<SEC-DOCUMENT>0000950142-26-001309.txt : 20260506
<SEC-HEADER>0000950142-26-001309.hdr.sgml : 20260506
<ACCEPTANCE-DATETIME>20260506211629
ACCESSION NUMBER:		0000950142-26-001309
CONFORMED SUBMISSION TYPE:	3
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20260504
FILED AS OF DATE:		20260506
DATE AS OF CHANGE:		20260506

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			GAP Coinvestments CDA, L.P.
		CENTRAL INDEX KEY:			0001356474
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-43254
		FILM NUMBER:		26950470

	BUSINESS ADDRESS:	
		STREET 1:		55 EAST 52ND STREET, 32ND FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10055
		BUSINESS PHONE:		212 715 4000

	MAIL ADDRESS:	
		STREET 1:		55 EAST 52ND STREET, 32ND FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10055

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			General Atlantic Partners (Lux), SCSp
		CENTRAL INDEX KEY:			0001795410
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			N4
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-43254
		FILM NUMBER:		26950469

	BUSINESS ADDRESS:	
		STREET 1:		55 EAST 52ND STREET
		STREET 2:		FLOOR 33
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10055
		BUSINESS PHONE:		212-715-4000

	MAIL ADDRESS:	
		STREET 1:		55 EAST 52ND STREET
		STREET 2:		FLOOR 33
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10055

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			General Atlantic GenPar (Lux) SCSp
		CENTRAL INDEX KEY:			0001857517
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			N4
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-43254
		FILM NUMBER:		26950467

	BUSINESS ADDRESS:	
		STREET 1:		412F ROUTE D'ESCH
		CITY:			LUXEMBOURG
		STATE:			N4
		ZIP:			2086
		BUSINESS PHONE:		212-715-4000

	MAIL ADDRESS:	
		STREET 1:		412F ROUTE D'ESCH
		CITY:			LUXEMBOURG
		STATE:			N4
		ZIP:			2086

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			General Atlantic (Lux) S.a r.l.
		CENTRAL INDEX KEY:			0001858361
		ORGANIZATION NAME:           	
		STATE OF INCORPORATION:			P7
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		3
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-43254
		FILM NUMBER:		26950468

	BUSINESS ADDRESS:	
		STREET 1:		412F ROUTE D'ESCH
		CITY:			LUXEMBOURG
		STATE:			P7
		ZIP:			10055
		BUSINESS PHONE:		212-715-4000

	MAIL ADDRESS:	
		STREET 1:		412F ROUTE D'ESCH
		CITY:			LUXEMBOURG
		STATE:			P7
		ZIP:			10055

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Seaport Therapeutics, Inc.
		CENTRAL INDEX KEY:			0002042347
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		ORGANIZATION NAME:           	03 Life Sciences
		EIN:				992235719
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		6 TIDE STREET
		STREET 2:		SUITE 400
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02110
		BUSINESS PHONE:		617-807-4062

