<SUBMISSION>
<ACCESSION-NUMBER>0001181431-12-021297
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20120331
<FILING-DATE>20120402
<DATE-OF-FILING-DATE-CHANGE>20120402
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>WILLIAM & SUSAN OBERNDORF TRUST
<CIK>0001252467
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-12079
<FILM-NUMBER>12735058
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>591 REDWOOD HIGHWAY
<STREET2>STE 3215
<CITY>MILL VALLEY
<STATE>CA
<ZIP>94941
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>JOHN H SCULLY LIVING TRUST
<CIK>0001273627
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-12079
<FILM-NUMBER>12735057
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>591 REDWOOD HIGHWAY
<STREET2>SUITE 3215
<CITY>MILL VALLEY
<STATE>CA
<ZIP>94941
</MAIL-ADDRESS>
</REPORTING-OWNER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>OBERNDORF WILLIAM E
<CIK>0001218663
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-12079
<FILM-NUMBER>12735059
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>SPO PARTNERS & CO
<STREET2>591 REDWOOD HWY STE 3215
<CITY>MILL VALLEY
<STATE>CA
<ZIP>94941
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>CALPINE CORP
<CIK>0000916457
<ASSIGNED-SIC>4911
<IRS-NUMBER>770212977
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>717 TEXAS AVENUE
<STREET2>SUITE 1000
<CITY>HOUSTON
<STATE>TX
<ZIP>77002
<PHONE>7138302000
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>717 TEXAS AVENUE
<STREET2>SUITE 1000
<CITY>HOUSTON
<STATE>TX
<ZIP>77002
</MAIL-ADDRESS>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Edward & Elizabeth McDermott Trust
<CIK>0001545752
<STATE-OF-INCORPORATION>CA
<FISCAL-YEAR-END>1231
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-12079
<FILM-NUMBER>12735056
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>591 REDWOOD HIGHWAY
<STREET2>SUITE 3215
<CITY>MILL VALLEY
<STATE>CA
<ZIP>94941
<PHONE>415-383-6600
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>591 REDWOOD HIGHWAY
<STREET2>SUITE 3215
<CITY>MILL VALLEY
<STATE>CA
<ZIP>94941
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>rrd339877.xml
<DESCRIPTION>FORM 4 - WEO DEPARTURE
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0305</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2012-03-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000916457</issuerCik>
        <issuerName>CALPINE CORP</issuerName>
        <issuerTradingSymbol>CPN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001218663</rptOwnerCik>
            <rptOwnerName>OBERNDORF WILLIAM E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>591 REDWOOD HIGHWAY, SUITE 3215</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MILL VALLEY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94941</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001252467</rptOwnerCik>
            <rptOwnerName>WILLIAM &amp; SUSAN OBERNDORF TRUST</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>591 REDWOOD HIGHWAY, SUITE 3215</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MILL VALLEY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94941</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001273627</rptOwnerCik>
            <rptOwnerName>JOHN H SCULLY LIVING TRUST</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>591 REDWOOD HIGHWAY , SUITE 3215</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MILL VALLEY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94941</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001545752</rptOwnerCik>
            <rptOwnerName>Edward &amp; Elizabeth McDermott Trust</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>591 REDWOOD HIGHWAY</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 3215</rptOwnerStreet2>
            <rptOwnerCity>MILL VALLEY</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94941</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2012-03-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>0</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>77501208</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnotes</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">On March 31, 2012, the John H. Scully Living Trust (&quot;JHS Trust&quot;) and the Edward &amp; Elizabeth McDermott Trust (&quot;EHM Trust&quot;) purchased one-third of the outstanding shares of SPO Advisory Corp. (&quot;SPO Corp.&quot;) previously owned by the William E. &amp; Susan C. Oberndorf Trust. William E. Oberndorf (&quot;WEO&quot;) left the SPO reporting group on March 31, 2012 and is no longer a controlling person of SPO Corp.  Following the transaction which caused this filing, WEO beneficially owns 28,700 shares of the Issuer's common stock held in the WEO individual retirement account, which is self directed.  These shares are no longer included in the SPO filing group.  Additionally, 5,451 restricted stock units are owned by WEO, a director of the Issuer.  Pursuant to the partnership agreement governing SPO Partners II, L.P. (&quot;SPO Partners&quot;), these shares may be deemed to be indirectly beneficially owned by SPO Partners together with any profits arising therefrom.</footnote>
        <footnote id="F2">Additionally, following the transaction which caused this filing, 70,541,012 shares of the Issuer's common stock are owned directly by SPO Partners and may be deemed to be indirectly beneficially owned by (i) SPO Advisory Partners, L.P. (&quot;SPO Advisory&quot;), the sole general partner of SPO Partners, (ii) SPO Corp., the sole general partner of SPO Advisory, and (iii) John H. Scully (&quot;JHS&quot;) and Edward H. McDermott (&quot;EHM&quot;), the two controlling persons of SPO Corp.  Additionally, 4,234,400 shares of the Issuer's common stock are owned directly by SPO Partners II Co-Investment Partnership, L.P. (&quot;SPO Co-Invest&quot;), and may be deemed to be indirectly beneficially owned by (i) SPO Advisory, the sole general partner of SPO Co-Invest, (ii) SPO Corp., the sole general partner of SPO Advisory, and (iii) JHS and EHM, the two controlling persons of SPO Corp.</footnote>
        <footnote id="F3">Additionally, following the transaction which caused this filing, 2,697,096 shares of the Issuer's common stock are owned directly by San Francisco Partners, L.P. (&quot;SF Partners&quot;), and may be deemed to be indirectly beneficially owned by (i) SF Advisory Partners, L.P. (&quot;SF Advisory&quot;), the sole general partner of SF Partners, (ii) SPO Corp., the sole general partner of SF Advisory, and (iii) JHS and EHM, the two controlling persons of SPO Corp.  Additionally, JHS beneficially owns 5,000 shares of the Issuer's common stock held in the JHS individual retirement accounts, which are self directed.  Additionally, EHM beneficially owns 5,600 shares of the Issuer's common stock held in the EHM individual retirement account, which is self directed.</footnote>
    </footnotes>

    <remarks>The individuals and entities listed in the Notes above may be deemed to form a &quot;group&quot;, as such term is defined in Rule 13d-5(b)(1) promulgated under the Securities Exchange Act of 1934. This filing shall not be deemed as an admission by the Reporting Person that such person is, for purposes of Section 16 of the Securities Exchange Act of 1934 or otherwise, the beneficial owner of any equity securities covered by this statement. The Reporting Person disclaims beneficial ownership of the reported securities except to the extent of his pecuniary interest, if any, therein.</remarks>

    <ownerSignature>
        <signatureName>Kim M. Silva, Attorney-in-fact</signatureName>
        <signatureDate>2012-04-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
