CENTURY ALUMINUM CO (CENX) Business

Item 1.  Business

Overview

Century Aluminum Company is a global producer of primary aluminum and operates aluminum reduction facilities, or "smelters," in the United States and Iceland. Aluminum is an internationally traded commodity, and its price is effectively determined on the London Metal Exchange (the "LME"), plus applicable regional and value-added product premiums. Our smelters produce standard-grade and value-added primary aluminum products. Our current annual production capacity was approximately 770,000 tonnes per year ("tpy") as of December 31, 2025. We produced approximately 638,000 tonnes of primary aluminum in 2025.

In addition to our primary aluminum assets, we have a 55% joint venture interest in the Jamalco bauxite mining operation and alumina refinery in Jamaica ("Jamalco"). The remaining 45% interest in Jamalco is indirectly owned by the Government of Jamaica. Century's share of Jamalco's production capacity is approximately 770,000 tpy. We also own a carbon anode production facility located in the Netherlands ("Vlissingen"). Carbon anodes are consumed in the production of primary aluminum. Vlissingen supplies carbon anodes to our aluminum smelter in Grundartangi, Iceland. Each of our aluminum smelters in the United States produces anodes at on-site facilities.

At Century, we aim to provide innovative and reliable aluminum products to our customers, a safe and sustainable workplace for our people and the communities in which we operate, and a compelling value proposition for our stockholders. We seek to operate our businesses in a responsible manner by balancing the twin priorities of (i) maintaining a strong balance sheet across commodity cycles and (ii) making investments to lower our cost structure, expand our production capacity, and increase our competitiveness.

Century has invested significant capital in recent years to increase production and grow our product portfolio to include more value-added aluminum products to better serve our customers in the U.S. and Europe. We believe that our focus on lowering costs and decommoditizing our product line will enable us to deliver profitable long-term growth and differentiate us from overseas competitors with longer supply lines into the markets we serve.

We conduct our business with a focus on sustainability, including the health and safety of our people and the communities in which we operate. Through our Natur-AlTM product line, we are able to provide our customers with world-class, low-carbon aluminum products that demonstrate our commitment to sustainability.

We operate our business on a consolidated basis, through one operating segment and thus, one reportable segment. Additional information about our segment reporting is available in Note 19. Business Segments to the Consolidated Financial Statements included herein.

Century Aluminum Company is a Delaware corporation with our principal executive offices located at One South Wacker Drive, Suite 1000, Chicago, Illinois 60606.

Recent Developments

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. See “New Smelter Project” below.

On February 2, 2026, we sold our aluminum smelter property in Hawesville, Kentucky, which had been fully curtailed since 2022, to an affiliate of Terawulf Inc. for $200.0 million and a 6.8% non-dilutive interest in a data center project to be built on that property. See “Sale of Hawesville” below.

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Primary Aluminum Facilities

Overview of Facilities

We operate two U.S. aluminum smelters, in Robards, Kentucky ("Sebree") and Goose Creek, South Carolina ("Mt. Holly"), and one aluminum smelter in Grundartangi, Iceland ("Grundartangi").

Our primary aluminum smelters and their respective primary aluminum capacities are shown in the following table:

(1)The tonnes per year (tpy) figures in this column reflect an estimate of the facility's total production capacity based on plant design, historical operating results and operating efficiencies and does not necessarily represent each facility’s maximum production capability.

Grundartangi

The Grundartangi facility, located in Grundartangi, Iceland, is a primary aluminum smelter owned and operated by our wholly-owned subsidiary, Nordural Grundartangi ehf. Grundartangi is our most modern facility with a current production capacity of approximately 320,000 tonnes. Grundartangi produces standard-grade aluminum ingot and a value-added product called primary foundry alloy, which is sold at a premium to standard-grade aluminum.

In October 2025, Grundartangi was forced to temporarily idle production on the larger one of its two potlines due to an electrical equipment failure. As a result, production at the smelter has been temporarily reduced by approximately two-thirds. Grundartangi’s other smaller potline remains unaffected and in full production. We expect that losses arising from this event, less applicable deductibles, will be covered under our insurance policies. We currently estimate that resumption of production of the idled potline will begin by the end of April 2026.

