White Mountains Insurance Group, Ltd. (WTM)
WTM moved a median of 0.00% 30 minutes after news, and 0.00% by the close. How WTM actually reacts to news — the realized, point-in-time move the market made, measured across 212 labeled events over the last three years with zero look-ahead.
WTM’s median reaction, across the day.
| Horizon | Median | % positive | Events |
|---|---|---|---|
| 5-min | 0.00% | 31% | 207 |
| 30-min | 0.00% | 34% | 212 |
| 60-min | 0.00% | 36% | 212 |
| to close | 0.00% | 42% | 210 |
| Middle 50% of WTM reactions | -0.00% to +0.05% |
|---|---|
| Median reaction (30-min) | 0.00% |
| Measured reactions | 212 |
Half of all White Mountains Insurance Group, Ltd. news events land between -0.00% and +0.05% at 30 minutes.
Reaction stats as of 2026-09-21. Newest measured event . Reaction = percent move vs. the price at the news timestamp.
Email me when WTM moves on news.
One email per qualifying move — the headline, the measured reaction, and how it compares to WTM's baseline. Nothing else.
Recent WTM events, each with its measured reaction.
| Date | Headline | Event | Source | 5-min | To close |
|---|---|---|---|---|---|
| Form 8-K WHITE MOUNTAINS INSURANC For: Aug 26 | SEC filing · Form 8-K | SEC EDGAR | -0.35% | -0.47% | |
| Stephen Klar Elected to the White Mountains Board | Press release | PR Newswire | -0.35% | -0.47% | |
| Form N-PX WHITE MOUNTAINS INSURANC For: Jun 30 | SEC filing · Form N-PX | SEC EDGAR | -0.35% | -0.47% | |
| Form 13F-HR WHITE MOUNTAINS INSURANC For: Jun 30 | SEC filing · Form 13F-HR | SEC EDGAR | +0.39% | +1.25% | |
| Form 10-Q WHITE MOUNTAINS INSURANC For: Jun 30 | SEC filing · Form 10-Q | SEC EDGAR | +0.36% | +0.16% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: Aug 06 | SEC filing · Form 8-K | SEC EDGAR | +0.36% | +0.16% | |
| WHITE MOUNTAINS REPORTS SECOND QUARTER RESULTS | Press release | PR Newswire | +0.36% | +0.16% | |
| Form 11-K WHITE MOUNTAINS INSURANC For: Dec 31 | SEC filing · Form 11-K | SEC EDGAR | -0.74% | -0.56% | |
| Australian Financial Planning Group Secures Minority Investment from Kudu Investment Management to Fund Growth Initiatives | Press release | PR Newswire | +0.18% | -0.10% | |
| Australia's Drummond Capital Partners Secures Investment from Kudu Investment Management | Press release | PR Newswire | +0.11% | +0.41% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: Jun 05 | SEC filing · Form 8-K | SEC EDGAR | +1.05% | +2.40% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: May 21 | SEC filing · Form 8-K | SEC EDGAR | +1.04% | +0.47% | |
| White Mountains to Hold 2026 Annual Investor Information Meeting on June 5, 2026 | Press release | PR Newswire | +0.41% | -0.03% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: May 14 | SEC filing · Form 8-K | SEC EDGAR | -0.03% | +0.83% | |
| Form 13F-HR WHITE MOUNTAINS INSURANC For: Mar 31 | SEC filing · Form 13F-HR | SEC EDGAR | +1.08% | +0.70% | |
| Form 10-Q WHITE MOUNTAINS INSURANC For: Mar 31 | SEC filing · Form 10-Q | SEC EDGAR | +0.01% | -3.31% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: May 06 | SEC filing · Form 8-K | SEC EDGAR | +0.01% | -3.31% | |
| WHITE MOUNTAINS REPORTS FIRST QUARTER RESULTS | Press release | PR Newswire | +0.01% | -3.31% | |
| WHITE MOUNTAINS PARTNERS ANNOUNCES ACQUISITION OF HAWKEYE ELECTRIC BY ENTERPRISE SOLUTIONS | Press release | PR Newswire | +1.72% | +0.63% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: Apr 01 | SEC filing · Form 8-K | SEC EDGAR | -0.26% | -0.30% | |
| Form ARS WHITE MOUNTAINS INSURANC For: Dec 31 | SEC filing · Form ARS | SEC EDGAR | -0.26% | -0.30% | |
| Form DEF 14A WHITE MOUNTAINS INSURANC For: May 21 | SEC filing · Form DEF | SEC EDGAR | -0.26% | -0.30% | |
| WHITE MOUNTAINS PARTNERS ANNOUNCES ACQUISITION OF BASESIX | Press release | PR Newswire | -0.26% | -0.30% | |
| Form 10-K WHITE MOUNTAINS INSURANC For: Dec 31 | SEC filing · Form 10-K | SEC EDGAR | +0.41% | +0.14% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: Feb 26 | SEC filing · Form 8-K | SEC EDGAR | +0.41% | +0.14% | |
| Form 13F-HR WHITE MOUNTAINS INSURANC For: Dec 31 | SEC filing · Form 13F-HR | SEC EDGAR | -0.83% | +0.44% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: Feb 06 | SEC filing · Form 8-K | SEC EDGAR | +2.03% | +1.58% | |
| WHITE MOUNTAINS REPORTS FOURTH QUARTER RESULTS | Press release | PR Newswire | +2.03% | +1.58% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: Jan 07 | SEC filing · Form 8-K | SEC EDGAR | +0.30% | +0.94% | |
