CENTURY ALUMINUM CO

9. Shareholders' Equity

Common Stock

As of December 31, 2025 and 2024, we had 195,000,000 shares of common stock, $0.01 cent par value, authorized under our Restated Certificate of Incorporation, of which 106,155,528 shares were issued and 98,969,007 shares were outstanding at December 31, 2025;100,475,086 shares were issued and 93,288,565 shares were outstanding at December 31, 2024.

The rights, preferences and privileges of holders of our common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of our preferred stock which are currently outstanding, including our Series A Convertible Preferred Stock, or which we may designate and issue in the future.

Preferred Stock

As of December 31, 2025 and 2024, we had 5,000,000 shares of preferred stock, $0.01 cent par value per share, authorized under our Restated Certificate of Incorporation. Our Board of Directors may issue preferred stock in one or more series and determine for each series the dividend rights, conversion rights, voting rights, redemption rights, liquidation preferences, sinking fund terms and the number of shares constituting that series, as well as the designation thereof. Depending upon the terms of preferred stock established by our Board of Directors, any or all of the preferred stock could have preference over the common stock with respect to dividends and other distributions and upon the liquidation of Century. In addition, issuance of any shares of preferred stock with voting powers may dilute the voting power of the outstanding common stock.

Series A Convertible Preferred Stock

Shares Authorized and Outstanding. In 2008, we issued 160,000 shares of our Series A Convertible Preferred Stock. Glencore held all of the issued and outstanding Series A Convertible Preferred Stock. At December 31, 2024,49,715 shares were outstanding. In November 2025, Glencore sold 9,000,000 shares of our common stock. Due to the sale, and in accordance with automatic conversion features of the Series A Convertible Preferred Stock, the remaining Series A Convertible Preferred Stock held by Glencore were converted into common stock. As of December 31, 2025, there wereno shares outstanding. The conversion of preferred to common shares was 100 shares of common for each share of preferred stock. Our Series A Convertible Preferred Stock had a par value of $0.01 per share.

Stock Repurchase Program

In 2011, our Board of Directors authorized a $60.0 million stock repurchase program and during the first quarter of 2015, our Board of Directors increased the size of the program by $70.0 million. Under the program, Century is authorized to repurchase up to $130.0 million of our outstanding shares of common stock, from time to time, on the open market at prevailing market prices, in block trades or otherwise. The timing and amount of any shares repurchased will be determined by our management based on its evaluation of market conditions, the trading price of our common stock and other factors. The stock repurchase program may be suspended or discontinued at any time.

Shares of common stock repurchased are recorded at cost as treasury stock and result in a reduction of shareholders’ equity in the Consolidated Balance Sheets. From time to time, treasury shares may be reissued as contributions to our employee benefit plans and for the conversion of preferred stock. When shares are reissued, we use an average cost method for determining cost. The difference between the cost of the shares and the reissuance price is added to or deducted from additional paid-in capital.

Through December 31, 2025, we repurchased 7,186,521 shares of common stock for an aggregate purchase price of $86.3 million. We have madeno repurchases since April 2015 and have approximately $43.7 million remaining under the repurchase program authorization as of December 31, 2025.

10. Inventories

Inventories, at December 31, consist of the following:

For the year ended December 31, 2025, we recorded an inventory markdown of $8.4 million within Other operating expenses - net related to inventory at Hawesville that was sold during the first quarter of 2026 at a price below its carrying value.

11. Property, Plant and Equipment

Property, plant and equipment, at December 31, consist of the following:

For the years ended December 31, 2025, 2024 and 2023, we recorded depreciation, amortization and depletion expense of $91.8 million, $86.7 million, and $79.0 million, respectively.

12. Accumulated Other Comprehensive Loss ("AOCL")

(1)The allocation of the income tax effect to the components of other comprehensive loss is as follows:

The following table summarizes the changes in the accumulated balances for each component of AOCL:

Reclassifications out of AOCL were included in the Consolidated Statements of Operations as follows:

13. Pension and Other Postretirement Benefits

Pension Benefits

We maintain noncontributory defined benefit pension plans for certain foreign and domestic hourly and salaried employees. For the eligible domestic salaried employees, plan benefits are based primarily on years of service and average compensation during the later years of employment. For hourly employees, plan benefits are based primarily on a formula that provides a specific benefit for each year of service. Plan benefits are available to all permanent foreign employees. Our funding policy is to contribute amounts based upon actuarial and economic assumptions designed to achieve adequate funding of the projected benefit obligations and to meet the minimum funding requirements of the Employee Retirement Income Security Act of 1974 ("ERISA"). In addition, we maintain the supplemental executive retirement benefit ("SERB") plan for certain current and former executive officers, which is frozen to future accruals.

Other Postretirement Benefits ("OPEB")

In addition to providing pension benefits, we provide certain healthcare and life insurance benefits for certain foreign and domestic retired employees. We accrue the estimated cost of providing postretirement benefits during the working careers of those employees who could become eligible for such benefits when they retire. We fund these benefits as the retirees submit claims.

