Basis of Presentation (Policies)	9 Months Ended
Sep. 30, 2025
Accounting Policies [Abstract]
Description of the Business	Description of the Business The principal business of Superior Industries International, Inc. (referred herein as the “Company” or “Superior”) is the design and manufacture of aluminum wheels for sale to original equipment manufacturers (“OEMs”) in North America and Europe, and to the aftermarket in Europe. The Company’s aluminum wheels are primarily sold to OEMs for factory installation on new light vehicles. Aluminum wheels sold in the European aftermarket are under the brands ATS, RIAL, ALUTEC, and ANZIO. North America and Europe represent the primary markets for the Company’s products, but it has a diversified global customer base consisting of North American, European, and Asian OEMs.
Merger	Merger On December 8, 2025 (the “Closing Date”), the Company, SUP Parent Holdings, LLC, a Delaware limited liability company (“Parent”), and SUP Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of Parent (“Merger Sub”) completed the previously announced Merger, contemplated by that certain Agreement and Plan of Merger, dated as of July 8, 2025 (the “Merger Agreement”). At the effective time of the Merger on the Closing Date (the “Effective Time”), in accordance with the Merger Agreement, Merger Sub merged with and into the Company (the “Merger”), with the Company surviving the Merger as a direct wholly owned subsidiary of Parent. Immediately prior to the Effective Time, Parent held Common Shares that represented approximately 17.6% of the total voting power of the Company. At the Effective Time, in accordance with the terms and conditions set forth in the Merger Agreement, each Common Share and each share of preferred stock, par value $0.01 per share designated as Series A Preferred Shares (the “Series A Preferred Shares” and, together with the Common Shares, the “Shares”), in each case, issued and outstanding immediately prior to the Effective Time (other than Shares owned by (i) Parent or Merger Sub or any of their respective Subsidiaries, (ii) the Company as treasury stock and (iii) holders of Common Shares who have not voted in favor of the Merger or consented thereto and have properly exercised and perfected and not withdrawn, waived or lost a demand for appraisal rights pursuant to Section 262 of the Delaware General Corporation Law) was converted into the right to receive: • with respect to each Common Share, $0.09 per Common Share in cash, without interest thereon; and • with respect to each Series A Preferred Share, (1) $39.49 per Series A Preferred Share in cash and (2) 0.23 units of limited liability company interests of Parent per Series A Preferred Share. At the Effective Time, in accordance with the Merger Agreement: • each outstanding time-based restricted stock unit (a “Company Restricted Stock Unit”) that was granted under the Company’s 2018 Equity Incentive Plan (the “Company Stock Plan”) that was outstanding as of immediately prior to the Effective Time, whether vested or unvested, became fully vested and terminated and automatically cancelled as of immediately prior to the Effective Time in exchange for the right to receive a lump sum cash payment of an amount equal to $0.09 per Company Restricted Stock Unit; and • each outstanding performance-based restricted stock unit (a “Company Performance Stock Unit”) that was granted under the Company Stock Plan that was outstanding as of immediately prior to the Effective Time, whether vested or unvested, became fully vested as if the applicable level of performance was achieved at target and terminated and automatically cancelled as of immediately prior to the Effective Time in exchange for the right to receive a lump sum cash payment of an amount equal to $0.09 per Company Performance Stock Unit. The Company used the proceeds of borrowings under the Third Amendment (as defined in Note 8 “Debt and Other Financing Arrangements”) to pay the cash consideration in the Merger. Additional information about the Merger is set forth in the Company’s Current Report on Form 8-K filed with the SEC on December 8, 2025.
Basis of Presentation - Interim Financial Statements	Basis of Presentation - Interim Financial Statements The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States (“U.S. GAAP”) pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) for interim financial information. Accordingly, they do not include all the information and notes required by U.S. GAAP for complete financial statements. These unaudited condensed consolidated financial statements include all adjustments, of a normal and recurring nature, which management believes are necessary for fair presentation of the financial statements. This Quarterly Report on Form 10-Q should be read in conjunction with the audited consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024, which was filed with the SEC on March 6, 2025 (the “2024 Form 10-K”). These unaudited condensed consolidated financial statements include the accounts of the Company and its subsidiaries. All intercompany transactions are eliminated in consolidation. Interim financial reporting standards require the use of estimates that are based on assumptions regarding the outcome of future events and circumstances not known at that time. Inevitably, some assumptions may not materialize, unanticipated events or circumstances may occur which vary from those estimates and such variations may significantly affect future results. Additionally, operating results for the three and nine months ended September 30, 2025 are not necessarily indicative of the results that may be expected for the year ending December 31, 2025. Going Concern During the second quarter of 2025, certain of the Company's customers in North America began to resource to other suppliers substantially all outstanding purchase orders and not issue any additional purchase orders to the Company thereafter. Prior to these resourcing actions, the Company estimated these customers to represent approximately 33% of its projected consolidated net sales for the 2025 fiscal year. These customers represented approximately 40% of the Company’s consolidated net sales for the year ended December 31, 2024, and approximately 36% of the Company’s consolidated net sales for the year ended December 31, 2023. During the nine months ended September 30, 2025, the Company borrowed $42.5 million on its revolving credit facility, as the actions described above significantly affected the Company’s ability to generate cash from operating activities or from the sale of trade receivables. In addition, as of September 30, 2025, the Company was in violation of its financial covenants under the Senior Secured Credit Facilities. On December 8, 2025 the Company completed the previously announced Merger with Parent, and Merger Sub pursuant to the Merger Agreement, and entered into amendments to its Senior Secured Credit Facilities. The Third Amendment to the Company’s Senior Secured Credit Facilities entered into on December 8, 2025, removed certain financial covenants under the Term Loan Facility and waived the financial covenants under the Revolving Credit Facility through June 30, 2026. In