FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * PASQUESI JOHN M   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) __X__ Other (specify below) Vice Chairman (Last) (First) (Middle) C/O OTTER CAPITAL LLC, 755 PAGE MILL ROAD 3. Date of Earliest Transaction (Month/Day/Year) 05/12/2011 (Street) PALO ALTO, CA 94304 4. If Amendment, Date 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 (City) (State) (Zip) 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, $.01 par value per share 05/12/2011   M   900,000 (5) A $ 6.667 936,744 (5) D   Common Shares, $.01 par value per share 05/12/2001   F   172,225 (3) D $ 34.84 764,519 D   Common Shares, $.01 par value per share 05/13/2011   S   446,513 D $ 34.2944 (4) 318,006 D   Common Shares, $.01 par value per share               1,152,804 (5) I By Limited Liability Company (1) Common Shares, $.01 par value per share               62,211 (5) I By Trust (2)

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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 Underlying Securities (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 of Derivative Security: 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)

$ 6.667

05/12/2011

M

900,000

10/23/2002

10/23/2011

Common Shares, $.01 par value per share

900,000

$ 6.667

1,352,838 (5)

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
PASQUESI JOHN M C/O OTTER CAPITAL LLC 755 PAGE MILL ROAD PALO ALTO, CA 94304	X			Vice Chairman

Signatures

/s/ John M. Pasquesi		05/16/2011
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	The security holder is Otter Capital LLC, for which Mr. Pasquesi serves as managing member. All indicated securities are included because of his affiliation with Otter Capital LLC.
(2)	The reporting person contributed his directly owned shares of the company to a revocable trust. The reporting person and his spouse are the trustees.
(3)	On May 12, 2011, the reporting person exercised 900,000 stock options and, under the net settlement provisions of the applicable stock option agreement, 172,225 common shares were withheld in payment of the exercise price.
(4)	Represents a weighted average sales price; the sales prices range from $34.2621 to $34.6863. Upon request, the full sale information regarding the number of shares sold at each price increment will be provided to the Commission or a security holder of the issuer.
(5)	The amount of common shares includes common shares acquired in connection with a 3-for-one share split effectuated by Arch Capital Group Ltd. on May 11, 2011.

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