Retiree medical welfare changes

Under the current Hawesville labor agreement, employees who retire during the term of the labor agreement have been divided into sub-groups based on attributes such as Medicare eligibility, hire date, age and years of service. Levels of benefits are defined for the sub-groups and range from no substantive change from the benefits provided under the previous labor agreement to replacement of the defined retiree medical benefit program with individual health reimbursement accounts for each eligible participant. The health reimbursement accounts are funded based on established rates per hour worked by each eligible participant. Eligible participants will be able to withdraw from their health reimbursement accounts to fund their own retiree medical coverage. On February 13, 2026, we terminated our labor agreement with United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union ("USW") for former employees at our Hawesville facility. See "Participation in Multi-employer Pension Plans" below for additional information.

During 2017, the Company amended its non-union retiree medical and life insurance benefits to align the Company’s benefits with the market and achieve a uniform retiree medical benefit design across the Company’s U.S. locations. Effective January 1, 2018, non-union retiree medical and life insurance benefits are restricted to current participants who meet the eligibility criteria as of January 1, 2018. Additionally, effective January 1, 2019, Century no longer administers non-union retiree medical, prescription drug, dental, or vision benefits and instead makes fixed health reimbursement account contributions.

Obligation and Funded Status

The change in benefit obligation and change in plan assets as of December 31 are as follows:

The increase in the defined benefit plans' benefit obligation was mainly driven by actuarial gains in 2025, which were primarily attributable to the changes in the discount rates from fiscal year 2024 to 2025. The decrease in OPEB plans' benefit obligation was mainly driven by a change in the post-65-years-of-age participant insurance coverage for post-65-years-of-age participants from fiscal year 2024 to 2025.

The change in actual return on plan assets in 2025 was primarily attributable to fluctuations in market prices during the year.

Pension Plans That Are Not Fully Funded

At December 31, 2025, the projected benefit obligation, accumulated benefit obligation and fair value of plan assets for the pension plans with accumulated benefit obligations in excess of plan assets were$347.4 million, $318.0 million, and$288.7 million, respectively.

At December 31, 2024, the projected benefit obligation, accumulated benefit obligation and fair value of plan assets for the pension plans with accumulated benefit obligations in excess of plan assets were $342.5 million, $303.4 million and $272.2 million, respectively.

Components of net periodic benefit cost and other amounts recognized in other comprehensive income (loss):

Net Periodic Benefit Cost:

Other changes in Plan Assets and Benefit Obligations Recognized in Accumulated Other Comprehensive Income (Loss) (pre-tax):

Weighted average assumptions used to determine benefit obligations at December 31:

Weighted average assumptions used to determine net periodic benefit cost for the years ended December 31:

(1)We use the Ryan Above Median Yield Curve to determine the discount rate.

(2)For 2025, the rate of compensation increase is 3.2%. For 2024, the rate of compensation increase was 3.5%. For 2023, the rate of compensation increase was 4% per year for the first year and 3.5% per year thereafter.

(3)The rate for each of our defined benefit plans was selected by taking into account our expected asset mix and is based on historical performance as well as expected future rates of return on plan assets.

For measure ment purposes, medical cost inflation for locations other than Jamaica is initially estimated to be 8.5% for both pre- and post-65-years-of-age participants, declining to 4.5% over ten years and continuing thereafter. For Jamaica, it is initially estimated to be 8.0% for both pre- and post-65-years-of-age participants and for the next two years.

Benefit Plan Assets

Pension Plan Investment Strategy and Policy

The Pension Plans’ assets are invested in a prudent manner for the exclusive purpose of providing benefits to participants.

Other objectives are to:

•Provide a total return that, over the long term, provides sufficient assets to fund the pension plan liabilities subject to a level of risk, contributions and pension expense deemed appropriate by the company.

•Minimize, where possible, pension expense volatility, and inclusion of liability driven investing as an investment strategy when appropriate. As the funding ratio improves, the objectives will evolve to minimize the funded status volatility.

•Diversify investments within asset classes to reduce the impact of losses in single investments.

The assets of the Pension Plans are invested in compliance with ERISA, as amended, and any subsequent applicable regulations and laws.

Performance

Our performance objective is to outperform the return of weighing passive investment alternatives by the policy target allocations after fees at a comparable level of risk. This investment objective is expected to be achieved over the long term and is measured over rolling multi-year periods. Peer-relative performance comparisons will also be considered especially when performance deviates meaningfully from market indexes. Investment objectives for each asset class are included below.

Asset Allocation Policy

Asset allocation policy is the principal method for achieving the Pension Plans' investment objectives stated above. The Pension Plans’ weighted average long-term strategic asset allocation policy targets are as follows:

Global equities are held for their long-term expected return premium over fixed income investments and inflation. Fixed income is held for diversification relative to equities, and as a hedging instrument to interest rate volatility for the pension obligation. Diversified Credit and Real Assets are held for diversification relative to equities and for income generation.

The strategic role of global equities is to:

•Provide higher expected returns of the major asset classes.

•Maintain a diversified exposure within global stock markets through the use of multi-manager portfolio strategies.

The strategic role of fixed income is to:

•Diversify the Pension Plans’ equity exposure by investing in fixed income securities that exhibit a low correlation to equities, thereby lowering the overall return volatility of the entire investment portfolio.

•Maintain a diversified exposure within the U.S. fixed income market through the use of portfolio strategies targeting treasury bond exposures.

•Hedge the interest rate risk of the pension obligation by investing in securities that target a similar duration to the pension obligation cash flows.

The strategic role of diversified credit is to:

•Diversify the Pension Plans’ equity exposure by investing in alternative credit securities that exhibit a low correlation to equities, thereby lowering the overall return volatility of the entire investment portfolio.

