For Shareholders

HAMILTON, Bermuda, April 23 /PRNewswire-FirstCall/ -- White Mountains Re Ltd., the Bermuda-based reinsurance unit of White Mountains Insurance Group, Ltd. (NYSE: WTM), announced today three new promotions on the Folksamerica Reinsurance Company underwriting teams.

Melissa Emmendorfer has been named Chief Underwriting Officer of the Professional Liability, Clash and Workers Comp business. She has over 17 years of experience working in both actuarial and underwriting positions. Prior to joining Folksamerica she was employed by XL Re America.

Joann De Blasis has been named Chief Underwriting Officer of the Accident and Health business. She has over 25 years of experience in underwriting accounting and auditing positions. Prior to joining Folkamerica in 2000, she held senior management positions at Risk Capital Re, Life Re and CIGNA Re.

Anthony A. Sasso has been named Chief Underwriting Officer of the Property business. He began his career at AIG and has over 30 years of underwriting experience including the last 5 years at Folksamerica.

ADDITIONAL INFORMATION

White Mountains Re is a global multi-line reinsurance organization that provides reinsurance for property, casualty, accident & health, agriculture, aviation and space and certain other exposures on a world-wide basis through its subsidiaries, Folksamerica, Sirius International and WMRe (Bermuda). White Mountains Insurance Group, Ltd. 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 White Mountains' web site located at www.whitemountains.com .

Safe Harbor Statement under the Private Securities Litigation Reform Act of 1995

The press release may contain "forward-looking statements" within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. All statements, other than statements of historical facts, included or referenced in this release which address activities, events or developments which we expect or anticipate will or may occur in the future are forward-looking statements. The words "will," "believe," "intend," "expect," "anticipate," "project," "estimate," "predict" and similar expressions are also intended to identify forward-looking statements. These forward-looking statements include, among others, statements with respect to White Mountains':

    -- growth in book value per share or return on equity;

    -- business strategy;

    -- financial and operating targets or plans;

    -- incurred losses and the adequacy of its loss and loss adjustment
       expense reserves and related reinsurance;

    -- projections of revenues, income (or loss), earnings (or loss) per
       share, dividends, market share or other financial forecasts;

    -- expansion and growth of our business and operations; and

    -- future capital expenditures.

These statements are based on certain assumptions and analyses made by White Mountains in light of its experience and perception of historical trends, current conditions and expected future developments, as well as other factors believed to be appropriate in the circumstances. However, whether actual results and developments will conform to our expectations and predictions is subject to a number of risks and uncertainties that could cause actual results to differ materially from expectations, including:

    -- the risks associated with Item 1A of White Mountains' 2007 Annual
       Report on Form 10-K.

    -- claims arising from catastrophic events, such as hurricanes,
       earthquakes, floods or terrorist attacks;

    -- the continued availability of capital and financing;

    -- general economic, market or business conditions;

    -- business opportunities (or lack thereof) that may be presented to it
       and pursued;

    -- competitive forces, including the conduct of other property and
       casualty insurers and reinsurers;

    -- changes in domestic or foreign laws or regulations, or their
       interpretation, applicable to White Mountains, its competitors or its
       clients;

    -- an economic downturn or other economic conditions adversely affecting
       its financial position;

    -- recorded loss reserves subsequently proving to have been inadequate;

    -- other factors, most of which are beyond White Mountains' control.

Consequently, all of the forward-looking statements made in this press release are qualified by these cautionary statements, and there can be no assurance that the actual results or developments anticipated by White Mountains will be realized or, even if substantially realized, that they will have the expected consequences to, or effects on, White Mountains or its business or operations. White Mountains assumes no obligation to update publicly any such forward-looking statements, whether as a result of new information, future events or otherwise.

CONTACT: Christine Repasy

Tel: (860) 408-7312

SOURCE White Mountains Insurance Group, Ltd.
CONTACT: Christine Repasy for White Mountains Insurance Group, Ltd.,
+1-860-408-7312