<SEC-DOCUMENT>0001127602-25-003954.txt : 20250210
<SEC-HEADER>0001127602-25-003954.hdr.sgml : 20250210
<ACCEPTANCE-DATETIME>20250210184216
ACCESSION NUMBER:		0001127602-25-003954
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20250206
FILED AS OF DATE:		20250210
DATE AS OF CHANGE:		20250210

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ALEXANDER SUSAN H
		CENTRAL INDEX KEY:			0001263839
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-19311
		FILM NUMBER:		25607118

	MAIL ADDRESS:	
		STREET 1:		C/O BIOGEN IDEC INC.
		STREET 2:		14 CAMBRIDGE CENTER
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			BIOGEN INC.
		CENTRAL INDEX KEY:			0000875045
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		ORGANIZATION NAME:           	03 Life Sciences
		IRS NUMBER:				330112644
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		225 BINNEY STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142
		BUSINESS PHONE:		7814642000

	MAIL ADDRESS:	
		STREET 1:		225 BINNEY STREET
		CITY:			CAMBRIDGE
		STATE:			MA
		ZIP:			02142

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BIOGEN IDEC INC.
		DATE OF NAME CHANGE:	20070427

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	BIOGEN IDEC INC
		DATE OF NAME CHANGE:	20031112

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	IDEC PHARMACEUTICALS CORP / DE
		DATE OF NAME CHANGE:	19970530
</SEC-HEADER>
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    <periodOfReport>2025-02-06</periodOfReport>

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        <issuerCik>0000875045</issuerCik>
        <issuerName>BIOGEN INC.</issuerName>
        <issuerTradingSymbol>BIIB</issuerTradingSymbol>
    </issuer>

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        <reportingOwnerId>
            <rptOwnerCik>0001263839</rptOwnerCik>
            <rptOwnerName>ALEXANDER SUSAN H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>BIOGEN INC.</rptOwnerStreet1>
            <rptOwnerStreet2>225 BINNEY STREET</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02142</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>EVP Chief Legal Officer</officerTitle>
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                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Susan H. Alexander 2021 Irrevocable Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Unit</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2025-02-06</value>
            </transactionDate>
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                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
                    <value>14750</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2028-02-06</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>14750</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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        </derivativeTransaction>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
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                    <value>2190</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
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                </transactionAcquiredDisposedCode>
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            <exerciseDate>
                <footnoteId id="F2"/>
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            <expirationDate>
                <value>2026-02-08</value>
            </expirationDate>
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                <underlyingSecurityTitle>
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                </underlyingSecurityTitle>
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                </directOrIndirectOwnership>
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            <exerciseDate>
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    <footnotes>
        <footnote id="F1">The restricted stock units vest in three equal yearly installments beginning on the first anniversary of the grant date of February 6, 2025.</footnote>
        <footnote id="F2">The restricted stock units vest in three (3) equal annual installments commencing one year after the grant date of 2/8/2023.</footnote>
        <footnote id="F3">The restricted stock units vest in three (3) equal annual installments, commencing one year after the grant date of 02/07/2024.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Wendell Taylor, attorney-in-fact for Susan Alexander</signatureName>
        <signatureDate>2025-02-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
