements.

Our future success to a large extent depends on the continued services of our Chairman and key executive officers. We do not carry key person insurance on any of our personnel. If we lose the services of any of our Chairman or key executive officers, it could be difficult to find and integrate replacement personnel in a short period of time, which could harm our operations and the growth of our business.

We may have difficulty attracting and retaining skilled employees, who are critical to our future success.

The success of our business depends upon attracting and retaining experienced executives, engineers and other employees to implement our strategy. The competition for skilled employees is intense. We expect demand for personnel in Taiwan to increase in the future as new wafer fabrication facilities and other businesses are established in Taiwan. We also expect demand for experienced personnel in other locations to increase significantly as our competitors establish and expand their operations. Some of our competitors are willing to offer better compensation than that we do to our executives, engineers and other employees. We do not have long-term employment contracts with any of our employees. If we were unable to retain our existing personnel or attract, assimilate and recruit new experienced personnel in the future, it could seriously disrupt our operations and delay or restrict the growth of our business.

Our transactions with affiliates and stockholders may hurt our profitability and competitive position.

We have provided foundry services to several of our affiliates and stockholders. We currently do not provide any preferential treatment to any of these affiliates and stockholders. However, we may in the future reserve or allocate our production capacity to these companies if there is a shortage of foundry services in the market to enable these companies to maintain their operations and/or to protect our investments in them. This reservation or allocation may reduce our capacity available for our other customers, which may damage our relationships with other customers and discourage them from using our services. This may hurt our profitability and competitive position.

If we fail to maintain an effective system of internal control over financial reporting, we may be unable to accurately report our financial results or prevent fraud, and investor confidence in our company may be adversely affected.

We are required to comply with the R.O.C and the U.S. securities laws and regulations in connection with internal controls. As a public company in the United States, our management is required to assess the effectiveness of our internal control over financial reporting using the criteria established in Internal Control-Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission (2013 framework), or the COSO criteria, as required by Section 404 of the Sarbanes-Oxley Act of 2002.

However, although effective internal controls can provide reasonable assurance with respect to the preparation and fair presentation of financial statements, they may not prevent or detect misstatements because of their inherent limitations, including the possibility of human error, the circumvention or overriding of controls, fraud or corruption. If we fail to maintain the adequacy of our internal controls, our business and operating results could be harmed, we could fail to meet our reporting obligations, and there could be a material adverse effect on the market price of our common shares and ADSs.

The trend of adopting protectionist measures in certain countries, including the United States, could have a material adverse impact on our results of operations and financial condition.

Governments in the United States, PRC and certain other countries have implemented fiscal and monetary programs to stimulate economic growth as a result of the recent economic downturn, and many of these programs include protectionist measures that encourage the use of domestic products and labor. Recent policy developments by the governments in China and elsewhere also suggest an increased unwillingness to allow international companies to invest in or acquire local businesses. Since many of our direct customers and other downstream customers in the supply chain are located in or have operations in the countries where protectionist measures were adopted, such protectionist measures may have a material adverse effect on demand for our manufacturing services.

Any future outbreak of contagious diseases may materially and adversely affect our business and operations, as well as our financial condition and results of operations.

Any future outbreak of contagious diseases, including but not limited to Zika virus, Ebola virus, avian or swine influenza or severe acute respiratory syndrome, may disrupt our ability to adequately staff our business and may generally disrupt our operations. If any of our employees is suspected of having contracted any contagious disease, we may under certain circumstances be required to quarantine such employees and the affected areas of our premises. Therefore, we may have to temporarily suspend part of or all of our operations. Furthermore, any future outbreak may restrict the level of economic activities in affected regions, including Taiwan, and affect the willingness and ability of our employees and customers to travel, which may also adversely affect our business and prospects. As a result, we cannot assure you that any future outbreak of contagious diseases would not have a material adverse effect on our financial condition and results of operations.

Currency fluctuations could increase our costs relative to our revenues, which could adversely affect our profitability.

More than half of our net operating revenues are denominated in currencies other than New Taiwan dollars, primarily in U.S. dollars. On the other hand, more than half of our costs of direct labor, raw materials and overhead are incurred in New Taiwan dollars. Although we hedge a portion of the resulting net foreign exchange position through the use of foreign exchange spot transactions, or currency forward contracts, we are still affected by fluctuations in foreign exchange rates among the U.S. dollar, the New Taiwan dollar and other currencies. Any significant fluctuation in exchange rates may impact on our financial condition and the U.S. dollar value of the ADSs and the U.S. dollar value of any cash dividends we distributed, which could have a corresponding effect on the market price of the ADSs.

Risks Relating to Manufacturing

Our manufacturing processes are highly complex, costly and potentially vulnerable to impurities and other disruptions that can significantly increase our costs and delay product shipments to our customers.

Our manufacturing processes are highly complex, require advanced and costly equipment and are continuously being modified to improve manufacturing yields and product performance. Impurities or other difficulties in the manufacturing process or defects with respect to equipment or supporting facilities can lower manufacturing yields, interrupt production or result in losses of products in process. As system complexity has increased and process technology has become more advanced, manufacturing tolerances have been reduced and requirements for precision have become even more demanding. Although we have been enhancing our manufacturing capabilities and efficiency, from time to time we have experienced production difficulties that have caused delivery delays and quality control problems, as is common in the semiconductor industry. In the past we have encountered the following problems:

Should these problems repeat, we may suffer delays in delivery and/or loss of business and revenues. In addition, we cannot guarantee that we will be able to increase our manufacturing capacity and efficiency in the future to the same extent as in the past.

Our profit margin may substantially decline if we are unable to continuously improve our manufacturing yields, maintain high capacity utilization and optimize the technology mix of our silicon wafer production.

Our ability to maintain our profitability depends, in part, on our ability to:

Our manufacturing yields directly affect our ability to attract and retain customers, as well as the price of our services. Our capacity utilization affects our operating results because a large percentage of our operating costs are fixed. Our technology mix affects utilization of our equipment and process technologies, as well as the prices we can charge, either of which can affect our margins. If we are unable to continuously improve our manufacturing yields, maintain high capacity utilization or optimize the technology mix of our wafer production, our profit margin may substantially decline.

We may have difficulty in ramping up production in accordance with our schedule, which could cause delays in product deliveries and decreases in manufacturing yields.

As is common in the semiconductor industry, we have from time to time experienced difficulties in ramping up production at new or existing facilities or effecting transitions to new manufacturing processes. As a result, we have suffered delays in product deliveries or reduced manufacturing yields. We may encounter similar difficulties in connection with:

We may face construction delays, interruptions, infrastructure failure and delays in upgrading or expanding existing facilities, or changing our process technologies, any of which might adversely affect our production schedule. Our failure to achieve our production schedule could delay the time required to recover our investments and seriously affect our profitability.

Our production schedules could be delayed and we may lose customers if we are unable to obtain raw materials and equipment in a timely manner.

We depend on our suppliers for raw materials. To maintain competitive manufacturing operations, we must obtain from our suppliers, in a timely manner, sufficient quantities of quality materials at acceptable prices. Although we source our raw materials from several suppliers, a small number of these suppliers account for a substantial amount of our supply of raw materials because of the consistent quality of their products. For example, in 2014, 2015 and 2015,2016, we purchased a majority of our silicon wafers from fivefour makers, Shin-Etsu Handotai Corporation, or Shin-Etsu, Siltronic AG, SunEdisonGlobalWafers Corporation, or GlobalWafers, and Sumco Group (including Sumco Corporation and Formosa Sumco Technology Corporation) and GlobalWafers.. We may have long-term contracts with most of our suppliers if necessary. From time to time, our suppliers have extended lead time or limited the supply of required materials to us because of capacity constraints. Consequently, from time to time, we have experienced difficulty in obtaining the quantities of raw materials we need on a timely basis.

In addition, from time to time we may reject materials that do not meet our specifications, resulting in declines in output or manufacturing yields. We cannot assure you that we will be able to obtain sufficient quantities of raw materials and other supplies in a timely manner. If the supply of materials is substantially diminished or if there are significant increases in the costs of raw materials, we may be forced to incur additional costs to acquire sufficient quantities of raw materials to sustain our operations, which may increase our marginal costs and reduce profitability.

We also depend on a limited number of manufacturers and vendors that make and maintain the complex equipment we use in our manufacturing processes. We also rely on these manufacturers and vendors to improve our technology to meet our customers’ demands as technology improves. In periods of unpredictable and highly diversified market demand, the lead time from order to delivery of this equipment can be as long as six to twelve months. If there are delays in the delivery of equipment or in the availability or performance of necessary maintenance, or if there are increases in the cost of equipment, it could cause us to delay our introduction of new manufacturing capacity or technologies and delay product deliveries, which may result in the loss of customers and revenues.

