Neuberger Berman Group LLC ownership in WTM / White Mountains Insurance Group, Ltd.

White Mountains Insurance Group, Ltd.

US ˙ NYSE ˙ BMG9618E1075

Security	WTM / White Mountains Insurance Group, Ltd.
Institution	Neuberger Berman Group LLC
Latest Disclosed Ownership	121,583 shares
Ownership	4.90%

2026-05-07 - Neuberger Berman Group LLC has filed an SCHEDULE 13G/A form with the Securities and Exchange Commission (SEC) disclosing ownership of 121,583 shares of White Mountains Insurance Group, Ltd. (US:WTM). This represents 4.9 percent ownership of the company. In their previous filing dated 2026-02-05 , Neuberger Berman Group LLC had reported owning 129,654 shares, indicating a decrease of -6.23 percent.

Institutional Ownership: 13D/G Filings

This table shows a history of the 13D/G filings made by the investor and/or investor group. Note that the share values in this table are not directly comparable to any numbers shown in the 13F table (if any).

File Date	Effective Date	Form	Prev Shares	Latest Shares	ΔShares (Percent)	Ownership (Percent)	ΔOwnership (Percent)
2026-05-07	2026-05-07	13G/A	129,654	121,583	-6.23	4.90	-3.92
2026-02-05	2026-02-05	13G		129,654		5.10

Important Note: One of the primary uses of the 13D/G filings is to evaluate the ability of a firm to control a company (ie, the "beneficial ownership"). To that end, firms are required to report not just direct holdings in companies, but indirect holdings that they control. For investment firms, these indirect holdings can include shares in funds they manage, advisory accounts, and in the case of activist campaigns, pledged votes. Therefore, share counts listed in 13D/G filings can differ significantly than share counts listed in 13F filings.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

Upgrade to unlock premium data and export to Excel Premium Registration Required .

Disclosed Equity Positions (from 13F/NPORT Filings)

