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)