Summary of Significant Accounting Policies	12 Months Ended
Dec. 29, 2024
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Principles of Consolidation and Reporting The consolidated financial statements include the accounts of ATI Inc. and its subsidiaries. The financial results of majority-owned joint ventures are consolidated into the Company’s operating results and financial position, with the minority ownership interest recognized in the consolidated statement of operations as net income attributable to noncontrolling interests, and as equity attributable to the noncontrolling interests within total stockholders’ equity. The results for the Shanghai STAL Precision Stainless Steel Company Limited (STAL) are reported on a one month lag. Investments in which the Company exercises significant influence, but which it does not control (generally a 20% to 50% ownership interest) are accounted for under the equity method of accounting, whereby ATI’s carrying value of the equity method investment on the consolidated balance sheet is the capital investment and any undistributed profit or loss. The investments are classified in other (noncurrent) assets on the consolidated balance sheet. The profit or loss attributable to ATI from equity method investments is included in the consolidated statements of operations as a component of Other (non-operating) income (expense). See Note 7 for further explanation of the Company’s joint ventures. Intercompany accounts and transactions have been eliminated. Unless the context requires otherwise, “ATI” and the “Company” refer to ATI Inc. and its subsidiaries. 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. Unless otherwise stated, references to years in this Annual Report on Form 10-K relate to fiscal years, rather than calendar years. Fiscal years 2024, 2023 and 2022 ended on December 29, 2024, December 31, 2023 and January 1, 2023, respectively. All fiscal years presented include 52 weeks of operations. Risks and Uncertainties and Use of Estimates The preparation of consolidated financial statements in conformity with United States (U.S.) generally accepted accounting principles requires management to make estimates and assumptions that affect reported amounts of assets and liabilities at the date of the financial statements, as well as the reported amounts of income and expenses during the reporting period. Actual results could differ from those estimates. Management believes that the estimates are reasonable. The Company markets its products to a diverse customer base, principally throughout the U.S. No single customer accounted for more than 10% of sales for any year presented. The core end markets for ATI’s products are customers in the aerospace & defense, specialty energy, electronics, and medical markets. At December 29, 2024, ATI has approximately 7,700 active employees, of which approximately 15% are located outside the U.S. Approximately 35% of ATI’s workforce is covered by various collective bargaining agreements (CBAs), predominantly with the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied & Industrial Service Workers International Union (USW). The Company is currently renegotiating the CBAs, which expire on February 28, 2025, that cover approximately 1,100 USW-represented full-time employees within our Advanced Alloys & Solutions operations. There can be no assurance that the Company will successfully conclude these renegotiations to replace the expiring CBA. Cash and Cash Equivalents Cash equivalents are highly liquid investments that are readily convertible to cash with original maturities of three months or less. Accounts Receivable Accounts receivable are presented net of a reserve for doubtful accounts of $15.0 million and $3.2 million at December 29, 2024 and December 31, 2023, respectively. Trade credit is extended based upon periodically updated evaluations of each customer’s ability to perform its obligations. The Company determines a reserve for doubtful accounts based on an aging of accounts receivable and reviews of specific accounts identified as collection risks, as well as expected credit losses. Amounts are written-off against the reserve in the period it is determined that the receivable is uncollectible. Inventories Inventories are stated at the lower of cost or net realizable value with the cost of inventories determined using either first in, first out (FIFO) or average cost methods. Costs include direct material, direct labor and applicable manufacturing and engineering overhead, and other direct costs. The term net realizable value is defined as estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The Company evaluates product lines on a quarterly basis to identify inventory carrying values that exceed estimated net realizable value. The calculation of a resulting reserve, if any, is recognized as an expense in the period that the need for the reserve is identified. It is the Company’s general policy to write-down to scrap value any inventory that is identified as slow-moving or aged more than twelve months, subject to sales, backlog and anticipated order considerations. In some instances this aging criterion is up to twenty-four months. Inventory valuation reserves also include amounts pertaining to intercompany profit elimination between different subsidiaries. Long-Lived Assets Property, plant and equipment are recorded at cost, including capitalized interest, and include long-lived assets acquired under finance leases. Depreciation is primarily recorded using the straight-line method. The Company periodically reviews estimates of useful life and production capacity assigned to new and in-service assets. Significant enhancements, including major maintenance activities that extend the lives of property and equipment, are capitalized. Costs related to repairs and maintenance are charged to expense in the period incurred. The cost and related accumulated depreciation of property and equipment retired or disposed of are removed from the accounts and any related gains or losses are included in income. The Company monitors the recoverability of the carrying value of its long-lived assets. An impairment charge is recognized when an indicator of impairment occurs and the expected net undiscounted future cash flows from an asset’s use (including any proceeds from disposition) are less than the asset’s carrying value and the asset’s carrying value exceeds its fair value. If an impairment loss is recognized, the adjusted carrying value of the long-lived asset is its new cost basis and this new cost basis is depreciated over the remaining useful life of the asset. Assets to be disposed of by sale are stated at the lower of their fair values or carrying amounts and depreciation is no longer recognized. Leases The Company classifies leases as either operating or financing and records a right-of-use (ROU) asset and a lease liability on the consolidated balance sheets as further discussed below. The lease liability is equal to the present value of the minimum lease payments for the term of the lease, including any optional renewal periods determined to be reasonably certain to be exercised, using the discount rate determined at lease commencement. This discount rate is the rate implicit in the lease, if known; otherwise, the incremental borrowing rate (IBR) for the expected lease term is used. The Company’s IBRs approximate the rate the Company would have to pay to borrow on a collateralized basis over a similar term at lease inception. The ROU asset is equal to the initial measurement of the lease liability plus any lease payments made to the lessor at or before the commencement date and any unamortized initial direct costs incurred by the lessee, less any unamortized lease incentives received. The Company has elected to not separate lease components from non-lease components for all asset classes, and has made an accounting policy election to apply the short-term exception, which does not require the capitalization of leases with terms of 12 months or less. ROU assets for operating leases are classified in other long-term assets, and ROU assets for finance leases are classified in property, plant and equipment on the consolidated balance sheet. For operating leases, short-term lease liabilities are classified in other current liabilities, and long-term lease liabilities are classified in other long-term liabilities on the consolidated balance sheet. For finance leases, short-term lease liabilities are classified in short-term debt, and long-term lease liabilities are classified in long-term debt on the consolidated balance sheet. On the cash flow statement, payments for operating leases are classified as operating activities. Payments for finance leases are classified as a financing activity, except for the interest component of the payment which is classified as an operating activity. The Company has lease contracts for real property and machinery and equipment. At inception of a contract, the Company determines whether the contract is or contains a lease. If the Company has a right to obtain substantially all of the economic benefits from the use of the identified asset and the right to direct the use of the asset, then the contract contains a lease. Several of the Company’s real property lease contracts include options to extend the lease term, and the Company reassesses the likelihood of renewal on at least an annual basis. In addition, several real property leases include variable lease payments, for items such as common area maintenance and utilities, which are expensed as incurred as variable lease expense. Goodwill Goodwill is reviewed annually for impairment, or more frequently if impairment indicators arise. The review for goodwill impairment requires a comparison of the fair value of each reporting unit that has goodwill associated with its operations with its carrying amount, including goodwill. If this comparison reflects impairment, then the loss would be measured as the excess of the carrying value over the calculated fair value. Generally accepted accounting principles provide the option to qualitatively assess goodwill for impairment before completing a quantitative assessment. Under the qualitative approach, if, after assessing the totality of events or circumstances, including both macroeconomic, industry and market factors, and entity-specific factors, the Company determines it is likely (more likely than not) that the fair value of a reporting unit is greater than