[Form 4] CENTURY ALUMINUM CO Insider Trading Activity

Rhea-AI Filing Summary

Glencore International AG, Glencore AG, and Glencore plc filed a Form 4 for Century Aluminum (CENX) detailing significant insider activity on 11/10/2025. The reporting group, noted as a Director and 10% Owner, sold 9,000,000 shares of common stock at $30.25 (Transaction Code S), leaving 18,500,000 shares directly beneficially owned by Glencore International AG. Separately, an automatic conversion (Code C) of 49,485.91 shares of Series A Convertible Preferred Stock resulted in 4,948,591 common shares, which are held indirectly, with 17,505,947 shares beneficially owned indirectly after the transaction.

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Insider transactions specialist

Large sale and preferred-to-common conversion disclosed by a 10% owner.

Glencore-affiliated entities reported two actions on 11/10/2025: a sale of 9,000,000 CENX common shares at $30.25 (Code S) and the automatic conversion (Code C) of 49,485.91 Series A preferred into 4,948,591 common shares, consistent with the stated 100:1 ratio in the Certificate of Designation.

Post-transaction, the filing lists 18,500,000 shares directly beneficially owned and 17,505,947 owned indirectly through affiliated entities. The filing identifies the reporting persons as a Director and 10% Owner, indicating ongoing significant ownership.

The disclosure outlines ownership changes and instrument mechanics; actual market impact depends on holder decisions and broader trading activity.

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
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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^*

GLENCORE INTERNATIONAL AG

(Last) (First) (Middle)

BAARERMATTSTRASSE 3

P.O. BOX 1363

(Street)

BAAR V8 CH-6341

(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	X	10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
11/10/2025

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

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

	Form filed by One Reporting Person
X	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	11/10/2025		S		9,000,000	D	$30.25	18,500,000	D
Common Stock	11/10/2025		C		4,948,591(1)	A	(2)	17,505,947	I	See Footnote(3)

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
Series A Convertible Preferred Stock	(2)	11/10/2025		C			49,485.91	(2)	(2)	Common Stock	4,948,591(1)	(2)	0	I	See Footnote(3)

1. Name and Address of Reporting Person^*

GLENCORE INTERNATIONAL AG

(Last) (First) (Middle)

BAARERMATTSTRASSE 3

P.O. BOX 1363

(Street)

BAAR V8 CH-6341

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Glencore AG

(Last) (First) (Middle)

BAARERMATTSTRASSE 3

P.O. BOX 1363

(Street)

BAAR V8 CH-6341

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

Glencore plc

(Last) (First) (Middle)

BAARERMATTSTRASSE 3

P.O. BOX 1363

(Street)

BAAR V8 CH-6341

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

Explanation of Responses:

1. Represents shares of Common Stock acquired upon the automatic conversion of 49,485.91 shares of Series A Convertible Preferred Stock upon the consummation of the transaction reported in Line 1 of Table 1.

2. Each share of Series A Convertible Preferred Stock is convertible into 100 shares of Common Stock at the times and under the circumstances described in the Certificate of Designation for the Series A Convertible Preferred Stock. The Series A Convertible Preferred Stock was acquired on July 8, 2008 and has no expiration date.

3. The shares of Common Stock reported in Line 2 of Table I and the shares of Series A Convertible Preferred Stock reported in Table II are held directly by Glencore AG, a direct wholly-owned subsidiary of Glencore International AG, and may be deemed to be indirectly beneficially owned by Glencore International AG. The Common Stock reported on Line 1 of Table I is held directly by Glencore International AG. Glencore International AG is wholly-owned by Glencore plc, which may be deemed an indirect beneficial owner of the securities held by Glencore AG and Glencore International AG.

Remarks:

Exhibit List: Exhibit 24.1 and Exhibit 24.2.

	GLENCORE INTERNATIONAL AG By: /s/ John Burton Name: John Burton Title: Attorney-in-Fact	11/13/2025
	GLENCORE AG By: /s/ John Burton Name: John Burton Title: Attorney-in-Fact	11/13/2025
	GLENCORE PLC By: /s/ John Burton Name: John Burton Title: Company Secretary	11/13/2025
	** 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 insider transactions did Glencore report for CENX on 11/10/2025?

A sale of 9,000,000 common shares at $30.25 (Code S) and an automatic conversion (Code C) of 49,485.91 Series A preferred into 4,948,591 common shares.

What is the conversion ratio for CENX’s Series A Convertible Preferred Stock?

Each preferred share is convertible into 100 common shares, as described in the Certificate of Designation.

How many CENX shares did the reporting persons own after the transactions?

The filing shows 18,500,000 shares directly beneficially owned and 17,505,947 shares indirectly beneficially owned.

Who are the reporting persons in this CENX Form 4?

Glencore International AG, Glencore AG, and Glencore plc, identified collectively as a Director and 10% Owner.

What do the Form 4 transaction codes S and C indicate?

Code S denotes a sale of securities. Code C denotes the conversion of a derivative security.

Which entities hold the CENX shares directly and indirectly?

Common stock in Line 1 is held directly by Glencore International AG. The converted shares and preferred were held by Glencore AG and may be deemed owned indirectly by the parent entities.