Rutten Guillaume Marie Jean

SEC source: 0001628280-26-063429 · wk-form4_1790282534.xml · derivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 2,619.5144

Underlying: Common Stock · 3.9978 shares

Expires not disclosed

F1 · derivative.exercise_price: Represents dividend equivalent units ("DEUs") accrued upon the payment of a dividend on September 22, 2026 with respect to time-vested restricted stock units ("RSUs") of Amkor Technology, Inc. (the "Issuer") granted to the Reporting Person on May 13, 2026. Each DEU represents an additional RSU subject to the same provisions as the RSU with respect to which the DEU was accrued.

F1 · derivative.exercise_date: Represents dividend equivalent units ("DEUs") accrued upon the payment of a dividend on September 22, 2026 with respect to time-vested restricted stock units ("RSUs") of Amkor Technology, Inc. (the "Issuer") granted to the Reporting Person on May 13, 2026. Each DEU represents an additional RSU subject to the same provisions as the RSU with respect to which the DEU was accrued.

F1 · derivative.expiration_date: Represents dividend equivalent units ("DEUs") accrued upon the payment of a dividend on September 22, 2026 with respect to time-vested restricted stock units ("RSUs") of Amkor Technology, Inc. (the "Issuer") granted to the Reporting Person on May 13, 2026. Each DEU represents an additional RSU subject to the same provisions as the RSU with respect to which the DEU was accrued.

SEC source: 0001628280-26-054882 · wk-form4_1786134969.xml · nonDerivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 461,732

F2 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $54.48 to $54.62. The Reporting Person hereby undertakes to provide, upon request, to the staff of the Securities and Exchange Commission, 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.

SEC source: 0001628280-26-054882 · wk-form4_1786134969.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 486,732

F1 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $55.31 to $55.43. 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 (1) to this Form 4.

SEC source: 0001628280-26-046953 · wk-form4_1783024525.xml · derivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 8,692 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: On February 20, 2025, the Reporting Person was granted 43,459 time-vested restricted stock units ("RSUs") which vested in five equal quarterly installments on each of June 30, 2025, September 30, 2025, December 31, 2025, March 31, 2026, and June 30, 2026, such that 100% was vested on June 30, 2026.

F1 · derivative.expiration_date: On February 20, 2025, the Reporting Person was granted 43,459 time-vested restricted stock units ("RSUs") which vested in five equal quarterly installments on each of June 30, 2025, September 30, 2025, December 31, 2025, March 31, 2026, and June 30, 2026, such that 100% was vested on June 30, 2026.

SEC source: 0001628280-26-046953 · wk-form4_1783024525.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 511,732

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001628280-26-045570 · wk-form4_1782420377.xml · derivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 2,615.5166

Underlying: Common Stock · 2.5166 shares

Expires not disclosed

F1 · derivative.exercise_price: Represents dividend equivalent units ("DEUs") accrued upon the payment of a dividend on June 23, 2026 with respect to time-vested restricted stock units ("RSUs") of Amkor Technology, Inc. (the "Issuer") granted to the Reporting Person on May 13, 2026. Each DEU represents an additional RSU subject to the same provisions as the RSU with respect to which the DEU was accrued.

F1 · derivative.exercise_date: Represents dividend equivalent units ("DEUs") accrued upon the payment of a dividend on June 23, 2026 with respect to time-vested restricted stock units ("RSUs") of Amkor Technology, Inc. (the "Issuer") granted to the Reporting Person on May 13, 2026. Each DEU represents an additional RSU subject to the same provisions as the RSU with respect to which the DEU was accrued.

F1 · derivative.expiration_date: Represents dividend equivalent units ("DEUs") accrued upon the payment of a dividend on June 23, 2026 with respect to time-vested restricted stock units ("RSUs") of Amkor Technology, Inc. (the "Issuer") granted to the Reporting Person on May 13, 2026. Each DEU represents an additional RSU subject to the same provisions as the RSU with respect to which the DEU was accrued.

