Form 4 Filing for ATI INC.

This Form 4 filing reports a transaction by Harris Timothy J, Senior VP and CDIO of ATI INC. On August 24, 2026, Mr. Harris sold 16,500 shares of common stock at a price of $206.92 per share. This sale was executed under a 10b5-1 Trading Plan established on May 21, 2026, for personal tax and estate planning purposes. Following this transaction, Mr. Harris owns 146,687 shares of ATI INC. common stock. The filing is signed by an attorney-in-fact on behalf of Mr. Harris.