X0306 4 2021-09-16 0 0001047127 AMKOR TECHNOLOGY, INC. AMKR 0001684564 Faust Megan 2045 E INNOVATION CIRCLE TEMPE AZ 85284 0 1 0 0 CFO Common Stock 2021-09-16 4 M 0 4500 8.88 A 19344 D Common Stock 2021-09-16 4 M 0 500 9.48 A 19844 D Common Stock 2021-09-16 4 S 0 5000 28.63 D 14844 D Employee Stock Option (Right-to-Buy) 8.88 2021-09-16 4 M 0 4500 0.00 D 2017-09-12 2026-09-12 Common Stock 4500 0 D Employee Stock Option (right-to-Buy) 9.48 2021-09-16 4 M 0 500 0.00 D 2020-02-15 2029-02-15 Common Stock 500 149500 D The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on February 11, 2021. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $28.45 to $28.73.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. This stock option (the "2016 Option") to acquire 75,000 shares of the Issuer's common stock (the "2016 Option Shares") was granted on September 12, 2016 (the "2016 Grant Date") and vested over four years as follows: (i) with respect to 25% of the 2016 Option Shares, on the first anniversary of the 2016 Grant Date; and (ii) with respect to the remainder of the 2016 Option Shares, in equal quarterly installments thereafter, such that 100% of the 2016 Option became vested on the fourth anniversary of the 2016 Grant Date. This stock option (the "2019 Option") to acquire 150,000 shares of the Issuer's common stock (the "2019 Option Shares") was granted on February 15, 2019 (the "2019 Grant Date") and vests over four years as follows: (i) with respect to 25% of the 2019 Option Shares, on the first anniversary of the 2019 Grant Date; and (ii) with respect to the remainder of the 2019 Option Shares, in equal quarterly installments thereafter, such that 100% of the 2019 Option will vest on the fourth anniversary of the 2019 Grant Date. Mark N. Rogers, Attorney-in-Fact for Megan Faust 2021-09-20