AMKOR TECHNOLOGY, INC.

1. Interim Financial Statements

Basis of Presentation. The Consolidated Financial Statements and related disclosures as of September 30, 2025, and for the three and nine months ended September 30, 2025 and 2024, contained in this Form 10-Q (the “Consolidated Financial Statements”) are unaudited pursuant to the rules and regulations of the SEC. The December 31, 2024 Consolidated Balance Sheet data contained in this Form 10-Q was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America (“U.S. GAAP”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to SEC rules and regulations. In our opinion, the Consolidated Financial Statements include all adjustments (consisting only of normal recurring adjustments) necessary for the fair statement of the results for the interim periods and should be read in conjunction with the financial statements included in the 2024 Form 10-K. The results of operations for the three and nine months ended September 30, 2025 are not necessarily indicative of the results to be expected for the full year ending December 31, 2025. Unless the context otherwise requires, all references to “Amkor,” “we,” “us” or “our” are to Amkor Technology, Inc. and its wholly and majority-owned subsidiaries.

Use of Estimates. The Consolidated Financial Statements have been prepared in conformity with U.S. GAAP, using management’s best estimates and judgments where appropriate. These estimates and judgments affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. The estimates and judgments will also affect the reported amounts for certain revenues and expenses during the reporting period. Actual results could differ materially from these estimates and judgments as a result of, for example, any worsening of the global business and economic environment.

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

Leases. Total long-term finance lease liabilities as of September 30, 2025 and December 31, 2024 were $89.3 million and $122.7 million, respectively.

Goodwill. The balance of goodwill in the Consolidated Balance Sheets contained in this Form 10-Q reflects adjustments for foreign currency translation.

Unbilled Receivables. Total unbilled receivables as of September 30, 2025 and December 31, 2024 were $332.4 million and $210.1 million, respectively.

Contract Liabilities. Contract liabilities were $83.1 million and $95.6 million as of September 30, 2025 and December 31, 2024, respectively. As of September 30, 2025 and December 31, 2024, the short-term portions of the liabilities were $56.2 million and $59.7 million, respectively. Of the remaining September 30, 2025 contract liability balance, $24.0 million is expected to be recognized in revenue over the next 1-5 years, and $2.9 million thereafter. Revenue recognized during the nine months ended September 30, 2025 and 2024 that was included in the contract liabilities balance at the beginning of the period was $48.7 million and $54.4 million, respectively.

Grant Accounting. From time to time, we may receive grants from governmental agencies. We recognize grants in our financial statements when there is reasonable assurance that we will comply with conditions attached to the grants and the grants will be received. On July 4, 2025, the One Big Beautiful Bill Act (the “OBBBA”) was enacted in the United States, which includes a provision to increase the investment tax credit rate under the CHIPS Act from 25% to 35% for qualified property placed in service after 2025. Investment tax credits and grants receivable recorded reduce the carrying amounts of the qualifying property, plant and equipment in our Consolidated Balance Sheets. The following table presents investment tax credits and grants receivable as of September 30, 2025 and December 31, 2024:

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In September 2025, we entered into an agreement to exchange approximately 56 acres of land acquired in 2024 for approximately 104 acres of land related to the Arizona Facility. The transaction is structured as a nonmonetary asset exchange with no cash consideration. The 104 acre parcel will be recorded at the carrying value of the land relinquished with no gain or loss recognized. The transaction is expected to close in the fourth quarter of 2025.

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 plan to adopt the new standard in the fourth quarter of 2025 using the prospective method, which will result in enhanced disclosures in our financial statements.

In November 2024, the FASB issued ASU 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses(“ASU 2024-03”), which was subsequently amended and clarified. ASU 2024-03 requires disaggregation of key expense categories such as inventory purchases, employee compensation, depreciation and intangible asset amortization in the financial statements. ASU 2024-03 is effective for annual reporting periods beginning after December 15, 2026, and interim periods within annual reporting periods beginning after December 15, 2027. Early adoption is permitted. Adoption of this ASU should be applied either prospectively after the effective date or retrospectively to any or all periods presented in the financial statements. We are currently evaluating the impact of this new standard on our financial statements, and we expect the new standard to result in enhanced disclosures.