its carrying amount, then the quantitative impairment analysis is not required. The quantitative assessment may be performed each year for a reporting unit at the Company’s option without first performing a qualitative assessment. The Company’s quantitative assessment of goodwill for possible impairment includes estimating the fair value of a reporting unit which has goodwill associated with its operations using discounted cash flow and multiples of cash earnings valuation techniques, plus valuation comparisons to recent public sale transactions of similar businesses, if any. These impairment assessments and valuation methods require the Company to make estimates and assumptions regarding revenue growth, changes in working capital and capital expenditures, selling prices and profitability that drive cash flows, and the weighted average cost of capital. Many of these assumptions are determined by reference to market participants identified by the Company. Although management believes that the estimates and assumptions used were reasonable, actual results could differ from those estimates and assumptions. Other events and changes in circumstances may also require goodwill to be tested for impairment between annual measurement dates. While a decline in stock price and market capitalization is not specifically cited as a goodwill impairment indicator, a company’s stock price and market capitalization should be considered in determining whether it is more likely than not that the fair value of a reporting unit is less that its carrying value. Additionally, a significant decline in a company’s stock price may suggest that an adverse change in the business climate may have caused the fair value of one or more reporting units to fall below carrying value. A sustained decline in market capitalization below book value may be determined to require an interim goodwill impairment review. Environmental Costs that mitigate or prevent future environmental contamination or extend the life, increase the capacity or improve the safety or efficiency of property utilized in current operations are capitalized. Other costs that relate to current operations or an existing condition caused by past operations are expensed. Environmental liabilities are recorded when the Company’s liability is probable and the costs are reasonably estimable, but generally not later than the completion of the feasibility study or the Company’s recommendation of a remedy or commitment to an appropriate plan of action. The accruals are reviewed periodically and, as investigations and remediations proceed, adjustments of the accruals are made to reflect new information as appropriate. Accruals for losses from environmental remediation obligations are not discounted to their present value. The accruals are not reduced by possible recoveries from insurance carriers or other third parties, but do reflect allocations among potentially responsible parties (PRPs) at Federal Superfund sites or similar state-managed sites after an assessment is made of the likelihood that such parties will fulfill their obligations at such sites and after appropriate cost-sharing or other agreements are entered. The measurement of environmental liabilities by the Company is based on currently available facts, present laws and regulations, and current technology. Such estimates take into consideration the Company’s prior experience in site investigation and remediation, the data concerning cleanup costs available from other companies and regulatory authorities, and the professional judgment of the Company’s environmental experts in consultation with outside environmental specialists, when necessary. Foreign Currencies Assets and liabilities of international operations are translated into U.S. dollars using fiscal year-end exchange rates, while revenues and expenses are translated at average exchange rates during the period. The resulting net translation adjustments are recorded as a component of accumulated other comprehensive income (loss) in stockholders’ equity. Gains and losses for transactions denominated in foreign currencies are reported in costs of sales or general and administrative expenses in the consolidated statement of operations based on the underlying nature of the transaction. Sales Recognition The Company’s contracts with customers are comprised of purchase orders, and for larger customers long-term agreements (LTAs). LTAs typically extend multiple years and are utilized by the Company and certain of its customers for its specialty materials, in the form of mill products, powders, parts and components, to reduce supply uncertainty. While LTAs generally define commercial terms including pricing, termination clauses and other contractual requirements, the Company has determined that the contract with a customer is established when the customer purchase order is accepted or acknowledged. Contracts (purchase orders) with customers typically relate to the manufacturing of products, which are defined on a line by line basis, and each distinct good represents a single performance obligation that is satisfied at a point in time when control of the product passes to the customer. For most transactions, control passes at the time of shipment in accordance with agreed upon delivery terms. On occasion, shipping and handling charges occur after the customer obtains control of the good. When this occurs, the shipping and handling services are considered activities to fulfill the promise to transfer the good. Sales for conversion services that transform customer-owned inventory to a different dimension, product form, and/or changed mechanical properties are recognized when the service is completed. Pricing for the Company’s products is also defined in the customer purchase order or LTA on a line item basis and, in some cases, includes variable consideration. Variable consideration is when the selling price of the good is not known or is subject to adjustment under certain conditions. Types of variable consideration may include volume discounts, customer rebates and surcharges. ATI also provides assurances that goods or services will meet the product specifications contained within the acknowledged customer contract. As such, returns and refunds reserves are estimated based upon past product line history or, at certain locations, on a claim by claim basis. Certain customer agreements involving production of parts and components require revenue to be recognized over time due to there being no alternative use for the product without significant economic loss and an enforceable right to payment including a normal profit margin from the customer in the event of contract termination. The Company uses an input method for determining the amount of revenue, and associated standard cost, to recognize over-time revenue, cost and gross margin for these customer agreements. The input methods used for these agreements include costs incurred and labor hours expended, both of which give an accurate representation of the progress made toward complete satisfaction of that particular performance obligation. Contract assets are recognized when ATI’s conditional right to consideration for goods or services have transferred to the customer. A conditional right indicates that additional performance obligations associated with the contract are yet to be satisfied. Contract assets are assessed separately for impairment purposes. When ATI’s right to consideration from the customer is unconditional, this asset is accounted for as a receivable and presented separately from contract assets. A right is unconditional if nothing other than the passage of time is required before payment of that consideration is due. Performance obligations that are recognized as revenue at a point-in-time and are billed to the customer are recognized as accounts receivable. Payment terms vary from customer to customer depending upon credit worthiness, prior payment history and other credit considerations. Contract costs are the incremental costs of obtaining and fulfilling a contract (i.e., costs that would not have been incurred if the contract had not been obtained) to provide goods and services to customers. Contract costs for ATI largely consist of design and development costs for molds, dies and other tools that ATI will own and that will be used in producing the products under the supply arrangement. Contract costs are classified as non-current assets and amortized to expense on a systematic and rational basis over a period consistent with the transfer to the customer of the goods or services to which the asset relates. Contract liabilities are recognized when ATI has received consideration from a customer to transfer goods or services at a future point in time when the Company performs under the contract. Elements of variable consideration discussed above may be recorded as contract liabilities. In addition, progress billings and advance payments from customers for costs incurred to date are also reported as contract liabilities. Research and Development Research, development and technical service activities are closely interrelated and directed toward development of new products, improvement of existing products, quality assurance, development of new manufacturing methods, improvement of existing manufacturing methods, and reducing the Company’s manufacturing costs. Research and development costs are expensed as incurred. Company funded research and development costs were $19.6 million in fiscal year 2024, $20.7 million in fiscal year 2023, and $16.3 million in fiscal year 2022. Customer funded research and development costs were $2.5 million in fiscal year 2024, $1.4 million in fiscal year 2023, and $1.4 million in fiscal year 2022. Government Assistance The Company enters into agreements with U.S. federal agencies, U.S. state and local governments, and foreign governments that provide financial assistance and incentives supporting both new capital projects to expand and enhance manufacturing capabilities and also to sustain and maintain existing operations. Depending on the nature of the government program, the financial impacts may be recorded as a reduction to cost of sales through direct offset of labor and overhead costs or lower depreciation expense, or as a reduction of selling, general and administrative expenses for property tax abatement or other similar categories. Benefits from government assistance are recognized as the activities are incurred, subject to