Century Aluminum

Sebree · 100% Owned

Mt. Holly · 100% Owned

Grundartangi · Facility 100% owned; long-term ground lease

Vlissingen · Facility 100% owned; long-term ground lease

Jamalco · 55% Joint venture interest; long-term ground lease

Chicago Corporate Office · Long-term office lease

Bauxite Mining Properties

Century has access to large bauxite deposit areas with mining rights that extend through 2031. The Company obtains bauxite from these resources in Jamaica. Tonnes of bauxite are reported on a zero-moisture basis in millions of dry metric tonnes (mdmt) unless otherwise stated.

As used in this Form 10-K, the terms “mineral resource,” “measured mineral resource,” “indicated mineral resource,” “inferred mineral resource” and “mineral reserve” are defined and used in accordance with subpart 1300 of Regulation S-K. Under subpart 1300 of Regulation S-K, mineral resources may not be classified as “mineral reserves” unless the determination has been made by a qualified person (as defined under subpart 1300 of Regulation S-K) that the mineral resources can be the basis of an economically viable project. The approach to mining at Jamalco is such that, in the qualified person's opinion, the documented mineral reserves are too small to merit reporting and as such, mineral reserves are not included in the discussion below. Refer to “Property History and Condition” below for more information on why reportable reserves are not available.

Part or all of the mineral deposits (including any mineral resources) in these categories may never be converted into mineral reserves. Further, except for the portion of mineral resources reclassified as mineral reserves, mineral resources do not have demonstrated economic value. Estimates of inferred mineral resources have too high of a degree of uncertainty as to their existence and may not be converted to a mineral reserve. Therefore, it should not be assumed that all or any part of an inferred mineral resource exists, that it can be the basis of an economically viable project, or that it will ever be upgraded to a higher category. Likewise, it should not be assumed that all or any part of measured or indicated mineral resources will ever be converted to mineral reserves. Management relies on estimates of our recoverable mineral reserves, which estimation is complex due to geological characteristics of the properties and the number of assumptions made and variable factors, some of which are beyond our control.

The information that follows is derived from the technical report summary relating to the property prepared in compliance with Item 601(b)(96) and subpart 1300 of Regulation S-K by Aluminium Industry Professionals Inc. (“Aluminpro”), which we engaged as a qualified person as defined under subpart 1300 of Regulation S-K. No employee of Aluminpro is an employee of the Company, and Aluminpro is not affiliated with the Company or with any other entity that has an ownership, royalty, or other interest in Jamalco or the mining properties. The scientific and technical information concerning our mineral resources in this Form 10-K have been reviewed and approved by Aluminpro. Portions of the following information are based on assumptions, qualifications, and procedures that are not fully described herein. Reference should be made to the full text of the Technical Report Summary dated February 27, 2025, with an effective date of December 31, 2024, incorporated by reference as Exhibit 96.1 to this Form 10-K (the “Jamalco TRS”).

Property Location and Description

Jamalco holds two Special Mining Leases, Special Mining Lease 130 ("SML 130") and Special Mining Lease 169 ("SML 169") in the southwestern region of Jamaica within the Parishes of Clarendon and Manchester and one Special Exclusive Prospecting License 580 ("SEPL 580") is in the St. Catherine Parish in the southeastern region of Jamaica.

On October 7, 1991, under SML 130, the Government of Jamaica granted Jamalco the rights to explore and mine the bauxite in the leased area for a period of 40 years, expiring in 2031. The center of SML 130 is located at 18°02’N and 77°25’W and covers 137.3mi2. The lease guarantees that no other company will be allowed to mine for bauxite in the leased area. Jamalco may surrender lands to the Government of Jamaica that it has mined out and restored or lands it no longer wishes to retain free of charge. Conversely, the Government of Jamaica may rescind lands under the mining lease that it deems necessary in the national interest of Jamaica: such lands will not be made available to other bauxite users.

On January 1, 2003, the Government of Jamaica granted Jamalco under SML 169 the rights to explore and mine the bauxite in the lease area for a period of 40 years, expiring in 2043. The center of SML 169 is at 18°10’24’’N and 77°33’15’’W and covers 46.0mi2. The conditions of the lease are the same as the conditions for SML 130.

