<SUBMISSION>
<ACCESSION-NUMBER>0001179110-07-014573
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20070703
<FILING-DATE>20070706
<DATE-OF-FILING-DATE-CHANGE>20070706
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>PROS Holdings, Inc.
<CIK>0001392972
<ASSIGNED-SIC>7371
<IRS-NUMBER>760168604
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>3100 MAIN STREET
<STREET2>SUITE 900
<CITY>HOUSTON
<STATE>TX
<ZIP>77002
<PHONE>713-335-5151
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>3100 MAIN STREET
<STREET2>SUITE 900
<CITY>HOUSTON
<STATE>TX
<ZIP>77002
</MAIL-ADDRESS>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>TA ADVENT VIII LP
<CIK>0001106837
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-33554
<FILM-NUMBER>07966794
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>125 HIGH ST
<CITY>BOSTON
<STATE>MA
<ZIP>02110
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>125 HIGH ST
<CITY>BOSTON
<STATE>MA
<ZIP>02110
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>TA INVESTORS LLC
<CIK>0001235809
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-33554
<FILM-NUMBER>07966795
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>125 HIGH STREET
<STREET2>SUITE 2500
<CITY>BOSTON
<STATE>MA
<ZIP>02110
<PHONE>6175746781
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>125 HIGH STREET
<STREET2>SUITE 2500
<CITY>BOSTON
<STATE>MA
<ZIP>02110
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>TA EXECUTIVES FUND LLC
<CIK>0001268755
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-33554
<FILM-NUMBER>07966796
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>125 HIGH STREET
<STREET2>SUITE 2500
<CITY>BOSTON
<STATE>MA
<ZIP>02110
<PHONE>6175746735
</BUSINESS-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>TA ASSOCIATES AAP III PARTNERS
<CIK>0001235814
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-33554
<FILM-NUMBER>07966798
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>125 HIGH STREET
<STREET2>SUITE 2500
<CITY>BOSTON
<STATE>MA
<ZIP>02110
<PHONE>6175746781
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>125 HIGH STREET
<STREET2>SUITE 2500
<CITY>BOSTON
<STATE>MA
<ZIP>02110
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>ADVENT ATLANTIC & PACIFIC III LP
<CIK>0001235810
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-33554
<FILM-NUMBER>07966799
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>125 HIGH STREET
<STREET2>SUITE 2500
<CITY>BOSTON
<STATE>MA
<ZIP>02110
<PHONE>6175746781
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>125 HIGH STREET
<STREET2>SUITE 2500
<CITY>BOSTON
<STATE>MA
<ZIP>02110
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>TA ASSOCIATES INC
<CIK>0001034569
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-33554
<FILM-NUMBER>07966800
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>125 HIGH STREET
<STREET2>SUITE 2500
<CITY>BOSTON
<STATE>MA
<ZIP>02110
<PHONE>6175746781
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>125 HIGH STREET
<STREET2>SUITE 2500
<CITY>BOSTON
<STATE>MA
<ZIP>02110
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>TA ASSOCIATES VIII LLC
<CIK>0001235812
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-33554
<FILM-NUMBER>07966797
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>125 HIGH STREET
<STREET2>SUITE 2500
<CITY>BOSTON
<STATE>MA
<ZIP>02110
<PHONE>6175746781
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>125 HIGH STREET
<STREET2>SUITE 2500
<CITY>BOSTON
<STATE>MA
<ZIP>02110
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-07-03</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001392972</issuerCik>
        <issuerName>PROS Holdings, Inc.</issuerName>
        <issuerTradingSymbol>PRO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001034569</rptOwnerCik>
            <rptOwnerName>TA ASSOCIATES INC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>JOHN HANCOCK TOWER</rptOwnerStreet1>
            <rptOwnerStreet2>200 CLARENDON ST., 56TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>See Remarks</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001235810</rptOwnerCik>
            <rptOwnerName>ADVENT ATLANTIC &amp; PACIFIC III LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>JOHN HANCOCK TOWER</rptOwnerStreet1>
            <rptOwnerStreet2>200 CLARENDON STREET, 56TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>See Remarks</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001235814</rptOwnerCik>
            <rptOwnerName>TA ASSOCIATES AAP III PARTNERS</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>JOHN HANCOCK TOWER</rptOwnerStreet1>
            <rptOwnerStreet2>200 CLARENDON STREET, 56TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>See Remarks</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001235812</rptOwnerCik>
