X0508 4 2026-02-18 0 0001047127 AMKOR TECHNOLOGY, INC. AMKR 0001965254 Engel Kevin K. 2045 EAST INNOVATION CIRCLE TEMPE AZ 85284 1 1 0 0 President and CEO 0 Common Stock 2026-02-18 4 A 0 1777 0 A 2563 D Common Stock 2026-02-18 4 F 0 814 46.74 D 1749 D Common Stock 2026-02-18 4 A 0 5594 0 A 7343 D Common Stock 2026-02-18 4 F 0 2398 46.74 D 4945 D Restricted Stock Units 0 2026-02-18 4 A 0 53487 0 A Common Stock 53487 53487 D Restricted Stock Units 0 2026-02-18 4 A 0 21394 0 A Common Stock 21394 21394 D This Form 4 reports the vesting on February 18, 2026 of 1,777 shares of common stock of Amkor Technology, Inc. (the "Issuer") underlying performance-vested restricted stock units ("PSUs") granted to the Reporting Person on February 20, 2024 pursuant to the Issuer's Equity Incentive Plan, as amended, and the related award agreement. The PSUs vested based on the attainment of a basic earnings per share performance goal over a one-year performance period beginning January 1, 2025 and ending on December 31, 2025. The transaction represents shares of the Issuer's common stock withheld by the Issuer in connection with the vesting of PSUs to satisfy the Reporting Person's tax withholding obligations. The Issuer will pay these taxes on behalf of the Reporting Person. The transaction represents the vesting on February 18, 2026 of 5,594 shares of common stock of the Issuer's underlying PSUs granted to the Reporting Person on February 20, 2025 pursuant to the Issuer's Equity Incentive Plan, as amended, and the related award agreement. The PSUs vested based on the attainment of a basic earnings per share performance goal over a one-year performance period beginning January 1, 2025 and ending on December 31, 2025. Represents shares of the Issuer's common stock underlying time-vested restricted stock units granted on February 18, 2026 (the "Grant Date") pursuant to the Issuer's Equity Incentive Plan (the "RSUs"). The RSUs were awarded for no consideration other than the Reporting Person's service as an officer of the Issuer and will vest in three equal annual installments beginning on the first anniversary of the Grant Date and annually thereafter, such that 100% will be vested on the third anniversary of the Grant Date. Represents shares of the Issuer's common stock underlying time-vested RSUs granted on February 18, 2026 (the "Grant Date") pursuant to the Issuer's Equity Incentive Plan. The RSUs were awarded for no consideration other than the Reporting Person's service as an officer of the Issuer and will vest in two equal annual installments beginning on December 31, 2026 such that 100% will be vested on December 31, 2027. /s/ Mark N. Rogers, Attorney-in-Fact for Kevin Engel 2026-02-20