Follow-The-Filings

WHITE MOUNTAINS INSURANCE GROUP LTD

Hanover, NH 3 13Fs · since 2025 Q3

  • $313M
  • 2 Positions
  • 2026 Q1
  • +19.5% QoQ
  • Top 5 100.0%

Portfolio

2026 Q1 · filed 5/12/2026 · 2 long

top 5 100.0% · top 10 100.0%

  1. Mediaalpha 53.0%
  2. SPY - Spdr S&P 47.0%

AUM over time

2026 Q1 $313M +19.5% QoQ
2025 Q3 · $203M 2025 Q3 · $203M
Q3'25
2025 Q4 · $262M · +29.1% QoQ 2025 Q4 · $262M · +29.1% QoQ
Q4'25
2026 Q1 · $313M · +19.5% QoQ 2026 Q1 · $313M · +19.5% QoQ
Q1'26

Latest book

2026 Q1 2025 Q4 · filed 12 May

Download CSV All activity → Full filing →
Mediaalpha 52.99% Hold $166M 17,856,614 $9.30 $166M — —
SPY - Spdr S&P 47.01% Add +403.3% $147M 226,500 $650.34 $147M +181,500 +$117M

* Reported price is value ÷ shares from the 13F as of period end — not a live market quote. Weight % is each long-equity position ÷ full 13F AUM, so rows may not sum to 100% when the filing includes options or other non-equity (excluded from this table). Share change and $ change are vs 2025 Q4. Click column headers to sort · click New / Exit / Add / Reduce to promote that move type to the top. Among managers we track.

filings history

3 periods · normalized AUM · click period for holdings

Newest filings
Period Holdings AUM QoQ Form Filed Filing ID
2026 Q1 2 $313M +19.5% 13F-HR 5/12/2026 000110465926059351
2025 Q4 2 $262M +29.1% 13F-HR 2/12/2026 000110465926014432
2025 Q3 1 $203M — 13F-HR 11/13/2025 000110465925110906

About

WHITE MOUNTAINS INSURANCE GROUP LTD

3 processed 13Fs · since 2025 Q3

SEC filing name
WHITE MOUNTAINS INSURANCE GROUP LTD
Location
Hanover, NH
All SEC filings
View on sec.gov