# Filing Detail

Form 10-K - Annual report [Section 13 and 15(d), not S-K Item 405]:
SEC Accession No. 0001628280-26-012603
Filing Date
2026-02-27
Accepted
2026-02-27 09:21:38
Documents
166
Period of Report
2025-12-31

Document Format Files

Seq | Description | Document | Type | Size
--- | --- | --- | --- | ---
1 | 10-K | wtm-20251231.htm iXBRL | 10-K | 7372998
2 | EX-4 | wtm10-k2025exhibit4.htm | EX-4 | 15332
3 | EX-14 | wtm10-k2025exhibit14.htm | EX-14 | 25679
4 | EX-19 | wtm10-k2025exhibit19.htm | EX-19 | 45762
5 | EX-21 | wtm10-k2025exhibit21.htm | EX-21 | 36598
6 | EX-23 | wtm10-k2025exhibit23.htm | EX-23 | 1694
7 | EX-24 | wtm10-k2025exhibit24.htm | EX-24 | 32093
8 | EX-31.1 | wtm10-k2025exhibit311.htm | EX-31.1 | 9079
9 | EX-31.2 | wtm10-k2025exhibit312.htm | EX-31.2 | 8966
10 | EX-32.1 | wtm10-k2025exhibit321.htm | EX-32.1 | 6571
11 | EX-32.2 | wtm10-k2025exhibit322.htm | EX-32.2 | 6782
17 |  | wtm-20251231_g1.jpg | GRAPHIC | 108500
18 |  | wtm10-k2025exhibit14001.jpg | GRAPHIC | 223332
19 |  | wtm10-k2025exhibit14002.jpg | GRAPHIC | 225608
20 |  | wtm10-k2025exhibit14003.jpg | GRAPHIC | 262612
21 |  | wtm10-k2025exhibit14004.jpg | GRAPHIC | 274986
22 |  | wtm10-k2025exhibit14005.jpg | GRAPHIC | 252061
23 |  | wtm10-k2025exhibit14006.jpg | GRAPHIC | 211649
24 |  | wtm10-k2025exhibit14007.jpg | GRAPHIC | 171964
| Complete submission text file | 0001628280-26-012603.txt |  | 36484439

Data Files

Seq | Description | Document | Type | Size
--- | --- | --- | --- | ---
12 | XBRL TAXONOMY EXTENSION SCHEMA DOCUMENT | wtm-20251231.xsd | EX-101.SCH | 181486
13 | XBRL TAXONOMY EXTENSION CALCULATION LINKBASE DOCUMENT | wtm-20251231_cal.xml | EX-101.CAL | 227641
14 | XBRL TAXONOMY EXTENSION DEFINITION LINKBASE DOCUMENT | wtm-20251231_def.xml | EX-101.DEF | 1234423
15 | XBRL TAXONOMY EXTENSION LABEL LINKBASE DOCUMENT | wtm-20251231_lab.xml | EX-101.LAB | 1766483
16 | XBRL TAXONOMY EXTENSION PRESENTATION LINKBASE DOCUMENT | wtm-20251231_pre.xml | EX-101.PRE | 1507965
169 | EXTRACTED XBRL INSTANCE DOCUMENT | wtm-20251231_htm.xml | XML | 7298535

Mailing Address 23 SOUTH MAIN STREET SUITE 3B HANOVER NH 03755
Business Address 23 SOUTH MAIN STREET SUITE 3B HANOVER NH 03755 603 640 2200
WHITE MOUNTAINS INSURANCE GROUP LTD (Filer) CIK: 0000776867 (see all company filings)

EIN.: 942708455 | State of Incorp.: D0 | Fiscal Year End: 1231
Type: 10-K | Act: 34 | File No.: 001-08993 | Film No.: 26693152
SIC: 6331 Fire, Marine & Casualty Insurance
(CF Office: 02 Finance)