•Maintain a diversified exposure within the alternative credit markets through the use of multi-manager portfolio strategies targeting, but not limited to, securitized credit, high yield securities, and emerging market debt.

•Achieve returns in excess of passive indexes through the use of active investment managers and strategies.

The strategic role of real assets is to:

•Diversify the Pension Plans’ equity exposure by investing in real assets that exhibit a low correlation to equities, thereby lowering the overall return volatility of the entire investment portfolio.

•Maintain a diversified exposure within the real asset markets through the use of multi-manager portfolio strategies targeting listed and unlisted exposures.

•Achieve returns in excess of passive indexes through the use of active investment managers and strategies.

The long-term strategic asset allocation policy is reviewed regularly or whenever significant changes occur to Century’s or the Pension Plans' financial position and liabilities.

Fair Value Measurements of Pension Plan assets

The following table sets forth by level the fair value hierarchy our Pension Plans' assets. These assets are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. Our assessment of the significance of a particular input to the fair value measurement requires judgment, and may affect the valuation of fair value assets and liabilities and the placement within the fair value hierarchy levels.

As more fully described within Note 7. Fair Value Measurements, the Company uses a three-level fair value hierarchy that prioritizes the inputs used to measure fair values. The fair value hierarchy provides transparency regarding the inputs we use to measure fair value. We categorize each fair value measurement in its entirety into the following three levels, based on the lowest level input that is significant to the entire measurement:

•Level 1 Inputs – quoted prices (unadjusted) in active markets for identical assets or liabilities that the reporting entity can access at the measurement date.

•Level 2 Inputs – inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly.

•Level 3 Inputs – unobservable inputs for the asset or liability.

The following summarizes the Company’s Pension Plans' assets fair value by asset category:

Our domestic Pension Plans’ assets are held in certain commingled funds and group trusts which do not have publicly quoted prices. The fair value of the commingled funds and group trusts is based on NAV of the underlying investments. The fair value of the underlying investments held by the commingled funds, separate accounts and common collective trusts is generally based on quoted prices in active markets. Though the Company believes the methods used to estimate fair value are consistent with those used by other market participants, the use of other methods or assumptions could result in a different estimate of fair value. Our foreign plan assets are held in bonds and equity securities which have publicly quoted prices.

Our other postretirement benefit plans are unfunded. We fund these benefits as the retirees submit claims.

Pension and OPEB Cash Flows

During 2025 and 2024, we made contributions of approximately $9.2 million and $2.5 million, respectively, to the qualified defined benefit and SERB plans we sponsor and $5.0 million and $5.5 million, respectively, to the other postretirement benefit plans.

We expect to make the following contributions for 2026:

Estimated Future Benefit Payments

The following table provides the estimated future benefit payments for the pension and other postretirement benefit plans:

Participation in Multi-employer Pension Plans

The union-represented employees at Hawesville are part of a United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union ("USW") sponsored multi-employer plan. Our contributions to the plan are determined at a fixed rate per hour worked. The risks of participating in a multi-employer plan are different from single employer plans in the following respects:

•Assets contributed to the multiemployer plan by one employer may be used to provide benefits to employees of other participating employers.

•If a participating employer stops contributing to the plan, the unfunded obligations of the plan may be borne by the remaining participating employers.

•If a participating employer chooses to stop participating in a multi-employer plan, the employer may be required to pay the plan an amount based on the underfunded status of the plan, referred to as a withdrawal liability.

Century’s participation in the plan for the year ended December 31, 2025, is outlined in the table below.

(1)The "EIN/Pension Plan Number" column provides the Employee Identification Number (EIN) and the three-digit plan number, if applicable.

(2)The most recent Pension Protection Act zone status available in 2025 and 2024 is for the plan's year-end December 31, 2024 and December 31, 2023, respectively. The zone status is based on information that Century received from the plan as well as publicly available information per the Department of Labor and is certified by the plan’s actuary. Among other factors, plans in the red zone are generally less than 65 percent funded, plans in the yellow zone are less than 80 percent funded, and plans in the green zone are at least 80 percent funded.

(3)The “Subject to Financial Improvement / Rehabilitation Plan” column indicates plans for which a financial improvement plan (FIP) or a rehabilitation plan (RP) is either pending or has been implemented. The last column lists the expiration date(s) of the collective-bargaining agreement(s) to which the plans are subject. On February 13, 2026, we terminated our labor agreement with USW for former employees at our Hawesville facility.

Century's contributions to the above plan is not 5% or more of the total contributions to the plan.

Century 401(k) Plans

We sponsor a tax-deferred savings plan under which eligible domestic employees may elect to contribute specified percentages of their compensation with Century. We match a portion of participants' contributions to the savings plan. Employee and matching contributions are considered fully vested immediately upon participation in the plan. Concurrent with the 2014 amendment to the Salaried Pension Plan that eliminated future accruals for participants who are under age 50 as of January 1, 2015 and closed the plan to new entrants, the Company increased the proportional match of contributions made to those affected by the amendment. The expense related to the plan was $6.7 million, $6.3 million, and $5.8 million for 2025, 2024, and 2023, respectively.

