X0306 4 2021-02-24 0 0001018963 ALLEGHENY TECHNOLOGIES INC ATI 0001520037 Davis Elliot S 1000 SIX PPG PLACE PITTSBURGH PA 15222 0 1 0 0 Sr VP, GC, CCO and Secretary Common Stock, par value $0.10 per share 2021-02-24 4 F 0 2213 21.28 D 208048.4709 D Common Stock, par value $0.10 per share 2021-02-25 4 A 0 16055 0.00 A 224103.4709 D Common Stock, par value $0.10 per share 2021-02-25 4 F 0 6981 21.26 D 217122.4709 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, 2021. Represents the average of the high and low trading prices for one share of the Issuer's common stock on the New York Stock Exchange on February 24, 2021. Settlement of performance-vested restricted stock units that were granted in 2018, the vesting of which was contingent upon the Issuer's achievement of specified performance criteria during the period form January 1, 2018 through December 31, 2020 (the "2018-2020 PSUs"). The shares underlying the 2018-2020 PSUs became payable as of February 25, 2021 following certification of the Issuer's achievement of such performance criteria by the Personnel and Compensation Committee of the Issuer's Board of Directors. Shares withheld for payment of taxes in connection with the February 25, 2021 settlement of the 2018-2020 PSUs. Represents the average of the high and low trading prices for one share of the Issuer's common stock on the New York Stock Exchange on February 25, 2021. /s/ Elliot S. Davis 2021-02-26