X0304 4 2012-02-26 0 0001163348 Allied World Assurance Co Holdings, AG AWH 0001456268 Gauthier John J ALLIED WORLD ASSURANCE CO. HOLDINGS, AG LINDENSTRASSE 8 BAAR/ZUG V8 CH-6340 SWITZERLAND 0 1 0 0 EVP & CIO, AWAC ServCo. Common Shares 2012-02-26 4 M 0 750 0.00 A 13007 D Common Shares 2012-02-26 4 D 0 375 67.7636 D 12632 D Common Shares 2012-02-26 4 F 0 128 68.16 D 12504 D Restricted Stock Units 2012-02-26 4 M 0 750 D Common Shares 750 6206 D On February 26, 2009, the reporting person was granted 3,000 Restricted Stock Units for no monetary consideration. The Restricted Stock Units convert into (i) 1,500 of the Company's Common Shares and (ii) cash equal to the market value of 1,500 Common Shares (measured at the date of vesting) upon the vesting of such Restricted Stock Units. The Restricted Stock Units vest in four equal annual installments with the first installment vesting on February 26, 2010. The number represents the cash portion of the above award and the price per share was determined using the daily volume-weighted average sales price of the Company's Common Shares for the five consecutive trading days prior to February 26, 2012. Exclusively represents shares withheld by the Company with respect to the payment of withholding tax liability incurred upon the vesting of Restricted Stock Units. /s/ Wesley D. Dupont, by Power Attorney 2012-02-28