We may be subject to the risk of loss due to fire because the materials we use in our manufacturing processes are highly flammable.

We use highly flammable materials such as silane and hydrogen in our manufacturing processes and may therefore be subject to the risk of loss arising from fires. The risk of fire associated with these materials cannot be completely eliminated. We maintain insurance policies to reduce losses caused by fire, including business interruption insurance. While we believe that our insurance coverage for damage to our property and business interruption due to fire is consistent with semiconductor industry practice, our insurance coverage is subject to deductibles and self-insured retention and may not be sufficient to cover all of our potential losses. If any of our fabs were to be damaged or cease operations as a result of a fire, it would temporarily reduce manufacturing capacity and reduce revenues.

We and many of our customers and suppliers are vulnerable to natural disasters and other events outside of our control, which may seriously disrupt our operations.

Most of our assets and many of our customers and suppliers are located in certain parts of Taiwan. Our operations and the operations of our customers and suppliers are vulnerable to earthquakes, floods, droughts, power losses and similar events that affect the locations of our operations. The occurrence of any of these events could interrupt our services and cause severe damages to wafers in process, or cause significant business interruptions.disruptions. For example, in early 2016, we experienced a severe earthquake which adversely affected our wafer manufacturing operations at our 300mm Fab 12A in Taiwan. Although we maintain property damagehad adopted practices in compliance with ISO 22301 business continuity standards which ensured the safety of our employees and business interruptionminimized supply disruptions resulting from the earthquake and we had settled our insurance policies which partially recovered the losses resulting for such risks,this earthquake, there is no guarantee that our business continuity practices will always be effective and any future damages or business loss from earthquakessevere natural disasters will be covered by such insurance, that we will be able to collect from our insurance carriers, should we choose to claim under our insurance policies, or that such coverage will be sufficient. In addition, our manufacturing facilities have occasionally experienced insufficient power supplies, and our operations have been disrupted.

Our operations may be delayed or interrupted and our business could suffer if we violate environmental, safety and health, or ESH, regulations.

The semiconductor manufacturing process requires the use of various gases, chemicals, hazardous materials and other substances such as solvents and sulfuric acid which may have an impact on the environment. We are always subject to ESH regulations, and a failure to manage the use, storage, transportation, emission, discharge, recycling or disposal of raw materials or to comply with these ESH regulations could result in (i) regulatory penalties, fines and other legal liabilities, (ii) suspension of production or delays in operation and capacity expansion, (iii) a decrease in our sales, (iv) an increase in pollution cleaning fees and other operation costs, or (v) damage to our public image, any of which could harm our business. In addition, as ESH regulations are becoming more comprehensive and stringent, we may incur a greater amount of capital expenditures in technology innovation and materials substitution in order to comply with such regulations, which may adversely affect our results of operations.

Climate change may negatively affect our business.

There is increasing concern that climate change is occurring and may have dramatic effects on human activity without aggressive remediation steps. A modest change in temperature would result in increased coastal flooding, changing precipitation patterns and increasing risk of extinction for the world’s species. Public expectations for reductions in greenhouse gas emissions could result in increased energy, transportation and raw material costs.

Scientific examination of, political attention to and rules and regulations on issues surrounding the existence and extent of climate change may result in an increase in the cost of production due to increase in the prices of energy and introduction of energy or carbon tax. Various regulatory developments have been introduced that focus on restricting or managing emissions of carbon dioxide, methane and other greenhouse gases. Enterprises may need to purchase at higher costs emission credits, new equipment or raw materials with lower carbon footprints. These developments and further legislation that is likely to be enacted could affect our operations negatively. Changes in environmental regulations, such those on the use of perfluorinated compounds, could increase our production costs, which could adversely affect our results of operation and financial condition.

In addition, more frequent droughts and floods, extreme weather conditions and rising sea levels could occur due to climate change. The impact of such changes could be significant as most of our factories are located in islands including Taiwan, Singapore and Xiamen in Fujian Province in China. For example, transportation suspension caused by extreme weather conditions could harm the distribution of our products. Similarly, our operations depend upon adequate supplies of water, and extended or serious droughts may affect our ability to obtain adequate supplies of water and threaten our production. We cannot predict the economic impact, if any, of disasters or climate change.

Disruptions in the international trading environment may seriously decrease our international sales.

A substantial portion of our net operating revenues is derived from sales to customers located in countries other than the countries where our fabs are located. In 2013, we operated fabs in Taiwan, Singapore, Japan2014, 2015 and China. In 2014 and 2015,2016, we operated fabs in Taiwan, Singapore and China. For the years ended December 31, 2013, 2014, 2015 and 2015,2016, we generated approximately 30.1%42.6%, 42.6%47.5% and 47.5%41.2% of our net operating revenues, respectively, from other than the countries where our fabs are located. We expect sales to customers from countries outside of Taiwan, Singapore and China will continue to represent a significant portion of our net operating revenues. The success and profitability of our international activities depend on certain factors beyond our control, such as general economic conditions, labor conditions, political stability, tax laws, import duties and foreign exchange controls of the countries in which we sell our products, and the political and economic relationships between these countries. As a result, our manufacturing services will continue to be vulnerable to disruptions in the international trading environment, including adverse changes in foreign government regulations, political unrest and international economic downturns.

These disruptions in the international trading environment affect the demand for our manufacturing services and change the terms upon which we provide our manufacturing services overseas, which could seriously decrease our international sales.

Political, Economic and Regulatory Risks

We face substantial political risks associated with doing business in Taiwan, particularly due to the tense relationship between the R.O.C. and the People’s Republic of China, or the PRC, that could negatively affect the value of your investment.

Our principal executive offices and most of our assets and operations are located in Taiwan. Accordingly, our business, financial condition and results of operations and the market price of our common shares and the ADSs may be affected by changes in R.O.C. governmental policies, taxation, inflation or interest rates and by social instability and diplomatic and social developments in or affecting Taiwan which are outside of our control. Taiwan has a unique international political status. Since 1949, Taiwan and the Chinese mainland have been separately governed. The PRC claims that it is the sole government in China and that Taiwan is part of China. Although significant economic and cultural relations have been established between the R.O.C. and the PRC in the past few years, such as the adoption of the Economic Cooperation Framework Agreement and memorandum regarding cross-strait financial supervision, we cannot assure you that relations between the R.O.C. and PRC will not become strained again. For example, the PRC government has refused to renounce the use of military force to gain control over Taiwan and, in March 2005, passed an Anti-Secession Law that authorizednon-peaceful means and other necessary measures should Taiwan move to gain independence from the PRC. Past developments in relations between the R.O.C. and the PRC have on occasions depressed the market prices of the securities of companies in the R.O.C. Such initiatives and actions are commonly viewed as having a detrimental effect to reunification efforts between the R.O.C. and the PRC. Relations between the R.O.C. and the PRC and other factors affecting military, political or economic conditions in Taiwan could materially and adversely affect our financial condition and results of operations, as well as the market price and the liquidity of our securities.

Our business depends on the support of the R.O.C. government, and a decrease in this support may increase our labor costs and decrease our income after tax.

The R.O.C. government has been very supportive of technology companies. For instance, the R.O.C.’s labor laws and regulations permit employees of semiconductor companies to work shifts of 10 hours each day on a two-days-on, two-days-off basis and do not require these employees to be unionized. We cannot assure you, however, that these labor laws and regulations will not be changed adversely against us in the future.

We, like many R.O.C. technology companies, have benefited from substantial tax incentives provided by the R.O.C. government. Among the incentives broadly enjoyed by R.O.C. technology companies, various tax benefits granted under Chapter 2 and Article70-1 of the Statute for Upgrading Industries expired on December 31, 2009. Despite the fact that we can still enjoy the tax holidays for the relevant investment plans approved by R.O.C. tax authority until 2020 under the grandfather clause of the Statute for Upgrading Industries, if more incentives are curtailed or eliminated, our net income may decrease significantly.

Our future tax obligations may adversely affect our profitability.

The R.O.C. government enacted the R.O.C. Income Basic Tax Act, also known as the “Alternative Minimum Tax Act”, or the AMT Act, which became effective on January 1, 2006 to impose an alternative minimum tax and to remedy the currently excessive tax incentives for individuals and businesses. Alternative minimum tax, or AMT, is a supplemental tax which is payable if the income tax payable pursuant to the R.O.C. Income Tax Act is below the minimum amount prescribed under the AMT Act. For the purpose of calculating the AMT, the taxable income defined under the AMT Act includes most income that is exempted from income tax under various legislations, such as those providing tax holidays and investment tax credits.