Sebree

Sebree, located adjacent to the Green River near Robards, Kentucky, is a primary aluminum smelter owned and operated by our wholly-owned subsidiary, Century Aluminum Sebree LLC ("Century Sebree"). Sebree has an annual production capacity of approximately 220,000 tonnes of primary aluminum. Sebree produces standard-grade aluminum that can be cast into sow and value-added products, including billet, that are sold at a premium to standard-grade aluminum or delivered directly to nearby customers as molten metal.

Mt. Holly

Mt. Holly, located in Goose Creek, South Carolina, is a primary aluminum smelter owned and operated by our wholly-owned subsidiary, Century Aluminum of South Carolina, Inc. ("CASC"). Mt. Holly has an annual production capacity of approximately 230,000 tonnes of primary aluminum. In December 2020, we began a multi-year project to restore previously curtailed capacity at Mt. Holly. The initial phase was completed in 2022 and returned annual active production capacity to approximately 172,500 MT per annum (75% of capacity). In August 2025, we began a project to restore the remaining curtailed capacity at Mt. Holly. We expect to achieve full production by end of June 2026. Mt. Holly produces standard-grade aluminum that is cast into sow as well as several value-added products, including billet and foundry products. These value-added primary aluminum products are sold at a premium to standard-grade aluminum.

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Primary Aluminum Shipment Volume

The following table shows our primary aluminum shipment volumes since 2021.

Carbon Anode Production Facility

Vlissingen

In addition to our primary aluminum assets, we own and operate a carbon anode production facility in Vlissingen, Netherlands, through our wholly-owned subsidiary, Century Aluminum Vlissingen B.V. The Vlissingen facility has an annual production capacity of approximately 161,000 tonnes of carbon anodes. It primarily supplies our Grundartangi smelter, fulfilling between 93% and 98% of Grundartangi’s carbon anode requirements at current production levels.

Bauxite Mining and Alumina Refining Facility

Jamalco

In May 2023, our wholly-owned subsidiary, Century Aluminum Jamaica Holdings, Inc., completed the acquisition of all the outstanding share capital of General Alumina Holdings Limited, the holder of a 55% interest in Jamalco, an unincorporated joint venture with the Government of Jamaica through its controlled entity Clarendon Alumina Production Limited ("CAP"). Jamalco is engaged in bauxite mining and alumina refining in Jamaica. The Company's wholly-owned subsidiary, General Alumina Jamaica Limited, is the managing partner of the Jamalco joint venture. Jamalco has alumina production capacity of approximately 1.4 million tonnes, and produced approximately 1.0 million tonnes of alumina in 2025 and approximately 1.1 million tonnes of alumina in 2024. Refer to Note 1. Summary of Significant Accounting Policies, Note 2. Acquisition of Jamalco, Note 22. Restatement of Previously Issued Financial Statements, and Note 23. Quarterly Financial Data (Unaudited and Restated) for further information.

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New Smelter Project

On January 26, 2026, we announced that we had entered into a joint development agreement with 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 of primary aluminum. Construction of the project is expected to start by the end of 2026, subject to the completion of detailed engineering work and completion of negotiations with Public Service Company of Oklahoma on a competitive long-term power supply agreement.

Sale of Hawesville

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 (the “Data Center Minority Interest”). A large portion of the proceeds is 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.

Pricing

Pricing for primary aluminum products is typically comprised of three components: (i) the base commodity price, which is based on quoted prices on the LME, plus (ii) any regional premium (i.e., the Midwest premium for metal sold in the United States and the European Duty Paid premium for metal sold into Europe) plus (iii) any value-added product premium. Our operating results are highly sensitive to changes in the LME price of primary aluminum and the amount of regional premiums and value-added product premiums. As a result, from time to time, we assess the appropriateness of mitigating the effects of fluctuations in the aluminum price through the use of fixed-price commitments, LME-linked supply contracts and other financial instruments. See Item 7A. Quantitative and Qualitative Disclosures about Market Risk for further discussion of how we manage our exposure to market risk.

