Commitments and Contingencies

3 Months Ended

Mar. 31, 2026

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

13.    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

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 for nine years, ending in 2026. As of March 31, 2026, $1.9 million was recorded in Accrued and other current liabilities.

Hawesville Partial Withdrawal

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 pension plan. 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 under the Employee Retirement Income Security Act of 1974. On February 13, 2026, we terminated our labor agreement with USW for former employees at our Hawesville facility. As a result of the termination, the Company recognized a partial withdrawal liability of $5.7 million. Although the liability represents our best estimate of the partial withdrawal liability at this time, actual costs could differ based on final funding assessments. Any changes to the estimate will be recorded in the period identified. We estimate our cash obligation to be $0.6 million quarterly for the next nine quarters and one final payment of $0.5 million in the tenth quarter.

Power Commitments and Contingencies

Sebree

Sebree has a power supply arrangement with Kenergy and Century Marketer, LLC ("Century Marketer"), Century's wholly-owned subsidiary. 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 automatic one-year extensions unless either party provides one-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 automatic one-year extensions unless either party provides one-year notice of termination prior to the December 31 anniversary date.

Mt. Holly

Century Aluminum of South Carolina ("CASC") has a power supply agreement with 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. The contract provides sufficient energy to allow Mt. Holly to operate at full production capacity.

Grundartangi

Grundartangi has power purchase agreements for approximately 545 MW of aggregate power 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.

Insurance Contingencies

We carry insurance policies to compensate us for certain losses, including property damage and business interruption. When recovery of property damage loss or other directly related expenses through insurance proceeds is demonstrated to be probable, an asset is recorded that offsets the loss or expenses up to the amount of the total loss or expenses within the period. Proceeds received from insurance claims in excess of losses and directly related expenses incurred within the period as well as proceeds received from business interruption insurance claims are recorded as a gain. No gain is recorded until it is realized or realizable, generally after the receipt of the proceeds.

In November 2024, a transformer unit that powers one of Grundartangi's two potlines failed. Accordingly, production output from the second potline decreased. In October 2025, following the failure of another transformer unit, production from the second potline ceased due to diminished power supply. The cessation of the second potline resulted in a temporary

reduction of output by about two-thirds. We filed a claim with our insurer to recover insurance losses related to property damage and the absent margin that we would have realized if production output was not affected.

For the three months ended March 31, 2026, we recognized a Gain on insurance proceeds of $33.0 million, comprised of $37.0 million of proceeds received in connection with the Grundartangi insurance claim net of directly related expense recovery of $4.0 million recognized in Cost of goods sold.

Other Commitments and Contingencies

Labor Commitments

The bargaining unit employees at our Grundartangi, Vlissingen, Sebree and Jamalco facilities are represented by labor unions, representing approximately 56% of our total workforce.

Approximately 87% of Grundartangi’s work force is represented by five 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 work force 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 35% of our U.S. based work force is represented by 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 63% of Jamalco’s work force is represented by the Union of Technical, Administrative, and Supervisory Personnel ("UTASP") through separately negotiated 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 March 31, 2026, the principal and accrued interest for the contingent obligation was $34.1 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 11.00%. As of March 31, 2026, 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.