ongoing assessments of meeting other relevant terms such as employment or expenditure levels. In November 2021, ATI entered into an agreement with the U.S. Department of Transportation under the Aviation Manufacturing Jobs Protection (AMJP) program for a grant of up to $22.2 million. The receipt of the award was primarily conditioned upon the Company committing to not furlough or lay off a defined group of employees in the High Performance Materials & Components (HPMC) segment operations during the six-month period of performance between November 2021 and May 2022. The AMJP grant benefit was recognized over the six-month performance period as a reduction to cost of sales in proportion to the compensation expense that the award was intended to defray, with $16.6 million recognized in fiscal year 2022 operating results. Cash receipts from the AMJP program were $11.0 million in fiscal year 2022, and this program is now completed. ATI is a party to various U.S. states’ economic development incentive programs that provide economic benefits in the forms of property tax relief or cash payments to offset capital expenditures. These programs generally include requirements for levels of capital spending and/or employment to qualify for the government assistance. For the fiscal years ended December 29, 2024, December 31, 2023 and January 1, 2023, these state-level programs reduced selling, general and administrative expenses by $1.7 million, $1.4 million, $1.6 million, respectively, and cash receipts were $2.5 million, $3.4 million and $2.8 million, respectively. Receivables for ongoing programs are $1.2 million as of both December 29, 2024 and December 31, 2023. Defined Benefit Pension and Postretirement Plans The remeasurement of projected benefit obligation and plan assets for defined benefit pension plans are immediately recognized in earnings through net periodic pension benefit cost within nonoperating retirement benefit expense on the consolidated statements of operations, with pension plans to be remeasured annually in the fourth quarter or on an interim basis as triggering events require remeasurement. For the remeasurement of projected benefit obligation and plan assets for defined benefit postretirement plans, the Company defers the recognition of these gains and losses in accumulated other comprehensive loss on the consolidated balance sheet, and the accumulated actuarial gains/losses are then amortized into net periodic benefit costs within nonoperating retirement benefit expense on the consolidated statements of operations over the average expected remaining life of plan participants. Stock-based Compensation The Company accounts for stock-based compensation transactions, such as nonvested restricted stock or stock units and performance equity awards, using fair value. Compensation expense for an award is estimated at the date of grant and is recognized over the requisite service period. Compensation expense is adjusted for equity awards that do not vest because service or performance conditions are not satisfied. However, compensation expense already recognized on awards which vest based solely on the attainment of market conditions, such as total shareholder return measures, is not adjusted based on the award attainment status at the end of the measurement period. Compensation expense is adjusted for estimated forfeitures over the award measurement period. Income Taxes The provision for, or benefit from, income taxes includes deferred taxes resulting from temporary differences in income for financial and tax purposes using the liability method. Such temporary differences result primarily from differences in the carrying value of assets and liabilities. Future realization of deferred income tax assets requires sufficient taxable income within the carryback and/or carryforward period available under tax law. The Company evaluates on a quarterly basis whether, based on all available evidence, it is probable that the deferred income tax assets are realizable. Valuation allowances are established when it is estimated that it is more likely than not that the tax benefit of the deferred tax asset will not be realized. The evaluation includes the consideration of all available evidence, both positive and negative, regarding the estimated future reversals of existing taxable temporary differences, estimated future taxable income exclusive of reversing temporary differences and carryforwards, historical taxable income in prior carryback periods if carryback is permitted, and potential tax planning strategies which may be employed to prevent an operating loss or tax credit carryforward from expiring unused. The verifiable evidence such as future reversals of existing temporary differences and the ability to carryback are considered before the subjective sources such as estimated future taxable income exclusive of temporary differences and tax planning strategies. It is the Company’s policy to classify interest and penalties recognized on underpayment of income taxes as income tax expense. It is also the Company’s policy to recognize deferred tax amounts stranded in accumulated other comprehensive income (AOCI), which result from tax rate differences on changes in AOCI balances, as an element of income tax expense in the period that the related balance sheet item associated with the AOCI balance ceases to exist. In the case of derivative financial instruments accounted for as hedges, or marketable securities, ATI uses the portfolio method where the stranded deferred tax amount is recognized when all items of a particular category, such as cash flow hedges of a particular risk such as a foreign currency hedge, are settled. In the case of defined benefit pension and other postretirement benefit plans, the stranded deferred tax balance is recognized as an element of income tax expense in the period the benefit plan is extinguished or divested. Net Income Per Common Share Basic and diluted net income per share are calculated by dividing the net income available to common stockholders by the weighted average number of common shares outstanding during the fiscal year. Diluted amounts assume the issuance of common stock for all potentially dilutive share equivalents outstanding. The calculations of all diluted income/loss per share figures for a period exclude the potentially dilutive effect of dilutive share equivalents if there is a net loss since the inclusion in the calculation of additional shares in the net loss per share would result in a lower per share loss and therefore be anti-dilutive. New Accounting Pronouncements Adopted In September 2022, the Financial Accounting Standards Board (FASB) issued new accounting guidance related to disclosures about supplier finance programs. Supplier finance programs allow a buyer to offer its suppliers the option for access to payment in advance of an invoice due date, which is paid by a third-party finance provider or intermediary on the basis of invoices that the buyer has confirmed as valid. This new guidance requires a buyer in a supplier finance program to disclose sufficient information about the program to allow a user of financial statements to understand the program’s nature, activity during the period, changes from period to period, and potential magnitude, using both qualitative and quantitative information about its supplier finance programs. This new guidance, with the exception of annual disclosures on rollforward information, was effective for the Company in fiscal year 2023, and the Company adopted this new accounting guidance effective January 2, 2023. The annual rollforward information disclosures were effective for the Company in fiscal year 2024, and the Company adopted this new accounting guidance effective January 1, 2024. The adoption of these changes did not have an impact on the Company’s consolidated financial statements other than disclosure requirements which are included in Note 9. In November 2023, the FASB issued new accounting guidance related to segment reporting disclosures. This guidance requires additional disclosures on an annual and interim basis of segment information, including significant segment expenses that are regularly provided to the chief operating decision maker (CODM) and the presentation and composition of other segment items, which is the difference between segment revenue less segment expenses and the measure of segment profit or loss. The guidance also requires that all current segment disclosures required on an annual basis be provided on an interim basis and requires disclosure of the title and position of the CODM and how the CODM uses the reported measure of segment profit or loss in assessing performance and allocating resources. This guidance does not change how an entity identifies its reportable segments. The Company adopted this new guidance for annual disclosures for fiscal year 2024 and will adopt it for interim disclosures in fiscal year 2025. The adoption of these changes did not have an impact on the Company’s consolidated financial statements other than disclosure requirements which are included in Note 18. Pending Accounting Pronouncements In December 2023, the FASB issued new accounting guidance related to income tax disclosures. This guidance requires entities to disclose specific categories in its annual rate reconciliation and provide additional information for reconciling items that meet a quantitative threshold. This guidance also requires additional annual disclosures for income taxes paid and requires disaggregation of income before tax, between domestic and foreign, and income tax expense, between federal, state and foreign. This guidance also eliminates several current disclosure requirements related to the nature and estimate of the range of the reasonably possible change in the unrecognized tax benefits balance in the next 12 months and making a statement that an estimate of the range cannot be made and disclosing the cumulative amount of each type of temporary difference when a deferred tax liability is not recognized because of the exceptions to comprehensive recognition of deferred taxes related to subsidiaries and corporate joint ventures. This new guidance will be effective for the Company for fiscal year 2025 and must be applied on a prospective basis with retrospective application permitted. Early adoption of this guidance is also 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. 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.