SEC source: 0001628280-26-035658 · wk-form4_1778877472.xml · derivative · entry 3

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 2,613

Underlying: Common Stock · 2,613 shares

Expires not disclosed

F2 · derivative.exercise_price: Represents shares of common stock underlying RSUs granted on May 13, 2026 (the "Grant Date") pursuant to the Plan (the "May 2026 RSUs"). Subject to the terms and conditions of the applicable award agreement, the May 2026 RSUs may be converted into common stock of the Issuer on a one-for-one basis and will vest in full on the earlier of the first anniversary of the Grant Date or the date of the Issuer's first annual meeting of stockholders immediately following the Grant Date. The May 2026 RSUs were awarded for no consideration other than the Reporting Person's service as a director of the Issuer.

F2 · derivative.exercise_date: Represents shares of common stock underlying RSUs granted on May 13, 2026 (the "Grant Date") pursuant to the Plan (the "May 2026 RSUs"). Subject to the terms and conditions of the applicable award agreement, the May 2026 RSUs may be converted into common stock of the Issuer on a one-for-one basis and will vest in full on the earlier of the first anniversary of the Grant Date or the date of the Issuer's first annual meeting of stockholders immediately following the Grant Date. The May 2026 RSUs were awarded for no consideration other than the Reporting Person's service as a director of the Issuer.

F2 · derivative.expiration_date: Represents shares of common stock underlying RSUs granted on May 13, 2026 (the "Grant Date") pursuant to the Plan (the "May 2026 RSUs"). Subject to the terms and conditions of the applicable award agreement, the May 2026 RSUs may be converted into common stock of the Issuer on a one-for-one basis and will vest in full on the earlier of the first anniversary of the Grant Date or the date of the Issuer's first annual meeting of stockholders immediately following the Grant Date. The May 2026 RSUs were awarded for no consideration other than the Reporting Person's service as a director of the Issuer.

SEC source: 0001628280-26-035658 · wk-form4_1778877472.xml · derivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 482 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: On April 1, 2026, the Reporting Person was granted 482 time-vested restricted stock units ("RSUs") pursuant to the Amkor Technology, Inc. (the "Issuer") 2021 Equity Incentive Plan, as amended (the "Plan"), and the applicable award agreement (the "April 2026 RSUs"). In connection with the vesting of the April 2026 RSUs on May 13, 2026, the April 2026 RSUs converted into common stock of the Issuer on a one-for-one basis.

F1 · derivative.exercise_date: On April 1, 2026, the Reporting Person was granted 482 time-vested restricted stock units ("RSUs") pursuant to the Amkor Technology, Inc. (the "Issuer") 2021 Equity Incentive Plan, as amended (the "Plan"), and the applicable award agreement (the "April 2026 RSUs"). In connection with the vesting of the April 2026 RSUs on May 13, 2026, the April 2026 RSUs converted into common stock of the Issuer on a one-for-one basis.

F1 · derivative.expiration_date: On April 1, 2026, the Reporting Person was granted 482 time-vested restricted stock units ("RSUs") pursuant to the Amkor Technology, Inc. (the "Issuer") 2021 Equity Incentive Plan, as amended (the "Plan"), and the applicable award agreement (the "April 2026 RSUs"). In connection with the vesting of the April 2026 RSUs on May 13, 2026, the April 2026 RSUs converted into common stock of the Issuer on a one-for-one basis.

SEC source: 0001628280-26-035658 · wk-form4_1778877472.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 503,040

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · shares: On April 1, 2026, the Reporting Person was granted 482 time-vested restricted stock units ("RSUs") pursuant to the Amkor Technology, Inc. (the "Issuer") 2021 Equity Incentive Plan, as amended (the "Plan"), and the applicable award agreement (the "April 2026 RSUs"). In connection with the vesting of the April 2026 RSUs on May 13, 2026, the April 2026 RSUs converted into common stock of the Issuer on a one-for-one basis.

F1 · price: On April 1, 2026, the Reporting Person was granted 482 time-vested restricted stock units ("RSUs") pursuant to the Amkor Technology, Inc. (the "Issuer") 2021 Equity Incentive Plan, as amended (the "Plan"), and the applicable award agreement (the "April 2026 RSUs"). In connection with the vesting of the April 2026 RSUs on May 13, 2026, the April 2026 RSUs converted into common stock of the Issuer on a one-for-one basis.

