<SEC-DOCUMENT>0000950138-26-000002.txt : 20260109
<SEC-HEADER>0000950138-26-000002.hdr.sgml : 20260109
<ACCEPTANCE-DATETIME>20260109162935
ACCESSION NUMBER:		0000950138-26-000002
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20251218
FILED AS OF DATE:		20260109
DATE AS OF CHANGE:		20260109

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			JOHNSON WILLIAM D
		CENTRAL INDEX KEY:			0001183048
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-42252
		FILM NUMBER:		26523377

	MAIL ADDRESS:	
		STREET 1:		801 E 86TH AVE
		CITY:			MERRILLVILLE
		STATE:			IN
		ZIP:			46410

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Terrestrial Energy Inc. /DE/
		CENTRAL INDEX KEY:			0002019804
		STANDARD INDUSTRIAL CLASSIFICATION:	FABRICATED PLATE WORK (BOILER SHOPS) [3443]
		ORGANIZATION NAME:           	04 Manufacturing
		EIN:				981785406
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2730 W. TYVOLA ROAD, SUITE 100
		CITY:			CHARLOTTE
		STATE:			NC
		ZIP:			28217
		BUSINESS PHONE:		203-930-2200

	MAIL ADDRESS:	
		STREET 1:		2730 W. TYVOLA ROAD, SUITE 100
		CITY:			CHARLOTTE
		STATE:			NC
		ZIP:			28217

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	HCM II Acquisition Corp.
		DATE OF NAME CHANGE:	20240415
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>form4a.xml
<DESCRIPTION>AMENDED STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0508</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2025-12-18</periodOfReport>

    <dateOfOriginalSubmission>2025-12-22</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0002019804</issuerCik>
        <issuerName>Terrestrial Energy Inc. /DE/</issuerName>
        <issuerTradingSymbol>IMSR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001183048</rptOwnerCik>
            <rptOwnerName>JOHNSON WILLIAM D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2730 W. TYVOLA ROAD, SUITE 100</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CHARLOTTE</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>28217</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2025-12-18</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1029</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1029</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6894</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each restricted stock unit represents a contingent right to acquire one share of Common Stock. So long as the Reporting Person provides continuous service to Terrestrial Energy, Inc., 100% of the restricted stock units will vest on December 31, 2026.</footnote>
        <footnote id="F2">On December 22, 2025, the Reporting Person filed a Form 4 in which there was an inadvertent error in the number of reported restricted stock units.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Steven M. Millsap, Attorney-in-Fact</signatureName>
        <signatureDate>2026-01-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
