X0303 4 2011-04-27 0 0000947484 ARCH CAPITAL GROUP LTD. ACGL 0001286007 GRANDISSON MARC WESSEX HOUSE, 45 REID STREET HAMILTON D0 HM 12 BERMUDA 0 1 0 0 Reinsur. Group Chairman & CEO Common Shares, $.01 par value per share 2011-04-27 4 M 0 20000 20 A 151408 D Common Shares, $.01 par value per share 2011-04-27 4 S 0 20000 102.4954 D 131408 D Common Shares, $.01 par value per share 220 I By spouse Stock Option (right to buy) 20 2011-04-27 4 M 0 20000 20 D 2011-10-23 Common Shares, $.01 par value per share 37500 17500 D The stock option became exercisable in three equal annual installments with the first installment becoming exercisable on November 20, 2001 and the second installment on October 23, 2002 and the third installment on October 23, 2003. Represents a weighted average sales price; the sales prices range from $102.4 to $102.68. 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. /s/ Marc Grandisson 2011-04-28