-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 DFRvU/bg+goRCJDwBc98hqVJGj+iJmG8jKbb1cJm87wQCxduEYidbhFHBGxa9C6Y
 Acf/jTX8VK2Hk3anCGx7bw==

<SEC-DOCUMENT>0001179110-09-009158.txt : 20090604
<SEC-HEADER>0001179110-09-009158.hdr.sgml : 20090604
<ACCEPTANCE-DATETIME>20090604165415
ACCESSION NUMBER:		0001179110-09-009158
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090602
FILED AS OF DATE:		20090604
DATE AS OF CHANGE:		20090604

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Smith Richard H
		CENTRAL INDEX KEY:			0001378132

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33077
		FILM NUMBER:		09874629

	MAIL ADDRESS:	
		STREET 1:		29621 NORTHWESTERN HIGHWAY
		CITY:			SOUTHFIELD
		STATE:			MI
		ZIP:			48034

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			FIRST MERCURY FINANCIAL CORP
		CENTRAL INDEX KEY:			0000929186
		STANDARD INDUSTRIAL CLASSIFICATION:	FIRE, MARINE & CASUALTY INSURANCE [6331]
		IRS NUMBER:				383164336
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		29621 NORTHWESTERN HWY
		STREET 2:		PO BOX 5096
		CITY:			SOUTHFIELD
		STATE:			MI
		ZIP:			48034
		BUSINESS PHONE:		8103584010

	MAIL ADDRESS:	
		STREET 1:		29621 NORTHWESTERN HGWY
		STREET 2:		PO BOX 5096
		CITY:			SOUTHFIELD
		STATE:			MI
		ZIP:			48086
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-06-02</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000929186</issuerCik>
        <issuerName>FIRST MERCURY FINANCIAL CORP</issuerName>
        <issuerTradingSymbol>FMR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001378132</rptOwnerCik>
            <rptOwnerName>Smith Richard H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>29110 INKSTER ROAD, SUITE 100</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SOUTHFIELD</rptOwnerCity>
            <rptOwnerState>MI</rptOwnerState>
            <rptOwnerZipCode>48034</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chairman, President and CEO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-06-02</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>19000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>960428</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1500</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By spouse</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Consists of 21 transactions as follows: a) 2,531 shares @ $14.25; b) 800 shares @ $14.255; c) 300 shares @ $14.2575; d) 2,816 shares @ $14.26; e) 100 shares @ $14.265; f) 2,252 shares @ $14.27; g) 1,002 shares @ $14.28; h) 300 shares @ $14.285; i) 100 shares @ $14.2875; j) 3,290 shares @ $14.29; k) 400 shares @ $14.295; l) 300 shares @ $14.2975; m) 1,100 shares @ $14.30; n) 600 shares @ $14.31; o) 100 shares @ $14.32; p) 100 shares @ $14.33; q) 2,019 shares @ $14.35; r) 460 shares @ $14.36; s) 560 shares @ $14.37; t) 400 shares @ $14.38; u) 100 shares @ $14.390. The weighted-average price of these transactions is $14.29076.  Mr. Smith intends to use substantially all of the proceeds from the sale of stock reported in this Form 4 to offset the payment of the exercise price of certain qualified stock options to acquire shares of First Mercury common stock and to satisfy taxes related to the sale of such shares and exercise of such options.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ John A. Marazza, as Attorney-In-Fact</signatureName>
        <signatureDate>2009-06-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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