What changed in this filing

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Item 9A. Controls and Procedures

2026-03-03 compared with 2025-03-03 · 43 added, 43 removed, 207 unchanged (29% of the section changed)

2 unchanged sentences

As of December 31, 2025, we carried out an evaluation, under the supervision and with the participation of our management, including our Chief Executive Officer and Chief Financial Officer, of the effectiveness of our disclosure controls and procedures.

Based upon that evaluation, our management, including the Chief Executive Officer and Chief Financial Officer, concluded that our disclosure controls and procedures were ineffective as of December 31, 2024, because of material weaknesses in internal controls over financial reporting described in Management’s Report on Internal Control Over Financial Reporting below.

Based upon that evaluation, our management, including the Chief Executive Officer and Chief Financial Officer, concluded that our disclosure controls and procedures were ineffective as of December 31, 2025, because of a material weakness in internal controls over financial reporting described in Management’s Report on Internal Control Over Financial Reporting below.

Management's Report on Internal Control over Financial Reporting

6 unchanged sentences

Management’s evaluation was based on the framework in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations (COSO) of the Treadway Commission.

Based on this evaluation, management concluded that our system of internal control over financial reporting was not effective as of December 31, 2024 due to the material weaknesses described below.

1 - The Company failed to design and implement appropriate information technology general controls in the areas of logical access controls including provisioning, deprovisioning, privileged access, user access review, application changes and monitoring related to Jamalco.

2 - The Company failed to design and implement appropriate business process level controls, including controls to address the completeness and accuracy of information derived from its affected information technology systems at Jamalco, which resulted in a material weakness related to reconciliation controls and insufficient review controls related to inventories, accounts payable, accrued expenses, cost of goods sold and property, plant, and equipment.

Notwithstanding the material weaknesses, management believes the consolidated financial statements included in this Annual Report on Form 10-K present fairly, in all material respects, the Company’s financial condition, results of operations and cash flows as of and for the periods presented in accordance with U.S.

Based on this evaluation, management concluded that our system of internal control over financial reporting was not effective as of December 31, 2025.

A material weakness is a deficiency, or a combination of deficiencies, in internal control over financial reporting, such that there is a reasonable possibility that a material misstatement of the company’s annual or interim financial statements will not be prevented or detected on a timely basis.

We identified deficiencies in the design and operating effectiveness of (1) business process level controls at our Jamalco joint venture, including reconciliation controls and insufficient review controls related to inventories, accounts payable, accrued expenses, cost of goods sold and property, plant, and equipment, and (2) financial reporting controls over the consolidation of the Jamalco joint venture.

These deficiencies constitute a material weakness in internal control over financial reporting which remains unremediated at December 31, 2025.

Notwithstanding the material weakness, management believes the consolidated financial statements included in this Annual Report on Form 10-K present fairly, in all material respects, the Company’s financial condition, results of operations and cash flows as of and for the periods presented in accordance with U.S.

The effectiveness of our internal control over financial reporting has been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their report which appears in Part II, Item 8 of this Annual Report on Form 10-K.

Remediation Plan for Material Weaknesses

Management plans to implement measures designed to ensure that the control deficiencies contributing to the material weaknesses are remediated, such that these controls are designed, implemented, and operating effectively.

The remediation actions for general information technology controls include:(i) designing and implementing controls related to deprovisioning, privileged access, and user access reviews, (ii) developing an enhanced risk assessment process to evaluate and monitor system changes, and (iii) providing training associated with control design and execution.

The remediation actions for business process controls include:

(i) designing and implementing controls related to account reconciliations (ii) improving the accuracy of supporting schedules underlying transactions, and (iii) timely capitalization of

fixed assets.

Additionally, we expect our remediation efforts to involve implementing additional controls to address the completeness and accuracy of information utilized in business process controls.

We believe that these actions will remediate the material weaknesses.

The material weaknesses will not be considered remediated, however, until the applicable controls operate for a sufficient period of time and management has concluded, through testing, that these controls are operating effectively.

Remediation Plan for Material Weakness

Management, with the oversight of the Audit Committee of our Board, has dedicated resources and efforts to improve our internal controls over financial reporting and has taken the following actions towards remediating the material weakness:

• Designed and implemented controls over information technology general controls to enhance the reliability of information derived from information systems at Jamalco.

• Designed new and enhanced existing account reconciliation controls including controls to reconcile source data across accounts and additional review procedures within account reconciliations.

• The Company appointed new individuals in key roles including accounting and IT department heads.

• Enhanced training was provided to individuals responsible for account reconciliations and their review and those responsible for the consolidation of the Jamalco joint venture.

