White Mountains Insurance Group LTD — Quarterly 13F Portfolio Report

CIK: 0000776867

Concentrated strategyMomentum followerQuality / disciplined sizing

Total reported value

$313.4M

Reporting period: 2026-03-31 · Number of holdings: 2

WHITE MOUNTAINS INSURANCE GROUP LTD disclosed 2 holdings in its latest 13F filing for the period ending 2026-03-31, with total reported value of $313.4M and a quarterly turnover rate of 63.2%.

Browse other institutions with $100M to $1B AUM Browse other institutions starting with "W"

Personality snowflake

Concentration: 100
Portfolio Stability: 63.2
Momentum/Contrarian: 100
Sector conviction: 0
Diversification: 4
Sizing Uniformity: 99.15

Sector classification currently covers about 0% of this portfolio's disclosed value; the remainder includes holdings (e.g. unmapped tickers, options, or other security types) not yet covered by our sector mapping.

Recent moves

Add SPY
+403.3%　$116.6M
Trim MAX
0.0%　-$65.2M

Holdings Map

New buyAddUnchangedTrim

Top 10 holdings by weight

Full holdings list this quarter

#	Ticker	Issuer	Asset Subclass	Weight	Weight Change	Shares Change	4Q Trend
1	MAX	Mediaalpha Inc-class A	Stock-Other	52.99%	-35.29%	—
2	SPY	Ss Spdr S&p 500 ETF Trust-us	ETF-Large Cap & Growth	47.01%	+35.29%	+403.33%

Portfolio Performance

Performance for Q3 2026

+33.5%

Performance Last 4 Quarters

+15.5%

Stdev: +36.4%
Beta: +0.5
Alpha: +6.4%
Max Drawdown: -38%
Annualized Perf: +9.7%
Batting Avg vs S&P: +47.2%
Sortino: +0.74
Stutzer: +0.13
Treynor: +0.31
Sterling: +0.24
Calmar: +0.26
Information Ratio: -0.08
Tracking Error: +36.4%
Stdev Down: +21%
Winning Months %: +52.8%
Losing Months %: +47.2%
Best 12 Months: +65.2%
Worst 12 Months: -36.3%
Efficiency Ratio: +0.11
Sharpe: +0.43
Stdev Sectors: —
Skewness: +0.62
Kurtosis: +1.61
Upside Potential: +2.61