For businesses, the income that previously enjoyedtax-exemption privileges under relevant tax regulations, such as Act for the Establishment and Administration of the Science Parks and Statute for Upgrading Industries, will be subject to the AMT system for the calculation of business taxpayers’ aggregate incomes. The AMT rate for business entities was 10% prior to 2013 and has increased to 12% since 2013. Under the AMT Act, a company will be subject to a 12% AMT if its annual taxable income under the Statute exceeds NT$0.5 million. However, the AMT Act grandfathered certain tax exemptions granted prior to the enactment of the AMT. For example, businesses who already qualified for five-year tax holidays and obtained the applicable permission issued by the competent authority before December 31, 2005 may continue to enjoy such tax incentives, and the income exempted thereunder will not to be added to the taxable income for calculating the AMT, so long as the construction of their investment projects breaks ground within one year from January 1, 2006 and was completed within three years from the day immediately following their receipts of the applicable permission issued by the competent authority. As the tax exemption periods expire or in the event of an increase in other taxable income subject to the AMT Act, it may adversely impact our net income after tax.

Compliance with laws such as the U.S. Conflict Minerals Law may affect our ability or the ability of our suppliers to purchase raw materials at an effective cost.

Many industries rely on materials which are subject to regulations concerning certain minerals sourced from the Democratic Republic of Congo, or the DRC, or adjoining countries, including: Sudan; Uganda; Rwanda; Burundi; United Republic of Tanzania; Zambia; Angola; Congo; and Central African Republic. These minerals are commonly referred to as conflict minerals. Conflict minerals which may be used in our industry or by our suppliers include Columbite-tantalite (derivative of tantalum [Ta]), Cassiterite (derivative of tin [Sn]), gold [Au], Wolframite (derivative of tungsten [W]), and Cobalt [Co]. Under present U.S. regulations, we and our customers are required to survey and disclose whether our processes or products use or rely on conflict materials. On August 22, 2012, the U.S. SEC adopted the final rule for disclosing the use of conflict minerals that require companies similar to us to make a report in a type and format similar to Form SD to disclose the use of conflict materials on an annual basis on or prior to May 31 each year. Our firstWe have filed the conflict mineral disclosure report was filed on May 31,every year since 2014. In order to comply with the aforementioned rules and regulations promulgated by the U.S. SEC, we will continue to verify the relevant information with our vendors and file the required report. Although we expect that we and our vendors will be able to comply with the requirements of the U.S. Conflict Minerals law and any new related regulations promulgated by the U.S. SEC, we cannot assure you that we will be able to gather all the information required to comply with such regulations. While we believe our suppliers do not rely on such conflict materials, we cannot assure you that we will continue to be able to obtain adequate supplies of materials needed in our production from supply chains outside the DRC and adjoining countries. The failure to obtain necessary information or to maintain adequate supplies of materials from supply chains outside the DRC and adjoining countries may delay our production, increasing the risk of losing customers and business.

Similarly, many jurisdictions have promulgated regulations with the intention to deter disregard and contempt for human rights within supply chains. Although our own operations comply with the relevant requirements under the laws of the jurisdictions where we have operations, possible violation by our suppliers may not be known to us and beyond our control. While we believe our suppliers comply with applicable human rights requirements, there can be no guarantee that they will continue to do so, or that we will be able to obtain the necessary information on their activities to comply with whatever future requirements may be enacted.

Data security and data privacy considerations and regulations may adversely affect our operations.

Our operations depend upon reliable and uninterrupted information technology services, including the integrity of ourweb-based and electronic customer service systems. Although we have put in place what we believe are reasonable precautions to prevent accidental and/or malicious disruption of these services, there can be no assurance that our preventive measures will preclude failure of the information technology,web-based and electronic customer service systems upon which our business depends. Disruption of these systems could adversely affect our ability to manufacture and to serve our customers.

In addition, in the course of our operations, we receive confidential information from and about our customers, vendors, partners and employees. Although we take what we believe are reasonable precautions to protect such information from disclosure to or interruption, there are no guarantees our precautions will prevent accidental or malicious access to such information. In the event of such access, our reputation could be adversely affected, customers and others may hesitate to entrust us with their confidential information, which would negatively affect our operations, and we would incur costs to remedy the breach.

Moreover, many jurisdictions have proposed regulations concerning data privacy. Although we have taken measures to comply with existing law and regulations in this regard, future laws may impose requirements that make our operations more expensive and/or less efficient. In addition, should we experience a breakdown in our systems or failure in our precautions that results in a violation of such regulations, we may suffer adverse customer reaction and face governmental penalties.

Risks Related to the Common Shares and ADSs and Our Trading Markets

Restrictions on the ability to deposit common shares into our ADS program may adversely affect the liquidity and price of the ADSs.

The ability to deposit common shares into our ADS program is restricted by R.O.C. law. Under current R.O.C. law, no person or entity, including you and us, may deposit common shares into our ADS program without specific approval of the R.O.C. FSC except for the deposit of the common shares into our ADS program and for the issuance of additional ADSs in connection with:

As a result of the limited ability to deposit common shares into our ADS program, the prevailing market price of our ADSs on the NYSE may differ from the prevailing market price of the equivalent number of our common shares on the Taiwan Stock Exchange.

Holders of our ADSs will not have the same proposal or voting rights as the holders of our common shares, which may affect the value of your investment.

Except for treasury common shares and common shares held by our subsidiaries which meet certain criteria provided under the R.O.C. Company Act, each common share is generally entitled to one vote and no voting discount will be applied. However, except as described in this annual report and in the deposit agreement, holders of our ADSs will not be able to exercise voting rights attached to the common shares evidenced by our ADSs on an individual basis. Holders of our ADSs will appoint the depositary or its nominee as their representative to exercise the voting rights attached to the common shares represented by the ADSs. The voting rights attached to the common shares evidenced by our ADSs must be exercised as to all matters brought to a vote of stockholders collectively in the same manner.

Moreover, holders of the ADSs do not have individual rights to propose any matter for stockholders’ votes at our stockholders’ meetings. However, holders of at least 51% of the ADS outstanding at the relevant record date may request the depositary to submit to us one proposal per year for consideration at our annual ordinary stockholders’ meeting, provided that such proposal meets certain submission criteria and limitations, including the language and the length of the proposal, the time of submission, the required certification or undertakings, and the attendance at the annual ordinary stockholders’ meeting. A qualified proposal so submitted by the depositary will still be subject to review by our board of directors and there is no assurance that the proposal will be accepted by our board of directors for inclusion in the agenda of our annual ordinary stockholders’ meeting. Furthermore, if we determine, at our discretion, that the proposal submitted by the depositary does not qualify, we have no obligation to notify the depositary or to allow the depositary to modify such proposal.

Furthermore, if holders of at least 51% of the ADSs outstanding at the relevant record date instruct the depositary to vote in the same manner regarding a resolution, including election of directors, the depositary will appoint our Chairman, or his designee, to represent the ADS holders at the stockholders’ meetings and to vote the common shares represented by the ADSs outstanding in the manner so instructed. If by the relevant record date the depositary has not received instructions from holders of ADSs holding at least 51% of the ADSs to vote in the same manner for any resolution, then the holders will be deemed to have instructed the depositary to authorize and appoint our Chairman, or his designee, to vote all the common shares represented by ADSs at his sole discretion, which may not be in your interest.

The rights of holders of our ADSs to participate in our rights offerings may be limited, which may cause dilution to their holdings.

We may from time to time distribute rights to our stockholders, including rights to acquire our securities. Under the deposit agreement, the depositary will not offer those rights to ADS holders unless both the rights and the underlying securities to be distributed to ADS holders are either registered under the Securities Act or exempt from registration under the Securities Act. We are under no obligation to file a registration statement with respect to any such rights or underlying securities or to endeavor to cause such a registration statement to be declared effective. Accordingly, holders of our ADSs may be unable to participate in our rights offerings and may experience dilution in their holdings.

Changes in exchange controls that restrict your ability to convert proceeds received from your ownership of ADSs may have an adverse effect on the value of your investment.

Your ability to convert proceeds received from your ownership of ADSs depends on existing and future exchange control regulations of the Republic of China. Under the current laws of the Republic of China, an ADS holder or the depositary, without obtaining further approvals from the R.O.C. Central Bank of China, or the CBC, or any other governmental authority or agency of the Republic of China, may convert NT dollars into other currencies, including U.S. dollars, in respect of:

In addition, the depositary may also convert into NT dollars incoming payments for purchases of common shares for deposit in the depositary receipt facility against the creation of additional ADSs. If you withdraw the common shares underlying your ADSs and become a holder of our common shares, you may convert into NT dollars subscription payments for rights offerings. The depositary may be required to obtain foreign exchange approval from the CBC on apayment-by-payment basis for conversion from NT dollars into foreign currencies of the proceeds from the sale of subscription rights of new common shares. Although it is expected that the CBC will grant approval as a routine matter, required approvals may not be obtained in a timely manner, or at all.