Management has implemented the remediation steps outlined above;

however, management is unable to conclude the controls designed and implemented to address the material weakness are operating effectively until the applicable controls operate for a sufficient period of time.

Management anticipates that remediation activities will be completed during fiscal year 2026.

Previously Reported Material Weakness

As of December 31, 2023, our management had identified a deficiency in the design of internal control over financial reporting related to the application of purchase accounting to our acquisition of Jamalco.

The design deficiency was determined to be a material weakness related to the review of the Company's allocation of excess fair value acquired between non-controlling interest and preliminary deferred bargain purchase gain.

In response to the identified material weakness above, during the three months ended March 31, 2024, management, with the oversight of the Audit Committee of the Board of Directors, took actions to remediate the material weakness in internal control over financial reporting in the first quarter of 2024.

We changed the design of our internal controls over financial reporting to include a review of the allocation of the excess fair value of the net assets acquired at an entity level.

We completed our assessment of the redesigned control related to the application of purchase accounting to determine if it was designed and operating effectively for all adjustments made during the three months ended March 31, 2024 in finalizing our purchase accounting.

As a result of our assessment, management concluded that the material weakness associated with the application of purchase accounting was remediated as of March 31, 2024.

As of December 31, 2024, our management had identified a deficiency in the design of internal control over financial reporting related to information technology general controls in the areas of logical access controls including provisioning, deprovisioning, privileged access, user access review, application changes and monitoring related to Jamalco.

In response to the identified material weakness, during the year ended December 31, 2025, management, with the oversight of the Audit Committee of the Board of Directors, took actions to remediate this material weakness in internal control over financial reporting.

Changes in Internal Control over Financial Reporting

On May 2, 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 JV ("Jamalco"), an unincorporated joint venture engaged in bauxite mining and alumina production in Jamaica.

Except for the remediation efforts related to the previous material weakness referred to above, during the year ended December 31, 2024, there were no changes in our internal control over financial reporting that materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Except for the remediation efforts related to the previous material weaknesses referred to above, during the three months ended December 31, 2025, there were no changes in our internal control over financial reporting that materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.

Other Information

12 unchanged sentences

Stockholder Affiliates related to the contracts did not exceed the value of USD $252 million for the year ended December 31, 2025.

Stockholder Affiliates do not allocate net profit on a country-by-country or activity-by-activity basis, but estimate that the net profit attributable to the contracts would not exceed a small fraction of the

gross revenue from such contracts.

It is not possible to determine accurately the precise net profit attributable to such contracts.

48 unchanged sentences

8-K 001-34474 April 12, 2021

4.5 Indenture for Century Aluminum Company's 7.5% Senior Secured Notes due 2028, dated as of April 14, 2021, by and among Century Aluminum Company, the guarantors party thereto and Wilmington Trust, National Association, as trustee and noteholder collateral agent

8-K 001-34474 April 15, 2021

4.6 Form of 7.5% Note for the Indenture for Century Aluminum Company's 7.5% Senior Secured Notes due 2028, dated as of April 14, 2021, by and among Century Aluminum Company, the guarantors party thereto and Wilmington Trust, National Association, as trustee and noteholder collateral agent

8-K 001-34474 April 15, 2021

4.5 Indenture for Century Aluminum Company's 6.875% Senior Secured Notes due 2032, dated as of July 22, 2025, by and among Century Aluminum Company, the guarantors party thereto and Wilmington Trust, National Association, as trustee and noteholder collateral agent.

8-K 001-34474 July 24, 2025

4.6 Form of 6.875% Senior Secured Note due 2032 (included as Exhibit A to the Indenture filed as Exhibit 4.5).

8-K 001-34474 July 24, 2025

4.7 Description of Common Stock.

2 unchanged sentences

8-K 001-34474 May 5, 2023

10.2 Second Lien Pledge and Security Agreement, dated as of April 14, 2021, by and among Century Aluminum Company, the other Grantors (as defined therein) and Wilmington Trust, National Association, as collateral agent of the 7.5% Senior Secured Notes due 2028

8-K 001-34474 April 15, 2021

10.3 Collateral Agency Agreement, dated as of April 14, 2021, by and among Century Aluminum Company, the other Grantors party thereto and Wilmington Trust, National Association, as trustee and collateral agent.

8-K 001-34474 April 15, 2021

10.4 Second Amended and Restated Loan and Security Agreement, dated as of May 16, 2018, among Century Aluminum Company, Century Aluminum of South Carolina, Inc., Century Aluminum of Kentucky General Partnership, NSA General Partnership and Century Aluminum Sebree LCC, as borrowers, and Wells Fargo Capital Finance, LLC, as agent and lender.