14. Share-based Compensation

Amended and Restated Stock Incentive Plan. Under our Amended and Restated Stock Incentive Plan (the "Stock Incentive Plan") we award service-based and performance-based share awards and nonqualified stock options to our salaried officers, non-employee directors, and other key employees. Our service-based and performance-based share awards typically vest over a period ofthree years from the date of grant, provided that the recipient is still our employee at the time of vesting. Our independent non-employee directors receive annual grants of service-based share awards that typically vest following 12 months of service. The Stock Incentive Plan has 12,900,000 shares authorized for issuance with approximately 1,899,785 shares remaining at December 31, 2025.

Long-Term Incentive Plan. We also grant annual long-term incentive awards under our Amended and Restated Long-Term Incentive Plan (the "LTIP"). The LTIP is designed to provide senior-level employees the opportunity to earn long-term incentive awards through the achievement of performance goals and to align compensation with the interests of our stockholders. This is achieved by linking compensation to share price appreciation and total stockholder return over a multi-year period. Awards made under the LTIP are granted subject to the Stock Incentive Plan to the extent the award is deliverable in stock. We providetwo types of LTIP awards: restricted stock units ("RSU") and performance stock units ("PSU").

RSUs are stock-settled awards which do not contain any performance-based vesting requirements. PSUs can be settled in cash or stock and vest based on the achievement of pre-determined performance metrics at the discretion of the Board. Our PSU liability, a component of both Accrued other current liabilities Other liabilities on the Consolidated Balance Sheets, was approximately $11.8 million and $7.1 million as of December 31, 2025 and 2024, respectively. Both the PSUs and RSUs vest, in their entirety, after three years.

Fair Value Measurement of Share-Based Compensation Awards. For our service-based awards, fair value is equal to the closing stock price on the date of grant. For our performance-based awards, fair value is equal to the closing stock price at each reporting period end.

The following table summarizes the compensation cost recognized for the years ended December 31, 2025, 2024 and 2023 for all service-based and performance-based share awards. The compensation cost is included as part of Selling, general and administrative expenses and Cost of goods sold in our Consolidated Statements of Operations.

No share-based compensation cost was capitalized during these periods and there were no significant modifications of any share-based awards in 2025, 2024 and 2023. As of December 31, 2025, we had unrecognized compensation cost of $23.5 million before taxes. This cost will be recognized over a weighted average period of 1.2 years.

15. Earnings Per Share

The following table shows the basic and diluted EPS for 2025, 2024, and 2023:

(1)In periods when we report a net loss, all share-based compensation awards, convertible preferred shares and convertible senior notes are excluded from the calculation of diluted weighted average shares outstanding because of their anti-dilutive effect on earnings (loss) per share.

16. Income Taxes

In 2025, the Company adopted ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, on a prospective basis. This guidance requires disaggregated information about the effective tax rate reconciliation, additional disaggregated data on income taxes paid by jurisdiction, and certain other amendments to improve the effectiveness of income tax disclosures. The adoption did not impact the Company’s consolidated financial position, results of operations, or cash flows but enhanced the income tax footnote disclosures for the year ended December 31, 2025.

The components of pre-tax book income (loss) consist of the following:

Significant components of income tax expense consist of the following:

A reconciliation of the statutory U.S. Federal income tax rate to the effective income tax rate on income (loss) is as follows:

(1)State taxes in Tennessee and Kentucky comprise the majority (greater than 50 percent) of the tax effect in this category.

The effective tax rate for the year ending December 31, 2025 was (482.7)% compared to the statutory US tax rate of 21%. This lower effective rate is primarily due to the non-taxable benefit of the Advanced Manufacturing Production Credit under Section 45X, which is discussed below and favorable changes in the current year regarding our US valuation allowance.

The following table presents the amounts paid for income taxes, net of refunds:

Section 45X of the Inflation Reduction Act of 2022 ("IRA") contains a production tax credit equal to 10% of certain eligible production costs, including, without limitation, labor, energy, depreciation and amortization and overhead expenses. On October 24, 2024, the U.S. Department of the Treasury and the Internal Revenue Service issued final regulations on the production tax credit requirements under Internal Revenue Code Section 45X (the "IRA Regulations"). The IRA Regulations provide guidance on rules that taxpayers must satisfy to qualify for the IRA Section 45X tax credit. For the year ended December 31, 2025 and December 31, 2024, we recognized $89.1 million and $89.7 million as a reduction in Cost of goods sold, and $3.8 million and $2.9 million as a reduction in selling, general and administrative expenses, respectively, within the Consolidated Statements of Operations.

In July 2025, the One Big Beautiful Bill Act (the "Act") became law. The Act removed the exemption for critical minerals related to the phase out of the advanced manufacturing production tax credit under Internal Revenue Code Section 45X of the Inflation Reduction Act of 2022 and final regulations issued in October of 2024. Under the Act, beginning in 2031, the amount of the tax credit will be reduced by 25% each year and reduced to 0% in 2034. Additionally, the Act made changes to, but not limited to, permanently extending bonus depreciation that permits full expensing of qualified property, and changes to limitations on the deductibility of interest expense. The Act did not have a material impact on our financial results for the year ending December 31, 2025. We will continue to evaluate the effects of the Act on our results as further guidance is issued.

The Company’s accounting policy with respect to releasing income tax effects from accumulated other comprehensive income is to apply a security by security approach whereby the tax effects are measured based on the change in the unrealized gains or losses reflected in Other comprehensive income (loss).

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes.

