X0306 4/A 2022-02-24 2022-02-28 0 0001018963 ALLEGHENY TECHNOLOGIES INC ATI 0001282236 NEWMAN DONALD P C/O ALLEGHENY TECHNOLOGIES INCORPORATED 1000 SIX PPG PLACE PITTSBURGH PA 15217 0 1 0 0 EVP and CFO Common Stock, par value $0.10 per share 2022-02-24 4 F 0 2636 23.54 D 144137 D Shares withheld for payment of taxes on restricted stock units awarded on February 24, 2020. One-third of such restricted stock units vested by their terms on February 24, 2022. This amended Form 4 is filed to reflect an administrative correction to the number of shares withheld for the payment of taxes with respect to the vesting of restricted stock units awarded on February 24, 2020, as reflected on Table I above. /s/ Amanda J. Skov, Attorney-in-Fact for Donald P. Newman 2022-03-25