addition, the Revolving Credit Facility was amended to mature on June 30, 2026. The Senior Secured Credit Facilities now also contain a monthly minimum liquidity threshold of not less than $10.0 million as of the last business day of each month. Refer to Note 1 “Description of the Business” and Note 8 “Debt and Other Financing Arrangements” for a full description of the transactions. While the Company has completed the previously announced Merger, it does not expect that it will have the cash and cash equivalents or sufficient liquidity to meet its financial obligations and comply with its minimum liquidity covenant over the next twelve months from the issuance date of these unaudited condensed consolidated financial statements. To address these conditions, management plans to obtain additional sources of funding or amend the applicable provisions in its credit agreements. However, such plans are not solely in the Company’s control and therefore cannot be considered probable of occurring. Therefore, these adverse conditions and events described above raise substantial doubt about the Company’s ability to continue as a going concern as of the issuance date. The unaudited condensed consolidated financial statements as of September 30, 2025, do not include any adjustments that might result from the outcome of this uncertainty.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents generally consist of cash, certificates of deposit, fixed deposits, and money market funds with original maturities of three months or less. The Company is required to provide cash collateral in connection with certain contractual arrangements. The Company has $0.8 million and $0.4 million of restricted cash as of September 30, 2025 and December 31, 2024 in support of these arrangements and requirements.
Accounting Standards Issued But Not Yet Adopted	Accounting Standards Issued But Not Yet Adopted Accounting Standards Update (ASU) 2023-09, “Income Taxes (Topic 740).” In December 2023, the FASB issued ASU 2023-09, “Income Taxes (Topic 740): Improvements to Income Tax Disclosures,” which is intended to enhance the transparency, decision usefulness, and effectiveness of income tax disclosures. This amendment requires a public entity to disclose a tabular tax rate reconciliation, using both percentages and currency, with specific categories. A public entity is also required to provide a qualitative description of the states and local jurisdictions that make up the majority of the effect of the state and local income tax category and the net amount of income taxes paid, disaggregated by federal, state, and foreign taxes and also disaggregated by individual jurisdictions. The amendment is effective prospectively for annual periods beginning after December 15, 2024, and early adoption and retrospective application are permitted. The Company is currently evaluating the effect of adopting this guidance. Accounting Standards Update (ASU) 2024-03, “Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures.” In November 2024, the FASB issued ASU 2024-03, “Disaggregation of Income Statement Expenses (Subtopic 220-40): Disaggregation of Income Statement Expenses”, which is intended to provide disaggregated information about a public business entity’s expenses to help financial statement users better understand the entity’s performance, better assess the entity’s prospects for future cash flows, and compare an entity’s performance over time and with that of other entities. The amendment is effective for fiscal years beginning after December 15, 2026 and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. The new standard may be applied either on a prospective or retrospective basis. The Company is currently evaluating the effect of adopting this guidance.
Derivatives, Methods of Accounting, Hedging Derivatives	Market Risks Foreign Currency Exchange Rate Risk The Company has manufacturing locations primarily in Mexico and Poland and sells its products globally. As a result, the Company’s financial results could be significantly affected by foreign currency exchange rates. To help mitigate gross margin and cash flow fluctuations due to changes in foreign currency exchange rates, certain subsidiaries in Mexico and Poland, whose functional currency is the U.S. dollar or the Euro, may hedge a portion of their forecasted foreign currency exposure denominated in the Mexican Peso and Polish Zloty using foreign currency forward contracts up to 48 months. The Company has designated some of its foreign currency contracts as cash flow hedging instruments. Interest Rate Risk The borrowings under the Company’s Senior Secured Credit Facilities (as subsequently defined) are at variable rates of interest and expose it to interest rate risk. If interest rates increase, debt service obligations on the variable rate indebtedness will increase even though the amount borrowed remains the same. The Company hedges a portion of its interest rate risk through interest rate swaps that exchange floating for fixed-rate interest payments and has designated these contracts as cash flow hedging instruments. Commodity Price Risk The principal raw material used in manufacturing aluminum wheels is aluminum alloys. While wheel prices under OEM customer contracts are adjusted for fluctuations in the cost of this material, the prices of its aftermarket wheels are generally fixed months in advance of the spring and winter sales seasons. Accordingly, the Company hedges a portion of its aftermarket aluminum purchases to offset the effect of fluctuating aluminum cost on its margins. In addition, the manufacture of aluminum wheels is energy-intensive so, the Company also fixes a portion of its natural gas and electricity purchases with derivatives or contractual arrangements with energy suppliers. Assets and Fair Values Measured at Fair Value on a Recurring Basis Asset and Liability Instruments The carrying amounts for cash and cash equivalents, accounts receivable, accounts payable, and accrued expenses approximate their fair values due to the short period of time until maturity. Derivative Financial Instruments During the second quarter of 2025, the Company terminated its outstanding foreign exchange, commodity, and interest rate derivative instruments. The derivative instruments have been derecognized and amounts in accumulated other comprehensive income (loss) remain there until the forecasted transactions affect earnings unless the forecasted transaction becomes probable of not occurring. The fair value of the Company’s derivative instruments is estimated using the income valuation approach, which projects future cash flows and discounts the future amounts to a present value using market-based expectations for interest rates, foreign exchange rates, commodity prices, and the contractual terms of the derivative instruments (Level 2). The discount rate used is the relevant benchmark rate (e.g., the secured overnight financing rate, “SOFR”) plus an adjustment for counterparty risk. The fair value of the Company’s embedded derivatives is estimated using either a market based approach or an income based approach, which uses Company-specific inputs and assumptions (Level 3), such as discount rates.