The significant components of our deferred tax assets and liabilities as of December 31 are as follows:

We regularly assess the likelihood that deferred tax assets will be recovered from future taxable income. To the extent we believe that it is more likely than not that a deferred tax asset will not be realized, a valuation allowance is established. When a valuation allowance is established or increased, an income tax charge is included in the Consolidated Statements of Operations and net deferred tax assets are adjusted accordingly. Future changes in tax laws, statutory tax rates and taxable income levels could result in actual realization of the deferred tax assets being materially different from the amounts provided for in the consolidated financial statements. If the actual recovery amount of the deferred tax asset is less than anticipated, we would be required to write-off the remaining deferred tax asset and increase the tax provision.

We have a valuation allowance of $471.0 million recorded against our net U.S. and Jamaican deferred tax assets, and a portion of our Icelandic deferred tax assets as of December 31, 2025. The Company is subject to the provisions of ASC 740-10, Income Taxes, which requires that the effect on deferred tax assets and liabilities of a change in tax rates be recognized in the period the tax rate change was enacted.

The changes in the valuation allowance are as follows:

The significant components of our NOLs are as follows:

(1)US federal NOLs begin to expire in 2028.

(2)US state NOLs begin to expire in 2027.

(3)NOLs in Iceland expire in 2026 and 2035.

(4)NOLs in Jamaica do not expire.

Our ability to utilize our deferred tax assets to offset future federal taxable income may be significantly limited if we experience an "ownership change" as defined in the Code. In general, an ownership change would occur if our "five-percent shareholders," as defined under the Code, collectively increase their ownership in us by more than 50 percentage points over a rolling three-year period. Future transactions in our stock that may not be in our control may cause us to experience such an ownership change and thus limit our ability to utilize net operating losses, tax credits and other tax assets to offset future taxable income.

A reconciliation of the beginning and ending amounts of gross unrecognized tax benefits (excluding interest) is as follows:

As of December 31, 2025, the Company’s gross unrecognized tax benefits totaled $3.6 million. Included in the above balances are tax positions relating to temporary differences where there is uncertainty about the timing of tax return inclusion, but not that the amounts will ultimately be tax deductible. Because of the impact of deferred tax accounting, other than interest and penalties, the timing would not impact the annual effective tax rate but could accelerate the payment of cash to the taxing authority to an earlier period. It is our policy to recognize potential accrued interest and penalties related to unrecognized tax benefits in income tax expense.

The Company considers the undistributed earnings of its foreign subsidiaries and joint ventures to be permanently reinvested and has not provided for U.S. federal income taxes on these unremitted earnings. No deferred tax liability has been recorded for the related outside basis differences in these entities. Determination of the amount of any unrecognized deferred tax liability on this outside basis difference is not practicable as such determination involves material uncertainties about the potential extent and timing of any reversals.

Century and its subsidiaries file income tax returns in the U.S. federal jurisdiction, various state and local jurisdictions, and several foreign jurisdictions.

Our federal income tax returns have been reviewed by the IRS through 2010. However, we have NOLs beginning in 2008 that are available for carryforward to future years. Under U.S. tax law, NOLs may be adjusted by the IRS until the statute of limitations expires for the year in which the NOL is used. Accordingly, our 2008 and later NOLs may be reviewed until they are used or expire.

We are subject to examination by tax authorities according to statutory periods defined in each jurisdiction. The earliest statutory period open is beginning in 2020.

17. Commitments and Contingencies

We have pending against us or may be subject to various lawsuits, claims and proceedings related primarily to employment, commercial, stockholder, environmental, safety and health matters and are involved in other matters that may give rise to contingent liabilities. While the results of such matters and claims cannot be predicted with certainty, we believe that the ultimate outcome of any such matters and claims will not have a material adverse impact on our financial condition, results of operations or liquidity. However, because of the nature and inherent uncertainties of litigation and estimating liabilities, should the resolution or outcome of these actions be unfavorable, our business, financial condition, results of operations and liquidity could be materially and adversely affected.

In evaluating whether to accrue for losses associated with legal or environmental contingencies, it is our policy to take into consideration factors such as the facts and circumstances asserted, our historical experience with contingencies of a similar nature, the likelihood of our prevailing and the severity of any potential loss. For some matters, no accrual is established because we have assessed our risk of loss to be remote. Where the risk of loss is probable and the amount of the loss can be reasonably estimated, we record an accrual, either on an individual basis or with respect to a group of matters involving similar claims, based on the factors set forth above. While we regularly review the status of, and our estimates of potential liability associated with, contingencies to determine the adequacy of any associated accruals and related disclosures, the ultimate amount of loss may differ from our estimates.

Legal Contingencies

Ravenswood Retiree Medical Benefits changes

In November 2009, Century Aluminum of West Virginia ("CAWV") filed a class action complaint for declaratory judgment against the United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union ("USW"), the USW’s local and certain CAWV retirees, individually and as class representatives ("CAWV Retirees"), seeking a declaration of CAWV’s rights to modify/terminate retiree medical benefits. Later in November 2009, the USW and representatives of a retiree class filed a separate suit against CAWV, Century Aluminum Company, Century Aluminum Master Welfare Benefit Plan, and various John Does with respect to the foregoing. On August 18, 2017, the District Court for the Southern District of West Virginia approved a settlement agreement in respect of these actions, pursuant to the agreement, CAWV agreed to make payments into a trust for the benefit of the CAWV Retirees in the aggregate amount of $23.0 million over the course of 10 years. Upon approval of the settlement, we paid $5.0 million to the aforementioned trust in September 2017 and recognized a gain of $5.5 million to arrive at the-then net present value of $12.5 million. CAWV has agreed to pay the remaining amounts under the settlement agreement in annual increments of $2.0 million fornine years. As of December 31, 2025,$1.9 million was recorded in other current liabilities, representing the current accrual of the final payment.