Under the Republic of China Foreign Exchange Control Law, the Executive Yuan of the Republic of China may, without prior notice but subject to subsequent legislative approval, impose foreign exchange controls or other restrictions in the event of, among other things, a material change in international economic conditions.

Our public stockholders may have more difficulty protecting their interests than they would as stockholders of a U.S. corporation.

Our corporate affairs are governed by our articles of incorporation and bylaws governing R.O.C. corporations. The rights of our stockholders to bring stockholders’ suits against us or our board of directors under R.O.C. law are much more limited than those of the stockholders of U.S. corporations. Therefore, our public stockholders may have more difficulty protecting their interests in connection with actions taken by our management, members of our board of directors or controlling stockholders than they would as stockholders of a U.S. corporation. Please refer to “Item 10. Additional Information—B. Memorandum and Articles of Association—Rights to Bring Stockholders’ Suits” included elsewhere in this annual report for a detailed discussion of the rights of our stockholders to bring legal actions against us or our directors under R.O.C. law.

Holders of our ADSs will be required to appoint several local agents in Taiwan if they withdraw common shares from our ADS program and become our stockholders, which may make ownership burdensome.

Non-R.O.C. persons wishing to withdraw common shares represented by their ADSs from our ADS program and hold our common shares represented by those ADSs are required to, among other things, appoint a local agent or representative with qualifications set forth by the applicable R.O.C. laws and regulations to open a securities trading account with a local brokerage firm, pay R.O.C. taxes, remit funds and exercise stockholders’ rights. In addition, the withdrawing holders are also required to appoint a custodian bank or a securities firm with qualifications set forth by the R.O.C. FSC to hold the securities in safekeeping, make confirmations, settle trades and report all relevant information, in which the securities firm is appointed as the custodian, the payments shall be held in safekeeping in a special account opened in a bank approved by the R.O.C. FSC. Without making this appointment and opening of the accounts, the withdrawing holders would not be able to subsequently sell our common shares withdrawn from a depositary receipt facility on the Taiwan Stock Exchange. Under R.O.C. law and regulations, except under limited circumstances, PRC persons are not permitted to withdraw the common shares underlying the ADSs or to register as a stockholder of our company. Under the Regulations Governing Securities Investment and Futures Trading in Taiwan by Mainland Area Investors promulgated by the R.O.C. Executive Yuan on April 30, 2009, as amended, only qualified domestic institutional investors, or QDIIs and limited entities or individuals, are permitted to withdraw the common shares underlying the ADSs, subject to compliance with the withdrawal relevant requirements, and only QDIIs, and limited entities or individuals who meet the qualification requirements set forth therein are permitted to own common shares of an R.O.C. company listed for trading on the Taiwan Stock Exchange or the Taipei Exchange, provided that among other restrictions generally applicable to investments made by PRC persons, their shareholdings are subject to certain restrictions as set forth in the abovementioned regulations and that such mainland area investors shall apply for a separate approval if their investment, individually or in aggregate, amounts to or exceeds 10 percent of the common shares of any R.O.C. listing company.

You may not be able to enforce a judgment of a foreign court in the R.O.C.

We are a company limited by shares incorporated under the R.O.C. Company Act. Most of our assets and most of our directors, executive officers and experts named in the registration statement are located in Taiwan. As a result, it may be difficult for you to enforce judgments obtained outside Taiwan upon us or such persons in Taiwan. We have been advised by our R.O.C. counsel that any judgment obtained against us in any court outside the R.O.C. arising out of or relating to the ADSs will not be enforced by R.O.C. courts if any of the following situations shall apply to such final judgment:

We may be considered a passive foreign investment company, which could result in adverse U.S. federal income tax consequences for U.S. investors.

We do not believe that we were a passive foreign investment company, or PFIC, for 20152016 and we do not expect to become one in the future, although there can be no assurance in this regard. Based upon the nature of our business activities, we may be classified as a PFIC for U.S. federal income tax purposes. Such characterization could result in adverse U.S. federal income tax consequences to you if you are a U.S. investor.

For example, if we are a PFIC, our U.S. investors may become subject to increased tax liabilities under U.S. federal income tax laws and regulations and will become subject to burdensome reporting requirements. The determination of whether or not we are a PFIC is made on an annual basis and will depend on the composition of our income and assets from time to time. Specifically, for any taxable year we will be classified as a PFIC for U.S. federal income tax purposes if either (i) 75% or more of our gross income in a taxable year is passive income or (ii) the average percentage of our assets (which includes cash) by value in a taxable year which produce or are held for the production of passive income is at least 50%. The calculation of the value of our assets will be based, in part, on the quarterly market value of common shares and ADSs, which is subject to change. In addition, the composition of our income and assets will be affected by how, and how quickly, we spend the cash we have raised in prior offerings. See “Taxation—U.S. Federal Income Tax Considerations For U.S. Persons—Passive Foreign Investment Company.”

The trading price of the common shares and ADSs may be adversely affected by the general activities of the Taiwan Stock Exchange and U.S. stock exchanges, the trading price of our common shares, increases in interest rates and the economic performance of Taiwan.

Our common shares are listed on the Taiwan Stock Exchange. The trading price of our ADSs may be affected by the trading price of our common shares on the Taiwan Stock Exchange and the economic performance of Taiwan. The Taiwan Stock Exchange is smaller and, as a market, more volatile than the securities markets in the United States and some European countries. The Taiwan Stock Exchange has experienced substantial fluctuations in the prices and volumes of sales of listed securities, and there are currently limits on the range of daily price movements on the Taiwan Stock Exchange. The Taiwan Stock Exchange is particularly volatile during times of political instability, such as when the relationship between Taiwan and the PRC becomes tense. Moreover, the Taiwan Stock Exchange has experienced disturbance caused by market manipulation, insider trading and payment defaults, and the government of Taiwan has from time to time intervened in the stock market by purchasing stocks listed on the Taiwan Stock Exchange. The recurrence of these or similar events could deteriorate the price and liquidity of our common shares and ADSs.

The market price of the ADSs may also be affected by general trading activities on the U.S. stock exchanges, which recently have experienced significant volatility with respect to trading prices of technology companies. Fluctuation in interest rates and other general economic conditions may also influence the market price of the ADSs.

Our legal and commercial name is United Microelectronics Corporation, commonly known as “UMC”. We were incorporated under the R.O.C. Company Law as a company limited by shares in May 1980 and our common shares were listed on the Taiwan Stock Exchange in 1985. Our principal executive office is located at No. 3Li-Hsin Road II, Hsinchu Science Park, Hsinchu, Taiwan, Republic of China, and our telephone number is886-3-578-2258. Our Internet website address is www.umc.com.www.umc.com. The information on our website does not form part of this annual report. Our ADSs have been listed on the NYSE under the symbol “UMC” since September 19, 2000.

We are one of the world’s largest independent semiconductor foundries and a leader in semiconductor manufacturing process technologies. Our primary business is the manufacture, or “fabrication”, of semiconductors, sometimes called “chips” or “integrated circuits”, for others. Using our own proprietary processes and techniques, we make chips to the design specifications of our many customers. Our company maintains a diversified customer base across industries, including communication devices, consumer electronics, computer, and others, while continuing to focus on manufacturing for high growth, large volume applications, including networking, telecommunications, internet, multimedia, PCs and graphics. We sell and market mainly wafers which in turn are used in a number of different applications by our customers. Percentages of our gross wafer sales derived from our products used in communication devices, consumer electronics, computer and other applications were 54.3%53.0%, 27.6%27.2%, 11.9%12.6% and 6.2%7.2%, respectively, in 2015.2016.

We focus on the development of leading mass-producible manufacturing process technologies. We were among the first in the foundry industry to go into commercial operation with such advanced capabilities as producing integrated circuits with line widths of 0.25, 0.18, 0.15, 0.13 micron and 90, 65,65/55, 45/40, 28, 14 nanometer and 10 nanometer.beyond. Advanced technologies have enabled electronic products, especially in relation to communication, consumer and computer products, to integrate their functions in new and innovative methods. Networking capabilities have allowed electronic products such as computers, tablets, cell phones, televisions, PDAs, CD-ROMsset-top boxes and digital cameraswearable devices to communicate with each other to exchange information. More powerful semiconductors are required to drive multimedia functions (e.g., processing visual data) and to resolve network bandwidth issues. At the same time, the trend toward personal electronic devices has resulted in products that are becoming physically smaller and consume less power. Process technology must also shrink the volumes of products aggressively to cater to this trend of integrating multiple functions, reducing the size of components needed for operation and lowering IC power consumption. Dedicated semiconductor foundries need to achieve this process improvement and at the same time develop multiple process technologies to satisfy the varying needs of communication, consumer and computer products. We believe our superior process technologies will enable us to continue to offer our customers significant performance benefits for their products, fastertime-to-market production, cost savings and other competitive advantages.