In September 2025, the FASB issued ASU 2025-06, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40) (“ASU 2025-06”). ASU 2025-06 removes all references to project stages throughout ASC 350-40 and clarifies the applicable threshold to begin capitalizing costs. ASU 2025-06 is effective for annual reporting periods beginning after December 15, 2027, and interim periods within those annual reporting periods. Early adoption is permitted as of the beginning of an annual reporting period. Adoption of this ASU should be applied using a prospective transition approach, a modified transition approach based on project status or a retrospective transition approach. We are currently evaluating the impact of this new standard on our financial statements and disclosures.

2. Business Segments, Product Groups and End Markets

The following table presents revenue, profit or loss and significant segment expenses for our single operating segment:

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(1) Other segment items include interest income, foreign currency (gain) loss, net and other (income) expense.

The following tables represent other balances included in net income or that are regularly provided to the Chief Operating Decision Maker (CODM):

The following table presents our net sales by product group:

(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.

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Net sales by end market consist of the following:

3. Other Income and Expense

Other income and expense consist of the following:

4. Income Taxes

Income tax expense of $59.8 million for the nine months ended September 30, 2025 reflects income taxes, foreign withholding taxes and minimum taxes.

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.

We maintain a valuation allowance on certain U.S. and foreign deferred tax assets. Such valuation allowances are released as the related tax benefits are realized or when sufficient evidence exists to conclude that it is more likely than not that the deferred tax assets will be realized.

Unrecognized tax benefits represent reserves for potential tax deficiencies or reductions in tax benefits that could result from federal, state or foreign tax audits. Gross unrecognized tax benefits were $35.7 million and $36.3 million as of September 30, 2025 and December 31, 2024, respectively. As of September 30, 2025, $29.6 million of our unrecognized tax benefits would reduce our effective tax rate if recognized. Our unrecognized tax benefits are subject to change for effective settlement of examinations, changes in the recognition threshold of tax positions, the expiration of statutes of limitations and other factors.

We have tax returns that are open to examination in various jurisdictions for tax years 2013-2024. 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. In certain circumstances where we elect to appeal the results of an examination, we may

-12- be required to make tax assessment payments to proceed with the administrative appeal process. Current examinations include 2021 and 2023 Philippine income tax returns, 2022-2024 Japan income tax returns and 2020-2021 California income tax returns.

On July 4, 2025, the OBBBA was enacted in the United States. The OBBBA includes significant provisions, including modifications to the international tax framework and restoration of tax treatment for certain business provisions. The legislation has multiple effective dates, with certain provisions effective in 2025 and others implemented through 2027. The OBBBA provisions have been reflected in the consolidated financial statements for the quarter ended September 30, 2025 and did not have a material impact on our consolidated financial statements.

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, performance-vested restricted stock units (“PSUs”) and time-vested restricted stock units (“RSUs”).

The following table summarizes the computation 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:

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6. Accumulated Other Comprehensive Income (Loss)

Changes in accumulated other comprehensive income (loss), net of tax, consist of the following:

(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).

(3) Beginning in April 2024, foreign currency translation includes the gain (loss) from net investment hedges (Note 13).

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7. Investments

All of our available-for-sale debt investments as of September 30, 2025 are available to fund current operations and are recorded at fair value (Note 14).

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

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(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)For nine months ended September 30, 2025 and 2024, we sold cash equivalent investments for proceeds of $20.4 million and $18.1 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 September 30, 2025:

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.

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As of September 30, 2025, the amortized cost and the fair market value of our held-to-maturity government bonds (Level 1) maturing within a year were $3.9 million. As of December 31, 2024, the amortized cost and the fair market value of our held-to-maturity government bonds (Level 1) maturing within a year were $4.4 million.