PBGC Settlement

In 2013, we entered into a settlement agreement with the Pension Benefit Guarantee Corporation ("the PBGC") regarding an alleged "cessation of operations" at our Ravenswood facility (the "PBGC Settlement Agreement"). Pursuant to the terms of the PBGC Settlement Agreement, we agreed to make additional contributions (above any minimum required contributions) to our defined benefit pension plans totaling approximately $17.4 million. Under certain circumstances, in periods of lower primary aluminum prices relative to our cost of operations, we were able to defer one or more of these payments, provided that we provide the PBGC with acceptable security for such deferred payments. We historically elected to defer certain payments under the PBGC Settlement Agreement and provided the PBGC with the appropriate security. On October 1, 2021, we amended the PBGC Settlement Agreement (the "Amended PBGC Settlement Agreement") such that we removed the deferral mechanism and agreed to contribute approximately $2.4 million per year to our defined benefit pension plans for a total of approximately $9.6 million, over four years beginning on November 30,2022 and ending on November 30, 2025, subject to acceleration if certain terms and conditions are met in such amendment. As of December 31, 2025, we have made all contributions under the Amended PBGC Settlement Agreement.

Sebree

Sebree has a power supply arrangement with Kenergy and Century Marketer LLC (“Century Marketer"), Century's wholly-owned subsidiary that acts as a Midcontinent Independent System Operator ("MISO") market participant. Under this arrangement, Sebree gets access to power at MISO pricing plus transmission and other costs. As the MISO Market Participant, Century Marketer purchases power from MISO for resale to Kenergy, which then resells the power to Sebree. Century Marketer's power supply arrangement with Kenergy has an effective term through May 31, 2028, with automaticone-year extensions unless either party providesone-year notice of termination prior to the May 31 anniversary date. Similarly, Kenergy's power supply contract with Sebree has a term through December 31, 2026, with automaticone-year extensions unless either party providesone-year notice of termination prior to the December 31 anniversary date.

Mt. Holly

Century Aluminum of South Carolina, Inc. ("CASC") has a power supply agreement with South Carolina Public Service Authority (“Santee Cooper”) that has an effective term through December 2031. Under this power supply agreement,100% of Mt. Holly’s electrical power requirements are supplied from Santee Cooper’s generation at cost of service based rates.

Grundartangi

Grundartangi has power purchase agreements for approximately 545 MW with HS Orka hf ("HS"), Landsvirkjun and Orkuveita Reykjavikur ("OR"). These power purchase agreements expire on various dates from 2026 through 2036 (subject to extension). The power purchase agreements with each of HS and OR provide power at LME-based variable rates for the duration of these agreements. The larger Landsvirkjun agreement provides for fixed rate with an additional variable rate linked to the LME. Grundartangi also has a separate 25 MW power purchase agreement with Landsvirkjun at an LME-based variable rate.

Other Commitments and Contingencies

Labor Commitments

The bargaining unit employees at our Grundartangi, Vlissingen, Hawesville, Sebree and Jamalco facilities are represented by labor unions, representing approximately 55% of our total workforce.

Approximately 84%of Grundartangi’s work force is represented byfive labor unions, governed by a labor agreement that establishes wages and work rules for covered employees. This agreement is effective through December 31, 2029.

100% of Vlissingen’s workforce is represented by the Federation for the Metal and Electrical Industry ("FME"), a Netherlands' employers' organization for companies in the metal, electronics, electrical engineering and plastic sectors. The FME negotiates working conditions with trade unions on behalf of its members, which, when agreed upon, are then applicable to all employees of Vlissingen. The current labor agreement is effective through December 31, 2026.

Approximately 36% of our U.S. based work force is represented by the Allied Industrial and Service Workers International Union ("USW") through separately negotiated labor agreements for each facility. The labor agreement for Hawesville employees was effective through April 1, 2026, but was terminated early on February 13, 2026. Mt. Holly employees are not represented by a labor union. Century Sebree's labor agreement with the USW for its employees is effective through October 28, 2028.

Approximately 62%of Jamalco's work force is represented by the Union of Technical, Administrative, and Supervisory Personnel ("UTASP") through separately labor agreements for hourly and salaried employee groups. Both contracts were effective through December 31, 2023. Jamalco is currently in the process of negotiating new contracts with both the salaried and hourly employee groups. Until new contracts are reached, employees will continue to operate under the current agreements.

Contingent Obligation

We have a contingent obligation in connection with the “unwind” of a contractual arrangement between CAKY, Big Rivers Electric Corporation ("Big Rivers") and a third party and the execution of a long-term cost-based power contract with Kenergy, a member of a cooperative of Big Rivers, in July 2009. This contingent obligation consists of the aggregate payments made to Big Rivers by the third party on CAKY’s behalf in excess of the agreed upon base amount under the long-term cost-based power contract with Kenergy. As of December 31, 2025, the principal and accrued interest for the contingent obligation was$33.7 million, which was fully offset by a derivative asset. We may be required to make installment payments for the contingent obligation in the future. These payments are contingent based on the LME price of primary aluminum and the level of Hawesville’s operations. Interest accrues at an annual rate equal to 10.94%. As of December 31, 2025, the LME forward market prices exceed the threshold for payment. In addition, based on the fact that we recently sold the Hawesville property, which is to be developed into a data center, we believe that we will not be required to make payments on the contingent obligation during the term of the agreement, which expires in 2028. There can be no assurance that circumstances will not change thus accelerating the timing of such payments.

