X0305 4 2012-05-09 0001141719 ALTERRA CAPITAL HOLDINGS Ltd ALTE 0001072504 HARTZBAND MERYL D C/O ALTERRA CAPITAL HOLDINGS LIMITED ALTERRA HOUSE, 2 FRONT STREET HAMILTON, BERMUDA D0 HM 11 BERMUDA 1 0 0 0 Common Shares 2012-05-09 4 A 0 5000 0 A 14000 D Common Shares 8465675 I See Note The Restricted Stock Award was granted pursuant to the Issuer's 2006 Equity Incentive Plan. Consists of 201,131 shares held of record or beneficially by Trident III Professionals Fund, L.P. and 8,264,544 shares held of record or beneficially by Trident III, L.P. Ms. Hartzband is a member and senior principal of Stone Point Capital LLC, a shareholder and a director of Stone Point GP Ltd., which is the general partner of Trident III Professionals Fund, L.P., and a member of the investment committee and owner of one of the five general partners of Trident Capital III, L.P., which is the general partner of Trident III, L.P. Ms. Hartzband disclaims beneficial ownership of the shares held of record or beneficially by Trident III Professionals Fund, L.P. and Trident III, L.P., except as to the extent of any pecuniary interest therein. H. Matthew Crusey, Attorney-in-Fact 2012-05-09