Accounting Policies

3 Months Ended

Mar. 29, 2026

Accounting Policies [Abstract]

Accounting Policies

Accounting Policies

The interim consolidated financial statements include the accounts of ATI Inc. and its subsidiaries. Unless the context requires otherwise, “ATI” and “the Company” refer to ATI Inc. and its subsidiaries.

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. Unless otherwise stated, references to years and quarters in this Quarterly Report on Form 10-Q relate to fiscal years and quarters, rather than calendar years and quarters.

These unaudited consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles for interim financial information and with the instructions for Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and note disclosures required by U.S. generally accepted accounting principles for complete financial statements. In management’s opinion, all adjustments (which include only normal recurring adjustments) considered necessary for a fair presentation have been included. These unaudited consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the Company’s 2025 Annual Report on Form 10-K. The results of operations for these interim periods are not necessarily indicative of the operating results for any future period. The December 28, 2025 financial information has been derived from the Company’s audited consolidated financial statements.

Pending Accounting Pronouncements

In November 2024, the FASB issued new accounting guidance related to expense disaggregation disclosures. This guidance requires entities to disclose specified information about certain costs and expenses including (1) the amounts of purchases of inventory, employee compensation, depreciation, and intangible asset amortization, (2) include certain amounts that are already required to be disclosed under current generally accepted accounting principles in the same disclosure as the other disaggregation requirements, (3) a qualitative description of the amounts remaining in relevant expense captions that are not separately disaggregated quantitatively, and (4) the total amount of selling expenses and, in annual reporting periods, an entity’s definition of selling expenses. This new guidance for annual disclosures will be effective for the Company for fiscal year 2027 and for interim disclosures will be effective for the Company for fiscal year 2028. The guidance can be applied prospectively or retrospectively and early adoption is permitted. The Company does not expect to early adopt this guidance and does not expect these changes to have an impact on the Company’s consolidated financial statements other than disclosure requirements.

Reclassifications

The Company reclassified certain prior period amounts in its unaudited condensed consolidated balance sheets to conform to our current period presentation. Specifically, we have reclassified certain amounts in “Other current liabilities” to “Accrued liabilities”. This reclassification has no impact on total liabilities or cash flows.