8. 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 three and nine months ended September 30, 2025, we sold receivables totaling $63.2 million and $88.7 million, respectively, net of discounts and fees, which were insignificant for the respective periods. For the three and nine months ended September 30, 2024, we sold receivables totaling $23.3 million and $59.4 million, respectively, net of discounts and fees, which were insignificant for the respective periods.

9. Property, Plant and Equipment

Property, plant and equipment consist of the following:

The following table summarizes our depreciation expense:

In September 2025, we amended certain finance lease agreements to accelerate the purchase of the underlying assets in October for $34.7 million, and we separately entered into an agreement to sell these assets along with additional existing machinery and equipment in November 2025 for $103.6 million. We expect to recognize a pre-tax gain on sale of approximately $34 million upon completion of the sale.

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10. Accrued Expenses

Accrued expenses consist of the following:

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11. Debt

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

(1)In July 2025, we redeemed $125.0 million (“July Redemption”) of our 6.625% Senior Notes due September 2027 (“2027 Notes”). In September 2025, we issued a redemption notice (“September Redemption” and, together with the July Redemption, the “2027 Notes Redemptions”) for the remaining amounts due under our 2027 Notes, which was completed in October 2025. The 2027 Notes Redemptions were funded with a portion of the net proceeds from the $500.0 million Term A Loans and a portion of the net proceeds from our issuance of the 2033 Notes described below. In accordance with the terms of the indenture governing the 2027 Notes, the redemption price for the 2027 Notes Redemptions was 100% of the principal amount of the 2027 Notes plus accrued and unpaid interest. As a result of the 2027 Notes Redemptions, we expect to record $1.8 million in charges for the early extinguishment of debt related costs, of which $0.5 million was recorded in the third quarter of 2025 with the remaining amount to be recorded in fourth quarter of 2025.

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(2)In September 2025, we issued $500.0 million of 5.875% Senior Notes due October 2033 (“2033 Notes”). The 2033 Notes were issued at par value and are senior unsecured obligations guaranteed by our wholly-owned subsidiary, Guardian Assets, Inc. (“Guardian”). Interest is payable semiannually on April 1 and October 1 of each year, commencing April 1, 2026. We incurred $6.7 million of debt issuance costs associated with the 2033 Notes. The proceeds will be used for the September Redemption and general corporate purposes.

(3)In May 2025, we entered into a $1.0 billion senior secured revolving credit facility (the “2025 Revolving Credit Facility”) guaranteed by Amkor Technology Singapore Holding Pte. Ltd. (“ATSH”) and Guardian that replaced an existing revolving credit facility guaranteed by ATSH and Guardian. The maximum borrowing capacity under the 2025 Revolving Credit Facility is $1.0 billion. The 2025 Revolving Credit Facility includes an uncommitted optional accordion of up to $200.0 million, which may be incurred in the form of revolving commitment increases or term loans. As of September 30, 2025, $1.0 billion was available for future borrowings under the 2025 Revolving Credit Facility.

(4)In June 2025, we amended the 2025 Revolving Credit Facility and created a new tranche of term loans (the “Term A Loans”), which are secured and guaranteed on apari passu basis to the revolver loans under the existing agreement. The Term A Loans have an aggregate principal amount of $500.0 million and will mature in May 2030. The payments are subject to 2.5% amortization of the original principal amount per year in 2026 and 2027, and 5% thereafter, payable quarterly, with the remaining balance due at maturity. The proceeds were used for the July Redemption, prepayment of outstanding term loans of Amkor Assembly & Test (Shanghai) Co., Ltd. (“AATS Loans”) and general corporate purposes.

(5)In April 2021, we entered into a ₩80.0 billion term loan agreement with the option to borrow and re-borrow the funds up tosix times per year through April 2024 at a fixed rate of 1.85%. In May 2024, we replaced this loan by entering into a ₩80.0 billion (approximately $59 million) term loan agreement with the option to borrow and re-borrow the funds up tosix times per year through May 2027. Principal is payable at maturity, and interest is payable monthly at a fixed rate of 3.95%. As of September 30, 2025, ₩80.0 billion, or approximately $57 million, was available to be drawn.

