AMKOR TECHNOLOGY INC

1. Description of Business and Summary of Significant Accounting Policies

Description of Business

Amkor is one of the world’s leading providers of outsourced semiconductor packaging and test services. Amkor was a pioneer in the outsourcing of semiconductor packaging and test services, and over the years we have built a leading position by:

•Designing and developing innovative packaging and test technologies focused on advanced packaging solutions in high growth markets, including artificial intelligence;

•Building expertise in high-volume manufacturing processes and developing a reputation for high quality and solid execution;

•Cultivating long-standing relationships with our customers, which include many of the world’s leading semiconductor companies;

•Collaborating with customers, foundries, OEMs and equipment and material suppliers;

•Focusing on strategic end markets that offer solid growth potential;

•Providing a geographically diverse operating base with manufacturing facilities in multiple countries across Asia and in Europe; and

•Developing a competitive cost structure through disciplined capital investment.

Basis of Presentation

Our Consolidated Financial Statements include the accounts of Amkor Technology, Inc. and its subsidiaries. Our Consolidated Financial Statements reflect the elimination of all significant inter-company accounts and transactions. Our investments in variable interest entities in which we are the primary beneficiary are consolidated. We reflect the remaining portion of variable interest entities and foreign subsidiaries that are not wholly owned as noncontrolling interests.

The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, we evaluate our estimates, including those related to revenue recognition, income taxes, inventory and long-lived assets. These estimates are based on management’s best knowledge of current events, historical experience, actions that we may undertake in the future and on various other assumptions that are believed to be reasonable under the circumstances. As a result, actual results could differ materially from these estimates and assumptions, including the impact of any deterioration in the global business and economic environment. Certain prior year amounts have been reclassified to conform to current year presentation.

Consolidation of Variable Interest Entities

We have variable interests in certain Philippine realty corporations in which we have a 40% ownership. We lease land and buildings in the Philippines from these entities and we are the primary beneficiary of these arrangements. As of December 31, 2023, the combined book value of the assets and liabilities associated with these Philippine realty corporations included in our Consolidated Balance Sheet was $17.3 million and $0.1 million, respectively. The impact of consolidating these variable interest entities on our Consolidated Statements of Income was not significant, and other than our lease payments, we have not provided any significant assistance or other financial support to these variable interest entities for the years ended December 31, 2023, 2022 or 2021. The creditors of the Philippine realty corporations have no recourse to our general credit.

Foreign Currency Translation

The U.S. dollar is the functional currency of our subsidiaries other than our Japan operations. The foreign currency asset and liability amounts at these subsidiaries are remeasured into U.S. dollars at end-of-period exchange rates, except for nonmonetary items which are remeasured at historical rates. Foreign currency income and expenses are remeasured at daily exchange rates, except for expenses related to balance sheet amounts which are remeasured at historical exchange rates. Exchange gains and losses arising from remeasurement of foreign currency-denominated monetary assets and liabilities are included in other (income) expense, net in the period in which they occur.

The Japanese yen is the functional currency of our Japan operations. The asset and liability amounts of our Japan operations are translated into U.S. dollars at end-of-period exchange rates. Income and expenses are translated into U.S. dollars at the daily exchange rate. The resulting translation adjustments are reported as a component of accumulated other comprehensive income in the stockholders’ equity section of the balance sheet. Assets and liabilities denominated in a currency other than the functional currency are remeasured into the functional currency prior to translation into U.S. dollars, and the resulting transaction exchange gains or losses are included in other (income) expense, net in the period in which they occur.

Risks and Concentrations

The semiconductor industry is characterized by rapid technological change, competitive pricing pressures and cyclical market patterns. Our financial results are affected by a wide variety of factors, including general economic conditions worldwide, economic conditions specific to the semiconductor industry, the timely implementation of new package and test technologies, the ability to safeguard patents and intellectual property in a rapidly evolving market and reliance on materials and equipment suppliers. In addition, the semiconductor market has historically been cyclical and subject to significant economic downturns at various times. Our profitability and ability to generate cash from operations is principally dependent upon demand for semiconductors, the utilization of our capacity, semiconductor package mix, the average selling price of our services, our ability to manage our capital expenditures and our ability to control our costs including labor, material, overhead and financing costs.

A significant portion of our revenues is concentrated with a small group of customers (Note 18). Direct sales to our largest customer accounted for 27.7% of our net sales for the year ended December 31, 2023. The loss of a significant customer, a business combination among customers, a reduction in orders or decrease in price from a significant customer or disruption in any of our significant strategic partnerships or other commercial arrangements could have a material adverse effect on our business, liquidity, results of operations, financial condition and cash flows.

Financial instruments, for which we are subject to credit risk, consist principally of accounts receivable and cash, cash equivalents and short-term investments. With respect to accounts receivable, we mitigate our credit risk by selling primarily to well-established companies, performing ongoing credit evaluations and making frequent contact with customers. In addition, we may utilize non-recourse factoring to mitigate credit risk when considered appropriate. We have historically mitigated our credit risk with respect to cash and cash equivalents through diversification of our holdings into various high quality money market funds and bank deposit accounts. Our short-term investments are principally investments in debt securities with maximum duration of twenty-four months and range from AAA to BBB-rated financial instruments. Our short-term investments are primarily in corporate bonds, direct obligations of the U.S. Government or its agencies, asset-backed securities and commercial paper. At December 31, 2023, our cash and cash equivalents were primarily maintained in various U.S. and foreign bank operating and time deposit accounts and invested in various available-for-sale debt investments. See Note 6 for further discussion regarding our available-for-sale debt investments.

