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


                                  JULY 25, 2001
                Date of Report (Date of earliest event reported)


                      WHITE MOUNTAINS INSURANCE GROUP, LTD.
             (Exact name of registrant as specified in its charter)



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


               80 SOUTH MAIN STREET, HANOVER, NEW HAMPSHIRE 03755
                    (Address of principal executive offices)


                                 (603) 643-1567
              (Registrant's telephone number, including area code)





ITEM 7.       FINANCIAL STATEMENTS AND EXHIBITS.

     (c)      Exhibits.  The following exhibits are filed herewith:

     Exhibit No.     Description
     -----------     -----------
     99 (a)            Text of press release issued by White Mountains Insurance
                       Group, Ltd., dated July 25, 2001.

ITEM 9.       REGULATION FD DISCLOSURE.

White Mountains Insurance Group, Ltd. (the "Registrant") announced preliminary
June 2001 underwriting results of its recently acquired principal subsidiary,
OneBeacon Insurance Group.

The Registrant's press release dated July 25, 2001 is furnished herewith as
Exhibit 99(a) and is incorporated by reference in its entirety.





                                   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: July 25, 2001                    By:  /s/ J. Brian Palmer
                                             -----------------------------------
                                             J. Brian Palmer
                                             Chief Accounting Officer






                                                                   EXHIBIT 99(a)


[WHITE MOUNTAINS(R) LOGO]

                                             PRESS
                                             RELEASE

                                             CONTACT:  Dennis Beaulieu
                                                       603-640-2206

                             WHITE MOUNTAINS REPORTS
                  PRELIMINARY UNDERWRITING RESULTS OF ONEBEACON

HAMILTON, Bermuda, July 25, 2001 - As a result of White Mountains' acquisition
of OneBeacon Insurance Group (formerly CGU Insurance Group) on June 1, 2001,
White Mountains' second quarter results will include the operations of OneBeacon
for the one-month period ended June 30, 2001.

White Mountains anticipates that OneBeacon's statutory combined ratio for the
month of June will be 126%, on earned premiums of $330 million. June results are
expected to include approximately 10 points attributable to catastrophes -
primarily storms in the mid-west and certain gulf-coast regions (CAT's 44 and
45).

Ray Barrette, Managing Director and CEO of OneBeacon, stated "The June combined
ratio of 126% represents a run rate of approximately 115% plus 7-8% points of
higher than average catastrophe activity, augmented by 3-4% points of additional
conservatism. Our balance sheet is in good shape and the reported combined ratio
is not impacted by prior years' claim developments. The underlying results are
worse than expected and are completely unacceptable. The management team and
staff at all levels are very focused on improving the underwriting results as
quickly as possible. Prices are up, poor and marginal accounts and agents are
being eliminated and claims handling is being strengthened. We are committed to
taking any and all actions necessary to produce acceptable underwriting results
within 18 months."

White Mountains will release its definitive earnings for the 2001 second quarter
by August 14, 2001.


SAFE HARBOR STATEMENT UNDER THE PRIVATE SECURITIES LITIGATION REFORM ACT OF 1995

This press release contains forward looking statements within the meaning of the
"safe harbor" provisions of the United States Private Securities Litigation
Reform Act of 1995. White Mountains cautions that a number of important factors
could cause actual results to differ materially from the plans, objectives,
expectations, estimates and intentions expressed in forward-looking statements
made by White Mountains. These factors include: (i) competitive forces,
including the conduct of other property and casualty insurers and reinsurers,
(ii) changes in domestic or foreign laws or regulations applicable to White
Mountains, its competitors or its clients, (iii) an economic downturn or other
economic conditions (such as a rising interest rate environment) adversely
affecting White Mountains' financial position, and (iv) loss reserves and other
balance sheet items established by White Mountains subsequently proving to have
been inadequate. White Mountains cautions that the foregoing list of important
factors is not exhaustive. In any event, such forward-looking statements made by
White Mountains speak only as of the date on which they are made, and White
Mountains does not undertake any obligation to update or revise such statements
as a result of new information, future events or otherwise.


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CORPORATE HEADQUARTERS: EXECUTIVE OFFICES: - ---------------------- ----------------- WHITE MOUNTAINS INSURANCE GROUP, LTD. WHITE MOUNTAINS INSURANCE GROUP, LTD. 12 CHURCH STREET, SUITE 322 80 SOUTH MAIN STREET, HANOVER, NH 03755 HAMILTON, HM 11 BERMUDA PH: 603-643-1567 - FAX: 603-643-4562 PH: 441-296-6011 - FAX: 441-296-9904 www.whitemountains.com