Investors and other interested parties can participate either in person or via Webcast. Ray Barrette, Chairman and CEO, and his senior partners will discuss White Mountains' operations and their outlook for the Company. Following a short presentation, Mr. Barrette and his partners will entertain questions from the audience.

For your convenience we have also posted this announcement and the Webcast instructions on the Company's Web site at www.whitemountains.com. The Company's 2007 Annual Report on Form 10-K, Notice of 2008 Annual General Meeting of Members and Proxy Statement, and 2007 Management Report are available online at www.edocumentview.com/wtm for viewing and downloading. These documents are also available on our website. Please contact Jennifer Pitts, our Corporate Secretary, at the Company's office at 80 South Main Street, Hanover, New Hampshire 03755 (Tel: 603-640-2200) for hard copies or further information.

                            ADDITIONAL INFORMATION

White Mountains is a Bermuda-domiciled financial services holding company traded on the New York Stock Exchange and the Bermuda Stock Exchange under the symbol WTM. Additional financial information and other items of interest are available at the Company's web site located at www.whitemountains.com.

    White Mountains Insurance Group, Ltd. Hosts Investor Meeting

                         Date: Tuesday, June 17, 2008
                             Time:  10:00 a.m. ET
                        Place: John Jacob Astor Salon
                  Waldorf-Astoria Hotel, New York City 10022

    To Attend Via Live Webcast:

Please follow these instructions to attend via live Webcast. We recommend connecting 10 minutes prior to the meeting.

    1. Audio Instructions - If you plan to listen by phone, please call this
       number to access the audio portion of the meeting before you logon to
       view the online portion.
    -- U.S. callers dial toll free: 800.901.5213
    -- If outside of the U.S., dial toll number: 617.786.2962
    -- When the operator answers the call, give the Passcode 11141592

    2. Online Instructions - If you plan to view or view and listen to the
       live slide presentation via the Web:
    -- Establish your Internet connection and launch your Internet browser
    -- Type the following URL in the address section and press enter:
       www.whitemountains.com
    -- Click on the "News and Events" link at the top of the home page; select
       "Events"
    -- On the Events page, click on the hyperlink "Click Here for Webcast"
    -- When prompted, enter the following:
       -- Your full name and email address
       -- Your company name
       -- Your title or position (optional)
    -- Select your media option. Click on "Hear this presentation by
       telephone" to just view the slides online (and listen by phone), or
       Windows Media Player or Real Player to access the full Webcast (live
       audio and slides).
    -- You will now be connected to the online portion of the meeting

    3. Replay Access: To view a recorded replay of the meeting
    -- Establish your Internet connection and launch your Internet browser
    -- Type the following URL in the address section and press enter:
       www.whitemoutains.com
    -- Click on the "News and Events" link at the top of the home page; select
       "Events"
    -- On the Events page, click on the hyperlink "Click Here for Webcast"
    -- When prompted, enter the following:
       -- Your full name and email address
       -- Your company name
       -- Your title or position (optional)
    -- You will now be connected to the online portion of the meeting.

    CONTACTS:  David Foy
               Tel:  (203) 458-5850

               Jennifer Pitts
               Tel:  (603) 640-2206