-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 NNgfCpbU9vKAb/IvLYB6t4vk4FoW/0wgvFvF/nMl/+QXkkVg2cDpD0rcDxtxid33
 bd/Ku5is0qudsqtb0McF4A==

<SEC-DOCUMENT>0001179110-04-018665.txt : 20040924
<SEC-HEADER>0001179110-04-018665.hdr.sgml : 20040924
<ACCEPTANCE-DATETIME>20040924110103
ACCESSION NUMBER:		0001179110-04-018665
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040922
FILED AS OF DATE:		20040924
DATE AS OF CHANGE:		20040924

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			EVANS DWIGHT R
		CENTRAL INDEX KEY:			0001227097

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-16209
		FILM NUMBER:		041044070

	MAIL ADDRESS:	
		STREET 1:		C/O ARCH REINSURANCE LTD
		STREET 2:		WESSEXHOUSE 3RD FL 45 PELD ST
		CITY:			HAMILTON
		STATE:			D0
		ZIP:			HA 712

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ARCH CAPITAL GROUP LTD
		CENTRAL INDEX KEY:			0000947484
		STANDARD INDUSTRIAL CLASSIFICATION:	FIRE, MARINE & CASUALTY INSURANCE [6331]
		IRS NUMBER:				061424716
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		20 HORSENECK LANE
		CITY:			GREENWICH
		STATE:			CT
		ZIP:			06830
		BUSINESS PHONE:		2038624300

	MAIL ADDRESS:	
		STREET 1:		20 HORSENECK LANE
		CITY:			GREENWICH
		STATE:			CT
		ZIP:			06830

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	RISK CAPITAL HOLDINGS INC
		DATE OF NAME CHANGE:	19950816

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	RISK CAPITAL RE INC
		DATE OF NAME CHANGE:	19950703
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4 -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-09-22</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000947484</issuerCik>
        <issuerName>ARCH CAPITAL GROUP LTD</issuerName>
        <issuerTradingSymbol>ACGL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001227097</rptOwnerCik>
            <rptOwnerName>EVANS DWIGHT R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ARCH REINSURANCE LTD.</rptOwnerStreet1>
            <rptOwnerStreet2>WESSEX HOUSE, 3RD FLOOR 45 REID STREET</rptOwnerStreet2>
            <rptOwnerCity>HAMILTON</rptOwnerCity>
            <rptOwnerState>D0</rptOwnerState>
            <rptOwnerZipCode>HM 12</rptOwnerZipCode>
            <rptOwnerStateDescription>BERMUDA</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Officer of subsidiary</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares, $.01 par value per share</value>
            </securityTitle>
            <transactionDate>
                <value>2004-09-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>6000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>66773</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>39.00</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2004-09-22</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>40000</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <value>2014-09-22</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Shares, $.01 par value per share</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>40000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>40000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents restricted shares that vest in three equal annual installments on September 22 in each of 2004, 2005 and 2006.</footnote>
        <footnote id="F2">The stock option will become exercisable in three equal annual installments, with the first installment exercisable on September 22, 2004 and the next two installments on September 22, 2005 and September 22, 2006.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Dwight R. Evans</signatureName>
        <signatureDate>2004-09-24</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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