-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 VYcUgVoOglIe5mhRBar8nqb7CKXhtvyz0rwd3r0sQbtuIFd4YDvLB6PFOfV3ie5R
 xShYycxwQbb7wGKcPomfdQ==

<SEC-DOCUMENT>0000908662-08-000145.txt : 20080516
<SEC-HEADER>0000908662-08-000145.hdr.sgml : 20080516
<ACCEPTANCE-DATETIME>20080516165018
ACCESSION NUMBER:		0000908662-08-000145
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080514
FILED AS OF DATE:		20080516
DATE AS OF CHANGE:		20080516

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NewStar Financial, Inc.
		CENTRAL INDEX KEY:			0001373561
		STANDARD INDUSTRIAL CLASSIFICATION:	FINANCE LESSORS [6172]
		IRS NUMBER:				542157878

	BUSINESS ADDRESS:	
		STREET 1:		500 BOYLSTON STREET
		STREET 2:		SUITE 1600
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116
		BUSINESS PHONE:		617-848-2500

	MAIL ADDRESS:	
		STREET 1:		500 BOYLSTON STREET
		STREET 2:		SUITE 1600
		CITY:			BOSTON
		STATE:			MA
		ZIP:			02116

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			COOPER BRADLEY E
		CENTRAL INDEX KEY:			0001008262
		STATE OF INCORPORATION:			NY
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33211
		FILM NUMBER:		08842974

	BUSINESS ADDRESS:	
		STREET 1:		UNIVERSAL AMERICAN FINANCIAL CORP
		STREET 2:		6 INTERNATIONAL DRIVE STE 190
		CITY:			RYE BROOK
		STATE:			NY
		ZIP:			10573
		BUSINESS PHONE:		2123261590

	MAIL ADDRESS:	
		STREET 1:		UNIVERSAL AMERICAN FINANCIAL CORP
		STREET 2:		6 INTERNATIONAL DR STE 190
		CITY:			RYE BROOK
		STATE:			NY
		ZIP:			10573
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-05-14</periodOfReport>

    <issuer>
        <issuerCik>0001373561</issuerCik>
        <issuerName>NewStar Financial, Inc.</issuerName>
        <issuerTradingSymbol>NEWS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001008262</rptOwnerCik>
            <rptOwnerName>COOPER BRADLEY E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O NEWSTAR FINANCIAL, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>500 BOYLSTON STREET, SUITE 1600</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02116</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>See Footnotes (1), (2) and (3)</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2008-05-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>7834184</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnote</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>6.40</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-05-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2015-05-14</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Includes securities of the Issuer directly held by Capital Z Financial Services Fund II, L.P. (&quot;Capital Z&quot;), Capital Z Financial Services Private Fund II, L.P. (&quot;Capital Z Private Fund&quot;) and Capital Z Management, LLC (&quot;Capital Z Management&quot;) as well as securities of the Issuer directly owned by Union Square Partners, L.P. (&quot;Union Square&quot;). The sole general partner of Capital Z and Capital Z Private Fund is Capital Z Partners, L.P. (&quot;Capital Z L.P.&quot;), and the sole general partner of Capital Z L.P. is Capital Z Partners Ltd.  Union Square GP, L.P. (&quot;Union Square LP&quot;) is the general partner of Union Square.  Union Square GP, Ltd. (&quot;Union Square GP&quot;) is the general partner of Union Square LP and the ultimate general partner of Union Square.  Union Square Partners Management, LLC (&quot;Union Square Partners Management&quot;) is the investment authority for Union Square, its principal business is performing investment 
management services for Union Square.</footnote>
        <footnote id="F2">Union Square Partners Management, Union Square GP, Union Square LP and Union Square may be deemed to be part of a &quot;group&quot; along with Capital Z, Capital Z Private Fund, Capital Z Ltd., Capital Z LP and Capital Z Management (within the meaning of Rule 13d-5(b) under the Securities Exchange of 1934, as amended and incorporated by reference in Rule 16a-1 of the Exchange Act) but each individual entity described above disclaims beneficial ownership of securities held by any other entity except to the extent of any indirect pecuniary interest therein (within the meaning of Rule 16a-1 of the Exchange Act) in an indeterminate portion of the securities benefically owned by such other entity.</footnote>
        <footnote id="F3">Mr. Cooper is a shareholder of Capital Z Partners Ltd. and an officer and co-owner of Capital Z Management.  Mr. Cooper is also an officer and co-owner of Union Square Partners Management.  Mr. Cooper may be deemed to be part of the group along with Capital Z, Capital Z Private Fund, Capital Z Ltd, Capital Z LP, Capital Z Management, Union Square GP, Union Square LP, Union Square and Union Square Partners Management and may be deemed to be the beneficial owner of the the securities held by such entities, although Mr. Cooper disclaims beneficial ownership of such securities except to the extent of any indirect pecuniary interest therein (within the meaning of Rule 16a-1 of the Exchange Act) in an indeterminate portion of the securities beneficially owned by Capital Z, Capital Z Private Fund, Capital Z LP, Capital Z Ltd., Capital Z Management, Union Square GP, Union Square LP, Union Square and Union Square Partners Management.</footnote>
        <footnote id="F4">The option will vest and become exercisable in three substantially equal installments on May 14, 2009, 2010 and 2011.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Daniel K. Crowley as Attorney-in-Fact for Bradley E. Cooper</signatureName>
        <signatureDate>2008-05-16</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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