<SEC-DOCUMENT>0001104659-25-098362.txt : 20251009
<SEC-HEADER>0001104659-25-098362.hdr.sgml : 20251009
<ACCEPTANCE-DATETIME>20251009161516
ACCESSION NUMBER:		0001104659-25-098362
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20251007
FILED AS OF DATE:		20251009
DATE AS OF CHANGE:		20251009

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:	001-42270
		FILM NUMBER:		251385236

	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 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:	001-42270
		FILM NUMBER:		251385238

	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:			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:	001-42270
		FILM NUMBER:		251385239

	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

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:	001-42270
		FILM NUMBER:		251385237

	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:			Zenas BioPharma, Inc.
		CENTRAL INDEX KEY:			0001953926
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		ORGANIZATION NAME:           	03 Life Sciences
		EIN:				000000000
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		852 WINTER STREET, SUITE 250
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451
		BUSINESS PHONE:		857-271-2954

	MAIL ADDRESS:	
		STREET 1:		852 WINTER STREET, SUITE 250
		CITY:			WALTHAM
		STATE:			MA
		ZIP:			02451

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Zenas BioPharma (Cayman) Ltd
		DATE OF NAME CHANGE:	20221108
</SEC-HEADER>
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<TYPE>4
<SEQUENCE>1
<FILENAME>tm2528449-1_4seq1.xml
<DESCRIPTION>OWNERSHIP DOCUMENT
<TEXT>
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<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-10-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001953926</issuerCik>
        <issuerName>Zenas BioPharma, Inc.</issuerName>
        <issuerTradingSymbol>ZBIO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001802528</rptOwnerCik>
            <rptOwnerName>Fairmount Funds Management LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 BARR HARBOR DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 400</rptOwnerStreet2>
            <rptOwnerCity>WEST CONSHOHOCKEN</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19428</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
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            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001769651</rptOwnerCik>
            <rptOwnerName>Fairmount Healthcare Fund II L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 BARR HARBOR DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 400</rptOwnerStreet2>
            <rptOwnerCity>WEST CONSHOHOCKEN</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19428</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001830177</rptOwnerCik>
            <rptOwnerName>Kiselak Tomas</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 BARR HARBOR DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 400</rptOwnerStreet2>
            <rptOwnerCity>WEST CONSHOHOCKEN</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19428</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001663607</rptOwnerCik>
            <rptOwnerName>Harwin Peter Evan</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>200 BARR HARBOR DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 400</rptOwnerStreet2>
            <rptOwnerCity>WEST CONSHOHOCKEN</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>19428</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2025-10-07</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>316219</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>19</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2209025</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Fairmount Healthcare Fund II L.P.</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">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>
    </footnotes>

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

    <ownerSignature>
        <signatureName>/s/ Tomas Kiselak, Managing Member of Fairmount Funds Management LLC</signatureName>
        <signatureDate>2025-10-09</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Tomas Kiselak, Managing Member of Fairmount Healthcare Fund II, L.P.</signatureName>
        <signatureDate>2025-10-09</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Tomas Kiselak</signatureName>
        <signatureDate>2025-10-09</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Peter Harwin</signatureName>
        <signatureDate>2025-10-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
