Vault-13

WHITE MTNS INS GROUP LTD WTM

COM · Common Stock · CUSIP G9618E107

356 institutional holders -12 vs Q1 2026
2,198,1822.2m shares reported held*
92.1% of all shares outstanding*
$4.6bnreported value*
33 new 96 added 146 reduced 42 sold out net sold ≈ $67.1m (-31.9k shares)

* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once ($8.0m this quarter). Holder counts are more reliable. Shares outstanding: 2.4m as of 2026-08-03, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $2073.78. Options: 0 managers hold calls (— notional), 1 hold puts ($296.5k).

Trends to Q2 2026

Institutional holders

Managers reporting a position, each quarter

0200400Q3 22: 253Q4 22: 264Q1 23: 262Q2 23: 258Q3 23: 272Q4 23: 295Q1 24: 303Q2 24: 306Q3 24: 304Q4 24: 325Q1 25: 323Q2 25: 326Q3 25: 338Q4 25: 353Q1 26: 368Q2 26: 356356Q3 22Q3 23Q3 24Q3 25Q2 26
Numbers
QuarterHolders
Q3 2022253
Q4 2022264
Q1 2023262
Q2 2023258
Q3 2023272
Q4 2023295
Q1 2024303
Q2 2024306
Q3 2024304
Q4 2024325
Q1 2025323
Q2 2025326
Q3 2025338
Q4 2025353
Q1 2026368
Q2 2026356

Buyers vs sellers

Managers adding to or starting a position, vs cutting or selling out

Bought or addedCut or sold out
2000200Q3 24: 132 bought or addedQ3 24: 108 cut or sold outQ4 24: 140 bought or addedQ4 24: 97 cut or sold outQ4 24Q1 25: 124 bought or addedQ1 25: 133 cut or sold outQ2 25: 133 bought or addedQ2 25: 138 cut or sold outQ2 25Q3 25: 147 bought or addedQ3 25: 130 cut or sold outQ4 25: 150 bought or addedQ4 25: 160 cut or sold outQ4 25Q1 26: 160 bought or addedQ1 26: 138 cut or sold outQ2 26: 129 bought or addedQ2 26: 188 cut or sold outQ2 26
Numbers
QuarterBought or addedCut or sold out
Q3 2024132108
Q4 202414097
Q1 2025124133
Q2 2025133138
Q3 2025147130
Q4 2025150160
Q1 2026160138
Q2 2026129188

Calls vs puts

Options held, notional value, last 4 quarters. P/C = puts ÷ calls

CallsPuts
$0$100k$200k$300kQ3 25 calls: $0Q3 25 puts: $0Q3 25P/C —Q4 25 calls: $0Q4 25 puts: $0Q4 25P/C —Q1 26 calls: $0Q1 26 puts: $0Q1 26P/C —Q2 26 calls: $0Q2 26 puts: $296.5kQ2 26P/C —
Numbers
QuarterCallsPutsP/C
Q3 2025$0$0—
Q4 2025$0$0—
Q1 2026$0$0—
Q2 2026$0$296.5k—

Biggest buyers

AMERICAN CENTURY COMPANIES INC Added +22,800+22.8k
GENDELL JEFFREY L Added +21,429+21.4k
Gotham Asset Management, LLC Added +8,893+8.9k
Qube Research & Technologies Ltd Added +8,657+8.7k
FIRST TRUST ADVISORS LP Added +7,546+7.5k
GEODE CAPITAL MANAGEMENT, LLC Added +7,293+7.3k
REINHART PARTNERS, LLC. Added +7,106+7.1k
UBS Group AG Added +5,757+5.8k
ARROWSTREET CAPITAL, LIMITED PARTNERSHIP Added +5,371+5.4k
WINMILL & CO. INC New +4,800+4.8k

Biggest sellers

COOKE & BIELER LP Reduced -19,737-19.7k
FIDUCIARY MANAGEMENT INC /WI/ Reduced -18,516-18.5k
MORGAN STANLEY Reduced -12,429-12.4k
SUSQUEHANNA INTERNATIONAL GROUP, LLP Sold out -10,965-11.0k
Select Equity Group, L.P. Sold out -10,560-10.6k
RAYMOND JAMES FINANCIAL INC Reduced -9,118-9.1k
UBS AM, a distinct business unit of UBS ASSET MANAGEMENT AMERICAS LLC Reduced -7,765-7.8k
T. Rowe Price Investment Management, Inc. Reduced -7,276-7.3k
NEUBERGER BERMAN GROUP LLC Reduced -5,574-5.6k
BNP PARIBAS FINANCIAL MARKETS Reduced -5,454-5.5k

Biggest calls

None

Biggest puts

Chapman Investment Management, LLC New $296.5k143 shares

Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.

Major shareholders (over 5%)

Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.

HolderStakeChangeShares Last filed
VANGUARD CAPITAL MANAGEMENT LLC 13G · institution new · filed 2026-04-30 5.2% new 128.0k≈ $265.4m 2026-04-30

Fell to 5% or below in the last year: Neuberger Berman Group LLC (4.9%, 2026-05-07), VANGUARD GROUP INC (0.0%, 2026-03-27; now reported by VANGUARD CAPITAL MANAGEMENT LLC), MORGAN STANLEY (3.0%, 2026-02-12)

Insider purchases and sales since 1 Apr 2026

Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.

