<SEC-DOCUMENT>0001104659-25-000640.txt : 20250103
<SEC-HEADER>0001104659-25-000640.hdr.sgml : 20250103
<ACCEPTANCE-DATETIME>20250103112652
ACCESSION NUMBER:		0001104659-25-000640
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20241231
FILED AS OF DATE:		20250103
DATE AS OF CHANGE:		20250103

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			GLENCORE INTERNATIONAL AG
		CENTRAL INDEX KEY:			0001032383
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34474
		FILM NUMBER:		25504408

	BUSINESS ADDRESS:	
		STREET 1:		BAARERMATTSTRASSE 3
		STREET 2:		P O BOX 555 CH 6341 BAAR
		CITY:			SWITZERLAND
		BUSINESS PHONE:		4142227722

	MAIL ADDRESS:	
		STREET 1:		BAARERMATTSTRASSE 3
		STREET 2:		P O BOX 555 CH 6341 BAAR
		CITY:			SWITZERLAND

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Glencore plc
		CENTRAL INDEX KEY:			0001521365
		STANDARD INDUSTRIAL CLASSIFICATION:	UNKNOWN SIC - 8880 [8880]
		ORGANIZATION NAME:           	International Corp Fin
		STATE OF INCORPORATION:			Y9
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34474
		FILM NUMBER:		25504406

	BUSINESS ADDRESS:	
		STREET 1:		BAARERMATTSTRASSE 3
		CITY:			BAAR
		STATE:			V8
		ZIP:			CH-6341
		BUSINESS PHONE:		41 41 709 2000

	MAIL ADDRESS:	
		STREET 1:		BAARERMATTSTRASSE 3
		CITY:			BAAR
		STATE:			V8
		ZIP:			CH-6341

	FORMER NAME:	
		FORMER CONFORMED NAME:	Glencore Xstrata plc
		DATE OF NAME CHANGE:	20130606

	FORMER NAME:	
		FORMER CONFORMED NAME:	GLENCORE INTERNATIONAL PLC
		DATE OF NAME CHANGE:	20110520

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Glencore AG
		CENTRAL INDEX KEY:			0001449539
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			V8
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34474
		FILM NUMBER:		25504407

	BUSINESS ADDRESS:	
		STREET 1:		BAARERMATTSTRASSE 3
		STREET 2:		P.O. BOX 1301
		CITY:			BAAR
		STATE:			V8
		ZIP:			CH-6341
		BUSINESS PHONE:		41 41 709 2512

	MAIL ADDRESS:	
		STREET 1:		BAARERMATTSTRASSE 3
		STREET 2:		P.O. BOX 1301
		CITY:			BAAR
		STATE:			V8
		ZIP:			CH-6341

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CENTURY ALUMINUM CO
		CENTRAL INDEX KEY:			0000949157
		STANDARD INDUSTRIAL CLASSIFICATION:	PRIMARY PRODUCTION OF ALUMINUM [3334]
		ORGANIZATION NAME:           	04 Manufacturing
		IRS NUMBER:				133070826
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1 SOUTH WACKER DRIVE
		STREET 2:		SUITE 1000
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606
		BUSINESS PHONE:		3126963101

	MAIL ADDRESS:	
		STREET 1:		1 SOUTH WACKER DRIVE
		STREET 2:		SUITE 1000
		CITY:			CHICAGO
		STATE:			IL
		ZIP:			60606
</SEC-HEADER>
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<TYPE>4
<SEQUENCE>1
<FILENAME>tm251829-1_4seq1.xml
<DESCRIPTION>OWNERSHIP DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2024-12-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000949157</issuerCik>
        <issuerName>CENTURY ALUMINUM CO</issuerName>
        <issuerTradingSymbol>CENX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001032383</rptOwnerCik>
            <rptOwnerName>GLENCORE INTERNATIONAL AG</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>BAARERMATTSTRASSE 3</rptOwnerStreet1>
            <rptOwnerStreet2>P.O. BOX 1363</rptOwnerStreet2>
            <rptOwnerCity>BAAR</rptOwnerCity>
            <rptOwnerState>V8</rptOwnerState>
            <rptOwnerZipCode>CH-6341</rptOwnerZipCode>
            <rptOwnerStateDescription>SWITZERLAND</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001449539</rptOwnerCik>
            <rptOwnerName>Glencore AG</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>BAARERMATTSTRASSE 3</rptOwnerStreet1>
            <rptOwnerStreet2>P.O. BOX 1363</rptOwnerStreet2>
            <rptOwnerCity>BAAR</rptOwnerCity>
            <rptOwnerState>V8</rptOwnerState>
            <rptOwnerZipCode>CH-6341</rptOwnerZipCode>
            <rptOwnerStateDescription>SWITZERLAND</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001521365</rptOwnerCik>
            <rptOwnerName>Glencore plc</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>BAARERMATTSTRASSE 3</rptOwnerStreet1>
            <rptOwnerStreet2>P.O. BOX 1363</rptOwnerStreet2>
            <rptOwnerCity>BAAR</rptOwnerCity>
            <rptOwnerState>V8</rptOwnerState>
            <rptOwnerZipCode>CH-6341</rptOwnerZipCode>
            <rptOwnerStateDescription>SWITZERLAND</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2024-12-31</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>C</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>210162</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12534438</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>27500000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Series A Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2024-12-31</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>C</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>2101.62</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>210162</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>49715.09</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents shares of Common Stock acquired upon conversion of 2,101.62 shares of Series A Convertible Preferred Stock on December 31, 2024.</footnote>
        <footnote id="F2">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 has no expiration date.</footnote>
        <footnote id="F3">The shares of Common Stock reported in Line 1 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 2 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.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>GLENCORE INTERNATIONAL AG By: /s/ John Burton Name: John Burton Title: Director By: /s/ Steven Kalmin Name: Steven Kalmin Title: Director</signatureName>
        <signatureDate>2025-01-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>GLENCORE AG By: /s/ Martin Haering Name: Martin Haering Title: Director By: /s/ Carlos Perezagua Name: Carlos Perezagua Title: Director</signatureName>
        <signatureDate>2025-01-03</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>GLENCORE PLC By: /s/ John Burton Name: John Burton Title: Company Secretary</signatureName>
        <signatureDate>2025-01-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
