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SEC EDGAR · Insider purchase

HEI-A: CULLIGAN THOMAS M reported buying shares

1 reported purchase of non-derivative securities. Code P includes open-market and private purchases; it does not establish motive.

Follow HEI-A
Became public
Oct 13, 2026
Event / period date
Oct 8, 2026
Collected
Nov 9, 2026, 12:36 AM EST

Why this is connected

This filing identifies HEICO CORP as the issuer of the security. The company's SEC identifier connects it to HEI-A.

Open the original source ↗Follow company activity in HEI-A

Reported transactions

CULLIGAN THOMAS M (Director)

795 shares · Class A Common Stock

Oct 8, 2026 · $220.3043 per share

Value calculated from the reported shares and prices: $175,141.92.

Code P covers open-market and private purchases. Grants, option exercises, and tax withholding are excluded from purchase results. Read the source footnotes for ownership and pricing details.

Source evidence

Read the source excerpt or record
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-10-08</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000046619</issuerCik>
        <issuerName>HEICO CORP</issuerName>
        <issuerTradingSymbol>HEI, HEI.A</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001217585</rptOwnerCik>
            <rptOwnerName>CULLIGAN THOMAS M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>3000 TAFT STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HOLLYWOOD</rptOwnerCity>
            <rptOwnerState>FL</rptOwnerState>
            <rptOwnerZipCode>33021</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1223</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5470</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By 409A Plan</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-10-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>795</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>220.3043</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>11825</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By 409A Plan</value>
                    <footnoteId id="F1"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents shares held for the Reporting Person by the HEICO Corporation Leadership Compensation Plan (409A Plan).</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Thomas M. Culligan</signatureName>
        <signatureDate>2026-10-13</signatureDate>
    </ownerSignature>
</ownershipDocument>

Price change after we could observe it

+1.64% HEI-A

Adjusted closing prices from Nov 10, 2026 to Nov 11, 2026. SPY changed 1.32% over the same dates. The start is the first available close after both publication and collection. This is a price comparison, not an executed trade, investor profit, or a backtested strategy.

Congressional trading in HEI-A

These disclosures provide context. Their presence does not establish a link between a trader and the event.

Original documents control. Public records can be amended, and company connections may require interpretation. Nothing here is investment advice.