ATI Inc. Officer Files Form 144 to Sell $1.73M in Common Stock

Executive Summary

On September 21, 2026, Timothy J. Harris, an Officer of ATI INC ($ATI), submitted a Form 144 notice proposing the sale of 9,000 shares of common stock through Fidelity Brokerage Services LLC. The aggregate market value of the proposed transaction is approximately $1,726,380, reflecting an implied price of $191.82 per share.

Transaction Details

• Securities to be Sold: 9,000 shares of Common Stock.
• Origin of Shares: Acquired between February 2020 and January 2022 via restricted stock vestings as equity compensation.
• Rule 10b5-1 Plan: The filing notes an adoption date of May 21, 2026, indicating the transactions are executing under a pre-scheduled trading plan.

Prior Sales (Past 3 Months)

Prior to this filing, the reporting owner executed four sales within the preceding 30 days under the same program:

• 08/24/2026: 16,500 shares for $3,414,180.00
• 08/31/2026: 16,500 shares for $3,465,165.00
• 09/08/2026: 16,500 shares for $3,424,410.00
• 09/14/2026: 16,500 shares for $3,185,490.00

Including the proposed 9,000 shares, the total recent selling volume reaches 75,000 shares valued at over $15.2M.

Significance Assessment

The proposed transaction represents less than 0.01% of ATI Inc.'s 136,170,383 shares outstanding. While the transaction size itself carries negligible dilution or market absorption risk, the frequency and cumulative dollar value of dispositions under the May 2026 10b5-1 plan warrant a Medium significance rating.