F1 · balance_after: On April 1, 2026, the Reporting Person was granted 482 time-vested restricted stock units ("RSUs") pursuant to the Amkor Technology, Inc. (the "Issuer") 2021 Equity Incentive Plan, as amended (the "Plan"), and the applicable award agreement (the "April 2026 RSUs"). In connection with the vesting of the April 2026 RSUs on May 13, 2026, the April 2026 RSUs converted into common stock of the Issuer on a one-for-one basis.

SEC source: 0001628280-26-034167 · wk-form4_1778618644.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 502,558

F1 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $73.37 to $74.98. 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 (1) to this Form 4.

SEC source: 0001628280-26-023399 · wk-form4_1775170763.xml · derivative · entry 3

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 482

Underlying: Common Stock · 482 shares

Expires not disclosed

F2 · derivative.exercise_price: Represents shares of common stock underlying RSUs (the "Director RSUs") granted on April 1, 2025 (the "Grant Date") pursuant to the Amkor Technology, Inc. (the "Issuer") 2021 Equity Incentive Plan, as amended. Subject to the terms and conditions of the applicable award agreement, the Director RSUs may be converted into common stock of the Issuer on a one-for-one basis and will vest in full on the earlier of the first anniversary of the Grant Date or the date of the Issuer's first annual meeting of stockholders immediately following the Grant Date. The Director RSUs were awarded for no consideration other than the Reporting Person's service as a director of the Issuer.

F2 · derivative.exercise_date: Represents shares of common stock underlying RSUs (the "Director RSUs") granted on April 1, 2025 (the "Grant Date") pursuant to the Amkor Technology, Inc. (the "Issuer") 2021 Equity Incentive Plan, as amended. Subject to the terms and conditions of the applicable award agreement, the Director RSUs may be converted into common stock of the Issuer on a one-for-one basis and will vest in full on the earlier of the first anniversary of the Grant Date or the date of the Issuer's first annual meeting of stockholders immediately following the Grant Date. The Director RSUs were awarded for no consideration other than the Reporting Person's service as a director of the Issuer.

F2 · derivative.expiration_date: Represents shares of common stock underlying RSUs (the "Director RSUs") granted on April 1, 2025 (the "Grant Date") pursuant to the Amkor Technology, Inc. (the "Issuer") 2021 Equity Incentive Plan, as amended. Subject to the terms and conditions of the applicable award agreement, the Director RSUs may be converted into common stock of the Issuer on a one-for-one basis and will vest in full on the earlier of the first anniversary of the Grant Date or the date of the Issuer's first annual meeting of stockholders immediately following the Grant Date. The Director RSUs were awarded for no consideration other than the Reporting Person's service as a director of the Issuer.

SEC source: 0001628280-26-023399 · wk-form4_1775170763.xml · derivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 8,692

Underlying: Common Stock · 8,692 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: On February 20, 2025, the Reporting Person was granted 43,459 time-vested restricted stock units ("RSUs") which vest in five equal quarterly installments on each of June 30, 2025, September 30, 2025, December 31, 2025, March 31, 2026, and June 30, 2026, such that 100% will be vested on June 30, 2026.

F1 · derivative.expiration_date: On February 20, 2025, the Reporting Person was granted 43,459 time-vested restricted stock units ("RSUs") which vest in five equal quarterly installments on each of June 30, 2025, September 30, 2025, December 31, 2025, March 31, 2026, and June 30, 2026, such that 100% will be vested on June 30, 2026.

SEC source: 0001628280-26-023399 · wk-form4_1775170763.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 552,558

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001628280-26-012300 · wk-form4_1772140576.xml · derivative · entry 3

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 10,748 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: Represents shares of the Issuer's common stock underlying time-vested restricted stock units ("RSUs") on February 24, 2022 (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 a service provider of the Issuer and vested in four equal annual installments beginning on the first anniversary of the Grant Date.

F2 · derivative.exercise_date: Represents shares of the Issuer's common stock underlying time-vested restricted stock units ("RSUs") on February 24, 2022 (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 a service provider of the Issuer and vested in four equal annual installments beginning on the first anniversary of the Grant Date.

F2 · derivative.expiration_date: Represents shares of the Issuer's common stock underlying time-vested restricted stock units ("RSUs") on February 24, 2022 (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 a service provider of the Issuer and vested in four equal annual installments beginning on the first anniversary of the Grant Date.