The consolidated financial statements include the accounts of ATI Inc. and its subsidiaries. The financial results of majority-owned joint ventures are consolidated into the Company’s operating results and financial position, with the minority ownership interest recognized in the consolidated statement of operations as net income attributable to noncontrolling interests, and as equity attributable to the noncontrolling interests within total stockholders’ equity. The results for the Shanghai STAL Precision Stainless Steel Company Limited (STAL) are reported on a one month lag. Investments in which the Company exercises significant influence, but which it does not control (generally a 20% to 50% ownership interest) are accounted for under the equity method of accounting, whereby ATI’s carrying value of the equity method investment on the consolidated balance sheet is the capital investment and any undistributed profit or loss. The investments are classified in other (noncurrent) assets on the consolidated balance sheet. The profit or loss attributable to ATI from equity method investments is included in the consolidated statements of operations as a component of Other (non-operating) income (expense). See Note 7 for further explanation of the Company’s joint ventures. Intercompany accounts and transactions have been eliminated. 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 in this Annual Report on Form 10-K relate to fiscal years, rather than calendar years. Fiscal years 2024, 2023 and 2022 ended on December 29, 2024, December 31, 2023 and January 1, 2023, respectively. All fiscal years presented include 52 weeks of operations.

The preparation of consolidated financial statements in conformity with United States (U.S.) generally accepted accounting principles requires management to make estimates and assumptions that affect reported amounts of assets and liabilities at the date of the financial statements, as well as the reported amounts of income and expenses during the reporting period. Actual results could differ from those estimates. Management believes that the estimates are reasonable.

