X0609 4 2026-09-02 0001018963 ATI INC ATI 0001635153 Morehouse David J false C/O ATI INC. 2021 MCKINNEY AVENUE, SUITE 1100 DALLAS TX 75201 true false false false false Common Stock, par value $0.10 per share 2026-09-02 4 S false 2485 201.61 D 35826 D The price reported is a weighted average price. The shares were sold in multiple transactions at prices ranging from $201.56 to to $201.82. The reporting person undertakes to provide to the Issuer, its security holders and the Staff of the U.S. Securities and Exchange Commission (the "SEC"), upon request, full information regarding the number of shares sold at each specific price within the range reported. /s/ Amanda J. Skov, Attorney-in-Fact for David J. Morehouse 2026-09-04