Customer Base

We have historically derived substantially all of our consolidated net sales of primary aluminum from a small number of customers. For the year ended December 31, 2025, we derived approximately 54.0% of our consolidated sales from Glencore plc and its affiliates (together, "Glencore"). Glencore purchased aluminum produced at our U.S. smelters at prices based on the LME price for primary aluminum plus the Midwest premium plus any additional market-based product premiums. Glencore also purchased aluminum produced at our Grundartangi, Iceland smelter at prices based on the LME plus the European Duty Paid premium plus any additional market-based product premiums. We have also entered into agreements with Glencore pursuant to which we sell certain amounts of alumina at market-based prices.

Glencore beneficially owns 36.4% of our outstanding common stock. See Note 4. Related Party Transactions to the consolidated financial statements included herein for additional information concerning our relationship with Glencore. We currently have agreements in place to sell a substantial portion of our 2026 production to Glencore. We expect that the rest of our 2026 customer base will remain fairly concentrated among a small number of customers under short-term contracts.

Key Production Costs

Alumina, electrical power, carbon products, labor, and other controllable costs are the principal components of our cost of production. These components together represented over 84% of our Cost of goods sold for the year ended December 31, 2025. For a description of certain risks related to our raw materials, electrical power, labor and other key supplies, see Item 1A. Risk Factors in this Annual Report on Form 10-K.

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Alumina Supply Agreements

For the year ended December 31, 2025, approximately 320,000 tonnes, or 31% of Jamalco's alumina production, was sold to our aluminum smelters. While Century may enter into other purchases of alumina as market conditions change, a summary of our principal alumina supply agreements is provided below:

(1) "API" refers to a published alumina price index.

Electrical Power Supply Agreements

The table below summarizes our long-term power supply agreements:

Electrical power represents one of the largest components of our Cost of goods sold. From time to time, we may enter into forward contracts or other hedging arrangements to mitigate our electrical power or natural gas price risk. See Note 17. Commitments and Contingencies to the consolidated financial statements included herein for additional information concerning our power arrangements.

Employees and Human Capital Resources

We believe our employees are key to achieving our business goals and growth strategy. As of December 31, 2025, we had 2,906 employees. Of these, 1,324 were domiciled in the United States, 857 in Jamaica, 636 in Iceland and 89 in the Netherlands.

Health, Safety and Wellness. Nothing is more important than the health and safety of our employees and the members of the communities in which we operate. We continuously assess the risks our employees face at our facilities and we work to mitigate those risks through frequent training and other preventative safety and health programs and on the job training. We strive for zero injuries and accidents, to foster systems and processes aimed to continuously improve our health and safety performance and to integrate risk management relating to health and safety into all aspects of our operations. We emphasize the importance of safety and seek to create a safety conscious culture by, among other things, including safety performance metrics and KPIs in our annual incentive awards to our executives.

Compensation and Benefits. The Company's non-union employees are all eligible to participate in the Company paid health, vision, dental, life, prescription and long-term disability insurance plans. The Company also provides employees with paid supplemental life and accident insurance plan. The Company offers employees the opportunity to contribute to a Flexible Spending Account and a Health Savings Account. The Company also offers employees a 401(k) retirement plan with a Company match. As part of our Century Well-being program, and in an effort to encourage employees to participate, Century provides financial incentives to its employees who choose to participate. Our Century Well-being program is specifically designed for Century employees and includes health benefits at no cost to our employees centered around diabetes management, mental health and substance abuse and counseling, and musculoskeletal conditions.

Talent Development. We continue to make progress in enhancing our internal performance management and talent management systems in an effort to continue to recognize and promote outstanding employees. We have worked to streamline

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the process for our employees and ensure they have the opportunity to provide input as part of the review process. We attend recruiting events at local colleges and institutes in our communities and offer educational opportunities to our employees to help them develop additional skills and knowledge and continue the process of developing leaders within Century's ranks.

Labor Agreements

The bargaining unit employees at our Grundartangi, Vlissingen, Sebree and Jamalco facilities are represented by labor unions, representing 55% of our total workforce. Our employees at Mt. Holly are not represented by a labor union.

