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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2019-10-03</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000823094</issuerCik>
        <issuerName>SOTHEBYS</issuerName>
        <issuerTradingSymbol>BID</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001300345</rptOwnerCik>
            <rptOwnerName>Loeb Daniel S</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>390 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10022</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <officerTitle></officerTitle>
            <otherText>See Remarks</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001040273</rptOwnerCik>
            <rptOwnerName>Third Point LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>390 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></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, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2019-10-03</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>6668765</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>57.00</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Remarks</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Pursuant to the Agreement and Plan of Merger dated as of June 16, 2019, by and among BidFair USA, Inc. (formerly a limited liability company known as BidFair USA LLC), BidFair MergeRight, Inc. and the Issuer, each share of the Issuer's Common Stock held by the reporting persons was converted into the right to receive $57 in cash at the effective time of the merger.</footnote>
        <footnote id="F2">Other than the 7,161 shares granted as quarterly director compensation to Mr. Loeb in the aggregate since August 15, 2016 which are held directly by Mr. Loeb as reported above, the remainder of the securities reported in this Form 4 are held indirectly as described in the remarks below.</footnote>
    </footnotes>

    <remarks>Other than the securities granted to Daniel S. Loeb as quarterly director compensation on and since August 15, 2016, the securities disclosed in this Form 4 were owned by certain funds (the &quot;Funds&quot;) managed by Third Point LLC (&quot;Third Point&quot;). Daniel S. Loeb is the Chief Executive Officer of Third Point. By reason of the provisions of Rule 16a-1 under the Securities Exchange Act of 1934, as amended, Third Point and Mr. Loeb may be deemed to have been the beneficial owners of the securities that were beneficially owned by the Funds. Third Point and Mr. Loeb disclaim beneficial ownership of all such securities, except to the extent of any indirect pecuniary interest.</remarks>

    <ownerSignature>
        <signatureName>DANIEL S. LOEB, /s/ William Song, as Attorney-in-Fact for Daniel S. Loeb</signatureName>
        <signatureDate>2019-10-04</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>THIRD POINT LLC, /s/ William Song, as Attorney-in-Fact for Daniel S. Loeb, Chief Executive Officer of Third Point</signatureName>
        <signatureDate>2019-10-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
