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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2021-02-26</periodOfReport>

    <notSubjectToSection16>true</notSubjectToSection16>

    <issuer>
        <issuerCik>0001744894</issuerCik>
        <issuerName>Sirius International Insurance Group, Ltd.</issuerName>
        <issuerTradingSymbol>SG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001769647</rptOwnerCik>
            <rptOwnerName>Friedman Robert L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>14 WESLEY STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HAMILTON</rptOwnerCity>
            <rptOwnerState>D0</rptOwnerState>
            <rptOwnerZipCode>HM11</rptOwnerZipCode>
            <rptOwnerStateDescription>BERMUDA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2021-02-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>36030</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>6923</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2021-02-26</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>6923</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents shares of common stock of the issuer (&quot;Sirius Shares&quot;) disposed of in connection with the merger of the issuer with Third Point Reinsurance Ltd. (&quot;TPRE&quot;) (the &quot;Merger&quot;), which closed on February 26, 2021 (the &quot;Effective Time&quot;), and exchanged for a combination of common shares, par value $0.10 per share, of TPRE (the &quot;TPRE Shares&quot;) and contingent value right (&quot;CVR&quot;) consideration comprising (1) 0.743 of a TPRE Share and (2) one contractual CVR, which represents the right to receive a contingent cash payment, which, taken together with the fraction of the TPRE Share received, guarantee that on the second anniversary of the Effective Time, the electing shareholder will have received equity and cash equal to at least $13.73 per Sirius Share.</footnote>
        <footnote id="F2">Represents restricted shares that immediately vested following the closing of the Merger. These shares were disposed of in connection with the Merger and exchanged for a combination of TPRE Shares and CVR consideration comprising (1) 0.743 of a TPRE Share and (2) one contractual CVR, which represents the right to receive a contingent cash payment, which, taken together with the fraction of the TPRE Share received, guarantee that on the second anniversary of the Effective Time, the electing shareholder will have received equity and cash equal to at least $13.73 per Sirius Share.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Robert L. Friedman</signatureName>
        <signatureDate>2021-03-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