	MAIL ADDRESS:	
		STREET 1:		6 TIDE STREET
		STREET 2:		SUITE 400
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02110
</SEC-HEADER>
<DOCUMENT>
<TYPE>3
<SEQUENCE>1
<FILENAME>es260776360_3-sptx2.xml
<DESCRIPTION>OWNERSHIP DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0607</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2026-05-04</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0002042347</issuerCik>
        <issuerName>Seaport Therapeutics, Inc.</issuerName>
        <issuerTradingSymbol>SPTX</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001356474</rptOwnerCik>
            <rptOwnerName>GAP Coinvestments CDA, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O GENERAL ATLANTIC SERVICE CO., L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>55 EAST 52ND STREET, 33RD FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10055</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001795410</rptOwnerCik>
            <rptOwnerName>General Atlantic Partners (Lux), SCSp</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>true</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>412F, ROUTE D'ESCH</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LUXEMBOURG</rptOwnerCity>
            <rptOwnerNonUSStateTerritory></rptOwnerNonUSStateTerritory>
            <rptOwnerCountry>N4</rptOwnerCountry>
            <rptOwnerZipCode>L-1471</rptOwnerZipCode>
            <rptOwnerStateDescription>LUXEMBOURG</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001858361</rptOwnerCik>
            <rptOwnerName>General Atlantic (Lux) S.a r.l.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>true</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>412F, ROUTE D'ESCH</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LUXEMBOURG</rptOwnerCity>
            <rptOwnerNonUSStateTerritory></rptOwnerNonUSStateTerritory>
            <rptOwnerCountry>N4</rptOwnerCountry>
            <rptOwnerZipCode>L-1471</rptOwnerZipCode>
            <rptOwnerStateDescription>LUXEMBOURG</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001857517</rptOwnerCik>
            <rptOwnerName>General Atlantic GenPar (Lux) SCSp</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>true</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>412F, ROUTE D'ESCH</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LUXEMBOURG</rptOwnerCity>
            <rptOwnerNonUSStateTerritory></rptOwnerNonUSStateTerritory>
            <rptOwnerCountry>N4</rptOwnerCountry>
            <rptOwnerZipCode>L-1471</rptOwnerZipCode>
            <rptOwnerStateDescription>LUXEMBOURG</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.0001 per share (&quot;Common Stock&quot;)</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6101582</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnote</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Reflects 6,101,582 shares of Common Stock held by General Atlantic (SP), L.P., or General Atlantic SP, including 3,351,582 shares of Common Stock issuable upon conversion of Series B preferred stock. The limited partners that share beneficial ownership of the shares held by General Atlantic SP, or the GA Funds, are General Atlantic Partners 100, L.P., or GAP 100, General Atlantic Partners (Lux), SCSp, or GAP Lux, GAP Coinvestments III, LLC, or GAPCO III, GAP Coinvestments IV, LLC, or GAPCO IV, GAP Coinvestments V, LLC, or GAPCO V, and GAP Coinvestments CDA, L.P., or GAPCO CDA. The general partner of GAP 100 is General Atlantic GenPar, L.P., (Cont'd in FN2)</footnote>
        <footnote id="F2">(Cont'd from FN1) or GA GenPar. General Atlantic, L.P., or GA LP, which is controlled by the Partnership Committee of GASC MGP, LLC (the &quot;Partnership Committee&quot;), is the managing member of GAPCO III, GAPCO IV and GAPCO V, the general partner of GAPCO CDA and GA GenPar, and the sole member of General Atlantic (SPV) GP, LLC, or GA SPV. The general partner of General Atlantic SP is GA SPV. The general partner of GAP Lux is General Atlantic GenPar, (Lux) SCSp, or GA GenPar Lux, and the general partner of GA GenPar Lux is General Atlantic (Lux) S.a r.l., or GA Lux. The sole shareholder of GA Lux is General Atlantic GenPar (Bermuda), L.P., or GenPar Bermuda. GAP (Bermuda) L.P., or GAP Bermuda, which is ultimately controlled by the Partnership Committee, is the general partner of GenPar Bermuda. (Cont'd in FN3)</footnote>
        <footnote id="F3">(Cont'd from FN2) There are six members of the Partnership Committee. Each of the members of the Partnership Committee disclaims ownership of the shares except to the extent that he or she has a pecuniary interest therein.</footnote>
    </footnotes>

    <remarks>GA LP, GAP Bermuda, GA Lux, GA GenPar Lux, GA SPV, and the GA Funds may be deemed to be members of a &quot;group&quot; for the purposes of the Securities Exchange Act of 1934. Each reporting person disclaims beneficial ownership of any securities deemed to be owned by the group that are not directly owned by the reporting person. This report shall not be deemed an admission that the reporting persons are a member of a group or the beneficial owner of any securities not directly owned by the reporting person. Each of the reporting persons is a director-by-deputization solely for purposes of Section 16 of the Exchange Act. // Form 2 of 2</remarks>

    <ownerSignature>
        <signatureName>/s/ Michael Gosk</signatureName>
        <signatureDate>2026-05-06</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Ingrid van der Hoorn</signatureName>
        <signatureDate>2026-05-06</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Ingrid van der Hoorn</signatureName>
        <signatureDate>2026-05-06</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Ingrid van der Hoorn</signatureName>
        <signatureDate>2026-05-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
