X0508 4 2026-01-05 0001018963 ATI INC ATI 0001773072 Fields Kimberly A C/O ATI INC. 2021 MCKINNEY AVE., SUITE 1100 DALLAS TX 75201 true true false false President, CEO and Director false Common Stock, par value $0.10 per share 2026-01-05 4 A false 12510 0 A 215178 D Common Stock, par value $0.10 per share 2026-01-05 4 M false 98620 0.00 A 313798 D Common Stock, par value $0.10 per share 2026-01-05 4 F false 38871 121.08 D 274927 D Common Stock, par value $0.10 per share 2026-01-05 4 A false 82216 0.00 A 357143 D Common Stock, par value $0.10 per share 2026-01-05 4 F false 32352 121.08 D 324791 D Common Stock, par value $0.10 per share 2026-01-05 4 F false 7028 121.08 D 317763 D Performance Stock Unit 0.00 2026-01-05 4 M false 35898 0.00 D 2026-12-31 2026-12-31 Common Stock, par value $0.10 per share 98620 35897 D Award of restricted stock units, which are settled in shares of stock upon vesting. The award vests in three equal annual installments on each of the first three anniversaries of the grant date. Awarded under the Issuer's 2022 Incentive Plan. Settlement of one-half of certain Performance Stock Units awarded in 2022 ("2022 Breakout Performance Units"), each of which represented a contingent right to receive shares of the Issuer's Common Stock if the Issuer's Common Stock achieved specified target market prices (based on a 20-trading day average) on the New York Stock Exchange ("NYSE") for at least 20 consecutive trading days (the "20-day Average Market Price") prior to December 31, 2025, up to a maximum of three shares per Unit. The shares underlying one-half of the 2022 Breakout Performance Units became payable as of January 5, 2026 following certification of the Issuer's achievement of the relevant performance criteria by the Compensation and Leadership Development Committee of the Company's Board of Directors (the "CLDC"). The remaining half of the 2022 Breakout Performance Units are scheduled by their terms to become payable in early 2027. Shares withheld for the payment of taxes in connection with the settlement of 2022 Breakout Performance Units. Represents the average of the high and low trading prices for one share of the Issuer's Common Stock on the NYSE on January 5, 2026. Settlement of performance-vested restricted stock units that were granted in 2023, the vesting of which was contingent on the Issuer's total shareholder return relative to a specified peer group during the period from January 1, 2023 through December 31, 2025 (the "2023-2025 PSUs"). The shares underlying the 2023-2025 PSUs became payable as of January 5, 2026 following certification of the Issuer's achievement of the relevant performance criteria by the CLDC. Shares withheld for the payment of taxes in connection with the settlement of the 2023-2025 PSUs. Shares withheld for payment of taxes on restricted stock units awarded in 2023, 2024 and 2025. One third of each such award vested by the terms thereof on January 5, 2026. /s/ Amanda J. Skov, Attorney-in-Fact for Kimberly A. Fields 2026-01-07