(6)We entered into various short-term term loans which mature semiannually. Principal and interest are payable in monthly installments. As of September 30, 2025, $3.4 million was available to be drawn.

Certain of our debt is collateralized by the land, buildings, equipment and capital stock of subsidiaries. As of September 30, 2025, the collateralized debt balance was $923.8 million, of which $656.8 million of assets and subsidiary capital stock were pledged as collateral.

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., ATSH and Guardian guarantee certain debt of our subsidiaries. The agreements governing our indebtedness contain affirmative and negative covenants, including, among others, covenants to maintain a minimum interest coverage ratio and a maximum consolidated leverage ratio, which restrict our ability to pay dividends and could restrict our operations. These restrictions 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 September 30, 2025.

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12. Pension Plans

Foreign Defined Benefit Pension Plans

Our subsidiaries in Japan, Korea, Malaysia, the Philippines and Taiwan sponsor defined benefit pension plans. Charges to expense are based upon actuarial analyses. The components of net periodic pension cost for these defined benefit pension plans are as follows:

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

Defined Contribution Pension Plans

We sponsor defined contribution pension plans in Korea, Malaysia, Taiwan and the U.S. The following table summarizes our defined contribution expense:

13. Derivatives

We use foreign currency forward contracts to mitigate foreign currency risk of certain monetary assets and 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.

We hedge certain net investment positions in foreign subsidiaries. To accomplish this, we enter into foreign currency forward contracts, generally settled monthly, that are designated as hedges of net investments.

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As of September 30, 2025 and December 31, 2024, our foreign exchange forward contracts consisted of the following:

For the three and nine months ended September 30, 2025, we incurred a net loss of $3.8 million and $10.3 million, respectively, due to the impact of derivatives not designated as hedging instruments, which includes the forward costs, and the revaluation of the related hedged items. For the three and nine months ended September 30, 2024, we incurred a net loss of $4.1 million and $10.8 million, respectively, due to the impact of derivatives not designated as hedging instruments, which includes the forward costs, and the revaluation of the related hedged items.

For the three and nine months ended September 30, 2025, a gain of $1.3 million and $4.0 million, respectively, was recognized in other (income) expense, net of the difference between the forward rate and the spot rate of the net investment hedge. For the three and nine months ended September 30, 2025, a gain of $2.7 million and a loss of $6.1 million, respectively, was recognized in other comprehensive income (loss) for the changes in fair value of the net investment hedges. For the three and nine months ended September 30, 2024, a gain of $1.7 million and $2.9 million, respectively, was recognized in other (income) expense, net of the difference between the forward rate and the spot rate of the net investment hedge. For the three and nine months ended September 30, 2024, a loss of $11.3 million and $8.1 million, respectively, was recognized in other comprehensive income (loss) for the changes in fair value of the net investment hedges.

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14. 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.

15. 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.

Insolvency payments associated with Nanium acquisition

In June 2025, we received $72.8 million for a receivable subject to bankruptcy proceedings included as part of our Nanium acquisition in May 2017 (“Nanium Insolvency Receipt”). The terms of the purchase agreement require us to

-23- remit any insolvency payments received to the selling shareholders, less certain costs, including tax costs, incurred by us. During the second quarter, we remitted $40.4 million to the selling shareholders. Such amounts were recorded on a net basis within selling, general and administrative expenses in our Consolidated Statements of Income and as operating cash flows within our Condensed Consolidated Statements of Cash Flows.

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 on our business, liquidity, results of operations, financial condition or cash flows. Our evaluation of the potential impact of these claims and legal proceedings could change in the future.

In accordance with the accounting guidance for loss contingencies, including legal proceedings, lawsuits, pending claims and other legal matters, we accrue for a loss contingency when we conclude that the likelihood of a loss is probable and the amount of the loss can be reasonably estimated. 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.

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