File Date	Effective Date	Form	Security	Class	ID	Reported Shares	ΔShares	ΔShares (%)	Reported Value (x1000)	ΔValue (%)	Alloc (%)
2026-05-14	2026-03-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	124,715	-4,939	-3.81	273,994	1.70	0.2085
2026-02-13	2025-12-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	129,654	14,639	12.73	269,425	40.14	0.2006
2025-11-12	2025-09-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	115,015	31,316	37.42	192,250	27.91	0.1405
2025-08-25	2025-06-30	13F/A-1	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	83,699	26,835	47.19	150,300	37.25	0.1157
2025-08-13	2025-06-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	83,699	26,835		150,300		0.0598
2025-05-13	2025-03-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	56,864	11,426	25.15	109,509	23.91	0.0917
2025-02-13	2024-12-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	45,438	12,328	37.23	88,380	57.37	0.0702
2024-11-14	2024-09-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	33,110	15,949	92.94	56,161	80.07	0.0438
2024-11-14	2024-06-30	13F/A-1	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	17,161	16,147	1,592.41	31,189	1,614.62	0.0256
2024-08-13	2024-06-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	17,161	16,147		31,189		0.0256
2024-11-14	2024-03-31	13F/A-1	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,014	-5	-0.49	1,819	18.66	0.0015
2024-05-13	2024-03-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,014	-5		1,819		0.0015
2024-11-14	2023-12-31	13F/A-2	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,019	-7	-0.68	1,534	-0.07	0.0013
2024-02-09	2023-12-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,019	-7		1,534		0.0013
2023-11-14	2023-09-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,026	-39	-3.66	1,535	3.72	0.0014
2023-08-11	2023-06-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,065	-7	-0.65	1,479	0.20	0.0013
2023-05-12	2023-03-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,072	21	2.00	1,477	-0.67	0.0014
2023-02-13	2022-12-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,051	-9	-0.85	1,486	7.60	0.0015
2022-11-15	2022-09-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,060	118	12.53	1,381	17.63	0.0014
2022-08-15	2022-06-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	942	1	0.11	1,174	9.82	0.0012
2022-05-23	2022-03-31	13F/A-1	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	941	-4	-0.42	1,069	15.69	0.0009
2022-05-13	2022-03-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	941	-4		1,029		0.0009
2022-02-11	2021-12-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	945	205	27.70	924	22.38	0.0007
2021-11-12	2021-09-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	740	0	0.00	755	-11.07	0.0007
2021-08-13	2021-06-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	740	-1	-0.13	849	2.78	0.0007
2021-05-13	2021-03-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	741	35	4.96	826	17.00	0.0008
2021-02-10	2020-12-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	706	11	1.58	706	30.50	0.0007
2020-11-12	2020-09-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	695	0	0.00	541	-12.32	0.0006
2020-08-13	2020-06-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	695	-185	-21.02	617	-22.97	0.0008
2020-05-14	2020-03-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	880	-210	-19.27	801	-34.07	0.0012
2020-02-12	2019-12-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,090	0	0.00	1,215	3.23	0.0014
2019-11-13	2019-09-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,090	12	1.11	1,177	6.90	0.0014
2019-08-13	2019-06-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,078	-2	-0.19	1,101	10.21	0.0013
2019-05-13	2019-03-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,080	-314	-22.53	999	-16.40	0.0012
2019-02-12	2018-12-31	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,394	-92	-6.19	1,195	-14.09	0.0017
2018-11-16	2018-09-30	13F/A-1	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,486	17	1.16	1,391	4.51	0.0016
2018-11-13	2018-09-30	13F	WHITE MOUNTAINS INSURANCE GROUP LT	Common	G9618E107	1,486	17		1,391
2018-08-13	2018-06-30	13F	OLD WHITE MTNS INS GROUP	Common	G9618E107	1,469	22	1.52	1,331	11.75	0.0015
2018-05-08	2018-03-31	13F	OLD WHITE MTNS INS GROUP	Common	G9618E107	1,447	63	4.55	1,191	1.10	0.0014
2018-02-14	2017-12-31	13F	OLDWHITE MTNS INS GROUP	Common	G9618E107	1,384	37	2.75	1,178	2.08	0.0014
2017-11-15	2017-09-30	13F	WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,347	89	7.07	1,154	5.58	0.0014
2017-08-08	2017-06-30	13F	WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,258	114	9.97	1,093	8.54	0.0014
2017-05-10	2017-03-31	13F	WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,144	51	4.67	1,007	10.18	0.0013
2017-02-06	2016-12-31	13F	WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,093	-28	-2.50	914	-1.72	0.0012
2016-11-02	2016-09-30	13F	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,121	0	0.00	930	-1.48	0.0013
2016-08-05	2016-06-30	13F	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,121	-514	-31.44	944	-28.05	0.0013
2016-05-06	2016-03-31	13F	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,635	436	36.36	1,312	50.63	0.0018
2016-01-28	2015-12-31	13F	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,199	99	9.00	871	5.96	0.0011
2015-11-10	2015-09-30	13F	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,100	0	0.00	822	14.17	0.0011
2015-07-31	2015-06-30	13F	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,100	0	0.00	720	-4.38	0.0008
2015-05-06	2015-03-31	13F	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,100	1,100	0.00	753		0.0008
2015-02-05	2014-12-31	13F	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	0	-1,100	-100.00	0	-100.00
2014-11-04	2014-09-30	13F	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,100	-57	-4.93	693	-1.56	0.0007
2014-08-05	2014-06-30	13F	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,157	-102	-8.10	704	-6.75	0.0007
2014-05-05	2014-03-31	13F	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,259	1	0.08	755	-0.53	0.0008
2014-02-11	2013-12-31	13F	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	1,258	408	48.00	759	57.47	0.0008
2013-10-29	2013-09-30	13F/A-1	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	850	100	13.33	482	11.83	0.0005
2013-10-29	2013-09-30	13F	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	6,982			3,503
2013-08-13	2013-06-30	13F	***WHITE MTNS INS GROUP	COMMON STOCK	G9618E107	750	750		431		0.0005

Legend

Shares: The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value: The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price: The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class: This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred

Allocation (%): The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation: The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%): The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis: The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss: This is the market value of the position as of the effective date minus the cost basis.