White Mountains to Commence Self-Tender Offer to Purchase up to 300,000 of Its Common Shares

White Mountains Insurance Group, Ltd. WTM announced today that it intends to commence a "modified Dutch auction" self-tender offer to purchase up to 300,000 of its common shares at a purchase price of not greater than $435 or less than $385 per share net to the seller in cash. The tender offer is expected to commence on August 18, 2011 and expire at 12:00 midnight, New York City time, on September 15, 2011, unless extended. White Mountains' common shares closed on the New York Stock Exchange at $403.00 per share on August 16, 2011. A "modified Dutch auction" self-tender offer allows shareholders to indicate how many shares and at what price within the Company's specified range they wish to tender their shares. Based on the number of shares tendered and the prices specified by the tendering shareholders, the Company will determine the lowest price per share within the range that will enable it to purchase 300,000 shares, or such lesser number of shares that are properly tendered and not properly withdrawn. All shares purchased by the Company in the tender offer will be purchased at the same price regardless of whether the shareholder tendered at a lower price. The Company will not purchase shares below a price stipulated by a shareholder, and in some cases, may actually purchase shares at a price above a shareholder's indication under the terms of the tender offer.