SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
____________
SCHEDULE 13D
Under the securities exchange act of 1934
(Amendment No. 6)*
____________
ARCH CAPITAL GROUP LTD.
(Name of Issuer)
COMMON SHARES, PAR VALUE $0.01 PER SHARE
(Title of Class of Securities)
011576290
(CUSIP Number)
____________
SCOTT A. ARENARE, ESQ.
WARBURG PINCUS LLC
466 LEXINGTON AVENUE
NEW YORK, NY 10017
(212) 878-0600
(Name, Address and Telephone Number of Person
Authorized to Receive Notices of Communication)
____________
Copy to:
ANDREW R. BROWNSTEIN, ESQ.
WACHTELL, LIPTON, ROSEN & KATZ
51 WEST 52ND STREET
NEW YORK, NY 10019
(212) 403-1000
April 28, 2008
(Date of Event Which Requires Filing of This Statement)
If the filing person has previously filed a statement on Schedule 13G to report the acquisition which is the subject of this Schedule 13D, and is filing this schedule because of
Rule 13d-1(b)(3) or (4), check the following box.  ¨
Check the following box if a fee is being paid with this statement  ¨  (A fee is not required only if the reporting person: (1) has a previous statement on file reporting beneficial
ownership of more than five percent of the class of securities described in Item 1; and (2) has filed no amendment subsequent thereto reporting beneficial ownership of five percent or
less of such class.) (See Rule 13d-7.)
Note:       Six copies of this statement, including all exhibits, should be filed with the Commission. See Rule 13d-1(a) for other parties   to whom copies are to be sent.
(Continued on the following pages)
(Page 1 of 12 pages)
_________________________
*		The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with
respect to the subject class of securities, and for any subsequent amendment containing information which would
alter disclosures provided in a prior cover page.
		The information required on the remainder of this cover page shall not be deemed to be “filed” for the pur-
pose of Section 18 of the Securities Exchange Act of 1934 or otherwise subject to the liabilities of that section of the
Act but shall be subject to all other provisions of the Act (however, see the Notes)

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CUSIP No. 011576290								13D		(Page 2 of 12)
1		NAME OF REPORTING PERSONS
		Warburg Pincus (Bermuda) Private Equity VIII, L.P.
		S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS
		13-4194502
2		CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP								(a) ¨
										(b) x
3		SEC USE ONLY
4		SOURCE OF FUNDS
		WC
5		CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
		TO ITEM 2(d) or 2(e)								¨
6		CITIZENSHIP OR PLACE OF ORGANIZATION
		Bermuda
NUMBER OF				7		SOLE VOTING POWER
		SHARES				3,738,983
BENEFICIALLY				8		SHARED VOTING POWER
OWNED BY						0
		EACH		9		SOLE DISPOSITIVE POWER
REPORTING						3,738,983
PERSON WITH				10		SHARED DISPOSITIVE POWER
						0
11		AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
		3,738,983
12		CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
		CERTAIN SHARES								¨
13		PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
		5.8%
14		TYPE OF REPORTING PERSON
		PN

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CUSIP No. 011576290								13D		(Page 3 of 12)
1		NAME OF REPORTING PERSONS
		Warburg Pincus (Bermuda) International Partners, L.P.
		S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS
		13-4194501
2		CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP								(a)¨
										(b)x
3		SEC USE ONLY
4		SOURCE OF FUNDS
		WC
5		CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
		TO ITEM 2(d) or 2(e)								¨
6		CITIZENSHIP OR PLACE OF ORGANIZATION
		Bermuda
NUMBER OF				7		SOLE VOTING POWER
		SHARES				3,593,045
BENEFICIALLY				8		SHARED VOTING POWER
OWNED BY						0
		EACH		9		SOLE DISPOSITIVE POWER
REPORTING						3,593,045
PERSON WITH				10		SHARED DISPOSITIVE POWER
						0
11		AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
		3,593,045
12		CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
		CERTAIN SHARES								¨
13		PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
		5.5%
14		TYPE OF REPORTING PERSON
		PN

