<SEC-DOCUMENT>0001231919-26-000429.txt : 20260429
<SEC-HEADER>0001231919-26-000429.hdr.sgml : 20260429
<ACCEPTANCE-DATETIME>20260429184609
ACCESSION NUMBER:		0001231919-26-000429
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20260429
FILED AS OF DATE:		20260429
DATE AS OF CHANGE:		20260429

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			RA Capital Healthcare Fund LP
		CENTRAL INDEX KEY:			0001315082
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-40708
		FILM NUMBER:		26918938

	BUSINESS ADDRESS:	
		STREET 1:		200 BERKELEY STREET
		STREET 2:		18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		6177782500

	MAIL ADDRESS:	
		STREET 1:		200 BERKELEY STREET
		STREET 2:		18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

	FORMER NAME:	
		FORMER CONFORMED NAME:	RA Capital Biotech Fund LP
		DATE OF NAME CHANGE:	20050121

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			RA CAPITAL MANAGEMENT, L.P.
		CENTRAL INDEX KEY:			0001346824
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-40708
		FILM NUMBER:		26918939

	BUSINESS ADDRESS:	
		STREET 1:		200 BERKELEY STREET, 18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		617-778-2500

	MAIL ADDRESS:	
		STREET 1:		200 BERKELEY STREET, 18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

	FORMER NAME:	
		FORMER CONFORMED NAME:	RA CAPITAL MANAGEMENT, LLC
		DATE OF NAME CHANGE:	20051213

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Kolchinsky Peter
		CENTRAL INDEX KEY:			0001384859
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-40708
		FILM NUMBER:		26918934

	MAIL ADDRESS:	
		STREET 1:		200 BERKELEY STREET
		STREET 2:		18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			RA Capital Nexus Fund III, L.P.
		CENTRAL INDEX KEY:			0001883840
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-40708
		FILM NUMBER:		26918935

	BUSINESS ADDRESS:	
		STREET 1:		200 BERKELEY STREET, 18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		617-778-2500

	MAIL ADDRESS:	
		STREET 1:		200 BERKELEY STREET, 18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Shah Rajeev M.
		CENTRAL INDEX KEY:			0001619841
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-40708
		FILM NUMBER:		26918933

	MAIL ADDRESS:	
		STREET 1:		200 BERKELEY STREET
		STREET 2:		18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			RA Capital Nexus Fund, L.P.
		CENTRAL INDEX KEY:			0001780117
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-40708
		FILM NUMBER:		26918937

	BUSINESS ADDRESS:	
		STREET 1:		200 BERKELEY STREET
		STREET 2:		18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		(617) 778-2500

	MAIL ADDRESS:	
		STREET 1:		200 BERKELEY STREET
		STREET 2:		18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			RA Capital Nexus Fund II, L.P.
		CENTRAL INDEX KEY:			0001825376
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-40708
		FILM NUMBER:		26918936

	BUSINESS ADDRESS:	
		STREET 1:		200 BERKELEY STREET, 18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		617-778-2500

	MAIL ADDRESS:	
		STREET 1:		200 BERKELEY STREET, 18TH FLOOR
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Climb Bio, Inc.
		CENTRAL INDEX KEY:			0001768446
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		ORGANIZATION NAME:           	03 Life Sciences
		EIN:				832273741
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		20 WILLIAM STREET
		STREET 2:		SUITE 145
		CITY:			WELLESLEY HILLS
		STATE:			MA
		ZIP:			02481
		BUSINESS PHONE:		1-866-857-2596

	MAIL ADDRESS:	
		STREET 1:		20 WILLIAM STREET
		STREET 2:		SUITE 145
		CITY:			WELLESLEY HILLS
		STATE:			MA
		ZIP:			02481