Contingencies and Litigation

We may be subject to certain legal proceedings, lawsuits and other claims, as discussed in Note 17. We accrue for a loss contingency, including legal proceedings, lawsuits, pending claims and other legal matters, when we conclude that the likelihood of a loss is probable and the amount of the loss can be reasonably estimated. When the reasonable estimate of the loss is within a range of amounts, and no amount in the range constitutes a better estimate than any other amount, we accrue for the amount at the low end of the range. We adjust our accruals from time to time as we receive additional information, but the loss we incur may be significantly greater than or less than the amount we have accrued. We disclose loss contingencies if we believe they are material and there is at least a reasonable possibility that a loss has been incurred. Attorney fees related to legal matters are expensed as incurred.

Cash and Cash Equivalents

We consider all highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Our cash and cash equivalents are primarily maintained in various U.S. and foreign bank operating and time deposit accounts and invested in various available-for-sale debt investments. See Note 6 for further discussion regarding our available-for-sale debt investments.

Restricted Cash

Restricted cash, non-current, mainly consists of collateral to fulfill utility requirements.

Investments

Generally, we classify our short-term investments in fixed income securities as available-for-sale debt investments. All of our available-for-sale debt investments as of December 31, 2023 are available to fund current operations and are recorded at fair value (Note 6). Unrealized gains and losses on our available-for-sale debt investments are included as a separate component of accumulated other comprehensive income (loss), net of tax. Realized gains and losses on our available-for-sale debt investments and declines in value judged to be an impairment are included in other (income) expense, net. The cost of short-term investments matured or sold is based on the average cost method.

We evaluate on an ongoing basis the market conditions, trends of earnings, financial condition, credit ratings, any underlying collateral and other key measures for our short-term investments in determining if and when a decline in value below the adjusted cost of our available-for-sale debt investments is an impairment. An impairment is considered if (i) we have the intent to sell the security, (ii) it is more likely than not that we will be required to sell the security before recovery of the entire amortized cost basis or (iii) we do not expect to recover the entire amortized cost basis of the security. If impairment is considered on condition (i) or (ii) above, the entire difference between the amortized cost and the fair value of the debt security is recognized in earnings. If impairment is considered based on condition (iii), the amount representing credit losses will be recognized in earnings and as an allowance for credit losses. The amount relating to all other factors will be recognized in other comprehensive income.

Inventories

Inventories consist of raw materials and purchased components and are stated at the lower of cost and net realizable value. Cost is principally determined by standard cost or the weighted moving average method, both of which approximate actual cost. We review and set our standard costs as needed, but at a minimum on a quarterly basis. We reduce the carrying value of our inventories for the cost of inventory we estimate is excess and obsolete based on the age of our inventories. When a determination is made that the inventory will not be utilized in production or is not saleable, it is written-off.

Other Current Assets

Other current assets consist principally of prepaid assets.

Property, Plant and Equipment

Property, plant and equipment are stated at cost. Depreciation is calculated by the straight-line method over the estimated useful lives of depreciable assets which are as follows:

Cost and accumulated depreciation for property retired or disposed of are removed from the accounts, and any resulting gain or loss is included in earnings. Expenditures for maintenance and repairs are charged to expense as incurred.

We review long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. Recoverability of a long-lived asset group to be held and used in operations is measured by a comparison of the carrying amount to the sum of the undiscounted cash flows expected to result from the use and eventual disposition of the asset group. If such asset group is considered to be impaired, the impairment loss is measured as the amount by which the carrying amount of the asset group exceeds its fair value. Long-lived assets to be disposed of are carried at the lower of cost or fair value less the costs of disposal.

Leases

We lease certain machinery and equipment, office space, and manufacturing facilities. Leases with an initial term of 12 months or less are not recorded on the balance sheet, and we recognize lease expense for these leases on a straight-line basis over the lease term. We combine lease components (e.g., fixed payments including rent, real estate taxes and insurance costs) with the non-lease components (e.g., common-area maintenance costs) for all asset classes. We use our incremental borrowing rate based on the information available at the lease commencement date to determine the lease liability. Our leases have remaining lease terms ranging from less thanone year to 82 years. For purposes of calculating our lease liabilities, our lease terms include options to extend or terminate the lease when it is reasonably certain that we will exercise those options. Certain leases also include options to purchase the leased property. Total long-term finance lease liabilities as of December 31, 2023 and December 31, 2022 were $47.8 million and $54.8 million, respectively.

Goodwill

Goodwill is recorded when the cost of an acquisition exceeds the fair value of the net tangible and identifiable intangible assets acquired. We review goodwill for impairment annually during the fourth quarter of each year and whenever events or changes in circumstances indicate that an impairment may exist. Impairment losses are recorded when the carrying amount of the reporting unit exceeds its fair value. The balance of goodwill in our Consolidated Balance Sheets reflects adjustments for foreign currency translation.

Other Assets

Other assets consist principally of deferred tax assets, refundable security deposits and advanced payments to vendors.

