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

    <schemaVersion>X0607</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2026-06-11</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0002092446</issuerCik>
        <issuerName>Avalanche Treasury Corp</issuerName>
        <issuerTradingSymbol>AVAT</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0002111237</rptOwnerCik>
            <rptOwnerName>Hadick Robert M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>AVALANCHE TREASURY COMPANY, LLC.</rptOwnerStreet1>
            <rptOwnerStreet2>11 W. 42ND STREET, 2ND FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10036</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2000000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Astral Horizon, L.P.</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Astral Horizon, L.P. (&quot;Astral Horizon Fund&quot;) is managed by its general partner, Astral Horizon GP, LLC, which is governed by a board of managers consisting of four natural persons, including Mr. Hadick. The managers of Astral Horizon GP, LLC collectively have the authority to manage and control the affairs of Astral Horizon Fund, including voting and investment decisions relating to its portfolio securities. Actions by the managers require approval of a majority of the managers, and no individual manager has authority to act unilaterally on behalf of the entity. Mr. Hadick disclaims beneficial ownership of the securities held by Astral Horizon Fund, except to the extent of his pecuniary interest therein, if any.</footnote>
    </footnotes>

    <remarks>Exhibit 24 - Power of Attorney</remarks>

    <ownerSignature>
        <signatureName>/s/ Laine Mihalchick Moljo, as Attorney-in-Fact</signatureName>
        <signatureDate>2026-06-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
