White Mountains (NYSE: WTM) CEO reports sale of 5,000 shares

Rhea-AI Filing Summary

White Mountains Insurance Group's chief executive officer and director reported an insider sale of 5,000 common shares on 12/19/2025 at a price of $2,050 per share. Following this transaction, the insider directly owned 13,809 common shares and 5,425 restricted common shares, plus 122 common shares held indirectly through a 401(k) account. The 401(k) balance reflects the accumulation of 2 additional common shares based on a plan report dated as of December 20, 2025.

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

OMB APPROVAL

OMB Number:			3235-0287
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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^*

Rountree George Manning

(Last) (First) (Middle)

C/O WHITE MOUNTAINS INSURANCE GROUP, LTD

23 SOUTH MAIN STREET, SUITE 3B

(Street)

HANOVER NH 03755

(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)

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

3. Date of Earliest Transaction (Month/Day/Year)
12/19/2025

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	12/19/2025		S		5,000	D	$2,050	13,809	D
Common Shares (restricted)								5,425	D
Common Shares								122(1)	I	by 401(k)

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. 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 December 20, 2025.

	Wesley C. Bell, by Power of Attorney	12/22/2025
	** 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.
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FAQ

What insider transaction did WHITE MOUNTAINS INSURANCE GROUP LTD (WTM) report?

The chief executive officer and director reported selling 5,000 common shares of WHITE MOUNTAINS INSURANCE GROUP LTD on 12/19/2025, coded as a sale transaction (Code S).

At what price were the WTM shares sold in this insider transaction?

The 5,000 common shares were reported sold at a price of $2,050 per share.

How many WHITE MOUNTAINS (WTM) shares does the insider own after this sale?

After the reported sale, the insider beneficially owned 13,809 common shares directly and 5,425 restricted common shares, plus 122 common shares held indirectly through a 401(k) account.

What roles does the reporting person hold at WHITE MOUNTAINS INSURANCE GROUP LTD (WTM)?

The reporting person is both a director and an officer, serving as the company’s Chief Executive Officer.

Was any indirect ownership of WTM shares disclosed in this filing?

Yes. The filing discloses 122 common shares held indirectly by the reporting person through a 401(k) account, with a note that 2 additional shares accumulated since the last report.

What date was used for the retirement plan information in the WTM insider report?

The information about the 401(k) holdings is based on a plan report dated as of December 20, 2025.