SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* LEE KEWSONG (Last) (First) (Middle) C/O WARBURG PINCUS 466 LEXINGTON AVE (Street) NEW YORK NY 10017 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol ARCH CAPITAL GROUP LTD. [ ACGL ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 04/30/2007
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Shares, $0.01 par value per share(1)(2)	04/30/2007		J(3)		4,922,860	D	(3)	13,959,285	I	See Footnotes
Common Shares, $0.01 par value per share(1)(2)	04/30/2007		A		30,627(3)	A	(3)	63,765	D
Common Shares, $0.01 par value per share(1)(2)								8,749(4)	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Option (right to buy)	$35.54							07/10/2003(5)	07/10/2013	Common Shares, $0.01 par value per share	3,300		3,300	D

Explanation of Responses:

1. The security holders are Warburg Pincus (Bermuda) Private Equity VIII, L.P. ("WP VIII Bermuda"), Warburg Pincus (Bermuda) International Partners, L.P. ("WPIP Bermuda") and Warburg Pincus Netherlands International Partners I, C.V. ("WPIP Netherlands I"). Warburg Pincus (Bermuda) Private Equity Ltd. ("WP VIII Bermuda Ltd.") is the sole general partner of WP VIII Bermuda. Warburg Pincus (Bermuda) International Ltd. ("WPIP Bermuda Ltd.") is the sole general partner of WPIP Bermuda. Warburg Pincus Partners, LLC ("WPP LLC"), a subsidiary of Warburg Pincus & Co. ("WP"), is the sole general partner of WPIP Netherlands I. WP VIII Bermuda, WPIP Bermuda and WPIP Netherlands I are managed by Warburg Pincus LLC ("WP LLC"). WP VIII Bermuda, WPIP Bermuda, WPIP Netherlands I, WP VIII Bermuda Ltd., WPIP Bermuda Ltd., WPP LLC, WP and WP LLC are referred to herein as the "Warburg Pincus Entities."

2. Kewsong Lee, a director of the Issuer, is a general partner of WP, a managing director and member of WP LLC and a beneficial owner of certain shares of capital stock of WP VIII Bermuda Ltd. and WPIP Bermuda Ltd. Other than 8,749 Common Shares of the Issuer which were granted to and are directly owned by Mr. Lee in consideration of his service as a director of the Issuer and 63,765 Common Shares, 30,627 of which were received by Mr. Lee pursuant to the distribution described in footnote (3) below, the Warburg Pincus Entities own 13,959,285 Common Shares. Mr. Lee may be deemed to have an indirect pecuniary interest (within the meaning of Rule 16a?1 under the Securities Exchange Act of 1934) in an indeterminate portion of the shares owned by WP VIII Bermuda, WPIP Bermuda and WPIP Netherlands I. Mr. Lee disclaims beneficial ownership of all shares owned by the Warburg Pincus Entities.

3. On April 30, 2007, WP VIII Bermuda, WPIP Bermuda and WPIP Netherlands I distributed an aggregate of 4,922,860 Common Shares to their limited and general partners. Mr. Lee received 30,627 Common Shares pursuant to the distributions.

4. Represents shares, including restricted shares vesting May 2, 2007, granted to and directly owned by Mr. Lee in connection with his compensation for serving as a director of the Issuer.

5. The Stock Options became exercisable in three equal annual installments commencing on July 10, 2003, and on the first and second anniversary thereafter.

	/s/ Kewsong Lee, Director	05/02/2007
	** Signature of Reporting Person	Date
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