<SEC-DOCUMENT>0001104659-26-076967.txt : 20260623
<SEC-HEADER>0001104659-26-076967.hdr.sgml : 20260623
<ACCEPTANCE-DATETIME>20260623215626
ACCESSION NUMBER:		0001104659-26-076967
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20260623
FILED AS OF DATE:		20260623
DATE AS OF CHANGE:		20260623

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Fairmount Healthcare Fund II L.P.
		CENTRAL INDEX KEY:			0001769651
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-37722
		FILM NUMBER:		261112869

	BUSINESS ADDRESS:	
		STREET 1:		200 BARR HARBOR DRIVE
		STREET 2:		SUITE 400
		CITY:			WEST CONSHOHOCKEN
		STATE:			PA
		ZIP:			19428
		BUSINESS PHONE:		(267) 760-4066

	MAIL ADDRESS:	
		STREET 1:		200 BARR HARBOR DRIVE
		STREET 2:		SUITE 400
		CITY:			WEST CONSHOHOCKEN
		STATE:			PA
		ZIP:			19428

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Harwin Peter Evan
		CENTRAL INDEX KEY:			0001663607
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-37722
		FILM NUMBER:		261112867

	MAIL ADDRESS:	
		STREET 1:		200 BARR HARBOR DRIVE
		STREET 2:		SUITE 400
		CITY:			WEST CONSHOHOCKEN
		STATE:			PA
		ZIP:			19428

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Kiselak Tomas
		CENTRAL INDEX KEY:			0001830177
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-37722
		FILM NUMBER:		261112868

	MAIL ADDRESS:	
		STREET 1:		200 BARR HARBOR DRIVE
		STREET 2:		SUITE 400
		CITY:			WEST CONSHOHOCKEN
		STATE:			PA
		ZIP:			19428

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Fairmount Funds Management LLC
		CENTRAL INDEX KEY:			0001802528
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-37722
		FILM NUMBER:		261112870

	BUSINESS ADDRESS:	
		STREET 1:		200 BARR HARBOR DRIVE
		STREET 2:		SUITE 400
		CITY:			WEST CONSHOHOCKEN
		STATE:			PA
		ZIP:			19428
		BUSINESS PHONE:		267-262-5300

	MAIL ADDRESS:	
		STREET 1:		200 BARR HARBOR DRIVE
		STREET 2:		SUITE 400
		CITY:			WEST CONSHOHOCKEN
		STATE:			PA
		ZIP:			19428

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Spyre Therapeutics, Inc.
		CENTRAL INDEX KEY:			0001636282
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		ORGANIZATION NAME:           	03 Life Sciences
		EIN:				464312787
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		221 CRESCENT STREET
		STREET 2:		BUILDING 23, SUITE 105
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02453
		BUSINESS PHONE:		6176515940

	MAIL ADDRESS:	
		STREET 1:		221 CRESCENT STREET
		STREET 2:		BUILDING 23, SUITE 105
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02453

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Aeglea BioTherapeutics, Inc.
		DATE OF NAME CHANGE:	20150311
</SEC-HEADER>
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        <issuerName>Spyre Therapeutics, Inc.</issuerName>
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    <reportingOwner>
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            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19428</rptOwnerZipCode>
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    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001663607</rptOwnerCik>
            <rptOwnerName>Harwin Peter Evan</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
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            <rptOwnerStreet2>SUITE 400</rptOwnerStreet2>
            <rptOwnerCity>WEST CONSHOHOCKEN</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19428</rptOwnerZipCode>
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            <otherText></otherText>
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    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-06-23</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>C</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>666680</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4684781</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Fairmount Healthcare Fund II L.P.</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-06-23</value>
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            <deemedExecutionDate></deemedExecutionDate>
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            <transactionAmounts>
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                <transactionPricePerShare>
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                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
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            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
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                    <value>By Fairmount Healthcare Fund II L.P.</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
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                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Tomas Kiselak</value>
                </natureOfOwnership>
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        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
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                    <value>406038</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Peter Harwin</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Series B Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2026-06-23</value>
            </transactionDate>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>16667</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
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            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>666680</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
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                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Fairmount Healthcare Fund II LP</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeHolding>
            <securityTitle>
                <value>Series A Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F3"/>
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            <exerciseDate>
                <footnoteId id="F3"/>
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            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
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                    <value>13841800</value>
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                <sharesOwnedFollowingTransaction>
                    <value>346045</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>I</value>
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    <footnotes>
        <footnote id="F1">Each share of Series B Preferred Stock is convertible at the option of the holder into 40 shares of Common Stock, subject to certain beneficial ownership limitations, including that a holder of Series B Preferred Stock is prohibited from converting shares of Series B Preferred Stock into shares of Common Stock if, as a result of such conversion, such holder, together with its affiliates, would beneficially own more than 9.99% of the total number of shares of Common Stock issued and outstanding immediately after giving effect to such conversion. On June 23, 2026, the Reporting Persons converted 16,667 shares of Series B Preferred Stock into 666,680 shares of Common Stock for no cash consideration, in accordance with the Certificate of Designations for the Series B Convertible Preferred Stock.</footnote>
        <footnote id="F2">Fairmount Funds Management LLC (&quot;Fairmount&quot;) is the investment manager for Fairmount Healthcare Fund II L.P. The managers of Fairmount are Peter Harwin and Tomas Kiselak. Fairmount, Mr. Harwin, and Mr. Kiselak disclaim beneficial ownership of any of the reported securities, except to the extent of their pecuniary interest therein.</footnote>
        <footnote id="F3">Each share of Series A Preferred Stock is convertible at the option of the holder into 40 shares of Common Stock, subject to certain beneficial ownership limitations, including that a holder of Series A Preferred Stock is prohibited from converting shares of Series A Preferred Stock into shares of Common Stock if, as a result of such conversion, such holder, together with its affiliates, would beneficially own more than 9.99% of the total number of shares of Common Stock issued and outstanding immediately after giving effect to such conversion.</footnote>
    </footnotes>

    <remarks>The Reporting Persons may each be deemed a director by deputization of Issuer by virtue of the fact that Tomas Kiselak serves on the board of directors of Issuer and is also a Managing Member of Fairmount Funds Management LLC.</remarks>

    <ownerSignature>
        <signatureName>/s/ Tomas Kiselak, Managing Member of Fairmount Funds Management LLC</signatureName>
        <signatureDate>2026-06-23</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Tomas Kiselak, Managing Member of Fairmount Healthcare Fund II, L.P.</signatureName>
        <signatureDate>2026-06-23</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Tomas Kiselak</signatureName>
        <signatureDate>2026-06-23</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>s/ Peter Harwin</signatureName>
        <signatureDate>2026-06-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</SEC-DOCUMENT>