Basis of Presentation (Policies)

9 Months Ended

Sep. 30, 2025

The principal business of Superior Industries International, Inc. (referred herein as the “Company” or “Superior”) is the design and manufacture of aluminum wheels for sale to original equipment manufacturers (“OEMs”) in North America and Europe, and to the aftermarket in Europe. The Company’s aluminum wheels are primarily sold to OEMs for factory installation on new light vehicles. Aluminum wheels sold in the European aftermarket are under the brands ATS, RIAL, ALUTEC, and ANZIO. North America and Europe represent the primary markets for the Company’s products, but it has a diversified global customer base consisting of North American, European, and Asian OEMs.

Merger

On December 8, 2025 (the “Closing Date”), the Company, SUP Parent Holdings, LLC, a Delaware limited liability company (“Parent”), and SUP Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of Parent (“Merger Sub”) completed the previously announced Merger, contemplated by that certain Agreement and Plan of Merger, dated as of July 8, 2025 (the “Merger Agreement”). At the effective time of the Merger on the Closing Date (the “Effective Time”), in accordance with the Merger Agreement, Merger Sub merged with and into the Company (the “Merger”), with the Company surviving the Merger as a direct wholly owned subsidiary of Parent. Immediately prior to the Effective Time, Parent held Common Shares that represented approximately 17.6% of the total voting power of the Company.

At the Effective Time, in accordance with the terms and conditions set forth in the Merger Agreement, each Common Share and each share of preferred stock, par value $0.01 per share designated as Series A Preferred Shares (the “Series A Preferred Shares” and, together with the Common Shares, the “Shares”), in each case, issued and outstanding immediately prior to the Effective Time (other than Shares owned by (i) Parent or Merger Sub or any of their respective Subsidiaries, (ii) the Company as treasury stock and (iii) holders of Common Shares who have not voted in favor of the Merger or consented thereto and have properly exercised and perfected and not withdrawn, waived or lost a demand for appraisal rights pursuant to Section 262 of the Delaware General Corporation Law) was converted into the right to receive:

•

with respect to each Common Share, $0.09 per Common Share in cash, without interest thereon; and

•

with respect to each Series A Preferred Share, (1) $39.49 per Series A Preferred Share in cash and (2) 0.23 units of limited liability company interests of Parent per Series A Preferred Share.