At December 29, 2024, ATI has approximately 7,700 active employees, of which approximately 15% are located outside the U.S. Approximately 35% of ATI’s workforce is covered by various collective bargaining agreements (CBAs), predominantly with the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied & Industrial Service Workers International Union (USW). The Company is currently renegotiating the CBAs, which expire on February 28, 2025, that cover approximately 1,100 USW-represented full-time employees within our Advanced Alloys & Solutions operations. There can be no assurance that the Company will successfully conclude these renegotiations to replace the expiring CBA.

Accounts receivable are presented net of a reserve for doubtful accounts of $15.0 million and $3.2 million at December 29, 2024 and December 31, 2023, respectively. Trade credit is extended based upon periodically updated evaluations of each customer’s ability to perform its obligations. The Company determines a reserve for doubtful accounts based on an aging of accounts receivable and reviews of specific accounts identified as collection risks, as well as expected credit losses. Amounts are written-off against the reserve in the period it is determined that the receivable is uncollectible.

Inventories are stated at the lower of cost or net realizable value with the cost of inventories determined using either first in, first out (FIFO) or average cost methods. Costs include direct material, direct labor and applicable manufacturing and engineering overhead, and other direct costs. The term net realizable value is defined as estimated selling price in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation.

The Company evaluates product lines on a quarterly basis to identify inventory carrying values that exceed estimated net realizable value. The calculation of a resulting reserve, if any, is recognized as an expense in the period that the need for the reserve is identified. It is the Company’s general policy to write-down to scrap value any inventory that is identified as slow-moving or aged more than twelve months, subject to sales, backlog and anticipated order considerations. In some instances this aging criterion is up to twenty-four months. Inventory valuation reserves also include amounts pertaining to intercompany profit elimination between different subsidiaries.

Property, plant and equipment are recorded at cost, including capitalized interest, and include long-lived assets acquired under finance leases. Depreciation is primarily recorded using the straight-line method. The Company periodically reviews estimates of useful life and production capacity assigned to new and in-service assets. Significant enhancements, including major maintenance activities that extend the lives of property and equipment, are capitalized. Costs related to repairs and maintenance are charged to expense in the period incurred. The cost and related accumulated depreciation of property and equipment retired or disposed of are removed from the accounts and any related gains or losses are included in income.

The Company monitors the recoverability of the carrying value of its long-lived assets. An impairment charge is recognized when an indicator of impairment occurs and the expected net undiscounted future cash flows from an asset’s use (including any proceeds from disposition) are less than the asset’s carrying value and the asset’s carrying value exceeds its fair value. If an impairment loss is recognized, the adjusted carrying value of the long-lived asset is its new cost basis and this new cost basis is depreciated over the remaining useful life of the asset. Assets to be disposed of by sale are stated at the lower of their fair values or carrying amounts and depreciation is no longer recognized.

The Company classifies leases as either operating or financing and records a right-of-use (ROU) asset and a lease liability on the consolidated balance sheets as further discussed below. The lease liability is equal to the present value of the minimum lease payments for the term of the lease, including any optional renewal periods determined to be reasonably certain to be exercised, using the discount rate determined at lease commencement. This discount rate is the rate implicit in the lease, if known; otherwise, the incremental borrowing rate (IBR) for the expected lease term is used. The Company’s IBRs approximate the rate the Company would have to pay to borrow on a collateralized basis over a similar term at lease inception. The ROU asset is equal to the initial measurement of the lease liability plus any lease payments made to the lessor at or before the commencement date and any unamortized initial direct costs incurred by the lessee, less any unamortized lease incentives received. The Company has elected to not separate lease components from non-lease components for all asset classes, and has made an accounting policy election to apply the short-term exception, which does not require the capitalization of leases with terms of 12 months or less.