Derivatives

We use foreign exchange forward contracts, generally settled monthly, to manage a portion of our exposure to foreign exchange risk. The derivatives are recorded at the fair value either in other current assets or accrued expenses, with the associated gains and losses charged toother (income) expense, net in the period in which they occur. We do not apply hedge accounting to the derivatives. Gains and losses recognized on our derivatives are classified as operating activities and are included within other, net in our Consolidated Statements of Cash Flows. See Note 15 for further discussion about the derivatives.

Fair Value Measurements

We apply fair value accounting for assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring or nonrecurring basis. We define fair value as the price that would be received from selling an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants at the measurement date. See Note 16 for further discussion of fair value measurements.

Revenue Recognition

We recognize revenue, net of sales, use, value-added and other similar taxes, as a performance obligation is satisfied in an amount reflecting the consideration to which we expect to be entitled. We apply a five-step approach in determining the amount and timing of revenue to be recognized: (1) identifying the contract with a customer; (2) identifying the performance obligations in the contract; (3) determining the transaction price; (4) allocating the transaction price to the performance obligations in the contract; and (5) recognizing revenue when the performance obligation is satisfied. Substantially all of our revenue is recognized as services are rendered.

Our packaging and test services are our performance obligations to our customers. Our packaging services include wafer bump, probe and assembly. We provide packaging and test services to our customers either individually or as part of a combined offering. In a combined offering, we account for the individual services separately if they are determined to be distinct. We determine a service to be distinct if it is separately identifiable from other services in the combined offering and if a customer can benefit from the unique service on its own or with other resources that are readily available to the customer.

The consideration, including variable consideration, is allocated between the distinct services in a combined offering based upon the stand-alone selling prices of the individual services. Our services involve a high degree of specialization which are unique based on the design and purpose of the customer’s wafers. Accordingly, our negotiated pricing reflects the customized nature of our services and represents a customer-specific stand-alone selling price. We recognize revenue as services are rendered, which generally occurs over the course of two to three weeks. Services are generally billed at completion of each individual packaging or test service or in some instances at the completion of all services in a combined offering.

We recognize revenue over time as services are rendered because our services create or enhance the customer’s wafer. We utilize an input method (cost incurred plus estimated margin) to determine the amount of revenue to recognize for in-process, but incomplete, customer orders at a reporting date. During the period of providing our services, we generally do not control or take ownership of customers’ wafers, nor do we include the cost of the wafer in our cost calculations. We believe that a cost-based input method is the most appropriate manner to measure how we satisfy our performance obligations to customers because the effort and costs incurred to package and/or test customer wafers are not linear over the duration of these services.

Shipping and handling costs are accounted for as a cost to fulfill our performance obligations to customers. Accordingly, we record customer payments of shipping and handling costs as a component of net sales, and the costs incurred for shipping and handling are then charged to cost of sales.

Unbilled receivables are revenues that have been recognized for performance obligations that have been satisfied, or partially satisfied, in advance of billing the customer. Revenue may be recognized in advance of billing as our contracts provide us with an unconditional right to consideration for work that is performed. Total unbilled receivables as of December 31, 2023 and 2022 were $260.8 million and $301.7 million, respectively. These amounts are included in accounts receivable, net of allowances in our Consolidated Balance Sheets.

At times, the company receives cash payments from customers in advance of the company’s performance. In such cases, we record deferred revenue until the performance obligation is satisfied, which represents a contract liability and is included in accrued expenses and other non-current liabilities in the consolidated balance sheets. These contract liabilities are classified as either current or long-term based on the timing of when the company expects to recognize revenue. Contract liabilities were $135.5 million and $170.6 million as of December 31, 2023 and December 31, 2022, respectively. As of December 31, 2023 and December 31, 2022, the short-term portion of the liability was $71.1 million and $81.5 million, respectively. The remainder of the December 31, 2023 contract liability balance is expected to be recognized in revenue over the next 1-5 years. Revenue recognized during the year that was included in the contract liability balance at the beginning of the period was $66.9 million, $101.2 million, and $29.0 million, for 2023, 2022 and 2021, respectively.

Research and Development Costs

Research and development expenses include costs attributable to the conduct of research and development programs primarily related to the development of new package designs or technologies and improving the efficiency and capabilities of our existing production processes. Such costs include labor, materials, supplies, depreciation and maintenance of research equipment, services provided by outside contractors and the allocable portions of facility costs such as rent, utilities, insurance, repairs and maintenance, depreciation and general support services. Costs associated with research and development are expensed as incurred.

Income Taxes

Income taxes are accounted for using the asset and liability method. Under this method, deferred income tax assets and liabilities are recognized for the future tax consequences attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax basis as well as for net operating loss and tax credit carryforwards. Deferred income tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which these temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance is provided for those deferred tax assets for which it is more likely than not that the related tax benefits will not be realized.

We monitor on an ongoing basis our ability to utilize our deferred tax assets and whether there is a need for a related valuation allowance. In evaluating our ability to recover our deferred tax assets in the jurisdictions from which they arise, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax-planning strategies and recent results of operations. With the exception of a certain foreign jurisdiction and select U.S. and foreign carryforwards, we consider it more likely than not that we will have sufficient taxable income to allow us to realize these deferred tax assets. However, in the event taxable income falls short of current expectations, we may need to establish a valuation allowance against such deferred tax assets.

We recognize in our Consolidated Financial Statements the impact of an income tax position, if that position is more likely than not of being sustained on audit, based on the technical merits of the position. Related interest and penalties are classified as income taxes in the financial statements. See Note 4 for further discussion regarding unrecognized income tax benefits.

