White Mountains Insurance Group Ltd.

In its 13F for Q4 2025 (holdings as of December 31, 2025, filed February 12, 2026), White Mountains Insurance Group Ltd. reported 2 stock positions worth $261.9 million. Its top holding was Mediaalpha Class A (MAX) at 88.3% of the portfolio, followed by SS SPDR S&P 500 ETF Trust-US (SPY, 11.7%). Compared with Q3 2025, it opened 1 new position. The biggest buy was a new position in SS SPDR S&P 500 ETF Trust-US (SPY).