OneBeacon Files $1 Billion Shelf Registration Statement That Also Permits Resale of Class B Shares Held by White Mountains

HAMILTON, Bermuda, July 2 /PRNewswire-FirstCall/ -- OneBeacon Insurance Group, Ltd. announced today that it has filed a shelf registration statement on Form S-3 with the Securities and Exchange Commission (SEC). When declared effective by the SEC, the registration statement will permit the company and certain of its subsidiaries, from time to time, to offer and sell up to $1 billion of common shares, preferred shares, depositary shares, debt securities and other specified securities. The terms of any offering by the company under the registration statement will be established at the time of the offering and will be described in a prospectus supplement. The registration statement is intended to provide the company with additional flexibility to access capital markets for general corporate purposes, subject to market conditions and the company's capital needs. OneBeacon has no intention to offer or sell any of its OneBeacon Class A common shares at this time.

In addition, the registration statement will permit the resale of up to 71,754,738 of OneBeacon Class B common shares owned by White Mountains Insurance Group, Ltd. and its subsidiaries ("White Mountains"). The Class B common shares will automatically convert into OneBeacon Class A common shares upon resale. OneBeacon will not receive any of the proceeds from the sale of any Class B common shares by White Mountains. White Mountains has informed OneBeacon that it has no intention to offer or sell any of its OneBeacon Class A common shares at this time

The registration statement has been filed with the SEC, but has not yet become effective. Any offers, solicitations of offers to buy or sales of these securities will only be made once the shelf registration statement has been declared effective by the SEC, including any prospectuses and prospectus supplements. These securities may not be sold, nor may offers to buy be accepted prior to the time that the registration statement becomes effective. This news release shall not constitute an offer to sell, or the solicitation of an offer to buy, nor shall there be any sale of these securities in any state in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state.

About OneBeacon: OneBeacon Insurance Group's underwriting companies offer a range of specialty and segmented commercial and personal insurance products sold primarily through select independent agents. As one of the oldest property and casualty insurers in the United States, OneBeacon traces its roots to 1831 and the Potomac Fire Insurance Company. Today, OneBeacon's specialty insurance products are available countrywide, and commercial and personal lines are offered in select geographic territories.

OneBeacon's U.S. headquarters is in Canton, Massachusetts. The company is publicly traded on the New York Stock Exchange under the symbol "OB" .

Forward-Looking Statements

This press release may contain "forward-looking statements" that are subject to certain risks, trends and uncertainties that could cause actual results and achievements to differ materially from those expressed in such statements. 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 OneBeacon's:

  --  future financial and capital-raising plans; and
  --  the resale of common shares owned by White Mountains Insurance Group,
      Ltd.

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 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;
  --  other factors, most of which are beyond OneBeacon's control; and
  --  the risks that are described from time to time in OneBeacon's filings
      with the Securities and Exchange Commission, including but not limited
      to OneBeacon's Annual Report on Form 10-K for the fiscal year ended
      December 31, 2007 filed February 29, 2008.

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 OneBeacon will be realized or, even if substantially realized, that they will have the expected consequences to, or effects on, OneBeacon or its business or operations. OneBeacon assumes no obligation to update publicly any such forward-looking statements, whether as a result of new information, future events or otherwise, except as otherwise required by law.