ATI INC

ATI Inc. is a Delaware corporation with its corporate headquarters located at 2021 McKinney Avenue, Suite 1100, Dallas, TX 75201, telephone number (800) 289-7454, Internet website address www.atimaterials.com. Our Internet website and content contained therein or connected thereto are not intended to incorporate into this Annual Report on Form 10-K. References to ATI, the Company, the Registrant, we, our and us and similar terms mean ATI Inc. and its subsidiaries, unless the context otherwise requires. When used in this Annual Report on Form 10-K, unless the context otherwise requires or unless otherwise specified, any reference to year is to the Company’s fiscal year. The Company follows a 4-4-5 or 5-4-4 fiscal calendar, whereby each fiscal quarter consists of thirteen weeks grouped into two four-week months and one five-week month, and its fiscal year ends on the Sunday closest to December 31. Fiscal years 2025, 2024 and 2023 ended on December 28, 2025, December 29, 2024, and December 31, 2023, respectively. All fiscal years presented include 52 weeks of operations. Our Business ATI produces specialty materials, highly differentiated by our materials science expertise and advanced process technologies. Our mission is to solve the world’s challenges through materials science. Aerospace & defense, our largest end markets, represent approximately 68% of total sales, led by products for jet engines and airframes in addition to a wide range of defense applications.