            <rptOwnerName>TA ASSOCIATES VIII LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>JOHN HANCOCK TOWER</rptOwnerStreet1>
            <rptOwnerStreet2>200 CLARENDON STREET, 56TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>See Remarks</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001268755</rptOwnerCik>
            <rptOwnerName>TA EXECUTIVES FUND LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>JOHN HANCOCK TOWER</rptOwnerStreet1>
            <rptOwnerStreet2>200 CLARENDON STREET, 56TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>See Remarks</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001235809</rptOwnerCik>
            <rptOwnerName>TA INVESTORS LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>JOHN HANCOCK TOWER</rptOwnerStreet1>
            <rptOwnerStreet2>200 CLARENDON STREET, 56TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>See Remarks</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001106837</rptOwnerCik>
            <rptOwnerName>TA ADVENT VIII LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>JOHN HANCOCK TOWER</rptOwnerStreet1>
            <rptOwnerStreet2>200 CLARENDON STREET, 56TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>See Remarks</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2007-07-03</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1260049</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.23</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6090671</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The shares are held as follows: (i) 4,967,603 shares held of record by TA/Advent VIII, L.P., (ii) 932,360 shares held of record by Advent Atlantic and Pacific III, L.P., (iii) 91,358 shares held of record by TA Executives Fund LLC, and (iv) 99,350 shares held of record by TA Investors LLC (such entities, collectively, the &quot;TA Funds&quot;).</footnote>
        <footnote id="F2">TA Associates, Inc. is the manager of TA Associates VIII LLC, which is the general partner of TA/Advent VIII L.P.  TA Associates, Inc. is also the general partner of TA Associates AAP III Partners, which is the general partner of Advent Atlantic and Pacific III, L.P.  TA Associates, Inc. is also the manager of TA Executives Fund LLC and TA Investors LLC.  Each of TA Associates, Inc., TA Associates VIII LLC and TA Associates AAP III Partners may be deemed to have a beneficial interest in shares held by the TA Funds.  Each of TA Associates, Inc., TA Associates VIII LLC and TA Associates AAP III Partners disclaims beneficial ownership of such shares, except to the extent of its pecuniary interest in such shares which is subject to indeterminable future events.</footnote>
    </footnotes>

    <remarks>The reporting persons are members of a 13(d) group owning more than 10% of the issuer's outstanding common stock.  The reporting persons have a representative on the issuer's board of directors.  Kurt R. Jaggers currently serves as the reporting persons' representative on the board of directors and, as such, the reporting persons are deemed directors of the issuer.</remarks>

    <ownerSignature>
        <signatureName>TA Associates, Inc., By Roberto E. Ramirez, Vice President of Finance</signatureName>
        <signatureDate>2007-07-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Advent Atlantic and Pacific III, L.P. By TA Associates AAP III Partners, Its General Partner, By TA Associates, Inc., Its General Partner, By Roberto E. Ramirez, Vice President of Finance</signatureName>
        <signatureDate>2007-07-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>TA Associates AAP III Partners, By TA Associates, Inc., Its General Partner, By Roberto E. Ramirez, Vice President of Finance</signatureName>
        <signatureDate>2007-07-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>TA Associates VIII LLC, By TA Associates, Inc., Its Manager, By Roberto E. Ramirez, Vice President of Finance</signatureName>
        <signatureDate>2007-07-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>TA Executives Fund LLC, By TA Associates, Inc., Its Manager, By Roberto E. Ramirez, Vice President of Finance</signatureName>
        <signatureDate>2007-07-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>TA Investors LLC, By TA Associates, Inc., Its Manager, By Roberto E. Ramirez, Vice President of Finance</signatureName>
        <signatureDate>2007-07-05</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>TA/Advent VIII, L.P., By TA Associates VIII LLC, Its General Partner, By TA Associates, Inc., Its Manager, By Roberto E. Ramirez, Vice President of Finance</signatureName>
        <signatureDate>2007-07-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
