X0508 4 2026-02-16 0 0001047127 AMKOR TECHNOLOGY, INC. AMKR 0001596796 Rutten Guillaume Marie Jean 2045 EAST INNOVATION CIRCLE TEMPE AZ 85284 1 0 0 0 1 Common Stock 2026-02-16 4 M 0 13920 0 A 349311 D Common Stock 2026-02-17 4 S 0 10000 45.89 D 339311 D Restricted Stock Units 0 2026-02-16 4 M 0 13920 0 D Common Stock 13920 13919 D The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on June 06, 2025. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $44.33 to $46.92. The Reporting Person hereby undertakes to provide, upon request, to the staff of the Securities and Exchange Commission, Amkor Technology, Inc. (the "Issuer"), or any security holder of the Issuer, full information regarding the number of shares sold at each separate price within the range set forth in this footnote (2) to this Form 4. Represents shares of the Issuer's common stock underlying time-vested restricted stock units granted on February 16, 2023 (the "RSU Grant Date") pursuant to the Issuer's 2021 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 four equal annual installments beginning on the first anniversary of the RSU Grant Date. /s/ Mark N. Rogers, Attorney-in-Fact for Guillaume Marie Jean Rutten 2026-02-18