18. Asset Retirement Obligations

The reconciliation of the changes in our AROs is presented below:

(1)Current portion of asset retirement obligations is recorded in Accrued and other current liabilities.

19. Business Segments

The Company is a producer of primary aluminum and alumina. The Company has organized itself, including management personnel and systems, financial processes, operational execution, governance and risk oversight, regulatory compliance, and every other aspect of the Company’s operations, to assess and manage the business on a holistic basis, from mine to metal, which tracks the upstream manufacturing process for aluminum. To better reflect this operational and organizational approach, and to further enhance the reporting of its financial and operating results, beginning with the quarter ended March 31, 2025, the Company’s Chief Executive Officer and Chief Operating Decision Maker ("CODM") regularly receives and reviews financial information at the consolidated level to evaluate business performance and make operating decisions. The CODM uses the U.S. GAAP measure of consolidated Net Income to develop forecasting, to evaluate the Company’s overall profitability and financial performance and to make key operating decisions, such as the allocation of resources.

Given the change described above, the Company has determined that neither itsthree smelters nor Jamalco’s mining and refining operations meet the definition of operating segments. As a result, the Company has determined that the Company has onlyone operating and onlyone reportable segment, and it is managed on a consolidated basis. In accordance with ASC 280-10-50-34, the corresponding information for earlier periods is recast in the tables below to conform with the updated presentation.

Segment assets are reported on our Consolidated Balance Sheets as Total assets. Our Consolidated Statements of Cash Flows presents Depreciation, depletion and amortization expense and includes the measure of Capital expenditures.

The following table presents information about the Company's single segment for the years ended December 31, .

(1)A component of Cost of goods sold.

(2)Includes raw materials, labor, energy, freight costs, FIFO inventory adjustments and other direct cost of goods sold.

(3)Advanced production credit related to Section 45X of the IRA.

(4)Includes inventory revaluation to lower of cost or net realizable value and changes in inventory reserve.

(5)Represents the depreciation expenses and expenses related to leased assets that are directly related to the cost of goods sold.

Long-lived Assets

(1)Includes long-lived assets other than financial instruments and deferred taxes.

Major customer information

Revenues from Glencore in 2025, 2024 and 2023 exceeded 10% of our net sales. See Note 4. Related Party Transactions for additional information on sales to Glencore.

20. Derivatives

As of December 31, 2025, we had an open position of 48,400 tonnes related to LME forward financial sales contracts to fix the forward LME aluminum price. These contracts are expected to settle monthly through June 2027. We had an open position of 89,800 tonnes related to MWP forward financial sales contracts to fix the forward MWP price. These contracts are expected to settle monthly through December 2027. We also enter into financial contracts with various counterparties to offset fixed price sales arrangements with certain of our customers ("fixed for floating swaps") to remain exposed to the LME and MWP aluminum prices. As of December 31, 2025, we hadno open fixed for floating swaps.

We have entered into financial contracts to hedge a portion of our Jamalco fuel cost exposure ("HFO price swaps"). The volume of heavy fuel oil ("HFO") consumed at Jamalco is measured per barrel and as of December 31, 2025, we had an open position of 225,000 barrels. The HFO price swaps are expected to settle monthly through October 2026.

We have entered into financial contracts to fix a portion of our exposure to the Indiana Hub power market at our Sebree plant ("Indiana Hub power price swaps"). As of December 31, 2025, we had an open position of 884,712 MWh. The Indiana Hub power price swaps are expected to settle monthly through June 2027.

Our agreements with derivative counterparties contain certain provisions requiring collateral to be posted in the event the market value of our position exceeds the margin threshold limit of our master agreement with the counterparty. As of December 31, 2025 and December 31, 2024, the Company hadno recorded restricted cash as collateral related to open derivative contracts under the master arrangements with our counterparties.

The following table sets forth the Company's derivative assets and liabilities that were accounted for at fair value and not designated as cash flow hedges as of December 31, 2025 and 2024, respectively:

(1)Commodity contracts reflect our outstanding LME and MWP forward financial sales contracts, fixed for floating swaps, HFO price swaps and Indiana Hub power price swaps. At December 31, 2025 and December 31, 2024, there wereno commodity contracts with Glencore.

(2)Foreign exchange contracts reflect our outstanding FX swaps and casthouse currency hedges.

The following table summarizes the net gain (loss) on forward and derivative contracts for the years ended December 31, 2025, 2024, and 2023:

21. Variable Interest Entity

The Company consolidates Jamalco, a bauxite mining and alumina refinery in Jamaica, under the variable interest entity ("VIE") model. Jamalco lacks sufficient equity investment at risk in accordance with relevant guidance. Based on its purpose and design, Jamalco is expected to require additional subordinated financial support, such as those in the form of equity contributions or other forms of subordinated financing, which the Company expects would require parent guarantees.

