White Mountains Announcements; Jack Byrne Elected Chairman, Results of Shareholder Vote and Declares Second Quarter Dividend.

Jack Byrne Elected Chairman of White Mountains 

Hamilton, Bermuda: May 26, 2006 -- White Mountains Insurance Group, Ltd. (NYSE: WTM) today announced that Jack Byrne has been elected Chairman of the Board. Mr. Byrne replaces George Gillespie, who remains a Director. Mr. Gillespie replaced Mr. Byrne as Chairman in November 2003.

Steve Fass, President and CEO, said: "The entire Board thanks George for his diligent leadership and enthusiastically welcomes Jack back to the head of the table."

Jack Byrne added, "George and I have been colleagues and good friends for almost three decades, and I would like to personally thank him for stepping in as Chairman for the past couple of years. I enthusiastically support Steve and the many talented managers at our operating companies and will be their biggest cheerleader going forward. As always, the Board and I will continue to focus our attention on delivering superior returns to our owners." 

White Mountains Reports Results of Shareholder Vote

Hamilton, Bermuda: May 26, 2006 -- White Mountains Insurance Group, Ltd. (NYSE: WTM) Annual General Meeting of Members was held on May 25, 2006.

Members approved proposals submitted to them by a majority of the shares voted as follows:

    -- Election of Class III director with terms ending in 2009:

         -- Howard L. Clark                                             80%

         -- Robert P. Cochran                                         99%

         -- A. Michael Frinquelli                                       99%

         -- Allan L. Waters                                                82%

    -- Election of directors of certain of the Company's subsidiaries 99%

    -- Appointment of PricewaterhouseCoopers as independent

       registered public accounting firm                        99%

President and Chief Executive Officer Steve Fass said, "We are gratified with the support our owners have shown us by their vote. We will continue to strive to achieve results worthy of their confidence and continued support."

White Mountains Declares Second Quarter Dividend 

Hamilton, Bermuda: May 26, 2006 -- At its regular meeting held on May 25, 2006, the Board of Directors of White Mountains Insurance Group, Ltd. declared a $2.00 per share quarterly dividend, payable in cash on June 28, 2006, to holders of record of Common Shares as of the close of business on June 19, 2006.