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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2019-05-16</periodOfReport>

    <dateOfOriginalSubmission>2019-05-17</dateOfOriginalSubmission>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001591956</issuerCik>
        <issuerName>Sphere 3D Corp</issuerName>
        <issuerTradingSymbol>ANY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001166564</rptOwnerCik>
            <rptOwnerName>CYRUS CAPITAL PARTNERS, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>65 EAST 55 STREET</rptOwnerStreet1>
            <rptOwnerStreet2>35TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001166774</rptOwnerCik>
            <rptOwnerName>CYRUS CAPITAL PARTNERS GP, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CYRUS CAPITAL PARTNERS, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>65 EAST 55TH STREET, 35TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001251783</rptOwnerCik>
            <rptOwnerName>FREIDHEIM STEPHEN C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CYRUS CAPITAL PARTNERS, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>65 EAST 55TH STREET, 35TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001530547</rptOwnerCik>
            <rptOwnerName>FBC HOLDINGS S.A.R.L.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CYRUS CAPITAL PARTNERS, L.P.</rptOwnerStreet1>
            <rptOwnerStreet2>65 EAST 55TH STREET, 35TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2019-05-16</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>125315</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>2.0830</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>145301</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnotes</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">The Common Shares of Sphere 3D Corp. (the &quot;Issuer&quot;) were directly owned, and sold, by FBC Holdings S.a r.l. (&quot;FBC&quot;).</footnote>
        <footnote id="F2">The price per share reported in Column 4 is a weighted average price. These Common Shares were sold in multiple transactions at prices ranging US$2.05 to US$2.29, inclusive. The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the Staff of the Securities Exchange Commission, upon request, full information regarding the number of Common Shares sold at each separate price within the range set forth in this footnote.</footnote>
        <footnote id="F3">This statement is being filed by Cyrus Capital Partners, L.P. (&quot;Cyrus&quot;), FBC, Cyrus Capital Partners GP, L.L.C. (&quot;Cyrus GP&quot;), and Stephen C. Freidheim (each of Cyrus, FBC, Cyrus GP, and Mr. Freidheim, collectively the &quot;Reporting Persons&quot;). FBC, is a wholly owned subsidiary of certain funds advised and managed by Cyrus, each of which are private investment funds engaged in the business of acquiring, holding and disposing of investments in various companies.</footnote>
        <footnote id="F4">Cyrus is the manager of FBC and the investment manager of each private fund holding an interest in FBC. Cyrus GP is the general partner of Cyrus. Mr. Freidheim is the sole member/manager of Cyrus GP. Mr. Freidheim is also the Chief Investment Officer of Cyrus.</footnote>
        <footnote id="F5">Pursuant to Rule 16a-1(a)(4) under the Exchange Act, this filing shall not be deemed an admission that each Reporting Person was, for the purposes of Section 16 of the Exchange Act or otherwise, the beneficial owner of any securities of the Issuer held by the Reporting Persons, and such beneficial ownership was and is expressly disclaimed by the Reporting Persons except to the extent of their pecuniary interest.</footnote>
    </footnotes>

    <remarks>This Amendment to the Form 4 filed by the Reporting Persons on May 17, 2019 is being filed solely to indicate that the Reporting Persons are no longer 10% owners of the Issuer. No other information has changed.</remarks>

    <ownerSignature>
        <signatureName>/s/Stephen C. Freidheim, Sole Member/Manager of Cyrus Capital Partners GP, L.L. C., the general partner of Cyrus Capital Partners, L.P.</signatureName>
        <signatureDate>2019-05-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/Stephen C. Freidheim, Sole Member/Manager of Cyrus Capital Partners GP, L.L.C.</signatureName>
        <signatureDate>2019-05-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/Stephen C. Freidheim, individually</signatureName>
        <signatureDate>2019-05-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/Stephen C. Freidheim, Sole Member/Manager of Cyrus Capital Partners GP, L.L.C., the general partner of Cyrus Capital Partners, L.P., the investment manager of FBC Holdings S.a r.l.'s shareholders</signatureName>
        <signatureDate>2019-05-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
