White Mountains Insurance Group Ltd.

In its 13F for Q3 2025 (holdings as of September 30, 2025, filed November 13, 2025), White Mountains Insurance Group Ltd. reported 1 stock position worth $203.2 million. Its top holding was Mediaalpha Class A (MAX) at 100.0% of the portfolio. Its holdings were unchanged from Q2 2025.

Most Recent 13F
Q2 2026
Location
Hanover, NH
CIK
0000776867
Portfolio Value
$203.2M (Q3 2025)
SEC Filing
0001104659-25-110906 ↗ filed Nov 13, 2025

Holdings Value

0$200.0M$400.0M$600.0M$800.0M Q1 2024: $617.2M Q1 2024 Q2 2024: $443.7M Q2 2024 Q3 2024: $543.2M Q3 2024 Q4 2024: $426.2M Q4 2024 Q1 2025: $285.9M Q1 2025 Q2 2025: $195.5M Q2 2025 Q3 2025: $203.2M $203.2M Q3 2025 Q4 2025: $261.9M Q4 2025 Q1 2026: $313.4M Q1 2026 Q2 2026: $393.6M Q2 2026

Holdings 1 stocks · $203.2M
MAX Mediaalpha Inc. Class A 100.00% 17,856,614 $203.2M No change

Portfolio Sells Q2 2025 → Q3 2025
None this quarter.

Portfolio Buys Q2 2025 → Q3 2025
None this quarter.

All Filings

QuarterPositions13F Reported ValueTop Holdings
Q2 2026 2$393.6MMAX, SPY
Q1 2026 2$313.4MMAX, SPY
Q4 2025 2$261.9MMAX, SPY
Q3 2025 1$203.2MMAX
Q2 2025 1$195.5MMAX
Q1 2025 2$285.9MMAX, SPY
Q4 2024 2$426.2MSPY, MAX
Q3 2024 2$543.2MMAX, SPY
Q2 2024 2$443.7MMAX, SPY
Q1 2024 2$617.2MMAX, SPY