Reported value over time

Sector allocation

Not enough sector-mapped data yet

Sector allocation over time

Quarterly history

Period	Holdings	Total value	Stability	Top holdings
2026-03-31	2	$313.4M	63	1MAX 2SPY Top holdings2026-03-31 1.MAX 2.SPY
2025-12-31	2	$261.9M	25	1MAX 2SPY Top holdings2025-12-31 1.MAX 2.SPY
2025-09-30	1	$203.2M	80	1MAX Top holdings2025-09-30 1.MAX
2025-06-30	1	$195.5M	0	1MAX Top holdings2025-06-30 1.MAX
2025-03-31	2	$285.9M	100	1MAX 2SPY Top holdings2025-03-31 1.MAX 2.SPY
2024-12-31	2	$426.2M	0	1SPY 2MAX Top holdings2024-12-31 1.SPY 2.MAX
2024-09-30	2	$543.2M	0	1MAX 2SPY Top holdings2024-09-30 1.MAX 2.SPY
2024-06-30	2	$443.7M	0	1MAX 2SPY Top holdings2024-06-30 1.MAX 2.SPY
2024-03-31	2	$617.2M	0	1MAX 2SPY Top holdings2024-03-31 1.MAX 2.SPY
2023-12-31	2	$392.6M	0	1MAX 2SPY Top holdings2023-12-31 1.MAX 2.SPY
2023-09-30	2	$440.9M	0	1SPY 2MAX Top holdings2023-09-30 1.SPY 2.MAX
2023-06-30	2	$508.2M	0	1SPY 2MAX Top holdings2023-06-30 1.SPY 2.MAX
2023-03-31	2	$611.1M	0	1SPY 2MAX Top holdings2023-03-31 1.SPY 2.MAX
2022-12-31	2	$502.4M	0	1SPY 2MAX Top holdings2022-12-31 1.SPY 2.MAX
2022-09-30	2	$194.7M	0	1MAX 2SPY Top holdings2022-09-30 1.MAX 2.SPY
2022-06-30	1	$166.9M	0	1MAX Top holdings2022-06-30 1.MAX
2022-03-31	1	$280.4M	0	1MAX Top holdings2022-03-31 1.MAX
2021-12-31	1	$261.6M	0	1MAX Top holdings2021-12-31 1.MAX
2021-09-30	1	$316.4M	0	1MAX Top holdings2021-09-30 1.MAX
2021-06-30	1	$713.2M	100	1MAX Top holdings2021-06-30 1.MAX
2021-03-31	1	$600.2M	29	1MAX Top holdings2021-03-31 1.MAX
2020-12-31	1	$802.2M	100	1MAX Top holdings2020-12-31 1.MAX
2015-12-31	1	$653.3M	0	187151Q Top holdings2015-12-31 1.87151Q
2015-09-30	1	$650.6M	27	187151Q Top holdings2015-09-30 1.87151Q
2015-06-30	1	$497.0M	6	187151Q Top holdings2015-06-30 1.87151Q
2015-03-31	1	$470.3M	2	187151Q Top holdings2015-03-31 1.87151Q
2014-12-31	1	$462.1M	1	187151Q Top holdings2014-12-31 1.87151Q
2014-09-30	1	$467.7M	3	187151Q Top holdings2014-09-30 1.87151Q
2014-06-30	1	$455.9M	14	187151Q Top holdings2014-06-30 1.87151Q
2014-03-31	2	$397.9M	4	187151Q2SIEGY Top holdings2014-03-31 1.87151Q 2.SIEGY
2013-12-31	2	$380.7M	6	187151Q2SIEGY Top holdings2013-12-31 1.87151Q 2.SIEGY
2013-09-30	2	$357.7M	11	187151Q2SIEGY Top holdings2013-09-30 1.87151Q 2.SIEGY
2013-06-30	2	$321.0M	—	187151Q2SIEGY Top holdings2013-06-30 1.87151Q 2.SIEGY

Holding changes this quarter

White Mountains Insurance Group LTD's most significant position changes for 2026-03-31: Add: Ss Spdr S&p 500 ETF Trust-us (SPY) — shares +403.33%.

Position changes disclosed by White Mountains Insurance Group LTD for the quarter ending 2026-03-31, including ticker, issuer, weight change, shares change, and action
#	Ticker	Issuer	Weight Change	Shares Change	Action
1	SPY	Ss Spdr S&p 500 ETF Trust-us	+35.3%	+403.33%	Add
2	MAX	Mediaalpha Inc-class A	-35.3%	—	Unchanged

