8-K

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

May 25, 2006
Date of Report (Date of earliest event reported)

WHITE MOUNTAINS INSURANCE GROUP, LTD.

(Exact name of registrant as specified in its charter)

Bermuda
(State or other jurisdiction of
incorporation or organization) 1-8993
(Commission file
number) 94-2708455
(I.R.S. Employer
Identification No.)

Harborside Financial Center, Plaza 5,
Jersey City, New Jersey 07311-1114
(Address of principal executive offices)

(201) 631-3300
 (Registrant’s telephone number, including area code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

o            Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o            Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o            Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o            Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

ITEM 8.01             Other Events.

White Mountains Insurance Group, Ltd. today announced that John J. Byrne has been elected Chairman of its Board of Directors. Mr. Byrne replaces George J. Gillespie, III, who remains a Director. Mr. Gillespie replaced Mr. Byrne as Chairman in November 2003.

ITEM 9.01             Financial Statements and Exhibits

(d)          Exhibits. The following exhibit is furnished herewith:

EXHIBIT INDEX

99.1Press Release of White Mountains Insurance Group, Ltd. dated May 26, 2006.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

	WHITE MOUNTAINS INSURANCE GROUP, LTD.
DATED: May 30, 2006	By:	/s/ J. BRIAN PALMER
		J. Brian Palmer Chief Accounting Officer

EX-99.1

Exhibit 99.1

	PRESS RELEASE
	CONTACT: David Foy                    Tel: (203) 458-5850

JACK BYRNE ELECTED CHAIRMAN
OF WHITE MOUNTAINS

HAMILTON, Bermuda, May 26, 2006 — White Mountains Insurance Group, Ltd. (NYSE:WTM) today announced that Jack Byrne has been elected Chairman of the Board. Mr. Byrne replaces George Gillespie, who remains a Director. Mr. Gillespie replaced Mr. Byrne as Chairman in November 2003.

Steve Fass, President and CEO, said: “The entire Board thanks George for his diligent leadership and enthusiastically welcomes Jack back to the head of the table.”

Jack Byrne added, “George and I have been colleagues and good friends for almost three decades, and I would like to personally thank him for stepping in as Chairman for the past couple of years. I enthusiastically support Steve and the many talented managers at our operating companies and will be their biggest cheerleader going forward. As always, the Board and I will continue to focus our attention on delivering superior returns to our owners.”

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.

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’ 2005 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.