White Mountains Insurance Group Ltd. (WTM) Insider Trading

Last 12 months

Insiders sold $20.8M and bought nothing on the open market.

None of the selling was scheduled in advance under a 10b5-1 plan. Director Reid Tarlton Campbell sold $10.3M on Dec 19, 2025, 32% of their stake, outside a plan. The last open-market buy by an executive or director was in Nov 2023.

Net open-market

−$20.8M

0 buys · 4 sales

Under a 10b5-1 plan

of the value sold

Insiders who bought / sold

0 / 3

executives and directors

Last open-market buy

Nov 2023

Nov 17, 2023

Get an email when WTM's executives or directors buy, or make a large sale outside a plan.

Trades · last 2 years

Date	Insider	Trade	Shares	Price	Value	Of their stake	Filing
Dec 19, 2025	Reid Tarlton Campbell Director	SoldNo plan	5,000	—	—	32%	Form 4
Dec 19, 2025	Reid Tarlton Campbell Director	SoldNo plan	5,000	$2,050.00	$10.3M	32%	Form 4
Dec 19, 2025	George Manning Rountree Chief Executive Officer	SoldNo plan	5,000	$2,050.00	$10.3M	21%	Form 4
Dec 16, 2025	Philip A Gelston Director	SoldNo plan	165	$2,048.51	$338k	9.5%	Form 4

Dec 19, 2025No plan
Reid Tarlton Campbell
Director · sold 5,000
—
32% of stake
Dec 19, 2025No plan
Reid Tarlton Campbell
Director · sold 5,000 at $2,050.00
$10.3M
32% of stake
Dec 19, 2025No plan
George Manning Rountree
Chief Executive Officer · sold 5,000 at $2,050.00
$10.3M
21% of stake
Dec 16, 2025No plan
Philip A Gelston
Director · sold 165 at $2,048.51
$338k
9.5% of stake

How to read this. Insiders sell for many reasons: taxes, diversifying, a house. Open-market buys are rarer and say more. A 10b5-1 plan is a trading schedule set up months in advance, so those sales were not timed on news. Large holders (funds and 10% owners) are listed under Everything but not counted as insiders. If you own or watch WTM, we send a push when an executive buys or makes a large sale outside a plan.

Source: SEC Form 4 filings, filed within two business days of each trade and checked for new ones every hour.

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Spot a number that looks wrong? Check it in WTM's SEC filings or

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Data sourced from SEC EDGAR filings and third-party price providers. Scores, valuations, and metrics are algorithmic estimates. This is not investment advice. See our Terms and Methodology.

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