• Norðurál Grundartangi ehf. Iceland⁷
• Norðurál ehf. Iceland⁷
• Skyliner, LLC Delaware⁷
• Virgin Islands Alumina Corporation LLC Delaware⁷

• We may be unable to continue to compete successfully in the markets in which we operate.
• Curtailment of aluminum production at our facilities could have a material adverse effect on our business, financial position, results of operations and liquidity.
• The restart of curtailed capacity at our Mt. Holly smelter is subject to certain risks and uncertainties.
• We experienced an electrical equipment failure in October 2025 that reduced production at our Grundartangi smelter by about two-thirds, and there can be no assurance that we will be able to restore Grundartangi to full and normal operations on the time frame we currently expect.
• Increases in our raw material costs and disruptions in our supply of raw materials could adversely affect our business.
• We may be unable to realize expected benefits of our capital projects.
• There is no assurance that we and EGA will make a final investment decision to proceed with the new smelter project, and if we do, we may not realize the anticipated benefits from the joint venture.
• The construction and operation of the new smelter joint venture project with EGA is subject to numerous risks and uncertainties.
• Certain of our raw material and services contracts contain "take-or-pay" obligations.
• We have historically derived substantially all of our revenue from a small number of customers, and we could be adversely affected by the loss of a major customer or changes in the business or financial condition of our major customers.
• We require substantial resources to pay our operating expenses and fund our capital expenditures.
• International operations expose us to political, economic, regulatory, currency and other related risks which may materially adversely impact our business.
• Unpredictable events may interrupt our operations, which may adversely affect our business.
• We engage in hedging transactions which involve risks that could have a material adverse effect on our business, financial position and liquidity.
• Jamalco’s operations are complex and we may experience substantial risks, delays and/or disruptions in connection with integration activities, a failure of which may result in a material adverse effect on Jamalco’s and Century’s business, financial condition and results of operations.
• Jamalco is operated as an unincorporated joint venture, which may pose unique risks to its operations.
• If we fail to maintain proper and effective internal controls over financial reporting, our financial results may not be accurately reported.
• Any failure to maintain satisfactory labor relations with our employees could adversely affect our business.
• A deterioration in our financial condition or credit rating could limit our ability to access the credit and capital markets on acceptable terms or to enter into hedging and financial transactions, lead to our inability to access liquidity facilities, and could adversely affect our financial condition and our business relationships.
• We may be unable to generate sufficient cash flow to meet our debt service requirements which may have a material adverse effect on our business, financial position, results of operations and liquidity.
• Our substantial indebtedness or any future additional indebtedness could adversely affect our business, results of operations or financial condition.
• We are subject to interest rate risk, which could adversely affect our borrowing costs, financial condition and results of operations.
• Our debt instruments subject us to covenants and restrictions.
• We depend upon intercompany transfers from our subsidiaries to meet our debt service obligations.
• Conversion of the Convertible Notes may dilute the ownership interest of our stockholders or may otherwise depress the price of our common stock.
• The accounting method for convertible debt securities that may be settled in cash, such as the Convertible Notes, could have a material effect on our reported financial results.
• The capped call transactions may affect the value of our common stock.
• We are subject to counterparty risk with respect to the capped call transactions.
• The failure of our information technology systems, network disruptions, cyber-attacks or other breaches in data security could have a material adverse effect on our business, results of operations and financial position.
• Climate change, climate change legislation or environmental regulations may adversely impact our operations.
• We are subject to a variety of environmental laws and regulations that may have a material adverse effect on our business, financial position, results of operations and liquidity.
• Our operations are subject to a variety of laws that regulate the protection of the health and safety of our employees, and changes in health and safety laws and regulations could result in significant costs, which could have a material adverse effect on our business, financial position, results of operations and liquidity.
• Changes in trade laws or regulations may have an adverse effect on our sales margins and profitability.
• We are subject to litigation and legal proceedings and may be subject to additional litigation, arbitration or legal proceedings in the future.
• The Inflation Reduction Act of 2022 ("IRA") contains production tax credits for certain critical minerals, including aluminum. The Company's ability to benefit from Section 45X production tax credits is not guaranteed and is dependent upon the federal government's ongoing implementation, guidance, regulations, and/or rulemakings that have been the subject of substantial public interest and debate.
• Our $500 million funding from the U.S. Department of Energy (“DOE”) is subject to review and will be subject to negotiation of specific terms and contingent on our compliance with the requirements negotiated with the DOE.
• Our ability to utilize certain net operating loss carryforwards to offset future taxable income may be significantly limited if we experience an "ownership change" under the Internal Revenue Code.
• Risks Related to Acquisitions
• Acquisitions could disrupt our operations and harm our operating results.
• Risks Related to Stock Ownership in the Company
• Glencore may exercise substantial influence over us, and they may have interests that differ from those of our other stockholders.