FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

    Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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Filed By Romeo & Dye's Instant Form 4 Filer
www.section16.net

1. Name and Address of Reporting Person*

Barrette Raymond

2. Issuer Name and Ticker or Trading Symbol
White Mountains Insurance Group, Ltd. (WTM)

6. Relationship of Reporting Person(s)
to Issuer (Check all applicable)
X Director                                       10% Owner
    Officer (give title below)          Other (specify below)

(Last)      (First)     (Middle)

c/o White Mountains Insurance Group, Ltd.
28 Gates Street

3. I.R.S. Identification Number
of Reporting Person,
if an entity (voluntary)

(Street)

White River Junction, VT 05001

(City)     (State)     (Zip)

Table I — Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1. Title of Security
(Instr. 3)

2. Trans-
action
Date
(Month/ Day/
Year)

2A. Deemed
Execution
Date,
if any
(Month/Day/
Year)

3. Trans-
action Code
(Instr. 8)

4. Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 & 5)

5. Amount of
Securities
Beneficially
Owned Follow-
ing Reported Transactions(s)
(Instr. 3 & 4)

6. Owner-
ship Form:
Direct (D)
or Indirect (I)
(Instr. 4)

7. Nature of Indirect
Beneficial Ownership
(Instr. 4)

Code

V

Amount

(A)
or
(D)

Price

Common Shares

12/30/02

12/30/02

F

389⁽¹⁾

D

$323.50⁽²⁾

23,416

D

Common Shares

12/30/02

12/30/02

M

1,000

A

$125.30

24,416

D

Common Shares

12/30/02

12/30/02

G

V

1,500

D

$323.50

22,916

D

Common Shares

426⁽³⁾

I

401K

Common Shares

3,700

I

IRA

Common Shares (restricted)

17,000

D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security

(Instr. 3)

2. Conver-
sion or
Exercise
Price of Derivative Security

3. Trans-
action Date

(Month/
Day/
Year)

4. Trans-
action
Code

(Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D)

(Instr. 3, 4 & 5)

6. Date Exercisable
and Expiration
Date
(Month/Day/
Year)

7. Title and Amount of Underlying Securities
(Instr. 3 & 4)

8. Price of Derivative Security
(Instr. 5)

9. Number of
Derivative
Securities
Beneficially
Owned
Following
Reported Transaction(s)
(Instr. 4)

10. Owner-
ship Form
of Deriv-
ative
Security:
Direct (D)
or Indirect (I)
(Instr. 4)

11. Nature of Indirect Beneficial Ownership
(Instr. 4)

Code

V

(A)

(D)

Date Exer-cisable

Expira-
tion
Date

Title

Amount or Number of
Shares

Shares Options

$125.30

12/30/02

12/30/02

M

1,000

 ⁽⁴⁾

 ⁽⁵⁾

Common Shares

1,000

7665

D

Phantom Shares

1 for 1

Common Shares

7,630⁽⁶⁾

D

Explanation of Responses:

(1) Common Shares delivered to WTM as payment for the December 30, 2002 exercise of options to purchase 1,000 Common Shares of WTM pursuant to that certain Incentive Stock Option Agreement between WTM and the Reporting Person dated February 28, 2000.
(2) Based on WTM's closing market price per Common Share on December 30, 2002
(3) Between January 1, 2002 and November 30, 2002, the Reporting Person acquired 12 shares of WTM's Common Shares under the OneBeacon Insurance Group 401(k) plan. The information in this report is based on a plan statement dated as of November 30, 2002.
(4) Reporting Person was originally granted 9,000 options to purchase Common Shares on February 28, 2000. 900 options become exercisable annually over a ten-year period. Options to purchase 335 Common Shares of WTM were exercised on December 27, 2001.
(5) Unexercised options expire ten years from the date of original grant.
(6) In March 2002, the Reporting Person was credited with 22 Phantom Shares representing dividends on deferred compensation balances payable at a future date in cash. Dividends are reinvested automatically into Phantom Shares on the date the dividends are deemed to be paid.

**Intentional misstatements or omissions of facts constitute Federal Criminal Violations.
See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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