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

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-07-02</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000853770</issuerCik>
        <issuerName>MFS INTERMARKET INCOME TRUST I</issuerName>
        <issuerTradingSymbol>CMK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001224071</rptOwnerCik>
            <rptOwnerName>THOMSEN LAURIE J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>THE TRAVELERS COMPANIES INC</rptOwnerStreet1>
            <rptOwnerStreet2>385 WASHINGTON STREET</rptOwnerStreet2>
            <rptOwnerCity>ST. PAUL</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55102</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <ownerSignature>
        <signatureName>CHRISTOPHER R. BOHANE</signatureName>
        <signatureDate>2026-08-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