ROU assets for operating leases are classified in other long-term assets, and ROU assets for finance leases are classified in property, plant and equipment on the consolidated balance sheet. For operating leases, short-term lease liabilities are classified in other current liabilities, and long-term lease liabilities are classified in other long-term liabilities on the consolidated balance sheet. For finance leases, short-term lease liabilities are classified in short-term debt, and long-term lease liabilities are classified in long-term debt on the consolidated balance sheet. On the cash flow statement, payments for operating leases are classified as operating activities. Payments for finance leases are classified as a financing activity, except for the interest component of the payment which is classified as an operating activity.

The Company has lease contracts for real property and machinery and equipment. At inception of a contract, the Company determines whether the contract is or contains a lease. If the Company has a right to obtain substantially all of the economic benefits from the use of the identified asset and the right to direct the use of the asset, then the contract contains a lease. Several of the Company’s real property lease contracts include options to extend the lease term, and the Company reassesses the likelihood of renewal on at least an annual basis. In addition, several real property leases include variable lease payments, for items such as common area maintenance and utilities, which are expensed as incurred as variable lease expense.

Goodwill is reviewed annually for impairment, or more frequently if impairment indicators arise. The review for goodwill impairment requires a comparison of the fair value of each reporting unit that has goodwill associated with its operations with its carrying amount, including goodwill. If this comparison reflects impairment, then the loss would be measured as the excess of the carrying value over the calculated fair value.

Generally accepted accounting principles provide the option to qualitatively assess goodwill for impairment before completing a quantitative assessment. Under the qualitative approach, if, after assessing the totality of events or circumstances, including both macroeconomic, industry and market factors, and entity-specific factors, the Company determines it is likely (more likely than not) that the fair value of a reporting unit is greater than its carrying amount, then the quantitative impairment analysis is not required. The quantitative assessment may be performed each year for a reporting unit at the Company’s option without first performing a qualitative assessment. The Company’s quantitative assessment of goodwill for possible impairment includes estimating the fair value of a reporting unit which has goodwill associated with its operations using discounted cash flow and multiples of cash earnings valuation techniques, plus valuation comparisons to recent public sale transactions of similar businesses, if any. These impairment assessments and valuation methods require the Company to make estimates and assumptions regarding revenue growth, changes in working capital and capital expenditures, selling prices and profitability that drive cash flows, and the weighted average cost of capital. Many of these assumptions are determined by reference to market participants identified by the Company. Although management believes that the estimates and assumptions used were reasonable, actual results could differ from those estimates and assumptions.

Other events and changes in circumstances may also require goodwill to be tested for impairment between annual measurement dates. While a decline in stock price and market capitalization is not specifically cited as a goodwill impairment indicator, a company’s stock price and market capitalization should be considered in determining whether it is more likely than not that the fair value of a reporting unit is less that its carrying value. Additionally, a significant decline in a company’s stock price may suggest that an adverse change in the business climate may have caused the fair value of one or more reporting units to fall below carrying value. A sustained decline in market capitalization below book value may be determined to require an interim goodwill impairment review.

Costs that mitigate or prevent future environmental contamination or extend the life, increase the capacity or improve the safety or efficiency of property utilized in current operations are capitalized. Other costs that relate to current operations or an existing condition caused by past operations are expensed. Environmental liabilities are recorded when the Company’s liability is probable and the costs are reasonably estimable, but generally not later than the completion of the feasibility study or the Company’s recommendation of a remedy or commitment to an appropriate plan of action. The accruals are reviewed periodically and, as investigations and remediations proceed, adjustments of the accruals are made to reflect new information as appropriate. Accruals for losses from environmental remediation obligations are not discounted to their present value. The accruals are not reduced by possible recoveries from insurance carriers or other third parties, but do reflect allocations among potentially responsible parties (PRPs) at Federal Superfund sites or similar state-managed sites after an assessment is made of the likelihood that such parties will fulfill their obligations at such sites and after appropriate cost-sharing or other agreements are entered. The measurement of environmental liabilities by the Company is based on currently available facts, present laws and regulations, and current technology. Such estimates take into consideration the Company’s prior experience in site investigation and remediation, the data concerning cleanup costs available from other companies and regulatory authorities, and the professional judgment of the Company’s environmental experts in consultation with outside environmental specialists, when necessary.

Assets and liabilities of international operations are translated into U.S. dollars using fiscal year-end exchange rates, while revenues and expenses are translated at average exchange rates during the period. The resulting net translation adjustments are recorded as a component of accumulated other comprehensive income (loss) in stockholders’ equity. Gains and losses for transactions denominated in foreign currencies are reported in costs of sales or general and administrative expenses in the consolidated statement of operations based on the underlying nature of the transaction.

The Company’s contracts with customers are comprised of purchase orders, and for larger customers long-term agreements (LTAs). LTAs typically extend multiple years and are utilized by the Company and certain of its customers for its specialty materials, in the form of mill products, powders, parts and components, to reduce supply uncertainty. While LTAs generally define commercial terms including pricing, termination clauses and other contractual requirements, the Company has determined that the contract with a customer is established when the customer purchase order is accepted or acknowledged.

