<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-09-29</periodOfReport>

    <notSubjectToSection16>true</notSubjectToSection16>

    <issuer>
        <issuerCik>0001820872</issuerCik>
        <issuerName>Global Business Travel Group, Inc.</issuerName>
        <issuerTradingSymbol>GBTG</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001924575</rptOwnerCik>
            <rptOwnerName>Huska Patricia Anne</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O GLOBAL BUSINESS TRAVEL GROUP, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>666 THIRD AVENUE</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>false</isDirector>
            <isOfficer>true</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle>Chief People Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>false</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-09-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>856752</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>413146</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-09-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>413146</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-09-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>206941</value>
                    <footnoteId id="F4"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>206941</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-09-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>206941</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Includes shares acquired under the Issuer's Employee Stock Purchase Plan on August 14, 2026.</footnote>
        <footnote id="F2">On September 29, 2026, pursuant to that certain Agreement and Plan of Merger (the &quot;Merger Agreement&quot;), dated May 2, 2026, by and among the Issuer, Gaia Purchaser, Inc. (&quot;Parent&quot;) and Gaia Merger Sub, Inc., a wholly owned subsidiary of Parent, the Issuer became a wholly owned subsidiary of Parent (the &quot;Merger&quot;). At the effective time of the Merger (the &quot;Effective Time&quot;), pursuant to the Merger Agreement, each share of Class A common stock, par value $0.0001 per share, of the Issuer (&quot;Company Common Stock&quot;) held by the reporting person as of immediately prior to the Effective Time was automatically cancelled and converted into the right to receive cash in an amount equal to $9.50, without interest thereon (the &quot;Per Share Price&quot;).</footnote>
        <footnote id="F3">As of immediately prior to the Effective Time, pursuant to the Merger Agreement, each award of restricted stock units of the Issuer (a &quot;Company RSU&quot;) that was outstanding as of immediately prior to the Effective Time was automatically cancelled and converted into the right to receive an amount in cash, without interest and subject to applicable withholding taxes, equal to the product of (i) the Per Share Price and (ii) the total number of shares of Company Common Stock subject to such Company RSU as of immediately prior to the Effective Time.</footnote>
        <footnote id="F4">Represents a deemed acquisition of shares of Company Common Stock underlying each award of performance stock units of the Issuer (a &quot;Company PSU&quot;) held by the reporting person that was unvested and outstanding as of immediately prior to the Effective Time based on the attainment of the applicable performance metrics at the greater of (i) the target number of shares of Company Common Stock subject to such Company PSU as of immediately prior to the Effective Time and (ii) the number of shares of Company Common Stock to be earned based on actual achievement of the performance criteria set forth in the applicable award agreement as of immediately prior to the Effective Time.</footnote>
        <footnote id="F5">As of immediately prior to the Effective Time, each Company PSU that was outstanding as of immediately prior to the Effective Time was automatically cancelled and converted into the right to receive an amount in cash, without interest and subject to applicable withholding taxes, equal to the product of (A) the Per Share Price and (B) the greater of (i) the target number of shares of Company Common Stock subject to such Company PSU as of immediately prior to the Effective Time and (ii) the number of shares of Company Common Stock to be earned based on actual achievement of the performance criteria set forth in the applicable award agreement as of immediately prior to the Effective Time.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Jennifer Giampietro, as Attorney-in-Fact</signatureName>
        <signatureDate>2026-09-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