Filing History

Period	Filed	Type	EDGAR
2026-03-31	2026-05-12	13F-HR	View on EDGAR
2025-12-31	2026-02-12	13F-HR	View on EDGAR
2025-09-30	2025-11-13	13F-HR	View on EDGAR
2025-06-30	2025-08-11	13F-HR	View on EDGAR
2025-03-31	2025-05-12	13F-HR	View on EDGAR
2024-12-31	2025-02-12	13F-HR	View on EDGAR
2024-09-30	2024-11-12	13F-HR	View on EDGAR
2024-06-30	2024-08-08	13F-HR	View on EDGAR
2024-03-31	2024-05-09	13F-HR	View on EDGAR
2023-12-31	2024-02-13	13F-HR	View on EDGAR
2023-09-30	2023-11-09	13F-HR	View on EDGAR
2023-06-30	2023-08-10	13F-HR	View on EDGAR
2023-03-31	2023-05-11	13F-HR	View on EDGAR
2022-12-31	2023-02-13	13F-HR	View on EDGAR
2022-09-30	2022-11-09	13F-HR	View on EDGAR
2022-06-30	2022-08-12	13F-HR	View on EDGAR
2022-03-31	2022-05-12	13F-HR	View on EDGAR
2021-12-31	2022-02-11	13F-HR	View on EDGAR
2021-09-30	2021-11-12	13F-HR	View on EDGAR
2021-06-30	2021-08-12	13F-HR	View on EDGAR
2021-03-31	2021-05-14	13F-HR	View on EDGAR
2020-12-31	2021-02-12	13F-HR	View on EDGAR
2015-12-31	2016-02-16	13F-HR	View on EDGAR
2015-09-30	2015-11-12	13F-HR	View on EDGAR
2015-06-30	2015-08-12	13F-HR	View on EDGAR
2015-03-31	2015-05-14	13F-HR	View on EDGAR
2014-12-31	2015-02-17	13F-HR	View on EDGAR
2014-09-30	2014-11-13	13F-HR	View on EDGAR
2014-06-30	2014-08-08	13F-HR	View on EDGAR
2014-03-31	2014-05-12	13F-HR	View on EDGAR
2013-12-31	2014-02-13	13F-HR	View on EDGAR
2013-09-30	2013-11-13	13F-HR	View on EDGAR
2013-06-30	2013-08-09	13F-HR	View on EDGAR

FAQ

What is White Mountains Insurance Group LTD and what type of investor is it?

White Mountains Insurance Group LTD is an investment manager that files SEC Form 13F quarterly, disclosing its U.S. public equity holdings to regulators. As of the most recent reporting period (2026-03-31), the firm manages a tracked equity portfolio valued at approximately $313.4M, spread across 2 disclosed positions.

What are White Mountains Insurance Group LTD's largest equity positions?

Based on the latest 13F filing, White Mountains Insurance Group LTD's top holdings by market value are: 1. Mediaalpha Inc-class A (MAX) — $166.1M (53.0%) 2. Ss Spdr S&p 500 ETF Trust-us (SPY) — $147.3M (47.0%)

What changes did White Mountains Insurance Group LTD make in its most recent portfolio filing?

In the latest quarter, White Mountains Insurance Group LTD was primarily adding exposure — initiating 0 new positions and adding to 1 existing holdings. The largest of these moves: Add: Ss Spdr S&p 500 ETF Trust-us (SPY) — shares +403.33%

What sectors does White Mountains Insurance Group LTD focus on?

Sector breakdown data is not yet available for White Mountains Insurance Group LTD. Check back after the next 13F processing cycle.

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White Mountains Insurance Group LTD — Quarterly 13F Portfolio Report

CIK: 0000776867

Concentrated strategyMomentum followerQuality / disciplined sizing

Total reported value

$313.4M

Reporting period: 2026-03-31 · Number of holdings: 2

WHITE MOUNTAINS INSURANCE GROUP LTD disclosed 2 holdings in its latest 13F filing for the period ending 2026-03-31, with total reported value of $313.4M and a quarterly turnover rate of 63.2%.

Browse other institutions with $100M to $1B AUM Browse other institutions starting with "W"

Personality snowflake

Concentration: 100
Portfolio Stability: 63.2
Momentum/Contrarian: 100
Sector conviction: 0
Diversification: 4
Sizing Uniformity: 99.15

Recent moves

Add SPY
+403.3%　$116.6M
Trim MAX
0.0%　-$65.2M

Holdings Map

New buyAddUnchangedTrim

Top 10 holdings by weight

Full holdings list this quarter

#	Ticker	Issuer	Asset Subclass	Weight	Weight Change	Shares Change	4Q Trend
1	MAX	Mediaalpha Inc-class A	Stock-Other	52.99%	-35.29%	—
2	SPY	Ss Spdr S&p 500 ETF Trust-us	ETF-Large Cap & Growth	47.01%	+35.29%	+403.33%