We provide high quality service based on our performance. In today’s marketplace, we believe it is important to make available not only the most manufacturable processes, but also the best solutions to enable customers to design integrated circuits that include entire systems on a chip. Through these efforts, we intend to be the foundry solution for SoC customer needs. To achieve this goal, we believe it is necessary to timely develop and offer the intellectual property and design support that customers need to ensure their specific design blocks work with the other design blocks of the integrated circuit system in the manner intended. Accordingly, we have a dedicated intellectual property and design support team which focuses on timely development of the intellectual property and process specific design blocks our customers need in order to develop products that operate and perform as intended. Our design service team actively cooperates with our customers and vendors of cell libraries and intellectual property offerings to identify, early in the product/market cycle, the offerings needed to ensure that these coordinated offerings are available to our customers in silicon verified form in a streamlined andeasy-to-use manner. As a result, we are able to ensure the timely delivery of service offerings from the earliest time in the customer design cycle, resulting in a shortertime-to-volume production. We also provide our customers with real-time online access to their confidential production data, resulting in superior communication and efficiency. We further address our customers’ needs using our advanced technology and proven methodology to achieve fast cycle time, high yield, production flexibility and close customer communication. For example, we select and configure our clean rooms and equipment and develop our processes to maximize the flexibility in meeting and adapting to rapidly changing customer and industry needs. As a result, our cycle time, or the period from customer order to wafer delivery, and our responsiveness to customer request changes are among the fastest in the dedicated foundry industry. We also provide high quality service and engineering infrastructure.

Our production capacity is comparable to that of certain largest companies in the semiconductor industry, and we believe our leading edge and high volume capability is a major competitive advantage.

Our technology and service have attracted two principal types of foundry industry customers: fabless design companies and integrated device manufacturers. Fabless design companies design, develop and distribute proprietary semiconductor products but do not maintain internal manufacturing capacity. Instead, these companies depend on outside manufacturing sources. Integrated device manufacturers, in contrast, traditionally have integrated internally all functions—manufacturing as well as design, development, sales and distribution.

Our primary customers, in terms of our sales revenues, include premier integrated device manufacturers, such as Texas Instruments, Intel Mobile and STMicroelectronics, and leading fabless design companies, such as Xilinx, Broadcom, MediaTek, Realtek, Qualcomm and Novatek. In 2015,2016, our company’s top ten customers accounted for 57.3%60.2% of our net operating revenues. We believe our success in attracting these customers is a direct result of our commitment to high quality service and our intense focus on customer needs and performance.

In addition to our semiconductor foundry business, we also established UMC New Business Investment Corporation to focus on investments in the solar energy and LED industries.

On March 16, 2011, our board of directors proposed an offer to the stockholders of Best Elite International Limited, a British Virgin Islands corporation, or Best Elite, to acquire up to an additional 30% equity interest of Best Elite. Hejian Technology (Suzhou) Co., Ltd., or Hejian, is a wholly owned subsidiary of Infoshine Technology Limited, or Infoshine, which is a wholly owned subsidiary of Best Elite. Hejian engages in the semiconductor foundry business and owns an8-inch fab in Suzhou, China. We received approval from the Investment Commission, Ministry of Economic Affairs, Executive Yuan on November 1, 2011, and as of December 31, 2012, we held a 35.03% equity stake in Best Elite, which included the 15.34% equity stake held by the trustee that was originally offered to us in March 2005, plus an additional 19.69% equity stake that was purchased from shareholders pursuant to the March 2011 offer. As part of our global expansion strategy, we have continued to integrate and increase our ownership of Best Elite since. As of March 31, 2016,2017, our cumulative ownership in Best Elite was approximately 91.08%96.32%. We intend to acquire the remaining outstanding shares in Best Elite for Hejian to become our wholly beneficially owned subsidiary.

We and Alpha Wisdom Limited, or AWL, together held 94.79% of issued and outstanding share capital of UMC Japan, or UMCJ, as of December 31, 2009 and UMCJ then delisted from the Jasdaq Securities Exchange in accordance with its listing rules on March 19, 2010. Since not all of the outstanding equity securities of UMCJ were acquired, we initiated certainsqueeze-out procedures as provided in the Japanese Companies Act. Pursuant to such procedures, as of the end of 2010, we, together with AWL, owned 100% of UMCJ. On May 19, 2011, we acquired the remaining outstanding equity securities of UMCJ from AWL, and AWL filed for liquidation on August 30, 2011.

On August 21, 2012, our board of directors approved the dissolution and liquidation of UMCJ. We decided to close our foundry operations in Japan to focus on our manufacturing facilities in Taiwan and Singapore and reduce operating expenses. On November 28, 2013, we sold all our equity securities of UMCJ to Mach Semiconductor Co., Ltd., and, to continuously serve our Japanese customers, we established UMC Group Japan as our new regional sales hub.

On August 29, 2014, we and Fujitsu Semiconductor Limited, or Fujitsu, announced an agreement where we invested ¥5 billion as an initial investment and received approximately 9.3% of the issued and outstanding share capital to became a minority shareholder of a newly formed subsidiary of Fujitsu named Mie Fujitsu Semiconductor Limited, or MIFS, which will operate a 300mm wafer manufacturing facility located in Kuwana, Mie, Japan. On December 16, 2015, our board has further approved the acquisition of additional newly issued shares of MIFS with an aggregate investment amount of NT$1.36 billion, which increased our ownership interest in MIFS to approximately 15.9%. Through this relationship with us, MIFS will targetplans to expand its business globally as a pure-play foundry company by strengthening its production and development capacity in a cost competitive manner.

On October 9, 2014, our board of directors approved an agreement with the Xiamen Municipal People’s Government and Fujian Electronics & Information Group to found a new company named United Semiconductor (Xiamen) Co., Ltd., or USC, based in Xiamen, Fujian Province, China that will focus on12-inch wafer foundry services. We anticipate that we may invest up to US$1.35 billion in USC over the next five years, with our investment starting in 2015 that will be deployed in installments based on the progress of this company. USC will manufacture12-inch wafers and initially offer 40 nanometer and 55 nanometer process technologies. Our participation in USC has complied and will continue to comply with R.O.C. rules and regulations and will continue to be subject to the review and approval by the relevant R.O.C. authorities. We have obtained the initial investment approval from the R.O.C. government on December 31, 2014.2014 with US$300 million invested by Hejian and US$450 million by UMC. The initial groundbreaking event of USC took place in March 2015. Moreover, Hejian has committed an additional cash investment2015 and the grand opening ceremony took place in November 2016. USC in 2016.had successfully realized commercial mass production by the end of 2016 after a pilot production stage. We expect this investment project to mitigate geographical riskscontinue to expand our worldwide foundry presence by tapping into the high growth semiconductor market in China, and to increase our exposure to the semiconductor supply chain in China while mitigating geographical risks, which allows us to be closer to our customers in China, which, in turn, enables us to provide better services, increaseincreases our manufacturing scale and stimulatestimulates revenue growth.

On December 24, 2014, we transferred our6-inch fabrication plant, or Fab 6A, including machinery equipment and building facilities to our subsidiary, Wavetek Microelectronics Corporation, or Wavetek, in order to further satisfy customer needs in the fast growing GaAs market and to improve the6-inch fabrication operational efficiency among our group by fully utilizing the existing assets and resources. In April 2015, Wavetek had successfully entered into the silicon-based CMOS foundry business after it had fully acquired our6-inch Fab 6A fixed assets and production lines. As of March 31, 2016,2017, our shareholdings in Wavetek was approximately 78.5%78.47%, making us its largest shareholder.

On December 26, 2014, our subsidiary, Topcell Solar International Co., Ltd., or Topcell, announced its plans to merge with Motech Industries, Inc., or Motech, through a share exchange transaction. The share exchange conversion was six ordinary shares of Topcell into one newly-issued ordinary share of Motech. The merger was completed in June 2015 and Motech became the surviving company while Topcell Solar was absorbed. Upon completion of the merger, our share ownership of Motech was approximately 8.8% of its total issued and outstanding share capital, which made us the second largest shareholder of Motech.

On April 1, 2015, our subsidiary, Wavetek, completed the merger with Epitron Technology Inc., a Taiwan based GaAs wafer manufacturer. The merger is expected to achieve better operational efficiency that will in turn enhance our competitiveness in the GaAs foundry industry.

Please refer to “Item 5. Operating and Financial Review andProspects-B. Liquidity and Capital Resources” for a discussion of our capital expenditures in the past three years and the plan for the current year.

