Company: CENX
Filing Date: 2025-11-21
Form Type: 8-K/A
Source: 0001628280-25-053603
Chunk: 1

Company: CENTURY ALUMINUM CO
Filing Date: 2025-11-21
Form: 8-K/A
Chunk 1
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(s) |     | Name of each exchange on which registered: |
| Common Stock, $0.01 par value per share |     | CENX              |     | Nasdaq Stock Market LLC                    |
|                                         |     |                   |     | -Nasdaq Global Select Market               |

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b– 2 of the Securities Exchange Act of 1934 (§ 240.12b–2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

### EXPLANATORY NOTE
This Amendment No. 1 on Form 8-K/A (this "Amendment") amends Form 8-K of Century Aluminum Company (the "Company") that was originally filed with the Securities and Exchange Commission on November 6, 2025 (the "Original Filing"). This Amendment is being filed solely to correct an inadvertent error in the submission of the Original Filing through EDGAR which referenced the incorrect Form 8-K Item Number (Item 2.01) in the EDGAR submission header. This Amendment is being filed through EDGAR to reference the correct Form 8-K Item Numbers (Items 2.02 and 9.01) in the EDGAR submission header. There are no changes to the Original Filing itself (which referenced the correct Item numbers) other than the date of this Amendment. Except as summarized above, this Amendment continues to speak as of the date of the Original Filing and does not reflect events occurring after the date of the Original Filing or modify or update the disclosures therein in any way.

### Item 2.02. Results of Operations and Financial Condition.
On November 6, 2025, Century Aluminum Company (the "Company") issued a press release announcing its results of operations for quarter ended September 30, 2025. A copy of the Company’s press release is attached as Exhibit 99.1 and is incorporated herein by reference.

The Company will hold a follow-up conference call on Thursday, November 6, 2025, at 5:00 p.m. Eastern Time.