SEC source: 0001628280-26-012300 · wk-form4_1772140576.xml · nonDerivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 543,866

F1 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $48.80 to $48.86. 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 (1) to this Form 4.

SEC source: 0001628280-26-012300 · wk-form4_1772140576.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 563,866

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001628280-26-011069 · wk-form4_1771967252.xml · derivative · entry 4

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 118,795

Underlying: Common Stock · 59,388 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_date: Represents shares of the Issuer's common stock underlying time-vested RSUs granted on February 20, 2025 (the "2025 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 a service provider of the Issuer and will vest in three equal annual installments beginning on the first anniversary of the 2025 Grant Date and annually thereafter, such that 100% will be vested on the third anniversary of the 2025 Grant Date.

F2 · derivative.expiration_date: Represents shares of the Issuer's common stock underlying time-vested RSUs granted on February 20, 2025 (the "2025 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 a service provider of the Issuer and will vest in three equal annual installments beginning on the first anniversary of the 2025 Grant Date and annually thereafter, such that 100% will be vested on the third anniversary of the 2025 Grant Date.

SEC source: 0001628280-26-011069 · wk-form4_1771967252.xml · derivative · entry 3

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 56,470

Underlying: Common Stock · 112,941 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: Represents shares of Amkor Technology, Inc. (the "Issuer") common stock underlying time-vested restricted stock units ("RSUs") granted on February 20, 2024 (the "2024 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 a service provider of the Issuer and will vest over three years, with 40% of the RSUs vesting on each of the first anniversary and the second anniversary of the 2024 Grant Date, and 20% vesting on the third anniversary of the 2024 Grant Date, such that 100% will be vested on the third anniversary of the 2024 Grant Date.

F1 · derivative.expiration_date: Represents shares of Amkor Technology, Inc. (the "Issuer") common stock underlying time-vested restricted stock units ("RSUs") granted on February 20, 2024 (the "2024 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 a service provider of the Issuer and will vest over three years, with 40% of the RSUs vesting on each of the first anniversary and the second anniversary of the 2024 Grant Date, and 20% vesting on the third anniversary of the 2024 Grant Date, such that 100% will be vested on the third anniversary of the 2024 Grant Date.

SEC source: 0001628280-26-011069 · wk-form4_1771967252.xml · nonDerivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 553,118

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001628280-26-011069 · wk-form4_1771967252.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 493,730

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001628280-26-010222 · wk-form4_1771622350.xml · nonDerivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 380,789

F2 · kind: This Form 4 reports the vesting on February 18, 2026 of 30,587 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.

SEC source: 0001628280-26-010222 · wk-form4_1771622350.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 350,202

F1 · kind: This Form 4 reports the vesting on February 18, 2026 of 10,891 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.

SEC source: 0001628280-26-009053 · wk-form4_1771449298.xml · nonDerivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 339,311

F1 · kind: 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.

F2 · price: 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.

SEC source: 0001628280-26-009053 · wk-form4_1771449298.xml · derivative · entry 3

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 13,919

Underlying: Common Stock · 13,920 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_price: 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.

F3 · derivative.exercise_date: 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.

F3 · derivative.expiration_date: 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.

SEC source: 0001628280-26-009053 · wk-form4_1771449298.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 349,311

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001628280-26-002639 · wk-form4_1768944674.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 335,391

F1 · kind: 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.

F2 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $52.25 to $54.00. 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.

SEC source: 0001628280-26-000440 · wk-form4_1767647798.xml · derivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 17,384

Underlying: Common Stock · 8,692 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: On February 20, 2025, the Reporting Person was granted 43,459 restricted stock units which vest in five equal quarterly installments on each of June 30, 2025, September 30, 2025, December 31, 2025, March 31, 2026, and June 30, 2026, such that 100% will be vested on June 30, 2026.

F1 · derivative.expiration_date: On February 20, 2025, the Reporting Person was granted 43,459 restricted stock units which vest in five equal quarterly installments on each of June 30, 2025, September 30, 2025, December 31, 2025, March 31, 2026, and June 30, 2026, such that 100% will be vested on June 30, 2026.

SEC source: 0001628280-26-000440 · wk-form4_1767647798.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 345,391

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001628280-25-057633 · wk-form4_1766005690.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 336,699

F1 · kind: 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.

