<SEC-DOCUMENT>0001127602-17-009812.txt : 20170302
<SEC-HEADER>0001127602-17-009812.hdr.sgml : 20170302
<ACCEPTANCE-DATETIME>20170302171820
ACCESSION NUMBER:		0001127602-17-009812
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170228
FILED AS OF DATE:		20170302
DATE AS OF CHANGE:		20170302

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			BIOGEN INC.
		CENTRAL INDEX KEY:			0000875045
		STANDARD INDUSTRIAL CLASSIFICATION:	BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
		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

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			COVINO GREGORY F
		CENTRAL INDEX KEY:			0001224116

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-19311
		FILM NUMBER:		17660119

	MAIL ADDRESS:	
		STREET 1:		C/O RICHARD W DAVIES HUBBELL INC
		STREET 2:		684 DERBY MILFORD RD
		CITY:			ORANGE
		STATE:			CT
		ZIP:			06477
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form4.xml
<DESCRIPTION>PRIMARY DOCUMENT
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    <periodOfReport>2017-02-28</periodOfReport>

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        <issuerName>BIOGEN INC.</issuerName>
        <issuerTradingSymbol>BIIB</issuerTradingSymbol>
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            <rptOwnerStreet2>225 BINNEY STREET</rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02142</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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            <transactionTimeliness></transactionTimeliness>
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                <transactionShares>
                    <value>321</value>
                    <footnoteId id="F9"/>
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                <transactionPricePerShare>
                    <value>0</value>
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                <transactionAcquiredDisposedCode>
                    <value>D</value>
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                <directOrIndirectOwnership>
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            <securityTitle>
                <value>Restricted Stock Unit</value>
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                <value>0</value>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>121</value>
                    <footnoteId id="F11"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
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            <exerciseDate>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <value>2017-02-12</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>121</value>
                    <footnoteId id="F11"/>
                </underlyingSecurityShares>
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            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                    <footnoteId id="F11"/>
                </sharesOwnedFollowingTransaction>
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    <footnotes>
        <footnote id="F1">This award vested on 2/23/2017 and the actual number of shares that vested was determined in accordance with the terms of such award.  Due to adjustments to the award to account for the Bioverativ Inc. spin-off, the number of vested shares was not determinable until 2/28/2017.  Such adjusted number of vested shares was distributed to the reporting person on 2/28/2017.</footnote>
        <footnote id="F2">This award vested on 2/22/2017 and the actual number of shares that vested was determined in accordance with the terms of such award.  Due to adjustments to the award to account for the Bioverativ Inc. spin-off, the number of vested shares was not determinable until 2/28/2017.  Such adjusted number of vested shares was distributed to the reporting person on 2/28/2017.</footnote>
        <footnote id="F3">This award vested on 2/12/2017 and the actual number of shares that vested was determined in accordance with the terms of such award.  Due to adjustments to the award to account for the Bioverativ Inc. spin-off, the number of vested shares was not determinable until 2/28/2017.  Such adjusted number of vested shares was distributed to the reporting person on 2/28/2017.</footnote>
        <footnote id="F4">This represents the difference between the maximum possible number of shares that were eligible for vesting and the actual number that vested.</footnote>
        <footnote id="F5">The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout.  One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date.  The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price on the grant date]).</footnote>
        <footnote id="F6">The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 200% of the number of shares at target payout. One-third of these RSUs are eligible to vest on each of the first three anniversaries of the grant date. The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the 30-day average closing stock price ending on the vesting date divided by the 30-day average closing stock price on the grant date]).</footnote>
        <footnote id="F7">This award was previously reported as covering 402 shares, but was adjusted pursuant to the anti-dilution provisions of the award in connection with the spin-off of Bioverativ Inc. on February 1, 2017</footnote>
        <footnote id="F8">This award was previously reported as covering 870 shares, but was adjusted pursuant to the anti-dilution provisions of the award in connection with the spin-off of Bioverativ Inc. on February 1, 2017</footnote>
        <footnote id="F9">This award was previously reported as covering 315 shares, but was adjusted pursuant to the anti-dilution provisions of the award in connection with the spin-off of Bioverativ Inc. on February 1, 2017</footnote>
        <footnote id="F10">The number of RSUs reported represents the maximum possible number of shares that are eligible for vesting, which is 150% of the number of shares at target payout.  One-fourth of these RSUs are eligible to vest on each of the first four anniversaries of the grant date.  The actual number of shares that will vest on each vesting date will be determined by comparing the price of Biogen Idec common stock on such vesting date to the price on the grant date (i.e., number of vested shares = number of shares at target payout times [the average 60 calendar-day closing stock price ending on the vesting date divided by the average 60 calendar-day closing stock price on the grant date]).</footnote>
        <footnote id="F11">This award was previously reported as covering 258 shares, but was adjusted pursuant to the anti-dilution provisions of the award in connection with the spin-off of Bioverativ Inc. on February 1, 2017</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Steven Avruch, Attorney in Fact for Gregory F. Covino</signatureName>
        <signatureDate>2017-03-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