The Company owns a 55% ownership interest in Jamalco through its wholly-owned subsidiary, GAJL, which serves as the managing partner. The Company is responsible for funding 55% of Jamalco's operating costs and capital requirements and is not obligated to provide additional financial support beyond its equity interest. Upon acquisition, the Company made an immediate equity contribution to Jamalco and has provided subsequent financing of costs for Jamalco to perform its activities in the ordinary course of business.

The Company obtains direct ownership of our 55% share of Jamalco’s outputs and purchases the remaining 45% of the output from the Government of Jamaica. Through direct ownership and purchase,100% of Jamalco’s output is either retained and utilized in the Company’s business operations or sold by the Company. The Company’s consolidated statement of cash flows reflects 100% of cash flows related to the Jamalco operations. The Company receives cash proceeds from the Government of Jamaica for its 45% interest of the Jamalco operating costs and capital requirements.

Although our partner has certain participating rights over some decisions of the entity, the Company has power over the majority of key activities at Jamalco that significantly affect its economic performance over which the counterparty does not have such participating rights; therefore, the Company is the primary beneficiary of the VIE.

The table below shows the carrying amounts and classification of the consolidated VIE's assets and liabilities included in the Consolidated Balance Sheets as of December 31, 2025 and 2024.

22. Restatement of Previously Issued Financial Statements

Subsequent to the issuance of our Annual Report on Form 10-K for the fiscal year ended December 31, 2024, the Company identified an error in accounting in its historical financial statements related to the consolidation of its Jamalco joint venture whereby the Company previously used the proportionate method of consolidation for certain of Jamalco's net assets versus the full consolidation method.

The Company has corrected the error in the Consolidated Financial Statements as of and for the periods ended December 31, 2024 and December 31, 2023 presented herein. Revisions to the Company’s previously reported disclosures have been reflected in Note 1. Summary of Significant Accounting Policies; Note 2. Acquisition of Jamalco; Note 11. Property, Plant and Equipment;Note 13. Pension and Other Postretirement Benefits; Note 18. Asset Retirement Obligations; Note 19. Business Segments; and Note 21. Variable Interest Entity. A summary of the revisions to the Company’s previously reported financial statements is provided in this Note 22. Restatement of Previously Issued Financial Statementsand Note 23. Revisions to Prior Period Quarterly Consolidated Financial Statements (unaudited).

The effects of the corrections described above on the Company’s Consolidated Statements of Operations were as follows:

The effects of the corrections described above on the Company's Consolidated Statements of Comprehensive Income (Loss) were as follows:

The effects of the corrections described above on the Company's Consolidated Balance Sheets were as follows:

The effects of the corrections described above on the Company’s Consolidated Statements of Cash Flows were as follows:

The effects of the corrections described above on the Company's Consolidated Statements of Shareholder's Equity were as follows:

The Company has also restated impacted amounts within the accompanying footnotes to the Consolidated Financial Statements.

23. Quarterly Financial Information (Unaudited and Restated)

As further discussed in Note 1. Summary of Significant Accounting Policies and Note 22. Restatement of Previously Issued Financial Statements, the Company determined that corrections to the unaudited condensed consolidated financial statements were required for all impacted periods previously included in each of the Company's Quarterly Reports on Form 10-Q for the quarterly periods ended March 31, 2025, June 30, 2025, September 30, 2025, March 31, 2024, June 30, 2024, and September 30, 2024. Restated amounts are computed independently for each quarter presented; therefore, the sum of the quarterly amounts may not equal the total amount for the year due to rounding.

The restatement impacts to the Company's consolidated statements of operations were as shown below.

The restatement impacts to the Company's consolidated balance statements were as shown below (dollars in millions).

The restatement impacts to the Company's consolidated statements of shareholders' equity as shown below (dollars in millions).

24. Subsequent Events

On January 26, 2026, we announced that we had entered into a joint development agreement with Emirates Global Aluminium (“EGA”) to build the first new primary aluminum smelter in the United States since our Mt. Holly facility came online in 1980. Under the joint development agreement, EGA will own 60 percent of the joint venture, with Century Aluminum owning the remaining 40 percent. The new plant, to be built in Inola, Oklahoma, is expected to produce 750,000 tonnes of aluminum per year, more than doubling current U.S. production. Construction of the project is expected to start by the end of 2026, with detailed engineering work already and negotiations with Public Service Company of Oklahoma and the state of Oklahoma on a competitive long-term power supply underway.

On February 2, 2026, we completed the sale of our Hawesville, Kentucky facility to an affiliate of Terawulf, Inc. for $200.0 million in cash and a 6.8% non-dilutive minority equity interest in the Terawulf affiliate that intends to develop and own a high-performance computing/artificial intelligence data center on the site. A large portion of the proceeds are intended to be deployed to expand our domestic primary aluminum production capacity through the restart of the last potline at our Mt. Holly facility and investments in our new smelter project.

In connection with our sale of the Hawesville facility, on February 2, 2026, we terminated the letter of credit in the amount of $8.1 million under our U.S. Credit Facility, effectively prepaying the IRBs.

As noted throughout this Form 10-K, on February 13, 2026, we terminated our labor agreement with United Steel, Paper and Forestry, Rubber, Manufacturing, Energy, Allied Industrial and Service Workers International Union ("USW") for former employees at our Hawesville facility, the impacts for which are disclosed herein.