For Shareholders

HAMILTON, Bermuda, Oct 22, 2010 /PRNewswire via COMTEX/ --

White Mountains Re Ltd., the reinsurance unit of White Mountains Insurance Group, Ltd. (NYSE: WTM), announced today that Stuart Liddell from the London office of Sirius International Insurance Corporation has assumed underwriting responsibility for the global Accident & Health business of the White Mountains Re group. Stuart has 20 successful years of experience underwriting U.S. and international Accident & Health business including the last eight years at Sirius. In his expanded role, Stuart will now also oversee Accident & Health underwriting for White Mountains Reinsurance Company of America.

Allan Waters, CEO of White Mountains Re, commented, "White Mountains and White Mountains Re have been leaders in Accident & Health insurance and reinsurance for decades. We value highly our broker, client, and managing general underwriter relationships, and under Stuart's seasoned leadership will carry on with the level of professional services our partners expect."

U.S. Accident & Health business will continue to be written on the balance sheets of both White Mountains Re America and Sirius. In his new capacity Stuart will work closely with White Mountains Re America CEO Dwight Evans and the U.S. accident and health underwriting team in Danbury, Connecticut.

ADDITIONAL INFORMATION

White Mountains Re Group Ltd. is a Bermuda holding company whose operating companies offer lead reinsurance capacity for property, casualty, accident & health, marine, and aviation exposures. 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 http://www.whitemountains.com/.

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

This press release may contain "forward-looking statements" within the meaning of Section27A of the Securities Act of 1933 and Section21E 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':

• change in adjusted book value per share or return on equity;
• business strategy;
• financial and operating targets or plans;
• incurred loss and loss adjustment expenses 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' 2009 Annual Report on Form 10-K;
• claims arising from catastrophic events, such as hurricanes, earthquakes, floods, fires, terrorist attacks or severe winter weather;
• 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 customers;
• an economic downturn or other economic conditions adversely affecting its financial position;
• recorded loss reserves subsequently proving to have been inadequate;
• actions taken by ratings agencies from time to time, such as financial strength or credit ratings downgrades or placing ratings on negative watch;
• 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 publicly update any such forward-looking statements, whether as a result of new information, future events or otherwise.

SOURCE White Mountains Insurance Group, Ltd.