Sec Form 4 Filing - Rutten Guillaume Marie Jean @ AMKOR TECHNOLOGY, INC. - 2025-02-19

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL OMB Number: 3235-0287 Expires: November 30, 2011 Estimated average burden hours per response... 0.5

1. Name and Address of Reporting Person Rutten Guillaume Marie Jean 2. Issuer Name and Ticker or Trading Symbol AMKOR TECHNOLOGY, INC. [ AMKR] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) President and CEO (Last) (First) (Middle) 2045 EAST INNOVATION CIRCLE 3. Date of Earliest Transaction (MM/DD/YY) 02/19/2025 (Street) TEMPE, AZ85284 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 02/19/2025 A( 1 ) 16,736 A $ 0 235,627 D Common Stock 02/20/2025 M 112,941 A $ 0 348,568 D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Restricted Stock Units $ 0 02/20/2025 M 112,941 ( 2 ) ( 2 ) Common Stock 112,941 $ 0 169,411 D Restricted Stock Units $ 0 02/20/2025 A 178,183 ( 3 ) ( 3 ) Common Stock 178,183 $ 0 178,183 D Restricted Stock Units $ 0 02/20/2025 A 43,459 ( 4 ) ( 4 ) Common Stock 43,459 $ 0 43,459 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Rutten Guillaume Marie Jean 2045 EAST INNOVATION CIRCLE TEMPE, AZ85284 X President and CEO Signatures Mark N. Rogers, Attorney-in-Fact for Guillaume Marie Jean Rutten 02/21/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )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. ( 2 )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. ( 3 )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. ( 4 )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.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.