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

    <schemaVersion>X0508</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2025-04-08</periodOfReport>

    <issuer>
        <issuerCik>0001844971</issuerCik>
        <issuerName>Greenidge Generation Holdings Inc.</issuerName>
        <issuerTradingSymbol>GREE</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001882294</rptOwnerCik>
            <rptOwnerName>Atlas Capital Resources GP LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 NORTHFIELD STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>true</isTenPercentOwner>
            <isOther>false</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001882313</rptOwnerCik>
            <rptOwnerName>Atlas Capital GP LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 NORTHFIELD STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>true</isTenPercentOwner>
            <isOther>false</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001880358</rptOwnerCik>
            <rptOwnerName>Atlas Capital Resources (A9) LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 NORTHFIELD STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>true</isTenPercentOwner>
            <isOther>false</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000905112</rptOwnerCik>
            <rptOwnerName>BURSKY ANDREW M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 NORTHFIELD STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>true</isTenPercentOwner>
            <isOther>false</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001394403</rptOwnerCik>
            <rptOwnerName>Fazio Timothy J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 NORTHFIELD STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>GREENWICH</rptOwnerCity>
            <rptOwnerState>CT</rptOwnerState>
            <rptOwnerZipCode>06830</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>true</isTenPercentOwner>
            <isOther>false</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>false</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock, par value $0.0001 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2025-04-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>false</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>90954</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.31</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3642774</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">In connection with the Equity Interest Payment Agreement (the &quot;Agreement&quot;), dated as of January 24, 2025, by and among Greenidge Generation Holdings Inc. (the &quot;Issuer&quot;) and Atlas Capital Resources (A9) LP (&quot;ACR9&quot;), Atlas Capital Resources (A9-Parallel) LP (&quot;ACR Parallel&quot;), and Atlas Capital Resources (P) LP (&quot;ACR P&quot; and, together with ACR9 and ACR Parallel, collectively, &quot;Atlas&quot;), the Issuer made a $119,204 payment to Atlas in the form of shares of Class A Common Stock based on the price formula set forth in the Agreement. Of the 90,954 shares of Class A Common Stock issued to Atlas thereunder, 65,170 shares were issued to ACR9, 23,400 shares were issued to ACR Parallel and 2,384 shares were issued to ACR P.</footnote>
        <footnote id="F2">Represents 962,744 shares of Class A Common Stock and 2,680,030 shares of Class B Common Stock, which are convertible at any time at the option of the holder into an equal number of shares of Class A Common Stock.</footnote>
        <footnote id="F3">Atlas Capital GP LP (&quot;ACR GPLP&quot;) is the general partner of ACR9, ACR Parallel, ACR P and GGH Bridge Investment LP (&quot;GGH&quot;). Atlas Capital Resources GP LLC (&quot;ACR GP&quot;) is the general partner of ACR GPLP. ACR GP, ACR GPLP, ACR9, ACR Parallel, ACR P, and GGH are collectively referred to as the &quot;Atlas Entities.&quot; Andrew M. Bursky and Timothy J. Fazio are each a managing partner of ACR GP and may be deemed to control the Atlas Entities.</footnote>
        <footnote id="F4">Each of Messrs. Bursky and Fazio and each of the Atlas Entities disclaims beneficial ownership interest of the Class A Common Stock except, in each case, to the extent he or it has any pecuniary interest therein.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Atlas Capital Resources GP LLC, /s/ Timothy J. Fazio, Managing Partner</signatureName>
        <signatureDate>2025-04-10</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Atlas Capital GP LLC, By: Atlas Capital Resources GP LLC, /s/ Timothy J. Fazio, Managing Partner</signatureName>
        <signatureDate>2025-04-10</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Atlas Capital Resources (A9) LP, By: Atlas Capital Resources GP LP, By: Atlas Capital Resources GP LLC, /s/ Timothy J. Fazio, Managing Partner</signatureName>
        <signatureDate>2025-04-10</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Andrew M. Bursky, /s/ Andrew M. Bursky</signatureName>
        <signatureDate>2025-04-10</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>Timothy J. Fazio, /s/ Timothy J. Fazio</signatureName>
        <signatureDate>2025-04-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