F2 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $44.37 to $45.18. 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.

SEC source: 0001628280-25-053216 · wk-form4_1763588332.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 346,699

F1 · kind: 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.

F2 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $31.03 to $32.05. 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.

SEC source: 0001628280-25-045367 · wk-form4_1760733589.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 356,699

F1 · kind: 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.

SEC source: 0001628280-25-043755 · wk-form4_1759437312.xml · derivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 26,076

Underlying: Common Stock · 8,692 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: On February 20, 2025, the Reporting Person was granted 43,459 restricted stock units which vest in five equal quarterly installments on each of June 30, 2025, September 30, 2025, December 31, 2025, March 31, 2026, and June 30, 2026, such that 100% will be vested on June 30, 2026.

F1 · derivative.expiration_date: On February 20, 2025, the Reporting Person was granted 43,459 restricted stock units which vest in five equal quarterly installments on each of June 30, 2025, September 30, 2025, December 31, 2025, March 31, 2026, and June 30, 2026, such that 100% will be vested on June 30, 2026.

SEC source: 0001628280-25-043755 · wk-form4_1759437312.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 366,699

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001628280-25-042480 · wk-form4_1758658526.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 358,007

F1 · kind: 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.

SEC source: 0001047127-25-000161 · wk-form4_1751494581.xml · derivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 34,768

Underlying: Common Stock · 8,691 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: On February 20, 2025, the Reporting Person was granted 43,459 restricted stock units which vest in five equal quarterly installments on each of June 30, 2025, September 30, 2025, December 31, 2025, March 31, 2026, and June 30, 2026, such that 100% will be vested on June 30, 2026.

F1 · derivative.expiration_date: On February 20, 2025, the Reporting Person was granted 43,459 restricted stock units which vest in five equal quarterly installments on each of June 30, 2025, September 30, 2025, December 31, 2025, March 31, 2026, and June 30, 2026, such that 100% will be vested on June 30, 2026.

SEC source: 0001047127-25-000161 · wk-form4_1751494581.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 368,007

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001047127-25-000050 · wk-form4_1740605890.xml · derivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 10,748

Underlying: Common Stock · 10,748 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: On February 24, 2022 (the "Grant Date"), the Reporting Person was granted 42,992 time-vested restricted stock units ("RSUs") of Amkor Technology, Inc. (the "Issuer") pursuant to the Issuer's 2021 Equity Incentive Plan, as amended, and the applicable award agreement. The RSUs convert into shares of the Issuer's common stock on a one-to-one basis and vest in four equal annual installments beginning on the first anniversary of the Grant Date.

F1 · derivative.exercise_date: On February 24, 2022 (the "Grant Date"), the Reporting Person was granted 42,992 time-vested restricted stock units ("RSUs") of Amkor Technology, Inc. (the "Issuer") pursuant to the Issuer's 2021 Equity Incentive Plan, as amended, and the applicable award agreement. The RSUs convert into shares of the Issuer's common stock on a one-to-one basis and vest in four equal annual installments beginning on the first anniversary of the Grant Date.

F1 · derivative.expiration_date: On February 24, 2022 (the "Grant Date"), the Reporting Person was granted 42,992 time-vested restricted stock units ("RSUs") of Amkor Technology, Inc. (the "Issuer") pursuant to the Issuer's 2021 Equity Incentive Plan, as amended, and the applicable award agreement. The RSUs convert into shares of the Issuer's common stock on a one-to-one basis and vest in four equal annual installments beginning on the first anniversary of the Grant Date.

SEC source: 0001047127-25-000050 · wk-form4_1740605890.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 359,316

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001047127-25-000036 · wk-form4_1740174105.xml · derivative · entry 5

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 43,459

Underlying: Common Stock · 43,459 shares

Expires not disclosed

F4 · derivative.exercise_date: Represents shares of the Issuer's common stock underlying time-vested RSUs granted on the 2025 Grant Date pursuant to the Issuer's Equity Incentive Plan, as amended. The RSUs were awarded for no consideration other than the Reporting Person's service as an officer of the Issuer and will vest in five equal installments on each of June 30, 2025, September 30, 2025, December 31, 2025, March 31, 2026, and June 30, 2026, such that 100% will be vested on June 30, 2026.

