<SEC-DOCUMENT>0001140361-15-018562.txt : 20150508
<SEC-HEADER>0001140361-15-018562.hdr.sgml : 20150508
<ACCEPTANCE-DATETIME>20150508180521
ACCESSION NUMBER:		0001140361-15-018562
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20150506
FILED AS OF DATE:		20150508
DATE AS OF CHANGE:		20150508

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CALPINE CORP
		CENTRAL INDEX KEY:			0000916457
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTRIC SERVICES [4911]
		IRS NUMBER:				770212977
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		717 TEXAS AVENUE
		STREET 2:		SUITE 1000
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77002
		BUSINESS PHONE:		7138302000

	MAIL ADDRESS:	
		STREET 1:		717 TEXAS AVENUE
		STREET 2:		SUITE 1000
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77002

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MERRITT DAVID C
		CENTRAL INDEX KEY:			0001254013

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-12079
		FILM NUMBER:		15848164

	MAIL ADDRESS:	
		STREET 1:		CHARTER COMMUNICATIONS INC
		STREET 2:		12405 POWERSCOURT DRIVE
		CITY:			ST LOUIS
		STATE:			MO
		ZIP:			63131
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-05-06</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001254013</rptOwnerCik>
            <rptOwnerName>MERRITT DAVID C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CALPINE CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>717 TEXAS AVENUE, STE. 1000</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77002</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.001 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2015-05-06</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>14000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>20.404</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15783</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.001 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2015-05-07</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>14000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>20.521</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>24000</value>
                    <footnoteId id="F4"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By David C. Merritt Defined Benefit Plan    &amp; Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The price reported in Column 4 is a weighted average price.  These shares were sold in multiple transactions. 3,011 shares were sold at $20.36 per share, 489 shares were sold at $20.39 per share, 3,500 shares were sold at $20.40 per share, 3,500 shares were sold at $20.41 per share, 2,800 shares were sold at $20.44 per share and 700 shares were sold at $20.45 per share.</footnote>
        <footnote id="F2">As an Internal Revenue Service regulation prohibits a transfer of shares from the reporting person's personal account directly into his pension fund account, the reporting person elected to effect the transfer by selling shares from his personal account and subsequently purchasing the same number of shares in the open market for deposit in his pension fund account to hold as a long-term investment. Reference Footnotes 3 and 4 below.</footnote>
        <footnote id="F3">The price reported in Column 4 is a weighted average price.  These shares were purchased in multiple transactions. 3,400 shares were purchased at $20.515 per share, 3,482 shares were purchased at $20.519 per share, 2,418 shares were purchased at $20.52 per share, 4,300 shares were purchased at $20.526 per share, and 400 shares were purchased at $20.53 per share.</footnote>
        <footnote id="F4">Represents shares purchased in an open market transaction by a trust established under a defined benefit plan in which the insider is the sole participant, the sole beneficiary, the sole trustee, and has sole investment control.  Reference Footnotes 1 and 2 above.</footnote>
    </footnotes>

    <remarks>The reporting person sold shares at $20.450 or less per share and repurchased the same number of shares at $20.515 or more per share. Transaction was effected solely to transfer personal investment from a personal account to a defined benefit plan and trust account.</remarks>

    <ownerSignature>
        <signatureName>/s/  W. Thaddeus Miller, as Attorney-in-Fact</signatureName>
        <signatureDate>2015-05-08</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