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	Eliem Therapeutics, Inc.
		DATE OF NAME CHANGE:	20190219
</SEC-HEADER>
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        <issuerName>Climb Bio, Inc.</issuerName>
        <issuerTradingSymbol>CLYM</issuerTradingSymbol>
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            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
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    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001780117</rptOwnerCik>
            <rptOwnerName>RA Capital Nexus Fund, L.P.</rptOwnerName>
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        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>200 BERKELEY STREET, 18TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001825376</rptOwnerCik>
            <rptOwnerName>RA Capital Nexus Fund II, L.P.</rptOwnerName>
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        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>200 BERKELEY STREET, 18TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
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    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001883840</rptOwnerCik>
            <rptOwnerName>RA Capital Nexus Fund III, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>200 BERKELEY STREET, 18TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
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    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001384859</rptOwnerCik>
            <rptOwnerName>Kolchinsky Peter</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O RA CAPITAL MANAGEMENT, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>200 BERKELEY STREET, 18TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
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    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001619841</rptOwnerCik>
            <rptOwnerName>Shah Rajeev M.</rptOwnerName>
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            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
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            <rptOwnerStreet2>200 BERKELEY STREET, 18TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
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            <otherText></otherText>
        </reportingOwnerRelationship>
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    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Pre-Funded Warrants (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.0001</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2026-04-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2106000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>9.4999</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2106000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>22546000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The Pre-Funded Warrants have no expiration date and are exercisable immediately. Notwithstanding the foregoing, the Reporting Persons shall not be entitled to exercise the Pre-Funded Warrant if it would cause the aggregate number of shares of Common Stock beneficially owned by the Reporting Persons, their affiliates and any persons who are members of a Section 13(d) group with the Reporting Persons or their affiliates to exceed 33.0% of the total number of issued and outstanding shares of Common Stock of the Issuer following such exercise.</footnote>
        <footnote id="F2">These securities are held directly by RA Capital Healthcare Fund, L.P. (the &quot;Fund&quot;).</footnote>
        <footnote id="F3">RA Capital Management, L.P. (the &quot;Adviser&quot;) is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the &quot;Nexus Fund&quot;), RA Capital Nexus II Fund, L.P. (the &quot;Nexus Fund II&quot;), RA Capital Nexus III Fund, L.P. (the &quot;Nexus Fund III&quot;) and a separately managed account (the &quot;Account&quot;). The general partner of the Adviser is RA Capital Management GP, LLC (the &quot;Adviser GP&quot;), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. The Fund and the Nexus Fund III collectively own approximately 75% of the outstanding equity interests of Sera Medicines, LLC (&quot;Sera&quot;). Accordingly, each of the Fund, the Nexus Fund III and the Adviser may be deemed to beneficially own the securities held by Sera. The Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of the reported securities, except to the extent of their respective pecuniary interest therein.</footnote>
    </footnotes>

    <remarks>Dr. Andrew Levin, a Partner and Managing Director of the Adviser, serves on the Issuer's board of directors.</remarks>

    <ownerSignature>
        <signatureName>/s/ Peter Kolchinsky, Manager of RA Capital Management, L.P.</signatureName>
        <signatureDate>2026-04-29</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Peter Kolchinsky, Manager of RA Capital Healthcare Fund GP, LLC the General Partner of RA Capital Healthcare Fund, L.P.</signatureName>
        <signatureDate>2026-04-29</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund GP, LLC, the General Partner of RA Capital Nexus Fund, L.P.</signatureName>
        <signatureDate>2026-04-29</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund II GP, LLC, the General Partner of RA Capital Nexus Fund II, L.P.</signatureName>
        <signatureDate>2026-04-29</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Peter Kolchinsky, Manager of RA Capital Nexus Fund III GP, LLC, the General Partner of RA Capital Nexus Fund III, L.P.</signatureName>
        <signatureDate>2026-04-29</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Peter Kolchinsky, individually</signatureName>
        <signatureDate>2026-04-29</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Rajeev Shah, individually</signatureName>
        <signatureDate>2026-04-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</SEC-DOCUMENT>