Portfolio Performance

Performance for Q3 2026

+33.5%

Performance Last 4 Quarters

+15.5%

Stdev: +36.4%
Beta: +0.5
Alpha: +6.4%
Max Drawdown: -38%
Annualized Perf: +9.7%
Batting Avg vs S&P: +47.2%
Sortino: +0.74
Stutzer: +0.13
Treynor: +0.31
Sterling: +0.24
Calmar: +0.26
Information Ratio: -0.08
Tracking Error: +36.4%
Stdev Down: +21%
Winning Months %: +52.8%
Losing Months %: +47.2%
Best 12 Months: +65.2%
Worst 12 Months: -36.3%
Efficiency Ratio: +0.11
Sharpe: +0.43
Stdev Sectors: —
Skewness: +0.62
Kurtosis: +1.61
Upside Potential: +2.61

Reported value over time

Sector allocation

Not enough sector-mapped data yet

Sector allocation over time

Quarterly history

Period	Holdings	Total value	Stability	Top holdings
2026-03-31	2	$313.4M	63	1MAX 2SPY Top holdings2026-03-31 1.MAX 2.SPY
2025-12-31	2	$261.9M	25	1MAX 2SPY Top holdings2025-12-31 1.MAX 2.SPY
2025-09-30	1	$203.2M	80	1MAX Top holdings2025-09-30 1.MAX
2025-06-30	1	$195.5M	0	1MAX Top holdings2025-06-30 1.MAX
2025-03-31	2	$285.9M	100	1MAX 2SPY Top holdings2025-03-31 1.MAX 2.SPY
2024-12-31	2	$426.2M	0	1SPY 2MAX Top holdings2024-12-31 1.SPY 2.MAX
2024-09-30	2	$543.2M	0	1MAX 2SPY Top holdings2024-09-30 1.MAX 2.SPY
2024-06-30	2	$443.7M	0	1MAX 2SPY Top holdings2024-06-30 1.MAX 2.SPY
2024-03-31	2	$617.2M	0	1MAX 2SPY Top holdings2024-03-31 1.MAX 2.SPY
2023-12-31	2	$392.6M	0	1MAX 2SPY Top holdings2023-12-31 1.MAX 2.SPY
2023-09-30	2	$440.9M	0	1SPY 2MAX Top holdings2023-09-30 1.SPY 2.MAX
2023-06-30	2	$508.2M	0	1SPY 2MAX Top holdings2023-06-30 1.SPY 2.MAX
2023-03-31	2	$611.1M	0	1SPY 2MAX Top holdings2023-03-31 1.SPY 2.MAX
2022-12-31	2	$502.4M	0	1SPY 2MAX Top holdings2022-12-31 1.SPY 2.MAX
2022-09-30	2	$194.7M	0	1MAX 2SPY Top holdings2022-09-30 1.MAX 2.SPY
2022-06-30	1	$166.9M	0	1MAX Top holdings2022-06-30 1.MAX
2022-03-31	1	$280.4M	0	1MAX Top holdings2022-03-31 1.MAX
2021-12-31	1	$261.6M	0	1MAX Top holdings2021-12-31 1.MAX
2021-09-30	1	$316.4M	0	1MAX Top holdings2021-09-30 1.MAX
2021-06-30	1	$713.2M	100	1MAX Top holdings2021-06-30 1.MAX
2021-03-31	1	$600.2M	29	1MAX Top holdings2021-03-31 1.MAX
2020-12-31	1	$802.2M	100	1MAX Top holdings2020-12-31 1.MAX
2015-12-31	1	$653.3M	0	187151Q Top holdings2015-12-31 1.87151Q
2015-09-30	1	$650.6M	27	187151Q Top holdings2015-09-30 1.87151Q
2015-06-30	1	$497.0M	6	187151Q Top holdings2015-06-30 1.87151Q
2015-03-31	1	$470.3M	2	187151Q Top holdings2015-03-31 1.87151Q
2014-12-31	1	$462.1M	1	187151Q Top holdings2014-12-31 1.87151Q
2014-09-30	1	$467.7M	3	187151Q Top holdings2014-09-30 1.87151Q
2014-06-30	1	$455.9M	14	187151Q Top holdings2014-06-30 1.87151Q
2014-03-31	2	$397.9M	4	187151Q2SIEGY Top holdings2014-03-31 1.87151Q 2.SIEGY
2013-12-31	2	$380.7M	6	187151Q2SIEGY Top holdings2013-12-31 1.87151Q 2.SIEGY
2013-09-30	2	$357.7M	11	187151Q2SIEGY Top holdings2013-09-30 1.87151Q 2.SIEGY
2013-06-30	2	$321.0M	—	187151Q2SIEGY Top holdings2013-06-30 1.87151Q 2.SIEGY

