White Mountains (NYSE: WTM) director reports sale of 165 company shares

Rhea-AI Filing Summary

White Mountains Insurance Group Ltd reported that a director disposed of 165 common shares on 12/16/2025, leaving 1,568 shares beneficially owned in direct form.

The transaction is coded "S" in the filing and lists a price of $2,048.51 for the common shares. The report is filed for one reporting person and identifies the filer’s relationship to the company as a director.

Insider Trade Summary

Net Seller: 165 shares

Net Sell 1 txn

Insider Gelston Philip A

Role Director

Sold 165 shs ($338K)

Type	Security	Shares	Price	Value
Sale	Common Shares	165	$2,048.51	$338K

Holdings After Transaction: Common Shares — 1,568 shares (Direct)

FAQ

What insider transaction did White Mountains Insurance Group Ltd (WTM) report?

The report shows a director disposed of 165 common shares of White Mountains Insurance Group Ltd on 12/16/2025, coded as transaction type "S" with a listed price of $2,048.51.

How many White Mountains Insurance Group Ltd (WTM) shares does the reporting person own after the transaction?

Following the reported transaction, the director is shown as beneficially owning 1,568 common shares in direct form.

What is the relationship of the reporting person to White Mountains Insurance Group Ltd (WTM)?

The filing identifies the reporting person’s relationship to White Mountains Insurance Group Ltd as a director.

On what date did the reported White Mountains Insurance Group Ltd (WTM) transaction occur?

The earliest transaction date reported in this filing is 12/16/2025.

Is this White Mountains Insurance Group Ltd (WTM) report filed for one or multiple insiders?

The form indicates it is filed by one reporting person, not by more than one reporting person.

What type of security is involved in this White Mountains Insurance Group Ltd (WTM) insider transaction?

The transaction involves common shares of White Mountains Insurance Group Ltd.

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Form 4 Insider Transactions: What Each Field Means →

Accepted by SEC EDGAR 12/16/2025 - 08:41 PM Learn about SEC filing dates

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
Estimated average burden
hours per response:			0.5

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^*

Gelston Philip A

(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
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
12/16/2025

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	12/16/2025		S		165	D	$2,048.51	1,568	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. 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:

	Wesley C. Bell, by Power of Attorney	12/16/2025
	** 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.
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.