A summary of our key labor agreements is provided below:

(1)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.

See Note 17. Commitments and Contingencies to the consolidated financial statements included herein for additional information concerning our labor agreements.

Competition

The market for primary aluminum is global, and demand for aluminum varies widely from region to region. We compete with aluminum producers domestically and internationally, as well as with producers of alternative materials such as steel, copper, carbon fiber, composites, plastic and glass, each of which may be substituted for aluminum in certain applications. Our competitive position depends, in part, on the availability at competitive prices of electricity, alumina and other raw materials key to our operations. We face global competition from companies who may have access to these key production costs at lower prices, and they may also receive various subsidies from local, state and federal governments. Many of our competitors are also larger than we are and have vertically integrated operations with superior cost positions. As a result, these companies may be better able to withstand reductions in price or other adverse industry or economic conditions.

Competitive Advantages

While we face significant competition, we also have several competitive advantages. We believe our key competitive advantages are:

Focus on Primary Aluminum Business. We operate principally in the production of primary aluminum. By concentrating our activities in primary aluminum production, we are able to focus our resources on optimizing the cost effectiveness of our existing operations, minimizing overhead costs and maintaining a market position where our products are ultimately targeted toward a broad range of end uses.

Strong Internal Growth Opportunities. Over the past several years, we have undertaken various expansion programs at all of our operating facilities and continue to pursue additional internal growth opportunities. In 2022, we completed a project to restart approximately 172,000 tonnes of production capacity at Mt. Holly (bringing its operations to 75% of Mt. Holly's maximum production capacity). In August 2025, we began a project to restore the remaining curtailed capacity at Mt. Holly. We expect to achieve full production by June 2026.

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Since our purchase of the Vlissingen facility, we have completed a variety of expansion projects and efficiency programs in order to more than double its production capacity. Vlissingen supplies anodes primarily to our Grundartangi smelter, meeting 93% to 98% of Grundartangi’s carbon anodes requirements at current production levels. We continue to pursue additional internal growth opportunities to maximize efficiencies and improve overall performance.

Additionally, with our acquisition of a 55% interest in Jamalco, we secured a long-term supply of alumina, our most critical raw material, and achieved increased transparency and control of our supply chain. Our vertical integration with Jamalco allows us to integrate our aluminum smelting operations with this critical upstream supply of bauxite and alumina to create a more balanced and robust operational footprint, resulting in an organization that is better positioned to deliver strong performance through industry cycles.

Sustainability. Our Natur-Al™ aluminum produced at our Grundartangi facility has one of the lowest carbon footprints in the industry due to Grundartangi’s access to hydroelectric and geothermal power sources. Our Grundartangi facility (along with our corporate headquarters in Chicago, Illinois) have also been certified by the Aluminum Stewardship Initiative (ASI) for responsible production, sourcing and stewardship of aluminum. In addition to providing additional value to our customers, our low carbon footprint in Iceland mitigates our exposure to current or future carbon regulations. Century is committed to exploring additional opportunities to reduce our carbon footprint across our global operations, including by continuing to improve our operational efficiencies, investigating new and alternative power sources, and reprocessing and reusing scrap aluminum in our operations.

Duty Free Access to our Major Customer Markets. Our facilities benefit from international and national trade laws and regulations. For example, the European Union imposes import tariffs on primary aluminum from producers outside the European Economic Area (the "EEA"), which includes Iceland, and the U.S. currently imposes a 50% tariff on certain primary aluminum imports into the United States. Our U.S. and Icelandic businesses currently access these respective markets duty-free which provides us with an advantage over our competitors who sell into these markets under these tariff regimes.

Close Proximity to our Major Customers in the Two Shortest Aluminum Markets in the World. The U.S. and the E.U. are the second and third largest aluminum consuming regions in the world but do not produce enough aluminum domestically to satisfy their own demand. Our production locations within these markets provide us with a significant competitive advantage over our foreign competitors by providing our customers with short, reliable supply chains, better technical service and opportunities for value added collaboration. Our U.S. facilities benefit from the proximity to our U.S. customer base, allowing us to capture the Midwest premium and providing a competitive advantage in freight costs over our foreign competitors. In Iceland, our proximity to European markets provides a competitive advantage for Grundartangi, allowing us to capture the European Duty Paid Premium and other logistical benefits compared to our competitors outside the EEA.