Our Strategy

To maintain and enhance our position as a market leader, we have adopted a business strategy with a focus on a partnership business model designed to accommodate our customers’ business needs and objectives and to promote their interests as our partners. We believe that our success and profitability are inseparable from the success of our customers. The goal in this business model is to create a network of partnerships or alliances among integrated device manufacturers, intellectual property and design houses, as well as foundry companies. We believe that we and our partners will benefit from the synergy generated through such long-term partnerships or alliances and the added value to be shared among the partners. The key elements of our strategy are:

Operate as a Customer-Driven Foundry. We plan to operate as a customer-driven foundry. The increasing complexity of 40 nanometer, 28 nanometer, and more advanced technologies has impacted the entire chip industry, as ICs can now be designed with greater gate density and higher performance while incorporating the functions of an entire system. These advanced designs have created a new proliferating market of advanced digital devices such as smart phones, which have decreased in size but greatly increased in functionality. We collaborate closely with our customers as well as partners throughout the entire supply chain, including equipment, electronic design automation tool and intellectual property vendors to work synergistically toward each customer’s SoC solution. We also possess experience andknow-how in system design and architecture to integrate customer designs with advanced process technologies and intellectual property. We believe the result is a higher rate of first-pass silicon success for our SoC solutions. Our customer-driven foundry solutions begin with a common logic-based platform, where designers can choose the process technologies and transistor options that best fit their specific application. From there, technologies such as radio frequency complementary metal-oxide-semiconductor, or RF CMOS, and embedded Flash memories can be used to further fine-tune the process for customers’ individual needs. Furthermore, as intellectual property has become critical resources for SoCs, our portfolio includes basic design building blocks as well as more complex intellectual property of optimized portability and cost, developed both internally and by third-party partners. With advanced technology, a broad intellectual property portfolio, system knowledge and advanced300-millimeter manufacturing, we offer comprehensive solutions that help customers deliver successful results in a timely fashion.

Build up Customer-focused Partnership Business Model. We have focused on building partnership relationships with our customers, and we strive to help our customers achieve their objectives through close cooperation. Unlike the traditionalbuy-and-sell relationship between a foundry and its customers, we believe our partnership business model will help us understand our customers’ requirements and, accordingly, better accommodate our customers’ needs in a number of ways, such as customized processes and services that optimize the entire value chain (not just the foundry portion) and intellectual property-related support. We believe that this business model will enable us to deliver our products to our customers at the earliest time our customers require for their design cycle, resulting in shortertime-to-market andtime-to-volume production. Furthermore, we believe we will render more cost-effective services by focusing our research and development expenditures on the specific requirements of our customers. We believe our partnership business model will help us not only survive a market downturn, but also achieve a better competitive position.

Continue to Focus on High Growth Applications and Customers and Actively Explore New Market Opportunities. We believe one measure of a successful foundry company is the quality of its customers. We focus our sales and marketing on customers who are established or emerging leaders in industries with high growth potential. Our customers include industry leaders such as Broadcom, MediaTek, Realtek, Texas Instruments Xilinx and Qualcomm. We seek to maintain and expand our relationships with these companies. We strive to demonstrate to these customers the superiority and flexibility of our manufacturing, technology and service capabilities and to provide them with production and design assistance. We are also making efforts to further diversify our customer portfolio in order to maintain a balanced exposure to different applications and different customers. We believe these efforts strengthen our relationships with our customers and enhance our reputation in the semiconductor industry as a leading foundry service provider.

In addition to customer diversification, we have also been actively exploring new market opportunities in consumer electronics such as Internet of Things.

Maintain Our Leading Position in Mass-Producible Semiconductor Technology and Selectively Pursue Strategic Investments in New Technologies. We believe that maintaining and enhancing our leadership in mass-producible semiconductor manufacturing technology is critical to attract and retain customers. Our reputation for technological excellence has attracted both established and emerging leaders in the semiconductor industries who work closely with us on technology development. In addition, we believe our superior processing expertise has enabled us to provide flexible production schedules to meet our customers’ particular needs. We plan to continue enhancing capital expenditures in research and development and building internal research and development expertise, to focus on process development and to establish alliances with leading and specialty semiconductor companies to accelerate access to next-generation and specialized technologies. For example, we introduced our 28-nanometer technology to customers in 2011 to significantly increase the competitive advantages of our customers by providing better device performance in a smaller die size. In 2011, we achieved more than 10 customers and tapeouts for our 28-nanometer technology in 2011 and delivered pilot production on this generation to our lead customer. In 2014, our28-nanometer technology further led to over 40 tapeouts. With our continuous technology development efforts and capital investment, in 2015,2016, revenue derived from28-nanometer technology had significantly increased from 2014.2015. We believe our progress in developing more advanced process technologies has benefited our customers in the fields of computers, communications, consumer electronics and others with special preferences in certain aspects of the products, such as the ultimate performance, density and power consumption.

Moreover, we expect to strengthen our leading position and increase our market share by licensing our technologies to several corporate partners. For example, in 2014, we licensed to MIFS, which is expected to be a pure-play foundry company, our advanced 40 nanometer technology under a technology transfer and license agreement. We will continue to explore licensing opportunities based on UMC’sour comprehensive technology offerings to further drive our revenue. In addition, we also entered into an agreement with the Xiamen Municipal People’s Government and Fujian Electronics & Information Group in 2014 in connection with the newly established USC located in Xiamen, Fujian Province, China, which is focusing on the manufacturing of12-inch wafers with initial offering of 40 nanometer and 55 nanometer process technologies. In April 2017, we entered into a license agreement with USC to provide 28 nanometer process technologies aimed to further strengthen the wafer manufacturing capabilities of our subsidiary company. In addition, we also recently enhanced our technology platform by collaborating with additional technology parties for the research and development of specialty technologies. For example, in May 2016, we entered an agreement with Fujian Jin Hua Integrated Circuit Co., or Fujian Jinhua, in connection with the development of DRAM related technologies. Such developed technologies are expected to be jointly owned by both parties and will not be accessible for local chip design companies. We expect the collaboration to thrive on the strength of Taiwan’s semiconductor manufacturing technologies to fulfill the potential domestic demands for specialty DRAM in China. We will be in charge of technology development and currently do not intend to enter the DRAM industry or invest in Fujian Jinhua. We believe that such strategy enablesstrategies enable us to take advantage of our established research and development capabilities while expanding our footprint globally in a cost-effective manner.

We also recognize that every company has limited resources and that the foundry industry is ever-evolving. Accordingly, we believe we should invest in new research and development technology intelligently and in a cost-effective manner to achieve the ultimate output of the resulting technology. In doing so, we balance the rate of return of our research and development with the importance of developing a technology at the right time to enhance our competitive edge without unduly diluting our profitability. We intend to avoid investments in technologies that do not present a commercial potential for volume production. We believe that to develop the earliest and most advanced semiconductor technology without regard to its potential for near term volume production may prove costly to our operations and would not strengthen our competitive position. We perceive a benefit to defer investment in the premature equipment needed to claim the earliest advanced technology and instead to purchase a more advanced and less expensive version of equipment from vendors who design such equipment based onpre-production lessons learned from the earliest technology.

Maintain Scale and Capacity Capabilities to Meet Customer Requirements, with a Focus on12-inch Wafer Facilities for Future Expansion. We believe that maintaining our foundry capacity with advanced technology and facilities is critical to the maintenance of our industry leadership. Our production capacity is currently among the largest of all semiconductor foundries in the world. We intend to increase our12-inch wafer production capacity to meet the needs of our customers and to fully capitalize on the expected growth of our industry. We expect our future capacity expansion plans will focus on12-inch wafer facilities in order to maintain our technology leadership.12-inch wafers offer manufacturing advantages over8-inch wafers due to, among other reasons, the greater number of chips on each wafer and the advantages only offered on newer12-inch capable equipment. In addition,12-inch wafer facilities present a more cost-effective solution in achieving an economic scale of production. We intend to carefully monitor current market conditions in order to optimize the timing of our capital spending. We also plan to continue to expand our capacity and capabilities to meet customer requirements in different markets and expand our global presence by making strategic investments in other companies. For example, in 2014, we invested in MIFS in Japan with Fujitsu Semiconductor Limited and in USC in China with the Xiamen Municipal People’s Government and Fujian Electronics & Information Group that will focus on manufacturing semiconductors using12-inch wafers. These investments enable us to achieve a greater economy of scale with respect to 300mm wafer operations for advanced node process technologies. We also licensed our advanced technologies to these invested companies in order to provide feasible technology solutions to fulfill their needs.