| White Mountains Announces Final Results of Its Tender Offer | Press release | PR Newswire | -0.19% | -0.14% | |
| White Mountains Announces Preliminary Results of Its Tender Offer | Press release | PR Newswire | +0.73% | +2.81% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: Dec 05 | SEC filing · Form 8-K | SEC EDGAR | +0.42% | -0.96% | |
| White Mountains Completes Sale of Bamboo | Press release | PR Newswire | +0.42% | -0.96% | |
| White Mountains to Commence Self-Tender Offer to Purchase Up To $300 Million In Value of Its Common Shares | Press release | PR Newswire | +0.48% | +1.67% | |
| Form 13F-HR WHITE MOUNTAINS INSURANC For: Sep 30 | SEC filing · Form 13F-HR | SEC EDGAR | +0.45% | — | |
| Form 10-Q WHITE MOUNTAINS INSURANC For: Sep 30 | SEC filing · Form 10-Q | SEC EDGAR | +0.89% | -0.48% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: Nov 06 | SEC filing · Form 8-K | SEC EDGAR | +0.89% | -0.48% | |
| WHITE MOUNTAINS REPORTS THIRD QUARTER RESULTS | Press release | PR Newswire | +0.89% | -0.48% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: Oct 02 | SEC filing · Form 8-K | SEC EDGAR | +0.00% | +1.99% | |
| White Mountains to Sell Bamboo to CVC | Press release | PR Newswire | +3.23% | +3.17% | |
| Bamboo Pioneers MGA-Sponsored Sidecar Expansion with Accredited to Launch E&S Signature in Texas | Press release | PR Newswire | +0.00% | +0.47% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: Sep 02 | SEC filing · Form 8-K | SEC EDGAR | +0.19% | +0.19% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: Sep 02 | SEC filing · Form 8-K | SEC EDGAR | -0.61% | +1.19% | |
| LIAM CAFFREY TO BECOME CEO OF WHITE MOUNTAINS IN 2026 | Press release | PR Newswire | -0.61% | +1.19% | |
| Form N-PX WHITE MOUNTAINS INSURANC For: Jun 30 | SEC filing · Form N-PX | SEC EDGAR | -0.26% | -0.52% | |
| Form 13F-HR WHITE MOUNTAINS INSURANC For: Jun 30 | SEC filing · Form 13F-HR | SEC EDGAR | -0.10% | — | |
| Form 10-Q WHITE MOUNTAINS INSURANC For: Jun 30 | SEC filing · Form 10-Q | SEC EDGAR | +0.37% | -1.12% | |
| Form 8-K WHITE MOUNTAINS INSURANC For: Aug 07 | SEC filing · Form 8-K | SEC EDGAR | +0.37% | -1.12% | |
| WHITE MOUNTAINS REPORTS SECOND QUARTER RESULTS | Press release | PR Newswire | +0.37% | -1.12% | |
| BroadStreet Partners Completes Strategic Investment | Press release | Business Wire | +0.00% | +0.00% |
Each reaction is the move the market actually made, measured from the news timestamp. Headlines link through to the WTM section they belong to.
Where else WTM is measured.
WTM earnings → · Analyst actions → · SEC filings →
Other Financial Services names, measured the same way
| Ticker | Events | Median 30-min | % positive |
|---|---|---|---|
| PEOPLES FINCL CORP MISS (PFBX) | 212 | 0.00% | 12% |
| Sandy Spring Bancorp, Inc. (SASR) | 212 | -0.12% | 41% |
| Cushing NextGen Infrastructure Income Fund Common Shares of Beneficial Interest (SZC) | 211 | 0.00% | 46% |
| Bank OZK (OZK) | 210 | -0.07% | 45% |
Same sector, same measurement: percent move vs. the price at the news timestamp, read at 30 minutes. Sample sizes differ, so the medians are comparable but the confidence behind them is not.
All Financial Services names, measured the same way →
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How the numbers are made.
How is White Mountains Insurance Group, Ltd.'s median reaction calculated?
Every labeled WTM news event is measured from its own timestamp: the last trade before the news is the base price, and the move is read at fixed horizons — 30 minutes of trading, then the close. The median across 212 events is what this page reports. Point-in-time, zero look-ahead: no event borrows information from a later one.
What counts as a positive reaction?
Any event whose price move is above zero at the horizon, relative to the last trade before the news timestamp. 34% of WTM's measured events are up at 30 minutes; the rest close the window flat or negative.
How often is this page updated?
The news table refreshes automatically as new events are labeled and priced. The reaction medians are re-pulled in batches from the dataset — the figures here are as of 2026-09-21.
Does WTM's past reaction predict its next one?
No. These are realized facts about past events, not forecasts. They describe a distribution — they say nothing certain about any future move.