-----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,
 TGmXc/D9+D9/1vK+TjgAVcFJKCy77Qd+UVN/inMW1cx5dCZEPfTE4Fd7CauMjyPf
 ThouBsKCHKiTWa6ENLtyOA==

<SEC-DOCUMENT>0001179110-09-002380.txt : 20090210
<SEC-HEADER>0001179110-09-002380.hdr.sgml : 20090210
<ACCEPTANCE-DATETIME>20090210175935
ACCESSION NUMBER:		0001179110-09-002380
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20090206
FILED AS OF DATE:		20090210
DATE AS OF CHANGE:		20090210

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			THOMPSON MICHAEL L
		CENTRAL INDEX KEY:			0001179839

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-30747
		FILM NUMBER:		09587001

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		3104581531

	MAIL ADDRESS:	
		STREET 1:		120 WILSHIRE BLVD
		CITY:			SANTA MONICA
		STATE:			CA
		ZIP:			90401

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			PACWEST BANCORP
		CENTRAL INDEX KEY:			0001102112
		STANDARD INDUSTRIAL CLASSIFICATION:	NATIONAL COMMERCIAL BANKS [6021]
		IRS NUMBER:				330885320
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		6110 EL TORDO
		CITY:			RANCHO SANTA FE
		STATE:			CA
		ZIP:			92067
		BUSINESS PHONE:		8587563023

	MAIL ADDRESS:	
		STREET 1:		275 NORTH BREA BLVD
		CITY:			BREA
		STATE:			CA
		ZIP:			92821

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	FIRST COMMUNITY BANCORP /CA/
		DATE OF NAME CHANGE:	19991229
</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>2009-02-06</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001102112</issuerCik>
        <issuerName>PACWEST BANCORP</issuerName>
        <issuerTradingSymbol>PACW</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001179839</rptOwnerCik>
            <rptOwnerName>THOMPSON MICHAEL L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>401 WEST &quot;A&quot; STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN DIEGO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92101</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Executive Vice President</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-02-06</value>
            </transactionDate>
            <deemedExecutionDate>
                <value>2009-02-10</value>
            </deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>339</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>18.53</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>24661</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5125.116</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By 401(k) Plan</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Reflects market closing price on February 6, 2009.</footnote>
        <footnote id="F2">Includes 63.422 shares of PACW stock acquired by the reporting person between September 8, 2008 and February 10, 2009 under the PACW 401(k) plan.  The information in this report is based on a plan statement dated as of February 10, 2009.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Michael L. Thompson</signatureName>
        <signatureDate>2009-02-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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