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 * Lyons Mark Donald   2. Issuer Name and Ticker or Trading Symbol ARCH CAPITAL GROUP LTD. [ACGL] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) EVP,CFO & Treasurer (Last) (First) (Middle) 45 REID STREET, 5TH FLOOR 3. Date of Earliest Transaction (Month/Day/Year) 09/06/2012 (Street) HAMILTON, D0 HM 12 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, $.0033 par value per share 09/06/2012   A   60,000 A (2) 200,517 (1) D   Common Shares, $.0033 par value per share 09/06/2012   A   15,000 A (3) 215,517 (1) D

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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 Appreciation Right

$ 40.1

09/06/2012

A

60,000

09/06/2017(4)

09/06/2022

Common Shares, $.0033 par value per share

60,000

$ 0

60,000

D

Stock Appreciation Right

$ 40.1

09/06/2012

A

15,000

(5)

09/06/2022

Common Shares, $.0033 par value per share

15,000

$ 0

15,000

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Lyons Mark Donald 45 REID STREET, 5TH FLOOR HAMILTON, D0 HM 12			EVP,CFO & Treasurer

Signatures

/s/ Mark D. Lyons		09/10/2012
**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)	108,750 of such amount will settle in Issuer's common shares upon the termination of the Reporting Person's employment, as specifically provided in the award agreements.
(2)	Subject to the applicable award agreement, represents restricted shares that will vest in full on the fifth anniversary of the grant date.
(3)	Subject to the applicable award agreement, represents restricted shares that will vest in three equal annual installments on September 6th in each of 2013, 2014 and 2015.
(4)	The stock appreciation right will become exercisable on the fifth anniversary of the grant date, subject to the applicable award agreement.
(5)	The stock appreciation right will become exercisable in three equal annual installments, with the first installment becoming exercisable on September 6, 2013 and the next two installments on September 6, 2014 and September 6, 2015, subject to the applicable award agreement.

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