Exhibit 99.L October 29, 1999 White Mountains Insurance Group Ltd. Clarendon House 2 Church Street Hamilton, Bermuda Attn: Mr. K. Thomas Kemp President and Chief Executive Officer Re: Sale of U.S. $50,000,000 of Common Stock of Financial Security...Stock Purchase Agreement • December 9th, 1999 • White Mountains Insurance Group LTD • Fire, marine & casualty insurance • New York
