X0306 4 2023-02-10 0 0001047127 AMKOR TECHNOLOGY, INC. AMKR 0001158839 KIM JAMES J C/O SIANA CARR O'CONNOR & LYNAM, 1500 EAST LANCASTER AVENUE, PAOLI PA 19301-9713 1 0 1 1 Member of 10% owner group (5) Common Stock 2023-02-10 4 M 0 2630 0.00 A 2715980 D Common Stock 2023-02-10 4 F 0 1081 27.60 D 2714899 D Common Stock 2610776 I By spouse Common Stock 3470970 I By Self as Trustee of own GRATs Common Stock 164678 I By Self as Trustee of Trust U/A dtd. 12/11/12 Common Stock 49594980 I By 915 Investments, LP Common Stock 1957350 I By John T. Kim G-S Trust dtd 12/11/12 common Stock 7828682 I By John T. Kim Family Trust U/A dtd 12/11/12 Common Stock 1379943 I By Susan Y. Kim 2018-1 GRAT dtd 8/29/18 Common Stock 2298355 I By Susan Y. Kim 2020-1 GRAT dtd 4/1/20 Restricted Stock Units 0.00 2023-02-10 4 M 0 2630 0.00 D Common Stock 2630 5446 D The transaction represents shares withheld by Amkor Technology, Inc. (the "Issuer") in connection with the vesting of certain restricted stock units ("RSUs") granted to the Reporting Person on February 11, 2021 (the "Grant Date") pursuant to the Issuer's Second Amended and Restated 2007 Equity Incentive Plan, as amended, and the related award agreement. These shares were withheld to satisfy the Reporting Person's tax withholding obligations. The Issuer will pay these taxes on behalf of the Reporting Person. The Reporting Person is (i) a trustee of trusts for the benefit of his immediate family members which own 13,464,330 shares of the Issuer's Common Stock, (ii) a trustee of a trust which is a controlling member of a limited liability company being treated as a corporation for purposes of Section 16 , which limited liability company holds 164,678 shares of the Issuer's Common stock, (iii) a trustee of grantor retained annuity trusts of which he was the settlor and is the sole annuitant which own 3,470,970 shares of the Issuer's Common Stock and (iv) a general partner of a limited partnership which owns 49,594,980 shares of the Issuer's Common Stock. Pursuant to the Form 4 instructions, the Reporting Person is being treated as having a pecuniary interest in all of such shares. The Reporting Person disclaims beneficial ownership of these securities, except to the extent of the Reporting Person's pecuniary interest therein, and this report shall not be deemed an admission that the Reporting Person is the beneficial owner of such securities, except to the extent of the Reporting Person's pecuniary interest therein, for purposes of Section 16 of the Securities Exchange Act of 1934, as amended ("Section 16"), or for any other purpose. On the Grant Date, the Reporting Person was granted 10,893 RSUs which vest in four equal annual installments beginning on the first anniversary of the Grant Date. (5) The Reporting Person states that the filing of this Form 4 shall not be deemed an admission that the Reporting Person is the beneficial owner of the reported securities owned by the other members of the group, for the purpose of Section 16, or for any other purpose. Mark N. Rogers, Attorney-in-Fact for James J. Kim 2023-02-14