Holding changes this quarter

White Mountains Insurance Group LTD's most significant position changes for 2026-03-31: Add: Ss Spdr S&p 500 ETF Trust-us (SPY) — shares +403.33%.

Position changes disclosed by White Mountains Insurance Group LTD for the quarter ending 2026-03-31, including ticker, issuer, weight change, shares change, and action
#	Ticker	Issuer	Weight Change	Shares Change	Action
1	SPY	Ss Spdr S&p 500 ETF Trust-us	+35.3%	+403.33%	Add
2	MAX	Mediaalpha Inc-class A	-35.3%	—	Unchanged

Filing History

Period	Filed	Type	EDGAR
2026-03-31	2026-05-12	13F-HR	View on EDGAR
2025-12-31	2026-02-12	13F-HR	View on EDGAR
2025-09-30	2025-11-13	13F-HR	View on EDGAR
2025-06-30	2025-08-11	13F-HR	View on EDGAR
2025-03-31	2025-05-12	13F-HR	View on EDGAR
2024-12-31	2025-02-12	13F-HR	View on EDGAR
2024-09-30	2024-11-12	13F-HR	View on EDGAR
2024-06-30	2024-08-08	13F-HR	View on EDGAR
2024-03-31	2024-05-09	13F-HR	View on EDGAR
2023-12-31	2024-02-13	13F-HR	View on EDGAR
2023-09-30	2023-11-09	13F-HR	View on EDGAR
2023-06-30	2023-08-10	13F-HR	View on EDGAR
2023-03-31	2023-05-11	13F-HR	View on EDGAR
2022-12-31	2023-02-13	13F-HR	View on EDGAR
2022-09-30	2022-11-09	13F-HR	View on EDGAR
2022-06-30	2022-08-12	13F-HR	View on EDGAR
2022-03-31	2022-05-12	13F-HR	View on EDGAR
2021-12-31	2022-02-11	13F-HR	View on EDGAR
2021-09-30	2021-11-12	13F-HR	View on EDGAR
2021-06-30	2021-08-12	13F-HR	View on EDGAR
2021-03-31	2021-05-14	13F-HR	View on EDGAR
2020-12-31	2021-02-12	13F-HR	View on EDGAR
2015-12-31	2016-02-16	13F-HR	View on EDGAR
2015-09-30	2015-11-12	13F-HR	View on EDGAR
2015-06-30	2015-08-12	13F-HR	View on EDGAR
2015-03-31	2015-05-14	13F-HR	View on EDGAR
2014-12-31	2015-02-17	13F-HR	View on EDGAR
2014-09-30	2014-11-13	13F-HR	View on EDGAR
2014-06-30	2014-08-08	13F-HR	View on EDGAR
2014-03-31	2014-05-12	13F-HR	View on EDGAR
2013-12-31	2014-02-13	13F-HR	View on EDGAR
2013-09-30	2013-11-13	13F-HR	View on EDGAR
2013-06-30	2013-08-09	13F-HR	View on EDGAR