X0508 4 2025-01-03 0001018963 ATI INC ATI 0001572385 WETHERBEE ROBERT S 2021 MCKINNEY AVENUE SUITE 1100 DALLAS TX 75201 true true false false Executive Chairman false Common Stock, par value $0.10 per share 2025-01-03 4 A false 17822 0 A 454265.3409 D Common Stock, par value $0.10 per share 2025-01-03 4 F false 9144 55.81 D 445121.3409 D Common Stock, par value $0.10 per share 2025-01-06 4 F false 12541 56.63 D 432580.3409 D Common Stock, par value $0.10 per share 2025-01-06 4 A false 286824 0 A 719404.3409 D Common Stock, par value $0.10 per share 2025-01-06 4 F false 112866 56.63 D 606538.3409 D Award of restricted stock units, which are settled in shares of stock upon vesting. The award vests on the first anniversary of the grant date. Awarded under the Issuer's 2022 Incentive Plan. Shares withheld for payment of taxes on restricted stock units awarded in 2023 and 2024. One third of each such award vested by the terms thereof on January 3, 2025. 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 ("NYSE") on January 3, 2025 Shares withheld for the payment of taxes on restricted stock units awarded in 2022. On third of such award vested by its terms on January 6, 2025. Represents the average of the high and low trading prices for one share of the Issuer's stock on the NYSE on January 6, 2025. Settlement of performance-vested restricted stock units that were granted in 2022, the vesting of which was contingent upon the Issuer's total shareholder return relative to a specified peer group during the period from January 1, 2022 through December 31, 2024 (the "2022-2024 PSUs"). The shares underlying the 2022-2024 PSUs became payable as of January 6, 2025 following certification of the Issuer's achievement of the relevant performance criteria by the Compensation and Leadership Development Committee of the Issuer's Board of Directors. Shares withheld for the payment of taxes in connection with the settlement of the 2022-2024 PSUs. /s/ Amanda J. Skov, Attorney-in-Fact for Robert S. Wetherbee 2025-01-07