<SEC-DOCUMENT>0001104659-26-051483.txt : 20260429
<SEC-HEADER>0001104659-26-051483.hdr.sgml : 20260429
<ACCEPTANCE-DATETIME>20260429160522
ACCESSION NUMBER:		0001104659-26-051483
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20260427
FILED AS OF DATE:		20260429
DATE AS OF CHANGE:		20260429

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Lefebvre d'Ovidio Manfredi
		CENTRAL INDEX KEY:			0001840678
		ORGANIZATION NAME:           	

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-40777
		FILM NUMBER:		26915816

	MAIL ADDRESS:	
		STREET 1:		7 RUE DU GABIAN
		CITY:			MONACO
		STATE:			O9
		ZIP:			98000

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Arqit Quantum Inc.
		CENTRAL INDEX KEY:			0001859690
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-PREPACKAGED SOFTWARE [7372]
		ORGANIZATION NAME:           	06 Technology
		EIN:				000000000
		STATE OF INCORPORATION:			E9
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		3 ORCHARD PLACE
		CITY:			LONDON
		STATE:			X0
		ZIP:			SW1H 0BF
		BUSINESS PHONE:		44 203 91 70155

	MAIL ADDRESS:	
		STREET 1:		3 ORCHARD PLACE
		CITY:			LONDON
		STATE:			X0
		ZIP:			SW1H 0BF
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>tm2612984-1_4seq1.xml
<DESCRIPTION>OWNERSHIP DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0609</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2026-04-27</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001859690</issuerCik>
        <issuerName>Arqit Quantum Inc.</issuerName>
        <issuerTradingSymbol>ARQQ</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001840678</rptOwnerCik>
            <rptOwnerName>Lefebvre d'Ovidio Manfredi</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>true</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>3 ORCHARD PLACE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LONDON</rptOwnerCity>
            <rptOwnerNonUSStateTerritory></rptOwnerNonUSStateTerritory>
            <rptOwnerCountry>X0</rptOwnerCountry>
            <rptOwnerZipCode>SW1H 0BF</rptOwnerZipCode>
            <rptOwnerStateDescription>UNITED KINGDOM</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Business Combination Warrants (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2026-04-27</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>41</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.9</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2026-09-03</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>41</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>27622.16</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Beneficially owned through Heritage Assets SCSp</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Business Combination Warrants (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2026-04-28</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>421</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.5</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2026-09-03</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Ordinary Shares</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>421</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>27200.84</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Beneficially owned through Heritage Assets SCSp</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On September 19, 2024, Arqit Quantum Inc. (ARQQ) announced the implementation of a reverse stock split whereby every 25 outstanding ARQQ ordinary shares were consolidated into one ordinary share, par value $0.0025 per share. Each Business Combination Warrant has an exercise price of $11.50 and can be exercised at any time, at the holder's election, to purchase 0.04 of an ARQQ ordinary share on a post-reverse stock split basis, and cannot be exercised for fractional shares. Accordingly, on a post-reverse stock split basis holders of Business Combination Warrants are required to exercise at least 25 Business Combination Warrants in order to receive one whole ARQQ ordinary share at an aggregate exercise price of $287.50 per whole ARQQ ordinary share. The reporting person beneficially owns 680,021 Business Combination Warrants, which, if exercised in full, would be equivalent to 27,200.84 ARQQ ordinary shares on a post-reverse stock split basis.</footnote>
    </footnotes>

    <remarks>Due to the issuer's status as a foreign private issuer pursuant to Rule 3a12-3(b) under the Securities Exchange Act of 1934 (the &quot;Act&quot;), the reporting person's transactions in the issuer's securities are exempt from Sections 16(b) and 16(c) of the Act.</remarks>

    <ownerSignature>
        <signatureName>/s/ Amir Heyat, as Attorney-in-Fact</signatureName>
        <signatureDate>2026-04-29</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