Contracts (purchase orders) with customers typically relate to the manufacturing of products, which are defined on a line by line basis, and each distinct good represents a single performance obligation that is satisfied at a point in time when control of the product passes to the customer. For most transactions, control passes at the time of shipment in accordance with agreed upon delivery terms. On occasion, shipping and handling charges occur after the customer obtains control of the good. When this occurs, the shipping and handling services are considered activities to fulfill the promise to transfer the good. Sales for conversion services that transform customer-owned inventory to a different dimension, product form, and/or changed mechanical properties are recognized when the service is completed.

Pricing for the Company’s products is also defined in the customer purchase order or LTA on a line item basis and, in some cases, includes variable consideration. Variable consideration is when the selling price of the good is not known or is subject to adjustment under certain conditions. Types of variable consideration may include volume discounts, customer rebates and surcharges. ATI also provides assurances that goods or services will meet the product specifications contained within the acknowledged customer contract. As such, returns and refunds reserves are estimated based upon past product line history or, at certain locations, on a claim by claim basis.

Certain customer agreements involving production of parts and components require revenue to be recognized over time due to there being no alternative use for the product without significant economic loss and an enforceable right to payment including a normal profit margin from the customer in the event of contract termination. The Company uses an input method for determining the amount of revenue, and associated standard cost, to recognize over-time revenue, cost and gross margin for these customer agreements. The input methods used for these agreements include costs incurred and labor hours expended, both of which give an accurate representation of the progress made toward complete satisfaction of that particular performance obligation.

Contract assets are recognized when ATI’s conditional right to consideration for goods or services have transferred to the customer. A conditional right indicates that additional performance obligations associated with the contract are yet to be satisfied. Contract assets are assessed separately for impairment purposes. When ATI’s right to consideration from the customer is unconditional, this asset is accounted for as a receivable and presented separately from contract assets. A right is unconditional if nothing other than the passage of time is required before payment of that consideration is due. Performance obligations that are recognized as revenue at a point-in-time and are billed to the customer are recognized as accounts receivable. Payment terms vary from customer to customer depending upon credit worthiness, prior payment history and other credit considerations.

Contract costs are the incremental costs of obtaining and fulfilling a contract (i.e., costs that would not have been incurred if the contract had not been obtained) to provide goods and services to customers. Contract costs for ATI largely consist of design and development costs for molds, dies and other tools that ATI will own and that will be used in producing the products under the supply arrangement. Contract costs are classified as non-current assets and amortized to expense on a systematic and rational basis over a period consistent with the transfer to the customer of the goods or services to which the asset relates.

Contract liabilities are recognized when ATI has received consideration from a customer to transfer goods or services at a future point in time when the Company performs under the contract. Elements of variable consideration discussed above may be recorded as contract liabilities. In addition, progress billings and advance payments from customers for costs incurred to date are also reported as contract liabilities.

Research, development and technical service activities are closely interrelated and directed toward development of new products, improvement of existing products, quality assurance, development of new manufacturing methods, improvement of existing manufacturing methods, and reducing the Company’s manufacturing costs. Research and development costs are expensed as incurred. Company funded research and development costs were $19.6 million in fiscal year 2024, $20.7 million in fiscal year 2023, and $16.3 million in fiscal year 2022. Customer funded research and development costs were $2.5 million in fiscal year 2024, $1.4 million in fiscal year 2023, and $1.4 million in fiscal year 2022.

The Company enters into agreements with U.S. federal agencies, U.S. state and local governments, and foreign governments that provide financial assistance and incentives supporting both new capital projects to expand and enhance manufacturing capabilities and also to sustain and maintain existing operations. Depending on the nature of the government program, the financial impacts may be recorded as a reduction to cost of sales through direct offset of labor and overhead costs or lower depreciation expense, or as a reduction of selling, general and administrative expenses for property tax abatement or other similar categories. Benefits from government assistance are recognized as the activities are incurred, subject to ongoing assessments of meeting other relevant terms such as employment or expenditure levels.

In November 2021, ATI entered into an agreement with the U.S. Department of Transportation under the Aviation Manufacturing Jobs Protection (AMJP) program for a grant of up to $22.2 million. The receipt of the award was primarily conditioned upon the Company committing to not furlough or lay off a defined group of employees in the High Performance Materials & Components (HPMC) segment operations during the six-month period of performance between November 2021 and May 2022. The AMJP grant benefit was recognized over the six-month performance period as a reduction to cost of sales in proportion to the compensation expense that the award was intended to defray, with $16.6 million recognized in fiscal year 2022 operating results. Cash receipts from the AMJP program were $11.0 million in fiscal year 2022, and this program is now completed.

ATI is a party to various U.S. states’ economic development incentive programs that provide economic benefits in the forms of property tax relief or cash payments to offset capital expenditures. These programs generally include requirements for levels of capital spending and/or employment to qualify for the government assistance. For the fiscal years ended December 29, 2024, December 31, 2023 and January 1, 2023, these state-level programs reduced selling, general and administrative expenses by $1.7 million, $1.4 million, $1.6 million, respectively, and cash receipts were $2.5 million, $3.4 million and $2.8 million, respectively. Receivables for ongoing programs are $1.2 million as of both December 29, 2024 and December 31, 2023.

The remeasurement of projected benefit obligation and plan assets for defined benefit pension plans are immediately recognized in earnings through net periodic pension benefit cost within nonoperating retirement benefit expense on the consolidated statements of operations, with pension plans to be remeasured annually in the fourth quarter or on an interim basis as triggering events require remeasurement. For the remeasurement of projected benefit obligation and plan assets for defined benefit postretirement plans, the Company defers the recognition of these gains and losses in accumulated other comprehensive loss on the consolidated balance sheet, and the accumulated actuarial gains/losses are then amortized into net periodic benefit costs within nonoperating retirement benefit expense on the consolidated statements of operations over the average expected remaining life of plan participants.