F4 · derivative.expiration_date: Represents shares of the Issuer's common stock underlying time-vested RSUs granted on the 2025 Grant Date pursuant to the Issuer's Equity Incentive Plan, as amended. The RSUs were awarded for no consideration other than the Reporting Person's service as an officer of the Issuer and will vest in five equal installments on each of June 30, 2025, September 30, 2025, December 31, 2025, March 31, 2026, and June 30, 2026, such that 100% will be vested on June 30, 2026.

SEC source: 0001047127-25-000036 · wk-form4_1740174105.xml · derivative · entry 4

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 178,183

Underlying: Common Stock · 178,183 shares

Expires not disclosed

F3 · derivative.exercise_date: Represents shares of the Issuer's common stock underlying time-vested RSUs granted on February 20, 2025 (the "2025 Grant Date") pursuant to the Issuer's Equity Incentive Plan, as amended. 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 2025 Grant Date and annually thereafter, such that 100% will be vested on the third anniversary of the 2025 Grant Date.

F3 · derivative.expiration_date: Represents shares of the Issuer's common stock underlying time-vested RSUs granted on February 20, 2025 (the "2025 Grant Date") pursuant to the Issuer's Equity Incentive Plan, as amended. 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 2025 Grant Date and annually thereafter, such that 100% will be vested on the third anniversary of the 2025 Grant Date.

SEC source: 0001047127-25-000036 · wk-form4_1740174105.xml · derivative · entry 3

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 169,411

Underlying: Common Stock · 112,941 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_date: On February 20, 2024 (the "2024 Grant Date"), the Reporting Person was granted 282,352 restricted stock units ("RSUs"), 40% of which vest on the first and second anniversary of the 2024 Grant Date, and the remainder of which vest on the third anniversary of the 2024 Grant Date.

F2 · derivative.expiration_date: On February 20, 2024 (the "2024 Grant Date"), the Reporting Person was granted 282,352 restricted stock units ("RSUs"), 40% of which vest on the first and second anniversary of the 2024 Grant Date, and the remainder of which vest on the third anniversary of the 2024 Grant Date.

SEC source: 0001047127-25-000036 · wk-form4_1740174105.xml · nonDerivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 348,568

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001047127-25-000036 · wk-form4_1740174105.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 235,627

F1 · kind: This Form 4 reports the vesting on February 19, 2025 of 16,736 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, 2024 and ending on December 31, 2024.

SEC source: 0001047127-25-000019 · wk-form4_1740001140.xml · derivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 27,839

Underlying: Common Stock · 13,920 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_date: On February 16, 2023 (the "Grant Date"), the Reporting Person was granted 55,679 RSUs which vest in four equal annual installments beginning on the first anniversary of the Grant Date.

F1 · derivative.expiration_date: On February 16, 2023 (the "Grant Date"), the Reporting Person was granted 55,679 RSUs which vest in four equal annual installments beginning on the first anniversary of the Grant Date.

SEC source: 0001047127-25-000019 · wk-form4_1740001140.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 218,891

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001047127-24-000197 · wk-form4_1729197230.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 204,971

F1 · kind: The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 28, 2024.

F2 · price: The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $31.26 to $31.70. 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.

SEC source: 0001047127-24-000175 · wk-form4_1726691672.xml · derivative · entry 3

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 8,125 shares

Expires 2030-07-30

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_date: This stock option to acquire 375,000 shares of the Issuer's common stock was granted on July 30, 2020 and vested in equal quarterly installments over three years, such that 100% of the option vested on the third anniversary of the grant date.

SEC source: 0001047127-24-000175 · wk-form4_1726691672.xml · nonDerivative · entry 2

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 214,971

F1 · kind: The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 28, 2024.

SEC source: 0001047127-24-000175 · wk-form4_1726691672.xml · nonDerivative · entry 1

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 233,096

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001047127-24-000171 · wk-form4_1724099591.xml · derivative · entry 3

Rutten Guillaume Marie Jean · CIK 0001596796 · Director · President and CEO

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 8,125

Underlying: Common Stock · 15,000 shares

Expires 2030-07-30

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_date: This stock option to acquire 375,000 shares of the Issuer's common stock was granted on July 30, 2020 and vested in equal quarterly installments over three years, such that 100% of the option vested on the third anniversary of the grant date.