<SEC-DOCUMENT>0000874501-17-000028.txt : 20170306
<SEC-HEADER>0000874501-17-000028.hdr.sgml : 20170306
<ACCEPTANCE-DATETIME>20170306163718
ACCESSION NUMBER:		0000874501-17-000028
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20170302
FILED AS OF DATE:		20170306
DATE AS OF CHANGE:		20170306

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			AMBAC FINANCIAL GROUP INC
		CENTRAL INDEX KEY:			0000874501
		STANDARD INDUSTRIAL CLASSIFICATION:	SURETY INSURANCE [6351]
		IRS NUMBER:				133621676
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		ONE STATE ST PLZ
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10004
		BUSINESS PHONE:		2126680340

	MAIL ADDRESS:	
		STREET 1:		ONE STATE ST PLZ
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10004

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	AMBAC INC /DE/
		DATE OF NAME CHANGE:	19930328

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			REILLY MICHAEL FRANCIS
		CENTRAL INDEX KEY:			0001562285

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-10777
		FILM NUMBER:		17668363

	MAIL ADDRESS:	
		STREET 1:		C/O AMBAC FINANCIAL GROUP, INC.
		STREET 2:		ONE STATE STREET PLAZA
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10004
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_148883622480814.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-03-02</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000874501</issuerCik>
        <issuerName>AMBAC FINANCIAL GROUP INC</issuerName>
        <issuerTradingSymbol>AMBC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001562285</rptOwnerCik>
            <rptOwnerName>REILLY MICHAEL FRANCIS</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>AMBAC FINANCIAL GROUP, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>ONE STATE STREET PLAZA</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10004</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior Managing Director</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2017-03-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>106</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>22.35</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2952</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2017-03-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>106</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>22.35</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2846</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Deferred Share Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-03-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2517</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2517.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2517</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Deferred Share Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-03-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>106</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>22.35</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>106.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2411</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On March 2, 2017, the Grant Date, 106 deferred share units (&quot;DSUs&quot;) vested, were converted into shares of common stock and withheld by Ambac Financial Group, Inc. (the &quot;Company&quot;) to satisfy certain tax withholding obligations.</footnote>
        <footnote id="F2">Each DSU represents a contingent right to receive one share of the Company's common stock.</footnote>
        <footnote id="F3">The DSUs shall vest immediately and shall settle and convert into shares of common stock as follows: 50% of the DSUs shall settle and convert into shares of common stock on March 2, 2018, and the remaining 50% of the DSUs shall settle and convert into shares of common stock on March 2, 2019; provided however, that if the reporting person's employment with the Company is terminated for any reason, all of the DSUs will settle and convert into shares of common stock immediately. Notwithstanding the foregoing, a number of vested DSUs sufficient to satisfy certain tax withholding obligations imposed upon the Company may be converted into shares of common stock and withheld by the Company to satisfy such tax withholding obligations.</footnote>
        <footnote id="F4">The DSUs were awarded under the Company's 2013 Incentive Compensation Plan. The number of DSUs granted was calculated based on the closing price of the Company's common stock on March 2, 2017.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>William J. White, attorney-in-fact</signatureName>
        <signatureDate>2017-03-06</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>poa-michaelfreillyforedgar.htm
<DESCRIPTION>POWER OF ATTORNEY
<TEXT>
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<pre>
                                             POWER OF ATTORNEY



            I, MICHAEL F. REILLY, do hereby nominate, constitute and appoint each of William White, Stephen M. Ksenak and Yolanda Ortiz, as my true and lawful agent and attorney-in-fact, with full power and authority to act hereunder, in his or her discretion, in my name and on my behalf as fully as I could if I were present and acting in person, to make any and all required or voluntary filings under Section 16(a) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), and the applicable rules and regulations thereunder, with the Securities and Exchange Commission, the New York Stock Exchange, Ambac Financial Group, Inc., a Delaware corporation (the "Company"), and any other person or entity to which such filings may be required under Section 16(a) of the Exchange Act as a result of my service as an officer of the Company or beneficial ownership (within the meaning of Section 16(a) of the Exchange Act) of more than ten percent of any class of equity securities of the Company.

            I hereby consent to, ratify and confirm all that each said attorney-in-fact shall do or cause to be done by virtue of this Power of Attorney.  I hereby acknowledge that each attorney-in-fact, in serving in such capacity at my request, is not assuming, nor is the Company assuming, any of my responsibilities to comply with Section 16 of the Exchange Act.

            This Power of Attorney shall remain in full force and effect from this date forward for so long as I am an officer or director of the Company and for such time thereafter as may be necessary to make any such filings or until revoked or modified by me.  I hereby revoke all prior powers of attorney relating to the foregoing acts.

            IN WITNESS WHEREOF, I have hereunto signed my name this 17th day of December, 2013.




                                __/s/ Michael F. Reilly__





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