The Company accounts for stock-based compensation transactions, such as nonvested restricted stock or stock units and performance equity awards, using fair value. Compensation expense for an award is estimated at the date of grant and is recognized over the requisite service period. Compensation expense is adjusted for equity awards that do not vest because service or performance conditions are not satisfied. However, compensation expense already recognized on awards which vest based solely on the attainment of market conditions, such as total shareholder return measures, is not adjusted based on the award attainment status at the end of the measurement period. Compensation expense is adjusted for estimated forfeitures over the award measurement period.

The provision for, or benefit from, income taxes includes deferred taxes resulting from temporary differences in income for financial and tax purposes using the liability method. Such temporary differences result primarily from differences in the carrying value of assets and liabilities. Future realization of deferred income tax assets requires sufficient taxable income within the carryback and/or carryforward period available under tax law.

The Company evaluates on a quarterly basis whether, based on all available evidence, it is probable that the deferred income tax assets are realizable. Valuation allowances are established when it is estimated that it is more likely than not that the tax benefit of the deferred tax asset will not be realized. The evaluation includes the consideration of all available evidence, both positive and negative, regarding the estimated future reversals of existing taxable temporary differences, estimated future taxable income exclusive of reversing temporary differences and carryforwards, historical taxable income in prior carryback periods if carryback is permitted, and potential tax planning strategies which may be employed to prevent an operating loss or tax credit carryforward from expiring unused. The verifiable evidence such as future reversals of existing temporary differences and the

It is the Company’s policy to classify interest and penalties recognized on underpayment of income taxes as income tax expense. It is also the Company’s policy to recognize deferred tax amounts stranded in accumulated other comprehensive income (AOCI), which result from tax rate differences on changes in AOCI balances, as an element of income tax expense in the period that the related balance sheet item associated with the AOCI balance ceases to exist. In the case of derivative financial instruments accounted for as hedges, or marketable securities, ATI uses the portfolio method where the stranded deferred tax amount is recognized when all items of a particular category, such as cash flow hedges of a particular risk such as a foreign currency hedge, are settled. In the case of defined benefit pension and other postretirement benefit plans, the stranded deferred tax balance is recognized as an element of income tax expense in the period the benefit plan is extinguished or divested.

Basic and diluted net income per share are calculated by dividing the net income available to common stockholders by the weighted average number of common shares outstanding during the fiscal year. Diluted amounts assume the issuance of common stock for all potentially dilutive share equivalents outstanding. The calculations of all diluted income/loss per share figures for a period exclude the potentially dilutive effect of dilutive share equivalents if there is a net loss since the inclusion in the calculation of additional shares in the net loss per share would result in a lower per share loss and therefore be anti-dilutive.

In September 2022, the Financial Accounting Standards Board (FASB) issued new accounting guidance related to disclosures about supplier finance programs. Supplier finance programs allow a buyer to offer its suppliers the option for access to payment in advance of an invoice due date, which is paid by a third-party finance provider or intermediary on the basis of invoices that the buyer has confirmed as valid. This new guidance requires a buyer in a supplier finance program to disclose sufficient information about the program to allow a user of financial statements to understand the program’s nature, activity during the period, changes from period to period, and potential magnitude, using both qualitative and quantitative information about its supplier finance programs. This new guidance, with the exception of annual disclosures on rollforward information, was effective for the Company in fiscal year 2023, and the Company adopted this new accounting guidance effective January 2, 2023. The annual rollforward information disclosures were effective for the Company in fiscal year 2024, and the Company adopted this new accounting guidance effective January 1, 2024. The adoption of these changes did not have an impact on the Company’s consolidated financial statements other than disclosure requirements which are included in Note 9.

In November 2023, the FASB issued new accounting guidance related to segment reporting disclosures. This guidance requires additional disclosures on an annual and interim basis of segment information, including significant segment expenses that are regularly provided to the chief operating decision maker (CODM) and the presentation and composition of other segment items, which is the difference between segment revenue less segment expenses and the measure of segment profit or loss. The guidance also requires that all current segment disclosures required on an annual basis be provided on an interim basis and requires disclosure of the title and position of the CODM and how the CODM uses the reported measure of segment profit or loss in assessing performance and allocating resources. This guidance does not change how an entity identifies its reportable segments. The Company adopted this new guidance for annual disclosures for fiscal year 2024 and will adopt it for interim disclosures in fiscal year 2025. The adoption of these changes did not have an impact on the Company’s consolidated financial statements other than disclosure requirements which are included in Note 18.

In December 2023, the FASB issued new accounting guidance related to income tax disclosures. This guidance requires entities to disclose specific categories in its annual rate reconciliation and provide additional information for reconciling items that meet a quantitative threshold. This guidance also requires additional annual disclosures for income taxes paid and requires disaggregation of income before tax, between domestic and foreign, and income tax expense, between federal, state and foreign. This guidance also eliminates several current disclosure requirements related to the nature and estimate of the range of the reasonably possible change in the unrecognized tax benefits balance in the next 12 months and making a statement that an estimate of the range cannot be made and disclosing the cumulative amount of each type of temporary difference when a deferred tax liability is not recognized because of the exceptions to comprehensive recognition of deferred taxes related to subsidiaries and corporate joint ventures. This new guidance will be effective for the Company for fiscal year 2025 and must be applied on a prospective basis with retrospective application permitted. Early adoption of this guidance is also 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.

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.