Investor White Mountains Insurance Group Ltd
13D/G Filings

This page shows a list of all the recent 13D/G filings made by White Mountains Insurance Group Ltd . Schedule 13D is commonly referred to as a “beneficial ownership report.” The term "beneficial owner" is defined under SEC rules. It includes any person who directly or indirectly shares voting power or investment power (the power to sell the security).

When a person or group of persons acquires beneficial ownership of more than 5% of a voting class of a company’s equity securities, they are required to file a Schedule 13D within ten days after the purchase. Click the link icon to see the full transaction history.

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Date Form Target Prev
Shares		 Current
Shares		 Change
(Percent)		 Ownership
(Percent)		 Change
(Percent)
2025-08-08 13D/A MAX / MediaAlpha, Inc. 17,856,614 17,856,614
2024-05-09 13D/A MAX / MediaAlpha, Inc. 22,856,814 17,856,614
2024-05-03 13D/A MAX / MediaAlpha, Inc. 22,856,814 22,856,814
2024-01-03 13D/A MAX / MediaAlpha, Inc. 22,856,814 22,856,814
2023-11-02 13D/A MAX / MediaAlpha, Inc. 22,856,814 22,856,814
2023-06-30 13D MAX / MediaAlpha, Inc. 16,939,998 22,856,814
2023-02-10 13G MAX / MediaAlpha, Inc. 16,939,998 16,939,998
2022-02-14 13G/A MAX / MediaAlpha, Inc. 20,532,202 16,939,998
2021-02-12 13G MAX / MediaAlpha, Inc. 20,532,202
2018-01-29 13G/A G67742109 / OneBeacon Insurance Group Ltd. 71,754,738 0
2016-04-20 13G/A G67742109 / OneBeacon Insurance Group Ltd. 71,754,738
2015-02-12 13G/A SYA / Symetra Financial Corporation 20,048,879
2014-02-14 13G/A SYA / Symetra Financial Corporation 20,048,879
2013-02-13 13G/A G67742109 / OneBeacon Insurance Group Ltd. 71,754,738
2013-02-13 13G/A SYA / Symetra Financial Corporation 26,887,872
2012-02-03 13G/A SYA / Symetra Financial Corporation 26,887,872
2012-02-03 13G/A G67742109 / OneBeacon Insurance Group Ltd. 71,754,738