At the Effective Time, in accordance with the Merger Agreement:

•

each outstanding time-based restricted stock unit (a “Company Restricted Stock Unit”) that was granted under the Company’s 2018 Equity Incentive Plan (the “Company Stock Plan”) that was outstanding as of immediately prior to the Effective Time, whether vested or unvested, became fully vested and terminated and automatically cancelled as of immediately prior to the Effective Time in exchange for the right to receive a lump sum cash payment of an amount equal to $0.09 per Company Restricted Stock Unit; and

•

each outstanding performance-based restricted stock unit (a “Company Performance Stock Unit”) that was granted under the Company Stock Plan that was outstanding as of immediately prior to the Effective Time, whether vested or unvested, became fully vested as if the applicable level of performance was achieved at target and terminated and automatically cancelled as of immediately prior to the Effective Time in exchange for the right to receive a lump sum cash payment of an amount equal to $0.09 per Company Performance Stock Unit.

The Company used the proceeds of borrowings under the Third Amendment (as defined in Note 8 “Debt and Other Financing Arrangements”) to pay the cash consideration in the Merger.

Additional information about the Merger is set forth in the Company’s Current Report on Form 8-K filed with the SEC on December 8, 2025.

Basis of Presentation - Interim Financial Statements

The accompanying unaudited condensed consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States (“U.S. GAAP”) pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) for interim financial information. Accordingly, they do not include all the information and notes required by U.S. GAAP for complete financial statements. These unaudited condensed consolidated financial statements include all adjustments, of a normal and recurring nature, which management believes are necessary for fair presentation of the financial statements. This Quarterly Report on Form 10-Q should be read in conjunction with the audited consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024, which was filed with the SEC on March 6, 2025 (the “2024 Form 10-K”).

These unaudited condensed consolidated financial statements include the accounts of the Company and its subsidiaries. All intercompany transactions are eliminated in consolidation.

Interim financial reporting standards require the use of estimates that are based on assumptions regarding the outcome of future events and circumstances not known at that time. Inevitably, some assumptions may not materialize, unanticipated events or circumstances may occur which vary from those estimates and such variations may significantly affect future results. Additionally, operating results for the three and nine months ended September 30, 2025 are not necessarily indicative of the results that may be expected for the year ending December 31, 2025.

Going Concern

During the second quarter of 2025, certain of the Company's customers in North America began to resource to other suppliers substantially all outstanding purchase orders and not issue any additional purchase orders to the Company thereafter. Prior to these resourcing actions, the Company estimated these customers to represent approximately 33% of its projected consolidated net sales for the 2025 fiscal year. These customers represented approximately 40% of the Company’s consolidated net sales for the year ended December 31, 2024, and approximately 36% of the Company’s consolidated net sales for the year ended December 31, 2023. During the nine months ended September 30, 2025, the Company borrowed $42.5 million on its revolving credit facility, as the actions described above significantly affected the Company’s ability to generate cash from operating activities or from the sale of trade receivables. In addition, as of September 30, 2025, the Company was in violation of its financial covenants under the Senior Secured Credit Facilities.

On December 8, 2025 the Company completed the previously announced Merger with Parent, and Merger Sub pursuant to the Merger Agreement, and entered into amendments to its Senior Secured Credit Facilities. The Third Amendment to the Company’s Senior Secured Credit Facilities entered into on December 8, 2025, removed certain financial covenants under the Term Loan Facility and waived the financial covenants under the Revolving Credit Facility through June 30, 2026. In addition, the Revolving Credit Facility was amended to mature on June 30, 2026. The Senior Secured Credit Facilities now also contain a monthly minimum liquidity threshold of not less than $10.0 million as of the last business day of each month. Refer to Note 1 “Description of the Business” and Note 8 “Debt and Other Financing Arrangements” for a full description of the transactions.

While the Company has completed the previously announced Merger, it does not expect that it will have the cash and cash equivalents or sufficient liquidity to meet its financial obligations and comply with its minimum liquidity covenant over the next twelve months from the issuance date of these unaudited condensed consolidated financial statements. To address these conditions, management plans to obtain additional sources of funding or amend the applicable provisions in its credit agreements. However, such plans are not solely in the Company’s control and therefore cannot be considered probable of occurring. Therefore, these adverse conditions and events described above raise substantial doubt about the Company’s ability to continue as a going concern as of the issuance date.

The unaudited condensed consolidated financial statements as of September 30, 2025, do not include any adjustments that might result from the outcome of this uncertainty.