Diverse Value Added Product and Secondary Market Portfolio. We have the ability across our operations to cast a variety of aluminum products, both in terms of shapes and alloys. These value-added primary aluminum products are sold at a premium to standard-grade aluminum. Each of our smelters have value-added casthouses that have the ability to produce large volumes of billet, slab and other value-added products.

Access to Market Power. Our Kentucky operations benefit from market-based power contracts that have historically provided electricity to these operations at competitive prices.

Experienced Management Team. Our management team includes executives and managers with significant experience in the aluminum industry, the broader metals and mining sector, the development of large and complex projects and the functional disciplines we require to manage and grow our business. In addition, the managers of our production facilities have substantial backgrounds and expertise in the technical and operational aspects of these plants.

For additional information, see Item 1A. Risk Factors. We may be unable to continue to compete successfully in the highly competitive markets in which we operate.

Government Regulations

Our facilities and operations are subject to various laws and regulations in the countries in which we operate, including, but not limited to, environmental laws and regulations. We have spent, and expect to continue to spend, significant amounts for compliance with those various laws and regulations, including environmental laws and regulations. In addition, some of our past manufacturing activities or those of our predecessors have resulted in environmental consequences that require remedial measures. Under certain environmental laws, which may impose liability regardless of fault, we may be liable for the costs of remediation of contaminated property, including our current and formerly owned or operated properties or adjacent areas, or for

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the amelioration of damage to natural resources. We believe, based on currently available information, that compliance with existing laws and regulations has not had a material adverse effect upon our capital expenditures, earnings and our competitive position. Furthermore, we believe, based on currently available information, that our current liabilities are not likely to have a material adverse effect on Century. However, we cannot predict the requirements of future laws and future requirements at current or formerly owned or operated properties or adjacent areas or the outcome of certain existing litigation to which we are a party. Such future requirements or events may result in unanticipated costs or liabilities that may have a material adverse effect on our financial condition, results of operations or liquidity. More information concerning our contingencies can be found in Note 17. Commitments and Contingencies to the consolidated financial statements included herein.

There is also increasing focus and scrutiny from both the United States government, foreign governments and other regulatory authorities on greenhouse gas ("GHG") emissions and potential impacts relating to climate change. We continuously review our own GHG and other emissions streams and seek to limit the impact of our operations on the communities in which we operate. Future laws, regulations, or policies that are enacted in response to concerns over GHG emissions and climate change, such as mandatory reporting and disclosure obligations, carbon tax, any "cap and trade" programs or similar regulatory measures, could significantly increase our operational and compliance burdens and costs. We continuously review and monitor climate change related proposed legislation for potential impacts on Century and our operations. For more information on the risk of climate change related legislation, laws and regulations, see Item 1A. Risk Factors.

Intellectual Property

We own or have rights to use a number of intellectual property rights relating to various aspects of our operations. We do not consider our business to be materially dependent on any of these intellectual property rights.

Available Information

Additional information about Century may be obtained from our website, which is located at www.centuryaluminum.com. Our website provides access to periodic filings we have made through the EDGAR filing system of the SEC, including our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and any amendments to those reports. We also make available on our website a copy of our code of ethics that applies to all employees and ownership reports filed on Forms 3, 4 and 5 by our directors, executive officers and beneficial owners of more than 10% of our outstanding common stock. Reports that we have filed with the SEC are also available on the SEC website at www.sec.gov. In addition, we will make available free of charge copies of our Forms 10-K, Forms 10-Q and Forms 8-K upon request. Requests for these documents can be made by contacting our Investor Relations Department by mail at: One South Wacker Drive, Suite 1000, Chicago, IL 60606, or by phone at: (312) 696-3101. Information contained in our website is not incorporated by reference in, and should not be considered a part of, this Annual Report on Form 10-K.