X0304 4/A 2012-02-22 2012-02-23 0 0001163348 Allied World Assurance Co Holdings, AG AWH 0001444295 de Saint-Aignan Patrick ALLIED WORLD ASSURANCE CO. HOLDINGS, AG LINDENSTRASSE 8 BAAR/ZUG V8 CH-6340 SWITZERLAND 1 0 0 0 Common Shares 2012-02-22 4 A 0 1014 0.00 A 6852 D Common Shares 2012-02-22 4 F 0 212 66.88 D 6640 D Grant of Restricted Stock Units for no monetary consideration. Restricted Stock Units convert into Common Shares upon the vesting of such units on a one-for-one basis. Exclusively represents shares withheld by the Company with respect to the payment of Swiss withholding tax liability incurred upon the vesting of Restricted Stock Units. This Form 4/A is being filed to correct the number of Restricted Stock Units granted to the reporting person on February 22, 2012, which was reported incorrectly due to an administrative error in calculating the market value of the grant. /s/ Wesley D. Dupont, by Power of Attorney 2012-02-27