Cash and Cash Equivalents

Cash and cash equivalents generally consist of cash, certificates of deposit, fixed deposits, and money market funds with original maturities of three months or less. The Company is required to provide cash collateral in connection with certain contractual arrangements. The Company has $0.8 million and $0.4 million of restricted cash as of September 30, 2025 and December 31, 2024 in support of these arrangements and requirements.

Accounting Standards Issued But Not Yet Adopted

Accounting Standards Update (ASU) 2023-09, “Income Taxes (Topic 740).” In December 2023, the FASB issued ASU 2023-09, “Income Taxes (Topic 740): Improvements to Income Tax Disclosures,” which is intended to enhance the transparency, decision usefulness, and effectiveness of income tax disclosures. This amendment requires a public entity to disclose a tabular tax rate reconciliation, using both percentages and currency, with specific categories. A public entity is also required to provide a qualitative description of the states and local jurisdictions that make up the majority of the effect of the state and local income tax category and the net amount of income taxes paid, disaggregated by federal, state, and foreign taxes and also disaggregated by individual jurisdictions. The amendment is effective prospectively for annual periods beginning after December 15, 2024, and early adoption and retrospective application are permitted. The Company is currently evaluating the effect of adopting this guidance.

Accounting Standards Update (ASU) 2024-03, “Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures.” In November 2024, the FASB issued ASU 2024-03, “Disaggregation of Income Statement Expenses (Subtopic 220-40): Disaggregation of Income Statement Expenses”, which is intended to provide disaggregated information about a public business entity’s expenses to help financial statement users better understand the entity’s performance, better assess the entity’s prospects for future cash flows, and compare an entity’s performance over time and with that of other entities. The amendment is effective for fiscal years beginning after December 15, 2026 and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. The new standard may be applied either on a prospective or retrospective basis. The Company is currently evaluating the effect of adopting this guidance.

Derivatives, Methods of Accounting, Hedging Derivatives

Market Risks

Foreign Currency Exchange Rate Risk

The Company has manufacturing locations primarily in Mexico and Poland and sells its products globally. As a result, the Company’s financial results could be significantly affected by foreign currency exchange rates. To help mitigate gross margin and cash flow fluctuations due to changes in foreign currency exchange rates, certain subsidiaries in Mexico and Poland, whose functional currency is the U.S. dollar or the Euro, may hedge a portion of their forecasted foreign currency exposure denominated in the Mexican Peso and Polish Zloty using foreign currency forward contracts up to 48 months. The Company has designated some of its foreign currency contracts as cash flow hedging instruments.

Interest Rate Risk

The borrowings under the Company’s Senior Secured Credit Facilities (as subsequently defined) are at variable rates of interest and expose it to interest rate risk. If interest rates increase, debt service obligations on the variable rate indebtedness will increase even though the amount borrowed remains the same. The Company hedges a portion of its interest rate risk through interest rate swaps that exchange floating for fixed-rate interest payments and has designated these contracts as cash flow hedging instruments.

Commodity Price Risk

The principal raw material used in manufacturing aluminum wheels is aluminum alloys. While wheel prices under OEM customer contracts are adjusted for fluctuations in the cost of this material, the prices of its aftermarket wheels are generally fixed months in advance of the spring and winter sales seasons. Accordingly, the Company hedges a portion of its aftermarket aluminum purchases to offset the effect of fluctuating aluminum cost on its margins. In addition, the manufacture of aluminum wheels is energy-intensive so, the Company also fixes a portion of its natural gas and electricity purchases with derivatives or contractual arrangements with energy suppliers.

Assets and Fair Values Measured at Fair Value on a Recurring Basis

Asset and Liability Instruments

The carrying amounts for cash and cash equivalents, accounts receivable, accounts payable, and accrued expenses approximate their fair values due to the short period of time until maturity.

Derivative Financial Instruments

During the second quarter of 2025, the Company terminated its outstanding foreign exchange, commodity, and interest rate derivative instruments. The derivative instruments have been derecognized and amounts in accumulated other comprehensive income (loss) remain there until the forecasted transactions affect earnings unless the forecasted transaction becomes probable of not occurring.

The fair value of the Company’s derivative instruments is estimated using the income valuation approach, which projects future cash flows and discounts the future amounts to a present value using market-based expectations for interest rates, foreign exchange rates, commodity prices, and the contractual terms of the derivative instruments (Level 2). The discount rate used is the relevant benchmark rate (e.g., the secured overnight financing rate, “SOFR”) plus an adjustment for counterparty risk.

The fair value of the Company’s embedded derivatives is estimated using either a market based approach or an income based approach, which uses Company-specific inputs and assumptions (Level 3), such as discount rates.