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CUSIP No. 011576290								13D		(Page 4 of 12)
1		NAME OF REPORTING PERSONS
		Warburg Pincus Netherlands International Partners I, C.V.
		S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS
		13-4133834
2		CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP								(a)  ¨
										(b)  x
3		SEC USE ONLY
4		SOURCE OF FUNDS
		WC
5		CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
		TO ITEM 2(d) or 2(e)								¨
6		CITIZENSHIP OR PLACE OF ORGANIZATION
		The Netherlands
NUMBER OF				7		SOLE VOTING POWER
		SHARES				149,708
BENEFICIALLY				8		SHARED VOTING POWER
OWNED BY						0
		EACH		9		SOLE DISPOSITIVE POWER
REPORTING						149,708
PERSON WITH				10		SHARED DISPOSITIVE POWER
						0
11		AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
		149,708
12		CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
		CERTAIN SHARES								¨
13		PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
		Less than 1%
14		TYPE OF REPORTING PERSON
		PN

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CUSIP No. 011576290								13D		(Page 5 of 12)
1		NAME OF REPORTING PERSONS
		Warburg Pincus (Bermuda) Private Equity Ltd.
		S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS
		01-0569187
2		CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP								(a) ¨
										(b) x
3		SEC USE ONLY
4		SOURCE OF FUNDS
		WC
5		CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
		TO ITEM 2(d) or 2(e)								¨
6		CITIZENSHIP OR PLACE OF ORGANIZATION
		Bermuda
NUMBER OF				7		SOLE VOTING POWER
		SHARES				3,738,983
BENEFICIALLY				8		SHARED VOTING POWER
OWNED BY						0
		EACH		9		SOLE DISPOSITIVE POWER
REPORTING						3,738,983
PERSON WITH				10		SHARED DISPOSITIVE POWER
						0
11		AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
		3,738,983
12		CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
		CERTAIN SHARES								¨
13		PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
		5.8%
14		TYPE OF REPORTING PERSON
		CO

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CUSIP No. 011576290								13D		(Page 6 of 12)
1		NAME OF REPORTING PERSONS
		Warburg Pincus (Bermuda) International Ltd.
		S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS
		13-4194502
2		CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP								(a) ¨
										(b) x
3		SEC USE ONLY
4		SOURCE OF FUNDS
		WC
5		CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
		TO ITEM 2(d) or 2(e)								¨
6		CITIZENSHIP OR PLACE OF ORGANIZATION
		Bermuda
NUMBER OF				7		SOLE VOTING POWER
		SHARES				3,593,045
BENEFICIALLY				8		SHARED VOTING POWER
OWNED BY						0
		EACH		9		SOLE DISPOSITIVE POWER
REPORTING						3,593,045
PERSON WITH				10		SHARED DISPOSITIVE POWER
						0
11		AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
		3,593,045
12		CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
		CERTAIN SHARES								¨
13		PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
		5.5%
14		TYPE OF REPORTING PERSON
		CO

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CUSIP No. 011576290								13D		(Page 7 of 12)
1		NAME OF REPORTING PERSONS
		Warburg Pincus & Co.
		S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS
		13-6358475
2		CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP								(a)  ¨
										(b)  x
3		SEC USE ONLY
4		SOURCE OF FUNDS
		WC
5		CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
		TO ITEM 2(d) or 2(e)								¨
6		CITIZENSHIP OR PLACE OF ORGANIZATION
		New York
NUMBER OF				7		SOLE VOTING POWER
		SHARES				149,708
BENEFICIALLY				8		SHARED VOTING POWER
OWNED BY						0
		EACH		9		SOLE DISPOSITIVE POWER
REPORTING						149,708
PERSON WITH				10		SHARED DISPOSITIVE POWER
						0
11		AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
		149,708
12		CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
		CERTAIN SHARES								¨
13		PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
		Less than 1%
14		TYPE OF REPORTING PERSON
		CO

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CUSIP No. 011576290								13D		(Page 8 of 12)
1		NAME OF REPORTING PERSONS
		Warburg Pincus Partners, LLC
		S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS
		13-4069737
2		CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP								(a)  ¨
										(b)  x
3		SEC USE ONLY
4		SOURCE OF FUNDS
		WC
5		CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
		TO ITEM 2(d) or 2(e)								¨
6		CITIZENSHIP OR PLACE OF ORGANIZATION
		New York
NUMBER OF				7		SOLE VOTING POWER
		SHARES				149,708
BENEFICIALLY				8		SHARED VOTING POWER
OWNED BY						0
		EACH		9		SOLE DISPOSITIVE POWER
REPORTING						149,708
PERSON WITH				10		SHARED DISPOSITIVE POWER
						0
11		AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
		149,708
12		CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
		CERTAIN SHARES								¨
13		PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
		Less than 1%
14		TYPE OF REPORTING PERSON
		CO

