X0306 4 2015-02-22 0 0001163348 Allied World Assurance Co Holdings, AG AWH 0001368326 Grossack Marshall J ALLIED WORLD ASSURANCE CO. HOLDINGS, AG GUBELSTRASSE 24, PARK TOWER, 15TH FLOOR ZUG V8 6300 SWITZERLAND 0 1 0 0 EVP, Chief Actuary Common Shares 2015-02-22 4 M 0 1461 0.00 A 213505 D Common Shares 2015-02-22 4 M 0 894 0.00 A 214399 D Common Shares 2015-02-22 4 D 0 1617 40.4481 D 212782 D Common Shares 2015-02-22 4 F 0 342 40.54 D 212440 D Restricted Stock Units 2015-02-22 4 M 0 1461 D Common Shares 1461 12494 D Restricted Stock Units 2015-02-22 4 M 0 894 D Common Shares 894 11600 D On February 22, 2012, the reporting person was granted 5,850 Restricted Stock Units for no monetary consideration. The Restricted Stock Units convert into (i) 1,170 common shares and (ii) cash equal to the market value of 4,680 common shares (measured at the date of vesting) upon the vesting of such Restricted Stock Units. These Restricted Stock Units were previously reported as a grant of 1,950 Restricted Stock Units converting into (i) 390 common shares and (ii) cash equal to the market value of 1,560 common shares. These amounts have been adjusted to reflect the issuer's 3-for-1 stock split paid on May 23, 2014. On February 22, 2011, the reporting person was granted 3,570 Restricted Stock Units for no monetary consideration. The Restricted Stock Units convert into (i) 1,785 common shares and (ii) cash equal to the market value of 1,785 common shares (measured at the date of vesting) upon the vesting of such Restricted Stock Units. These Restricted Stock Units were previously reported as a grant of 1,190 Restricted Stock Units converting into (i) 595 common shares and (ii) cash equal to the market value of 595 common shares. These amounts have been adjusted to reflect the issuer's 3-for-1 stock split paid on May 23, 2014. The fair market value of the cash portion was determined using the daily volume-weighted average sales price of the common shares for the five consecutive trading days prior to February 22, 2015, which was on a Sunday. Exclusively represents shares withheld by the Company with respect to the payment of withholding tax liability incurred upon the vesting of Restricted Stock Units. The Restricted Stock Units vest in four equal installments with the first installment vesting on February 22, 2013. Represents Restricted Stock Units held by the reporting person that vest in whole or in part in cash. The Restricted Stock Units vested in four equal installments with the first installment vesting on February 22, 2012. /s/ Wayne H. Datz, by Power of Attorney 2015-02-24