Recently Issued Standards

In December 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures(“ASU 2023-09”). ASU 2023-09 requires disclosure of additional income tax information, primarily related to effective tax rate reconciliation and income taxes paid. ASU 2023-09 is effective for annual periods beginning after December 15, 2024. Early adoption is permitted. Adoption of this ASU should be applied on a prospective basis, but retrospective application is permitted. We are currently evaluating the impact of this new standard on our financial statements, which is expected to result in enhanced disclosures.

2. Share-Based Compensation Plans

For the years ended December 31, 2023, 2022 and 2021, we recognized share-based compensation of $8.3 million, $13.6 million and $11.0 million, respectively, primarily in selling, general and administrative expenses. The amount of compensation expense to be recognized is adjusted for an estimated forfeiture rate which is based on historical data. The corresponding deferred income tax benefits are $0.7 million, $1.7 million and $1.4 million for 2023, 2022 and 2021, respectively.

Equity Incentive Plans

Second Amended and Restated 2007 Equity Incentive Plan. The Second Amended and Restated 2007 Equity Incentive Plan (as amended, the “2007 Plan”) provided for the grant of the following types of incentive awards: (i) stock options; (ii) restricted stock; (iii) restricted stock units; (iv) stock appreciation rights; (v) performance units and performance shares; and (vi) other stock or cash awards. Those eligible for awards included employees, directors and consultants who provide services to Amkor and its subsidiaries. There were originally 17.0 million shares of our common stock reserved for issuance under the 2007 Plan. No awards have been or will be granted under the 2007 Plan after the effective date of the 2021 Plan (as defined below), but all outstanding awards under the 2007 Plan will continue in full force and effect, subject to their original terms.

2021 Equity Incentive Plan. On May 18, 2021, at our 2021 Annual Meeting of Stockholders (the “2021 Annual Meeting”), our stockholders approved the Amkor Technology, Inc. 2021 Equity Incentive Plan (as amended, the “2021 Plan”) to replace the 2007 Plan. The 2021 Plan provides for the grant of the following types of incentive awards: (i) stock options; (ii) restricted stock; (iii) restricted stock units; (iv) stock appreciation rights; (v) performance units and performance shares; and (vi) other stock or cash awards. Those eligible for awards include employees, directors and consultants who provide services to Amkor and its subsidiaries. The number of shares authorized and available for issuance under the 2021 Plan is 23,100,000 shares, reduced for certain awards granted under the 2007 Plan after December 31, 2020, but before May 18, 2021. There were originally 22.8 million shares of our common stock reserved for issuance under the 2021 Plan, and at December 31, 2023, there were 20.6 million shares available for grant under the 2021 Plan.

Stock options

Stock options are generally granted with an exercise price equal to the market price of the stock at the date of grant. Substantially all of the options granted are exercisable pursuant to aone tofour year vesting schedule, and the term of the options granted is no longer thanten years. Upon option exercise, we may issue new shares of common or treasury stock.

In order to calculate the fair value of stock options at the date of grant, we use the Black-Scholes option pricing model. Expected volatilities are based on historical performance of our stock. We also use historical data to estimate the timing and amount of option exercises and forfeitures within the valuation model. The expected term of the options is based on evaluations of historical and expected future employee exercise behavior and represents the period of time that options granted are expected to be outstanding. The risk-free interest rate for periods within the contractual life of the option is based on the U.S. Treasury yield curve in effect at the time of grant. The dividend yield is based on the annualized declared quarterly dividend rate divided by our closing stock price at the date of the grant.

The following table summarizes our stock option activity for the year ended December 31, 2023:

Total unrecognized compensation expense from stock options was $0.3 million as of December 31, 2023, which is expected to be recognized over a weighted-average period of approximately 0.79 years beginning January 1, 2024. The total intrinsic value of options exercised during fiscal years 2023, 2022, and 2021 was $5.8 million, $8.0 million, and $17.7 million, respectively.

Restricted shares

Restricted shares granted to our non-employee directors vest on the earlier of theone year anniversary of the grant date or the date of the annual meeting of stockholders immediately following the grant date, subject to the recipient’s continued service as a director of Amkor on the applicable vesting date. Generally, other restricted shares vest ratably over three years, with 8.33% of the shares vesting in equal quarterly installments such that 100% of the shares will become vested on the third anniversary of the award, subject to the recipient’s continued employment with us on the applicable vesting date. In addition, provided that the restricted shares have not been forfeited earlier, under the terms and conditions of the applicable award agreements for certain grants, the restricted shares will vest upon the recipient’s death or disability, or upon a change in control of Amkor. The value of the restricted shares is determined based on the fair market value of the underlying shares on the date of the grant and is recognized ratably over the vesting period.

The following table summarizes our restricted share activity for the year ended December 31, 2023:

For the year ended December 31, 2023, the total fair value of our vested restricted shares was $2.9 million, respectively.

