[Form 4] CENTURY ALUMINUM CO Insider Trading Activity

Rhea-AI Filing Summary

Kenneth L. Calloway, Senior Vice President, Human Resources of Century Aluminum Company (CENX), reported a sale of company stock on 09/19/2025. The Form 4 shows a disposition of 16,450 shares at a price of $27.50 per share. After the reported transaction, Calloway beneficially owned 28,706 shares, an amount the filing notes includes unvested restricted stock units granted under the issuer's long-term incentive plans. The filing was signed by an attorney-in-fact on 09/23/2025 and is submitted pursuant to Section 16 reporting requirements.

Positive

• Timely Section 16 disclosure of an officer transaction with date, amount, and price reported
• Ownership clarity showing 28,706 shares beneficially owned and explicit note that this includes unvested RSUs

Negative

• Officer sale of 16,450 shares may be perceived negatively by some investors, though the filing gives no context for the sale
• No statement in the filing indicating whether the sale was made under a Rule 10b5-1 trading plan or similar pre-arranged program

Insights

Securities Analyst

TL;DR: An officer reported a routine Section 16 sale of 16,450 shares; filing discloses remaining holdings and inclusion of unvested RSUs.

The Form 4 documents a sale (transaction code S) by a named executive officer of 16,450 shares at $27.50. The disclosure of 28,706 shares held after the sale, including unvested RSUs, provides a clear post-transaction ownership figure but does not state prior holdings or the proportion of total outstanding shares. From a market-impact perspective, the form itself is neutral; it reports the transaction required by Section 16 but contains no additional context such as whether the sale was pursuant to a pre-existing trading plan.

Corporate Governance Expert

TL;DR: Officer sale properly reported with RSU disclosure; filing provides necessary compliance information but no governance concerns are evident from the form alone.

The report identifies the reporting person as an officer (SVP, Human Resources) and notes the inclusion of unvested RSUs in the ownership total, which clarifies the nature of beneficial ownership. The form is signed by an attorney-in-fact and contains the required details: transaction date, amount sold, and price. There is no information in the filing about whether the sale was part of a Rule 10b5-1 plan or other compliance mechanism, so no governance conclusions beyond accurate reporting can be drawn from this document alone.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Calloway Kenneth L

(Last) (First) (Middle)

C/O CENTURY ALUMINUM COMPANY

1 S. WACKER DRIVE, SUITE 1000

(Street)

CHICAGO IL 60606

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
CENTURY ALUMINUM CO [ CENX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	SVP, Human Resources

3. Date of Earliest Transaction (Month/Day/Year)
09/19/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	09/19/2025		S		16,450	D	$27.5	28,706(1)	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Includes unvested RSUs granted to the Reporting Person under the Issuer's Long-Term Incentive Plans.

Remarks:

	/s/ Paul Sharobeem, attorney-in-fact for Kenneth L. Calloway	09/23/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What did Kenneth L. Calloway (CENX) report on the Form 4?

The Form 4 reports a sale of 16,450 shares of Century Aluminum (CENX) at $27.50 per share on 09/19/2025, with 28,706 shares beneficially owned after the transaction.

How many shares did Calloway own after the reported transaction?

The filing states he beneficially owned 28,706 shares following the sale, and that figure includes unvested RSUs granted under the company’s long-term incentive plans.

When was the Form 4 signed and filed?

The Form 4 was signed by an attorney-in-fact on 09/23/2025 and reports the transaction dated 09/19/2025.

Does the Form 4 say the sale was part of a 10b5-1 plan?

No. The filing does not indicate that the sale was executed pursuant to a Rule 10b5-1 trading plan or similar written plan.

What role does Calloway hold at Century Aluminum?

The Form 4 identifies him as an Officer, specifically SVP, Human Resources.