X0304 4 2012-02-14 0 0001171500 PLATINUM UNDERWRITERS HOLDINGS LTD PTP 0001295482 Mitchell H Elizabeth PLATINUM UNDERWRITERS REINSURANCE, INC. 2 WORLD FINANCIAL CENTER, SUITE 2300 NEW YORK NY 10281 0 1 0 0 President & CEO - Platinum US Market Share Units 2012-02-14 4 A 0 12490 0.00 A Common Shares 12490 D The Market Share Units vest on July 14, 2014. Each Market Share Unit represents a contingent right to recieve between 0 and 1-1/2 Common Shares of Platinum Underwriters Holdings, Ltd. based on the difference between the average closing prices of the Common Shares for twenty trading days ending on June 30, 2014 and December 31, 2011. /s/ Christina M. Parker, Attorney-in-Fact 2012-02-15