Restricted stock units

From time to time, and pursuant to the 2021 Plan, we grant time-vested restricted stock units (“RSUs”) to our non-employee directors and certain employees and performance-vested restricted stock units (“PSUs”) to certain employees. RSUs generally vest infour equal installments over afour-year period such that 100% of the RSUs will become vested on the fourth anniversary of the award, subject to the recipient’s continued employment with us on the applicable vesting dates. In some circumstances, we have granted RSUs subject to different vesting conditions, including RSUs that vest in full in a single installment. Provided that the RSUs have not been forfeited earlier, they will generally vest upon the recipient’s retirement, death or disability, or upon a change in control of Amkor, in accordance with the terms and conditions of the applicable award agreement. The value of the RSUs is determined based on the fair market value of the underlying shares on the date of the grant, reduced by the present value of dividends or dividend equivalent rights expected to be paid on our common stock prior to vesting, and is recognized ratably over the vesting period.

PSUs generally vest inone installment after atwo-year period such that any earned PSUs will become vested within 90 days of the second anniversary of the award, subject to the recipient’s continued employment with us on the applicable vesting date. Generally for PSUs, the number of shares of our common stock to be received at vesting will range from 0% to 200% of the target grant amount based on Cumulative Basic EPS (as defined in the applicable award agreement) over atwo-year performance measurement period. In some circumstances, we have granted PSUs subject to different vesting conditions, including PSUs that vest in full upon the achievement of performance goals other than Cumulative Basic EPS. Provided the PSUs have not been forfeited earlier, the PSUs will generally vest upon the recipient’s retirement, death or disability, or upon a change of control of Amkor, in accordance with the terms and conditions of the applicable award agreement. The value of the PSUs is initially determined based on the fair market value of the underlying shares on the date of the grant, reduced by the present value of dividends expected to be paid on our common stock prior to vesting, and is recognized over the vesting period.

The following table summarizes our RSU and PSU activity:

Total unrecognized compensation expense from RSUs and PSUs was $12.1 million as of December 31, 2023, which is expected to be recognized over a weighted-average period of approximately 1.3 years beginning January 1, 2024.

For the years ended December 31, 2023 and 2022, the total fair value of our vested RSUs and PSUs were $11.6 million and $0.5 million, respectively.

3. Other Income and Expense

Other income and expense consists of the following:

4. Income Taxes

Geographic sources of income (loss) before taxes are as follows:

The components of the provision (benefit) for income taxes are as follows:

The reconciliation between the U.S. federal statutory income tax rate of 21% and our effective tax rate is as follows:

In 2022, we reversed $17.8 million of valuation allowance recorded against U.S. foreign tax credit carryforwards previously projected to expire unused due to the limitations to utilize the credits under current tax law. Realization of these carryforwards is dependent on generating sufficient taxable income to overcome the foreign tax credit limitation provisions. Although utilization of these carryforwards is not assured, in light of our current earnings and recent estimates of future taxable income, management believes sufficient positive evidence exists to conclude that the respective valuation allowances are no longer needed, resulting in the reversal of these valuation allowances.

As a result of certain capital investments, export commitments and employment levels, income from operations in Korea, the Philippines and Singapore was subject to reduced income tax rates and, in some cases, was exempt from income taxes. The most significant tax rate impact is in Singapore where we have been granted a conditional reduced tax rate that expires at the end of 2028. We recognized $18.6 million, $84.5 million and $56.7 million in tax benefits as a result of the conditional reduced tax rates in 2023, 2022 and 2021, respectively. The benefit of the conditional reduced tax rates on diluted earnings per share was approximately $0.08, $0.34 and $0.23 for 2023, 2022 and 2021, respectively.

The following is a summary of the components of our deferred tax assets and liabilities:

We monitor on an ongoing basis our ability to utilize our deferred tax assets and whether there is a need for a related valuation allowance. In evaluating our ability to recover our deferred tax assets in the jurisdictions from which they arise, we consider all available positive and negative evidence, including scheduled reversals of deferred tax liabilities, projected future taxable income, tax-planning strategies and recent results of operations.

Valuation allowance against deferred tax assets consist of the following:

Our net operating loss carryforwards are as follows:

At December 31, 2023 and 2022, a portion of our remaining U.S. federal net operating loss carryforwards was reserved with a valuation allowance due to ownership change limitations from a prior year acquisition as well as certain state net operating loss carryforwards expected to expire unused. Also, we have a valuation allowance against foreign net operating loss carryforwards that we do not expect to have sufficient taxable income to realize as of December 31, 2023 and 2022.

Our tax credit carryforwards are as follows:

At December 31, 2023 and 2022, a portion of our U.S. and foreign tax credit carryforwards were reserved with a valuation allowance for the amount expected to expire unused.

Distributions of cash to the U.S. as dividends generally will not be subject to U.S. federal income tax. We have not provided foreign withholding taxes or state income taxes on the undistributed earnings of our foreign subsidiaries, over which we have sufficient influence to control the distribution of such earnings and have determined that substantially all such earnings have been reinvested indefinitely. These earnings could become subject to foreign withholding tax if they are remitted as dividends. For the year ended December 31, 2023, we estimate that repatriation of these foreign earnings would generate withholding taxes and state income taxes of approximately $165.9 million.

We operate in and file income tax returns in various U.S. and foreign jurisdictions which are subject to examination by tax authorities. We have tax returns that are open to examination in various jurisdictions for tax years 2013-2023. The open years contain matters that could be subject to differing interpretations of applicable tax laws and regulations related to the amount and/or timing of income, deductions and tax credits. There can be no assurance that the outcome of examinations will be favorable. Our unrecognized tax benefits are subject to change as examinations of specific tax years are completed in the respective jurisdictions. In certain circumstances where we elect to appeal the results of an examination, we may be required to make tax assessment payments to proceed with the administrative appeal process. Current examinations include 2019-2022 Korean income tax returns, 2017-2021 Malaysia income tax returns and 2021 Philippine income tax return.