Manufacturing Facilities

To maintain a leading position in the foundry business, we have placed great emphasis on achieving and maintaining a high standard of manufacturing quality. As a result, we seek to design and implement manufacturing processes that produce consistent, high manufacturing yields to enable our customers to estimate, with reasonable certainty, how many wafers they need to order from us. In addition, we continuously seek to enhance our production capacity and process technology, two important factors that characterize a foundry’s manufacturing capability. Our large production capacity and advanced process technologies enable us to provide our customers with volume production and flexible andquick-to-market manufacturing services. All of our fabs operate 24 hours per day, seven days per week. Substantially all maintenance at each of the fabs is performed concurrently with production.

As a step in our continuing expansion of our manufacturing complex in the Tainan Science Park in southern Taiwan, we completed the construction of our second 300mm fab in Taiwan in May 2009, and moved the equipment into this fab in July 2010.

The following table sets forth operational data of each of our manufacturing facilities as of December 31, 2015.2016.

The following table sets forth the size and primary use of our facilities and whether such facilities, including land and buildings, are owned or leased. Our land in the Hsinchu and Tainan Science Parks is leased from the R.O.C. government.

Location		Size (Land/Building)		Primary Use		Land (Owned or Leased)		Building (Owned or Leased)
		(in square meters)
Fab 8N, 333, Xinghua St., Suzhou Industrial Park, Suzhou, Jiangsu Province 215025, PRC		215,621 / 100,908		8-inch wafer production		Leased (expires in December 2052)		Owned
Fab 12A, 18, 20Nan-Ke 2nd Rd., Tainan Science Park, Sinshih, Tainan, Taiwan 74147, R.O.C.		243,250 / 629,916633,085		12-inch wafer production		Leased (expires in November 2034)		Owned
Fab 12i, 3 Pasir Ris Drive 12 Singapore 519528		84,836 / 144,980		12-inch wafer production		Leased (expires in March 2031)		Owned
Fab 12X, No. 899 Wan Jia Chun Road, Xiang’an District, Xiamen, PRC		254,698 / -355,890		12-inch wafer production		Leased (expires in January 2065)		Owned (construction in progress)
United Tower, 3Li-Hsin 2nd Rd., Hsinchu Science Park, Hsinchu, Taiwan 30078, R.O.C.		8,985 / 85,224		Administration office		Leased (expires in December 2033)		Owned
Neihu Rd. office, 8F, 68. Sec. 1, Neihu Rd., Taipei, Taiwan 11493, R.O.C.		626 / 4,817		Administration office		Owned		Owned

Location

Size (Land/Building)

Primary Use

Land (Owned or Leased)

Building (Owned or Leased)

(in square meters)

Testing Building, 1, Chin-Shan, 7th St., Hsinchu, Taiwan 30080, R.O.C.

10,762 / 41,318/41,318

Leased to several companies

Owned

Owned

R&D Building, 18Nan-Ke 2nd Rd., Tainan Science Park, Sinshih, Tainan, Taiwan 74147, R.O.C.

42,000 / 47,396

Research and development

Leased (expires in December 2023)

Owned

Nexpower, 2, Houke S. Rd., Houli District, Taichung, Taiwan 42152, R.O.C.

57,556 / 82,699

Solar PV modules production

Leased (expires in December 2026)

Owned

Unistars, 1F, 669, Sec. 4, Zhongxing Rd., Zhudong Township, Hsinchu, Taiwan 31061, R.O.C.

- / 1,955

High-power LED package and LEDLed lighting

N/A

Leased (expires in May October 2017)

Wavetek, 10, Chuangxin 1st Rd., Baoshan Township, Hsinchu, Taiwan 30076, R.O.C.

27,898 / 34,609

6-inch wafer production

Leased (expires in August 2035)

Owned

Process Technology

Process technology is a set of specifications and parameters that we implement for manufacturing the critical dimensions of the patterned features of the circuitry of semiconductors. Our process technologies are currently among the most advanced in the foundry industry. These advanced technologies have enabled us to provide flexible production schedules to meet our customers’ particular needs.

The continued enhancement of our process technologies has enabled us to manufacture semiconductor devices with smaller geometries, allowing us to produce more dice on a given wafer. We pioneered the production of semiconductor products with 0.25 and 0.18 micron process technology in 1997 and 1999, respectively, and used copper interconnect metallurgic to allow better reliability and higher conductibility than traditional aluminum interconnects. We began volume production using0.13-micron process technology in 2002. Our extensive experience in the0.13-micron process technology has helped smooth our transition to90-nanometer pilot production. Our90-nanometer process marks further advance in our technology achievements, incorporating up to nine copper metal layers, triple gate oxide and other advanced features and using chrome-less phase-shift masks. This technology has been in volume production since the second quarter of 2004 after passing several product certifications. In 2005, our research and development teams continued to work closely with the manufacturing staff to finalize our90-nanometer technology portfolio. These collaborative efforts, performed in ourbest-in-class 300mm facilities, contributed to the improvement of high density6T-SRAM yield to the maturity level of more than 90%. Our accomplishments led to multiple design awards followed by first silicon success, including a PC graphic IC and the world’s first90-nanometer Wireless Local Area Network (WLAN) RF chip featuring a unique and specially developed inductor scheme. In addition, we were able to develop, within 6 months, several customized90-nanometer processes tailored to our customers’ device specifications, and demonstrated product success by delivering record high yield for the first product lots. Our first fully-functional65-nanometer wireless digital baseband customer IC was produced in July of 2005, after only a year since this research and development project began at this facility.

Since the third quarter of 2006, we have begun the mass production of a next-generation65-nanometer FPGA product, which features a 65% logic capacity increase over previous generation of FPGAs with triple gate oxide and 11 copper metal layers. Our65/55-nanometer development team is not only independently developing our technologiesin-house but is also bringing up customized process technologies to match customer specific needs. Furthermore, our45/40-nanometer process technologies, which are jointly developed by us and our strategic partners have been in production since the first half of 2009, significantly increasing the competitive advantages of our customers by providing better device performance in a smaller die size. Our 28nm process technologies with Poly-SiON andHigh-k/metal gate are developed for low power consumption and high performance applications, respectively. In October 2008, we were the first foundry to deliver fully functional 28nm SRAM chips, and have proven in customer silicon theHigh-k/metal gate solution used for this technology node. UMC’sOur 28nm progress was also recognized by the industry with the foundry being selected to present at the 2009 IEDM on a hybridHigh-k/metal gate approach. Currently, we are already working with several customers to adopt their products on UMC’s 28nm technology. In 2013, we successfully developed and released into production 28nm Poly-SiON andHigh-k/metal gate technologies. Furthermore, weWe also joined the International Business Machines Corporation, or IBM chip alliance, for the 10nmadvanced process development. With IBM’sknow-how and support, we aim to continue to improve our internally developed 14nm technology, so as to offer a 14nm competitivelow-power enhanced technology for mobile computing and communication products, and furthermore to develop the 10nm process technology to meet the needs of our customers.products. We have also successfully developed specialty technologies, such as 55/40/28 eFlash, 55/40/28 eHV, 55nmBSI-CIS and 55nm BCD, for SoC applications.

The table below sets forth our actual process technology range, categorized by line widths, or the minimum physical dimensions of the transistor gate of integrated circuits in production by each fab, in 2015,2016, and the estimated annual full capacity of each fab, actual total annual output and capacity utilization rates in 2013, 2014, 2015 and 2015:2016:

The table below sets forth a breakdown of number and percentage of wafer output by process technologies in 2013, 2014, 2015 and 2015.2016.

Capacity and Utilization

The fabs in Taiwan that we own directly are named Wavetek, Fab 8A, Fab 8C, Fab 8D, Fab 8E, Fab 8F, Fab 8S and Fab 8S, all12A. All of whichthem are located in the Hsinchu Science Park in Taiwan, andexcept for Fab 12A which is located in the Tainan Science Park in Taiwan.Park. The fab in Singapore is named Fab 12i and the fab12i. The fabs in China isare named Fab 8N.8N and Fab 12X, located in SuZhou and Xiamen, respectively.

Our average capacity utilization rate was 82.3% in 2013, 89.0% in 2014, and 89.8% in 2015 and 88.6% in 2016, respectively.

Equipment

Considering the performance and productivity of our manufacturing capability highly relies on the quality of our capital equipment, we generally purchase equipment that not only meet the demand of our existing process technology, but also have the capability to be upgraded to match our future needs. The principal equipment we use to manufacture semiconductor devices are scanners/steppers, cleaners and track equipment, inspection equipment, etchers, furnaces, wet stations, strippers, implanters, sputters, CVD equipment, probers, testers and so on. We own all of the production equipment except for a few demonstration tools.

Our policy is to purchase high-quality equipment that demonstrates stable performance from vendors with dominant market share to ensure our continued competitiveness in the semiconductor field.

Some of the equipment is available from a limited number of qualified vendors and/or is manufactured in relatively limited quantities, and some equipment has only recently been developed. We believe that our relationships with equipment suppliers are strong enough that we can leverage our position as a major purchaser to purchase equipment on competitive terms, including shorter lead time, compared with the terms received by several other foundries.