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CUSIP No. 011576290								13D		(Page 9 of 12)
1		NAME OF REPORTING PERSONS
		Warburg Pincus LLC
		S.S. OR I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS
		13-3536050
2		CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP								(a)  ¨
										(b)  x
3		SEC USE ONLY
4		SOURCE OF FUNDS
		WC
5		CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
		TO ITEM 2(d) or 2(e)								¨
6		CITIZENSHIP OR PLACE OF ORGANIZATION
		New York
NUMBER OF				7		SOLE VOTING POWER
		SHARES				7,481,736
BENEFICIALLY				8		SHARED VOTING POWER
OWNED BY						0
		EACH		9		SOLE DISPOSITIVE POWER
REPORTING						7,481,736
PERSON WITH				10		SHARED DISPOSITIVE POWER
						0
11		AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
		7,481,736
12		CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES
		CERTAIN SHARES								¨
13		PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
		11.5%
14		TYPE OF REPORTING PERSON
		OO

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CUSIP No.  011576290				13D		(Page 10 of 12)

Reference is made to the Statement on Schedule 13D filed on November 20, 2001, as amended by
Amendment No. 1 thereto filed September 20, 2002, Amendment No. 2 thereto filed December 18, 2002,
Amendment No. 3 thereto filed May 5, 2006, Amendment No. 4 thereto filed May 2, 2007 and Amendment No.
5 thereto filed June 18, 2007 (as so amended, the “Schedule 13D”), on behalf of Warburg Pincus (Bermuda)
Private Equity VIII, L.P., a limited partnership organized under the laws of Bermuda (“WP VIII Bermuda”),
Warburg Pincus (Bermuda) International Partners, L.P., a limited partnership organized under the laws of Ber-
muda (“WPIP Bermuda”), Warburg Pincus Netherlands International Partners I, C.V., a limited partnership or-
ganized under the laws of The Netherlands (“WPIP Netherlands I” and together with WP VIII Bermuda, WPIP
Bermuda, the “Investors”), Warburg Pincus (Bermuda) Private Equity Ltd., a company organized under the
laws of Bermuda (“WP VIII Bermuda Ltd.”), Warburg Pincus (Bermuda) International Ltd., a company organ-
ized under the laws of Bermuda (“WPIP Bermuda Ltd.”), Warburg Pincus & Co., a New York general partner-
ship (“WP”), Warburg Pincus LLC, a New York limited liability company (“WP LLC”), and Warburg Pincus
Partners, LLC, a New York limited liability company (“WPP LLC”). Charles R. Kaye and Joseph P. Landy are
each a Managing General Partner of WP and a Managing Member and a Co-President of WP LLC and may be
deemed to control the Investors, WP VIII Bermuda Ltd., WPIP Bermuda Ltd., WP, WP LLC and WPP LLC.
The Investors, together with WP VIII Bermuda Ltd., WPIP Bermuda Ltd., WP, WP LLC and WPP LLC, are
referred to herein as the “Warburg Pincus Reporting Persons.” All capitalized terms used without definition in this
Amendment No. 6 to Schedule 13D shall have the meanings set forth in the Schedule 13D.
This Amendment No. 6 to Schedule 13D amends the Schedule 13D as follows.
ITEM 5.		Interest in Securities of the Issuer.
---------------------------------------------------------------
Item 5 of the Schedule 13D is hereby amended and supplemented by adding the following:
On April 28, 2008, the Warburg Pincus Reporting Persons distributed an aggregate of 3,492,586 Common
Shares of the Company to their limited and general partners.
As of April 28, 2008, the Investors collectively beneficially owned an aggregate of 7,481,736 Common
Shares, which represent approximately 11.5% of the outstanding Common Shares based on 64,875,951 Com-
mon Shares outstanding as of March 24, 2008, as reported in the Company’s proxy statement filed on April 1,
2008. By reason of its relationship with the Investors under Rule 13d-3 of the Exchange Act, the Warburg Pin-
cus Reporting Persons may be deemed to beneficially own all of the Common Shares that are beneficially
owned by the Investors.
Each Investor exercises voting power and dispositive power over its holdings of such shares through its re-
spective general partner, which, in turn, acts through its respective general partner.

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CUSIP No.  011576290				13D		(Page 11 of 12)
				SIGNATURES

     After reasonable inquiry and to the best of our knowledge and belief, the undersigned certify that the information set forth in this statement is true, complete and correct.

Dated April 29, 2008

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CUSIP No.  011576290		13D		(Page 12 of 12)

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