A reconciliation of the beginning and ending gross amount of unrecognized tax benefits is as follows:

The net decrease in our unrecognized tax benefits was $1.7 million from December 31, 2022 to December 31, 2023. The decrease was primarily related to the lapse of statutes of limitations. At December 31, 2023, all of our gross unrecognized tax benefits would reduce our effective tax rate, if recognized. It is reasonably possible that unrecognized tax benefits related to income attribution will decrease in the next 12 months by up to $0.8 million due to the lapse of statutes of limitations in foreign jurisdictions.

The liability related to our unrecognized tax benefits, before interest and penalties, is $23.0 million as of December 31, 2023 and is reported as a component of other non-current liabilities. The unrecognized tax benefits presented in the table above also include positions that have reduced deferred tax assets by $8.5 million. The balance of accrued and unpaid interest and penalties is $4.5 million and $4.9 million as of December 31, 2023 and 2022, respectively, and is included as a component of other non-current liabilities in connection with our unrecognized tax benefits.

5. Earnings Per Share

Basic earnings per share (“EPS”) is computed by dividing net income attributable to Amkor common stockholders by the weighted-average number of common shares outstanding during the period. The weighted-average number of common shares outstanding is reduced for treasury stock.

Diluted EPS is computed based on the weighted-average number of common shares outstanding plus the effect of dilutive potential common shares outstanding during the period. Dilutive potential common shares include outstanding stock options, PSUs, RSUs and unvested restricted shares.

The following table summarizes the computations of basic and diluted EPS:

The following table summarizes the potential shares of common stock that were excluded from diluted EPS, because the effect of including these potential shares was anti-dilutive:

6. Investments

The following table summarizes our cash equivalents and available-for-sale debt investments:

(1)All unrealized losses have been in a continuous loss position for less than 12 months. We do not intend to sell the investments in an unrealized loss position, and we do not believe it is more likely than not that we will be required to sell these investments before recovery of their amortized cost bases.

(2)During the years ended December 31, 2023, 2022, and 2021 we sold cash equivalent investments for proceeds of $47.0 million, $29.6 million and $12.8 million, respectively, and realized no gain or loss on such sales.

The following table summarizes the contractual maturities of our cash equivalents and available-for-sale debt investments as of December 31, 2023:

Actual maturities can differ from contractual maturities due to various factors including whether the issuers have the right to call or prepay obligations without call or prepayment penalties, and we view our available-for-sale debt investments as available for current operations.

As of December 31, 2023, the amortized cost and fair market value of our held-to-maturity government bonds (Level 1) maturing within a year were $5.2 million. As of December 31, 2022 the amortized cost and fair market value of our held-to-maturity government bonds (Level 1) maturing within a year were $4.4 million and $4.3 million, respectively.

7. Factoring of Accounts Receivable

For certain accounts receivable, we use non-recourse factoring arrangements with third-party financial institutions to manage our working capital and cash flows. Under these arrangements, we sell receivables to a financial institution for cash at a discount to the face amount. As part of the factoring arrangements, we perform certain collection and administrative functions for the receivables sold. For the years ended December 31, 2023 and 2022, we sold accounts receivable totaling $253.9 million and $386.5 million, net of discounts and fees of $1.3 million and $1.1 million, respectively.

8. Property, Plant and Equipment

Property, plant and equipment consist of the following:

The following table summarizes our depreciation expense:

In October 2023, we completed the first phase of construction for our Vietnam Facility and transferred $244.3 million from construction in progress to buildings and improvements.

9. Leases

The components of lease expense were as follows:

Other information related to leases was as follows:

Maturities of lease liabilities were as follows:

As of December 31, 2023, we have entered into additional lease agreements that have not yet commenced of approximately $8 million.

10. Accrued Expenses

Accrued expenses consist of the following:

11. Debt

Short-term borrowings and long-term debt consist of the following:

(1)In April 2021, we entered into a ₩80 billion term loan agreement with the option to borrow and re-borrow the funds up tosix times per year through April 2024. Principal is payable at maturity, and interest is payable monthly. As of December 31, 2023, ₩80.0 billion, or approximately $62 million, was available to be drawn.

(2)We entered into various short-term term loans which mature semiannually. Principal and interest are payable in monthly installments. As of December 31, 2023, $7.7 million was available to be drawn.

(3)In December 2023, we borrowed ¥17.5 billion (US$123.3 million) under a new term loan agreement due December 2028, guaranteed by Amkor Technology, Inc. and our subsidiary, ATSH. Principal is due in 20 equal, quarterly installments plus accrued interest, through maturity.

(4)In June 2023, Amkor Assembly & Test (Shanghai) Co. Ltd. amended all term loans to replace London Interbank Offered Rate (“LIBOR”) with a Secured Overnight Financing Rate (“SOFR”) plus 0.75% annual base rate. This contractual amendment is treated as a modification with no recognized gain or loss.

(5)In December 2023, we entered into a $45.0 million term loan. Principal is payable in semiannual installments of $0.5 million, with the remaining balance due at maturity. Interest is payable quarterly.

