ARCH CAPITAL GROUP LTD. — Director's Dealing 2011

May 17, 2011

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: ARCH CAPITAL GROUP LTD. (ACGL)
CIK: 0000947484
Period of Report: 2011-05-16

Reporting Person: Hele John C.R. (EVP,CFO & Treasurer)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2011-05-16	Common Shares, $.01 par value per share	M	36000	$18.58	Acquired	149598	Direct
2011-05-16	Common Shares, $.01 par value per share	S	36000	$34.332	Disposed	113598	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2011-05-16	Stock Option (right to buy)	$18.58	M	36000	Disposed	2019-04-01	Common Shares, $.01 par value per share (36000)	Direct

Footnotes

F1: The stock option became exercisable in three equal annual installments, with the first installment becoming exercisable on April 1, 2010 and the next two installments on April 1, 2011 and April 11, 2012, subject to the applicable award agreement.

F2: The amount of common shares includes common shares acquired in connection with a 3-for-1 share split effectuated on May 11, 2011.

F3: Represents a weighted average sale price; the sales prices range from $34.26 to $34.415. Upon request, the full sale information regarding the number of shares sold at each price increment will be provided to the Commission or to a security holder of the issuer.

F4: The shares were sold in order to satisfy state and federal income tax obligations.