White Mountains (NYSE: WTM) president awarded 775 restricted shares

Rhea-AI Filing Summary

Harrison Giles E reported acquisition or exercise transactions in this Form 4 filing.

WHITE MOUNTAINS INSURANCE GROUP LTD President Giles E. Harrison reported an equity grant in the form of 775 restricted common shares on February 25, 2026. The award carried a grant price of $0.00 per share and is scheduled to vest on January 1, 2029.

After this grant, his directly held common shares increased to 2,675. In addition, he indirectly holds 2 common shares through a company retirement plan account, reflecting accumulation in that plan report dated as of February 25, 2026.

SEC Form 4

FORM 4

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

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Harrison Giles E

(Last) (First) (Middle)

C/O WHITE MOUNTAINS INSURANCE GROUP, LTD

23 SOUTH MAIN STREET, SUITE 3B

(Street)

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
WHITE MOUNTAINS INSURANCE GROUP LTD [ WTM ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	President

3. Date of Earliest Transaction (Month/Day/Year)
02/25/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership 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 (restricted)	02/25/2026		A		775(1)	A	$0	2,675	D
Common Shares								2	I	by White Mountains Retirement Plan(2)

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. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. On February 25, 2026, the Reporting Person received a restricted share award of 775 Common Shares, which vests on January 1, 2029.

2. Reflects accumulation of 2 Common Shares in Reporting Person's Company Retirement account since his last filed report. The information in this report is based on a plan report dated as of February 25, 2026.

	Wesley C. Bell, by Power of Attorney	02/25/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transaction did WTM President Giles E. Harrison report on this Form 4?

Giles E. Harrison reported receiving a grant of 775 restricted common shares of WHITE MOUNTAINS INSURANCE GROUP LTD on February 25, 2026. The award was granted at $0.00 per share as equity compensation, rather than through an open-market purchase.

When do Giles E. Harrison’s newly granted WTM restricted shares vest?

The 775 restricted common shares granted to Giles E. Harrison are scheduled to vest on January 1, 2029. Vesting ties the award to continued service or other conditions, meaning the shares generally become fully owned by him only on that future date.

How many WHITE MOUNTAINS common shares does Giles E. Harrison own after this grant?

Following the February 25, 2026 restricted share award, Giles E. Harrison directly owns 2,675 common shares of WHITE MOUNTAINS INSURANCE GROUP LTD. He also indirectly holds 2 additional common shares through a company retirement plan account, according to the plan report used for this filing.

Were Giles E. Harrison’s new WTM shares bought on the open market?

No, the 775 WHITE MOUNTAINS common shares were received as a restricted share award with a grant price of $0.00 per share. This reflects equity compensation from the company, not an open-market purchase of stock by the executive.

What does the Form 4 say about Harrison’s indirect WTM share holdings?

The Form 4 notes that 2 common shares are held indirectly in Giles E. Harrison’s company retirement account. This reflects accumulation in that account since his last report, based on a plan statement dated as of February 25, 2026.