(6)In March 2022, ATT amended an existing revolving credit facility to reduce the availability from $36.0 million to $15.0 million. As of December 31, 2023, $15.0 million was available for future borrowings under such credit facility.

(7)In March 2022, ATSH entered into the 2022 Singapore Revolver, which is guaranteed by Amkor Technology, Inc., ATT and AATT. The maximum borrowing capacity under the 2022 Singapore Revolver is limited to a base amount equal to the lesser of: (1) $600.0 million; or (2) $250.0 million plus a variable amount equal to 37.5% of our consolidated accounts receivable balance. As of December 31, 2023, $600.0 million was available for future borrowings under the 2022 Singapore Revolver.

Certain of our foreign debt is collateralized by the land, buildings, equipment and accounts receivable in the respective locations. As of December 31, 2023 the collateralized debt balance was $679.7 million, of which $326.5 million of assets were pledged as collateral.

Interest Rates

Interest is payable semiannually on our senior notes and quarterly or monthly on our other fixed- and variable-rate debt. Refer to the table above for the interest rates on our fixed-rate debt and to the table below for the interest rates on our variable-rate debt.

Compliance with Debt Covenants

The debt of Amkor Technology, Inc. is structurally subordinated in right of payment to all existing and future debt and other liabilities of our subsidiaries. From time to time, Amkor Technology, Inc., ATT, AATT and ATSH guarantee certain debt of our subsidiaries. The agreements governing our indebtedness contain affirmative and negative covenants which restrict our ability to pay dividends and could restrict our operations. These restrictions are determined in part by calculations based upon cumulative net income and do not currently have a material impact on our ability to make dividend payments or stock repurchases.

We were in compliance with all debt covenants at December 31, 2023 and 2022.

Maturities

12. Pension and Severance Plans

Korean Severance Plan

Our subsidiary in Korea maintains an unfunded severance plan that covers certain employees that were employed prior to August 1, 2015. To the extent eligible employees are terminated, our subsidiary in Korea would be required to make lump-sum severance payments on behalf of these eligible employees for service provided prior to August 1, 2015. Factors used to determine severance benefits include employees’ length of service, seniority and rate of pay. The employees’ length of service and seniority are fixed as of July 31, 2015. The employees’ rate of pay is adjusted to the rate of pay at the time of termination. Accrued severance benefits are estimated assuming all eligible employees were to terminate their employment at the balance sheet date. Our contributions to the National Pension Plan of the Republic of Korea are deducted from accrued severance benefit liabilities. On August 1, 2015, our subsidiary in Korea began sponsoring a defined benefit pension plan and a defined contribution plan. Existing employees at that time were given the option of choosing either a defined benefit pension plan or a defined contribution plan for their future benefits and new employees since that date are enrolled in a defined contribution plan.

The changes to the balance of our accrued severance plan obligations are as follows:

Foreign Defined Benefit Pension Plans

Our subsidiaries in Japan, Korea, Malaysia, the Philippines and Taiwan sponsor defined benefit plans (the “Plans”). Charges to expense are based upon actuarial analyses. The following table summarizes the changes to the Plans’ benefit obligations, fair value of the Plans’ assets and the funded status of the Plans at December 31, 2023 and 2022:

The accumulated benefit obligation as of December 31, 2023 and 2022 was $128.3 million and $125.6 million, respectively.

The following table summarizes, by component, the change in accumulated other comprehensive income (loss), net of tax related to our Plans:

Information for pension plans with benefit obligations in excess of plan assets is as follows:

The following table summarizes total pension expense:

The components of net periodic pension cost other than the service cost component are included inother (income) expense, net in our Consolidated Statements of Income.

The following table summarizes the weighted-average assumptions used in computing the net periodic pension cost and projected benefit obligations:

The measurement date for determining the Plans’ assets and benefit obligations is December 31, each year. Discount rates are generally derived from yield curves constructed from high-quality corporate or foreign government bonds, for which the timing and amount of cash outflows approximate the estimated payouts.

The expected rate of return assumption is based on weighted-average expected returns for each asset class. Expected returns reflect a combination of historical performance analysis and the forward-looking views of the financial markets and include input from our actuaries. We have no control over the direction of our investments in our defined benefit plans in Taiwan as the local Labor Standards Law Fund mandates such contributions into a cash account balance at the Bank of Taiwan. Our defined benefit pension plan in Malaysia is a non-funded plan, and as such, no asset exists related to this plan. Our investment strategies for our defined benefit plans in Japan, Korea and the Philippines are based on long-term, sustained asset growth through low to medium risk investments. The current rate of return assumption targets are based on asset allocation strategies as follows:

The fair value of our pension plan assets, by asset category utilizing the fair value hierarchy as discussed in Note 16, is as follows:

The Taiwan retirement fund category of our plan assets represents accounts that our subsidiaries in Taiwan have in a government labor retirement fund in the custody of the Bank of Taiwan. The accounts earn a minimum guaranteed rate of return and are invested in a mix of cash, domestic and foreign equity securities and domestic and foreign debt securities.

We expect to make contributions of approximately $11 million during 2024. We closely monitor the funded status of the Plans with respect to legislative requirements. We intend to make at least the minimum contribution required by law each year.

The estimated future benefit payments related to our foreign defined benefit plans are as follows:

Defined Contribution Plans

We sponsor defined contribution plans in Korea, Malaysia, Taiwan and the U.S. Total defined contribution expense was $27.0 million, $24.2 million and $21.8 million for 2023, 2022 and 2021, respectively.