Although we face the challenge of procuring the right equipment in sufficient quantity necessary forramp-up or expansion of our fabrication facilities under constraint of short lead times, we have not in the past experienced any material problems in procuring the latest generation equipment on a timely basis even in periods of unpredictably high market demand. We manage the risks in the procurement process through timely internal communications among different divisions, efficient market information collection, early reservation of appropriate delivery slots and constant communications with our suppliers as well as by utilizing our good relationships with the vendors.

Raw Materials

Our manufacturing processes use many raw materials, primarily silicon wafers, chemicals, gases and various types of precious sputtering targets. These raw materials are generally available from several suppliers. Our policy with respect to raw material purchases, similar to that for equipment purchases, is to select only a small number of qualified vendors who have demonstrated quality and reliability on delivery time of the raw materials. We may have any long-term supply contracts with our vendors if necessary.

Our general inventory policy is to maintain sufficient stock of each principal raw material for production and rolling forecasts of near-term requirements received from customers. In addition, we have agreements with several key material suppliers under which they hold similar levels of inventory in their warehouses for our use. However, we are not under any obligation to purchase raw material inventory that is held by our vendors for our benefit until we actually order it. We typically work with our vendors to plan our raw material requirements on a monthly basis, with indicative pricing generally set on a quarterly basis. The actual purchase price is generally determined based on the prevailing market conditions. In the past, prices of our principal raw materials have not been volatile to a significant degree. Although we have not experienced any shortage of raw materials that had a material effect on our operations, and supplies of raw materials we use currently are adequate, shortages could occur in various critical materials due to interruption of supply or an increase in industry demand.

The most important raw material used in our production processes is silicon wafer, which is the basic raw material from which integrated circuits are made. The principal makers for our wafers are Shin-Etsu, Siltronic AG, SunEdisonGlobalWafers Corporation and Sumco Group and GlobalWafers.Group. We have in the past obtained and believe that we will continue to be able to obtain a sufficient supply of silicon wafers. We believe that we have close working relationships with our wafer suppliers. Based on such long-term relationships, we believe that these major suppliers will use their best efforts to accommodate our demand.

We use a large amount of water in our manufacturing process. We obtain water supplies from government-owned entities and recycle approximately 85% of the water that we use during the manufacturing process. We also use substantial amounts of dual loop electricity supplied by Taiwan Power Company in the manufacturing process. We maintainback-up generators that are capable of providing adequate amounts of electricity to maintain the required air pressure in our clean rooms in case of power interruptions. We believe ourback-up devices are reasonably adequate in preventing business interruptions caused by power outages and emergency situations.

Quality Management

We believe that our advanced process technologies and reputation for high quality and reliable services and products have been important factors in attracting and retaining leading international and domestic semiconductor companies as customers.

We structure our quality management system in accordance with the latest international quality standards and our customers’ strict quality and reliability requirements. Our quality management system incorporates comprehensive quality control programs into the entire business flow of foundry operation including, among others, new process development management, production release control, incoming raw material inspection, statistical process control and methodology development, process change management, technical documentation control, product final inspection, metrology tool calibration and measurement system analysis, quality audit program, nonconformity management, customer complaint disposition, eight-discipline problem solving and customer satisfaction monitoring.

We set a high quality goal to ensure consistent high yielding and reliable product performance. Our quality program is continually enhanced throughtop-down annual Business Policy Management andbottom-up Total Quality Management activities. In addition, our efforts to observe best practices among fabs in the foundry industry have also contributed to the improvement of our overall quality management system.

Many of our customers perform physical production site qualification process in the early development phase and routine quality conformance audits in the volume production phase. These audits include both quality system review and physical fabrication area inspection for verification of conformity with the international quality standard and customers’ quality requirement. Our quality management system and quality control programs have been qualified and routinely audited by numerous customers who are recognized as world-class semiconductor companies withbest-in-class quality standards.

Our Quality Assurance Division and Reliability Technology and Assurance Division collaborate to provide quality and reliability performance to customers. With our wafer processing quality and reliability conformance monitor program, we monitor the product quality and reliability at various stages of the entire manufacturing process before shipment to customers.

All our fabs are certified in compliance with ISO/TS 16949 and QC080000 IECQ HSPM standards. ISO/TS 16949 sets the criteria for developing a fundamental quality management system emphasizing on customer satisfaction in quality management, continual improvement, defect prevention and variation and waste reduction. QC080000 IECQ HSPM sets the criteria for developing a process management system for hazardous substances and focuses on developing environmentally friendly manufacturing processes. We are committed to continuously improve our quality management system and to deliver high quality product to our customers.

Services and Products

We primarily engage in wafer fabrication for foundry customers. To optimize fabrication services for our customers, we work closely with them as they finalize circuit design and contract for the preparation of masks to be used in the manufacturing process. We also offer our customers turnkey services by providing subcontracted assembly and test services. We believe that this ability to deliver a variety of foundry services in addition to wafer fabrication enables us to accommodate the needs of a full array of integrated device manufacturers, system companies and fabless design customers with differentin-house capabilities.

Wafer manufacturing requires many distinct and intricate steps. Each step in the manufacturing process must be completed with precision in order for finished semiconductor devices to work as intended. The processes require taking raw wafers and turning them into finished semiconductor devices generally through five steps: circuit design, mask tooling, wafer fabrication, assembly and test. The services we offer to our customers in each of these five steps are described below.

Circuit Design. At this initial design stage, our engineers generally work with our customers to ensure that their designs can be successfully and cost-effectively manufactured in our facilities. We have assisted an increasing number of our customers in the design process by providing them with access to our partners’ electronic design analysis tools, intellectual property and design services as well as by providing them with custom embedded memory macro-cells. In our Silicon Shuttle program, we offer customers and intellectual property providers early access to actual silicon samples with their desired intellectual property and content in order to enable early and rapid use of our advanced technologies. The Silicon Shuttle program is a multi-chip test wafer program that allows silicon verification of intellectual property and design elements. In the Silicon Shuttle program, several different vendors can test their intellectual property using a single mask set, greatly reducing the cost of silicon verification for us and the participating vendors. The high cost of masks for advanced processes makes this program attractive to intellectual property vendors. ARM Limited, Faraday Technology Corp., MIPS Technologies International, and Synopsys Inc. have utilized our Silicon Shuttle program. In our alliances with them, we coordinate with leading suppliers of intellectual property, design and ASIC services to ensure their offerings are available to our customers in an integrated, easy to use manner which matches customers’ need to our technologies. With a view to lowering customer design barriers, we expanded our design support functions from conventional design support to adding intellectual property development to complement third-party intellectual properties and to provide customers with the widest range of silicon-verified choices. Our offerings range from design libraries to basic analog mixed-mode intellectual properties which, together, have helped shorten our customer’s design cycle time.

Mask Tooling. Our engineers generally assist our customers to design and/or obtain masks that are optimized for our advanced process technologies and equipment. Actual mask production is usually provided by independent third parties specializing in mask tooling.

Wafer Fabrication. As described above, our manufacturing service provides all aspects of the wafer fabrication process by utilizing a full range of advanced process technologies. During the wafer fabrication process, we perform procedures in which a photosensitive material is deposited on the wafer and exposed to light through the mask to form transistors and other circuit elements comprising of a semiconductor. The unwanted material is then etched away, leaving only the desired circuit pattern on the wafer. As part of our wafer fabrication services, we also offer wafer probing services, which test, or probe, individual die on the processed wafers and identify dice that fail to meet required standards. We prefer to conduct wafer probing internally to obtain speedier and more accurate data on manufacturing yield rates.

Assembly and Testing. We offer our customers turnkey services by providing the option to purchase finished semiconductor products that have been assembled and tested. We outsource assembly and test services to leading assembly and test service providers, including Siliconware Precision Industries Co., Ltd., or Siliconware, and Advanced Semiconductor Engineering Inc. in Taiwan. After final testing, the semiconductors are shipped to our customers’ designated locations.

In addition to our foundry business, we also engage in the research, development and manufacture of products in the solar energy and LED industries.

Customers and Markets

Our primary customers, in terms of our sales revenues, include premier integrated device manufacturers, such as Texas Instruments, Intel Mobile and STMicroelectronics, and leading fabless design companies, such as Xilinx, Broadcom, MediaTek, Realtek, Qualcomm and Novatek. Although we are not dependent on any single customer, a significant portion of our net operating revenues has been generated from sales to a few customers. Our top ten customers accounted for approximately 57.3%60.2% of our net operating revenues in 2015.2016. Set forth below is a geographic breakdown of our operating revenues in 2013, 2014, 2015 and 20152016 by the location of our customers.