White Mountains Insurance Group Ltd
White Mountains Insurance Group Ltd reported 2 US-listed holdings worth $393.6 million in its 13F for the quarter ended 30 June 2026, filed 12 August 2026. Its largest: Mediaalpha Inc. (57.0%) and SPDR S&P 500 (43.0%). Against the quarter before, it opened 0 positions, added to 0, trimmed 0 and sold out of 0.
The 2 largest of its 2 positions, each sized by its share of the reported holdings, coloured by the change in shares against Q1 2026.
What the fund reported holding at each quarter's end; hover a bar for the number of positions
What its reported holdings returned
Held through each quarter, the holdings it reported returned -11.0% over the 7 quarters to 30 June 2026, against +30.2% for the S&P 500.
Not the fund's own return: each 13F's holdings are kept unchanged until the next one, so trades inside a quarter, dividends, cash and fees are left out. A rough guide to how its picks have done over time.
What it holds
| Company | Shares | Value | Of its book | Change in shares |
|---|---|---|---|---|
| Mediaalpha Inc. MAX | 17.9M | $224.5 million | 57.03% | no change |
| SPDR S&P 500 SPY | 226.5K | $169.1 million | 42.97% | no change |