13. Dividends

In October 2020, our Board of Directors approved the initiation of a regular quarterly cash dividend on our common stock. Each quarter since the adoption of this dividend policy, the Company has declared and paid a quarterly dividend. In November 2023, our Board of Directors approved a quarterly dividend of $0.07875 per share, a 5% increase from the rate set in November 2022.

14. Accumulated Other Comprehensive Income (Loss)

The following table reflects the changes in accumulated other comprehensive income (loss), net of tax:

(1)Amounts reclassified out of accumulated other comprehensive income (loss) are included as other (income) expense, net (Note 3).

(2)Amounts reclassified out of accumulated other comprehensive income (loss) are included as a component of net periodic pension cost (Note 12) or other (income) expense, net (Note 3).

15. Derivatives

We use foreign currency forward contracts to mitigate foreign currency risk of certain assets and monetary liabilities denominated in foreign currencies. We do not enter into such contracts for trading or speculative purposes. These derivative instruments are not designated as hedging instruments.

As of December 31, 2023 and 2022, our foreign exchange forward contracts consisted of the following:

For the years ended December 31, 2023, 2022 and 2021, the derivatives resulted in a net loss of $38.6 million, $60.2 million and $58.8 million, respectively, which were partially offset by the foreign currency gains associated with the underlying net assets or liabilities.

16. Fair Value Measurements

The accounting framework for determining fair value includes a hierarchy for ranking the quality and reliability of the information used to measure fair value, which enables the reader of the financial statements to assess the inputs used to develop those measurements. The fair value hierarchy consists of three tiers as follows: Level 1, defined as quoted market prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, model-based valuation techniques for which all significant assumptions are observable in the market or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and Level 3, defined as unobservable inputs that are not corroborated by market data. For our Level 2 short-term investments, we consider factors such as actual trade data, benchmark yields, broker/dealer quotes, and other similar data obtained from quoted market prices and independent pricing vendors to determine the fair value of these assets and liabilities.

The fair values of cash, accounts receivable, trade accounts payable, capital expenditures payable, and certain other current assets and accrued expenses approximate carrying values because of their short-term nature. The carrying value of certain other non-current assets and liabilities approximates fair value. Our assets and liabilities recorded at fair value on a recurring basis include restricted cash money market funds and short-term investments, including investments classified as cash equivalents. Cash equivalent money market funds and restricted cash money market funds are invested in U.S. money market funds and various U.S. and foreign bank operating and time deposit accounts, which are due on demand or carry a maturity date of less than three months when purchased. No restrictions have been imposed on us regarding withdrawal of balances with respect to our cash equivalents as a result of liquidity or other credit market issues affecting the money market funds we invest in or the counterparty financial institutions holding our deposits.

Our derivative financial instruments are valued using quoted market prices for similar assets. Counterparties to these derivative contracts are highly rated financial institutions.

We also measure certain assets and liabilities, including property, plant and equipment and goodwill, at fair value on a nonrecurring basis.

We measure the fair value of our debt for disclosure purposes. The following table presents the fair value of our debt:

The estimated fair value of our senior notes is based primarily on quoted market prices reported on or near the respective balance sheet dates. The estimated fair value of our revolving credit facilities and term loans is calculated using a discounted cash flow analysis, which utilizes market-based assumptions including forward interest rates adjusted for credit risk.

17. Commitments and Contingencies

We generally warrant that our services will be performed in a professional and workmanlike manner and in compliance with our customers’ specifications. We accrue costs for known warranty issues. Historically, our warranty costs have been immaterial.

Legal Proceedings

We are involved in claims and legal proceedings and may become involved in other legal matters arising in the ordinary course of our business. We evaluate these claims and legal matters on a case-by-case basis to make a determination as to the impact, if any, on our business, liquidity, results of operations, financial condition or cash flows. Although the outcome of these matters is uncertain, we believe that the ultimate outcome of these claims and proceedings, individually and in the aggregate, will not have a material adverse impact to us. Our evaluation of the potential impact of these claims and legal proceedings on our business, liquidity, results of operations, financial condition or cash flows could change in the future.

18. Business Segments, Customer Concentrations and Geographic Information

We operate as a single operating segment as managed by our Chief Executive Officer, who is considered our chief operating decision maker (“CODM”). The CODM bears the ultimate responsibility for, and is actively engaged in, the allocation of resources and the evaluation of our operating and financial results. We have concluded that we have a single operating segment based on the following:

•We are managed under a functionally-based organizational structure with the head of each function reporting directly to the CODM;

•We assess performance, including incentive compensation, based on consolidated operating performance and financial results;

•Our CODM allocates resources and makes other operating decisions based on specific customer business opportunities and

•We have an integrated process for the design, development and manufacturing services we provide to all of our customers. We also have centralized sales and administrative functions.

Net sales by product group consist of the following:

(1)Advanced Products include flip chip, memory and wafer-level processing and related test services.

(2)Mainstream Products include all other wirebond packaging and related test services.

Net sales by end market consist of the following:

Net sales by region based on customer headquarters location consist of the following:

In 2023, 2022 and 2021 one customer accounted for 27.7%,20.6% and 13.7% of total net sales, respectively. In 2022, a second customer accounted for 10.1% of total net sales.

Property, plant and equipment, net, based on physical location, consist of the following: