<SEC-DOCUMENT>0000919574-11-002755.txt : 20110420
<SEC-HEADER>0000919574-11-002755.hdr.sgml : 20110420
<ACCEPTANCE-DATETIME>20110420105309
ACCESSION NUMBER:		0000919574-11-002755
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20110418
FILED AS OF DATE:		20110420
DATE AS OF CHANGE:		20110420

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BROWN THOMAS K
		CENTRAL INDEX KEY:			0001378438

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-26719
		FILM NUMBER:		11769792

	MAIL ADDRESS:	
		STREET 1:		C/O SECOND CURVE CAPITAL, LLC
		STREET 2:		237 PARK AVENUE, 9TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10017

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MERCANTILE BANK CORP
		CENTRAL INDEX KEY:			0001042729
		STANDARD INDUSTRIAL CLASSIFICATION:	STATE COMMERCIAL BANKS [6022]
		IRS NUMBER:				383360865
		STATE OF INCORPORATION:			MI
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		310 LEONARD STREET NW
		CITY:			GRAND RAPIDS
		STATE:			MI
		ZIP:			49504
		BUSINESS PHONE:		616 406-3000

	MAIL ADDRESS:	
		STREET 1:		310 LEONARD STREET NW
		CITY:			GRAND RAPIDS
		STATE:			MI
		ZIP:			49504

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SECOND CURVE CAPITAL LLC
		CENTRAL INDEX KEY:			0001136704
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-26719
		FILM NUMBER:		11769793

	BUSINESS ADDRESS:	
		STREET 1:		237 PARK AVENUE
		STREET 2:		9TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10017
		BUSINESS PHONE:		646-563-7635

	MAIL ADDRESS:	
		STREET 1:		237 PARK AVENUE
		STREET 2:		9TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10017
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>p1190078.xml
<DESCRIPTION>21989-0009
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2011-04-18</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001042729</issuerCik>
        <issuerName>MERCANTILE BANK CORP</issuerName>
        <issuerTradingSymbol>MBWM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001136704</rptOwnerCik>
            <rptOwnerName>SECOND CURVE CAPITAL LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>237 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>9TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001378438</rptOwnerCik>
            <rptOwnerName>BROWN THOMAS K</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O SECOND CURVE CAPITAL, LLC</rptOwnerStreet1>
            <rptOwnerStreet2>237 PARK AVENUE, 9TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-04-18</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.25</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>863495</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By advisory clients of Second Curve Capital LLC</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-04-19</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>7500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>9.08</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>855995</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By advisory clients of Second Curve Capital LLC</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">These securities may be deemed to be beneficially owned by Second Curve Capital, LLC and Thomas K. Brown. Second Curve Capital, LLC is the investment manager of Second Curve Partners, LP, Second Curve Partners II, LP, Second Curve Partners International, Ltd., Second Curve Opportunity Fund, LP, Second Curve Opportunity Fund II, LP, Second Curve Opportunity Fund International, Ltd., Second Curve Vision Fund, LP, Second Curve Vision Fund International, Ltd. Thomas K. Brown is the managing member of Second Curve Capital, LLC. Each such Reporting Person disclaims beneficial ownership of the reported securities except to the extent of his or its pecuniary interest therein, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of the securities for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Second Curve Capital, LLC, By: /s/ Thomas K. Brown</signatureName>
        <signatureDate>2011-04-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Thomas K. Brown</signatureName>
        <signatureDate>2011-04-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