10.2 Second Lien Pledge and Security Agreement, dated as of July 22, 2025, by and among Century Aluminum Company, the other Grantors (as defined therein) and Wilmington Trust, National Association, as collateral agent of the 6.875% Senior Secured Notes due 2032.

8-K 001-34474 July 24, 2025

10.3 Collateral Agency Agreement, dated as of July 22, 2025, by and among Century Aluminum Company, the other Grantors party thereto and Wilmington Trust, National Association, as trustee and collateral agent.

8-K 001-34474 July 24, 2025

10-Q 001-34474 November 2, 2018

10.5 Amendment No.

1, dated as of June 17, 2020 to the Second Amended and Restated Loan and Security Agreement, dated as of May 16, 2018, among Century Aluminum Company, Century Aluminum of South Carolina, Inc., Century Aluminum of Kentucky General Partnership, NSA General Partnership and Century Aluminum Sebree LCC, as borrowers, and Wells Fargo Capital Finance, LLC, as agent and lender.

1, dated as of June 17, 2020 to the Second Amended and Restated Loan and Security Agreement.

8-K 001-34474 June 18, 2020

10.6 Amendment No.

2, dated as of June 15, 2021 to the Second Amended and Restated Loan and Security Agreement, dated as of May 16, 2018, among Century Aluminum Company, Century Aluminum of South Carolina, Inc., Century Aluminum of Kentucky General Partnership, NSA General Partnership and Century Aluminum Sebree LCC, as borrowers, and Wells Fargo Capital Finance, LLC, as agent and lender.

2, dated as of June 15, 2021 to the Second Amended and Restated Loan and Security Agreement.

10-Q 001-34474 August 5, 2021

10.7 Amendment No.

3, dated as of December 23, 2021 to the Second Amended and Restated Loan and Security Agreement, dated as of May 16, 2018, among Century Aluminum Company, Century Aluminum of South Carolina, Inc., Century Aluminum of Kentucky General Partnership, NSA General Partnership and Century Aluminum Sebree LCC, as borrowers, and Wells Fargo Capital Finance, LLC, as agent and lender.

3, dated as of December 23, 2021 to the Second Amended and Restated Loan and Security Agreement.

8-K 001-34474 December 27, 2021

10.8 Amendment No.

4 dated June 14, 2022 to the Second Amended and Restated Loan and Security Agreement, dated as of May 16, 2018, among Century Aluminum Company, Century Aluminum of South Carolina, Inc., Century Aluminum of Kentucky General Partnership, NSA General Partnership and Century Aluminum Sebree LCC, as borrowers, and Wells Fargo Capital Finance, LLC, as agent and lender.

4 dated June 14, 2022 to the Second Amended and Restated Loan and Security Agreement.

8-K 001-34474 June 16, 2022

10.9 Amendment No.

5 dated July 22, 2025, to the Second Amended and Restated Loan and Security Agreement.

8-K 001-34474 July 24, 2025

10.1 Facility Agreement dated 9 December 2022 among Century Aluminum Vlissingen B.V.

1 unchanged sentence

8-K 001-34474 December 12, 2022

10.10 Amendment to Facility Agreement dated October 1, 202 4 among Century Aluminum V lissingen B.V.

as borrower and Gl encore I nterna tional AG as lender

10.11 Amendment to Facility Agreement dated October 1, 2024 among Century Aluminum Vlissingen B.V.

as borrower and Glencore International AG as lender

10-Q 001-34474 November 4, 2024

68 unchanged sentences

8-K 001-34474 May 17, 2021

19.1 I nsider T rading Policy

19.1 Insider Trading Policy

10-K 001-34474 March 3, 2025

21.1 List of Subsidiaries

7 unchanged sentences

96.1 Technical Report Summary for Jamalco

10-K 001-34474 March 3, 2025

97.1 Incentive Compensation Recoupment Policy

10-K 001-34474 March 3, 2025

101.INS XBRL Instance Document (the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document)

6 unchanged sentences

* Management contract or compensatory plan.

** Confidential Information was omitted from this exhibit pursuant to a request for confidential treatment filed separately with the SEC.

Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

17 unchanged sentences

Tamla Olivier

/s/ GERALD C.

BIALEK Executive Vice President and Chief Financial Officer

/s/ PETER TRPKOVSKI Executive Vice President and Chief Financial Officer

(Principal Financial Officer) March 3, 2026

Peter Trpkovski

/s/ ROBERT HOFFMAN Vice President and Chief Accounting Officer

4 unchanged sentences

Compared sentence by sentence after normalising whitespace, quotation marks, case and digits, so re-formatting and restated figures do not read as changed language. Wording changes appear as one removal and one addition. The current filing and the prior one are authoritative.

What changed 10-K

Item 9A. Controls and Procedures