Officers and directors buying vs selling

Number of people, by quarter (10% owners not included)

BuyingSelling
404Q4 24: 0 buyingQ4 24: 0 sellingQ1 25: 0 buyingQ1 25: 0 sellingQ1 25Q2 25: 0 buyingQ2 25: 0 sellingQ3 25: 0 buyingQ3 25: 0 sellingQ3 25Q4 25: 0 buyingQ4 25: 3 sellingQ1 26: 0 buyingQ1 26: 0 sellingQ1 26Q2 26: 0 buyingQ2 26: 0 sellingQ3 26: 0 buyingQ3 26: 0 sellingQ3 26
Numbers
QuarterBuyingBoughtSellingSoldSold under a plan
Q4 20240—0——
Q1 20250—0——
Q2 20250—0——
Q3 20250—0——
Q4 20250—3$10.6m—
Q1 20260—0——
Q2 20260—0——
Q3 20260—0——

None reported since 1 Apr 2026.

Holders, Q2 2026

#ManagerLocationShares Value% of their portfolioChangeShares change
1 DIMENSIONAL FUND ADVISORS LP 0.06% of their portfolio AUSTIN, TX 158,954159.0k $329.6m $329.6m 0.06% Added +2.3k +2,336
2 NEUBERGER BERMAN GROUP LLC 0.16% of their portfolio NEW YORK, NY 119,141119.1k $247.0m $247.0m 0.16% Reduced -5.6k -5,574
3 BlackRock, Inc. 0.00% of their portfolio New York, NY 117,871117.9k $244.4m $244.4m 0.00% Added +4.5k +4,543
4 River Road Asset Management, LLC 2.67% of their portfolio LOUISVILLE, KY 115,880115.9k $240.3m $240.3m 2.67% Reduced -4.6k -4,639
5 VANGUARD PORTFOLIO MANAGEMENT LLC 0.01% of their portfolio MALVERN, PA 111,969112.0k $232.2m $232.2m 0.01% Reduced -3.6k -3,584
6 VANGUARD CAPITAL MANAGEMENT LLC 0.00% of their portfolio MALVERN, PA 107,479107.5k $222.8m $222.8m 0.00% Reduced -1.7k -1,678
7 FULLER & THALER ASSET MANAGEMENT, INC. 0.58% of their portfolio SAN MATEO, CA 101,892101.9k $211.3m $211.3m 0.58% Reduced -2.7k -2,669
8 COOKE & BIELER LP 2.04% of their portfolio PHILADELPHIA, PA 85,12085.1k $176.5m $176.5m 2.04% Reduced -19.7k -19,737
9 Wallace Capital Management Inc. 18.20% of their portfolio DALLAS, TX 80,06780.1k $166.0m $166.0m 18.20% Added +1.3k +1,272
10 FIDUCIARY MANAGEMENT INC /WI/ 1.96% of their portfolio MILWAUKEE, WI 66,55066.5k $138.0m $138.0m 1.96% Reduced -18.5k -18,516
11 GENDELL JEFFREY L 1.11% of their portfolio Greenwich, CT 59,24359.2k $122.8m $122.8m 1.11% Added +21.4k +21,429
12 Boston Partners 0.10% of their portfolio BOSTON, MA 55,56955.6k $115.3m $115.3m 0.10% Reduced -1.9k -1,890
13 LONDON CO OF VIRGINIA 0.64% of their portfolio RICHMOND, VA 54,02554.0k $112.1m $112.1m 0.64% Reduced -3.1k -3,106
14 STATE STREET CORP 0.00% of their portfolio BOSTON, MA 50,25750.3k $104.2m $104.2m 0.00% Added +1.1k +1,099
15 GEODE CAPITAL MANAGEMENT, LLC 0.01% of their portfolio BOSTON, MA 49,41249.4k $102.5m $102.5m 0.01% Added +7.3k +7,293
16 MORGAN STANLEY 0.01% of their portfolio NEW YORK, NY 46,86646.9k $97.2m $97.2m 0.01% Reduced -12.4k -12,429
17 REINHART PARTNERS, LLC. 2.11% of their portfolio MEQUON, WI 44,48044.5k $92.3m $92.3m 2.11% Added +7.1k +7,106
18 T. Rowe Price Investment Management, Inc. 0.05% of their portfolio BALTIMORE, MD 34,23734.2k $71.0m $71.0m 0.05% Reduced -7.3k -7,276
19 LORD, ABBETT & CO. LLC 0.19% of their portfolio JERSEY CITY, NJ 32,82932.8k $68.1m $68.1m 0.19% Reduced -281 -281
20 AMERICAN CENTURY COMPANIES INC 0.03% of their portfolio KANSAS CITY, MO 31,10831.1k $64.5m $64.5m 0.03% Added +22.8k +22,800
21 NORGES BANK 0.01% of their portfolio OSLO, Q8 27,95628.0k $58.0m $58.0m 0.01% Not comparable
22 Cannell & Spears LLC 1.02% of their portfolio NEW YORK, NY 27,57727.6k $57.2m $57.2m 1.02% Reduced -450 -450
23 BANK OF AMERICA CORP /DE/ 0.00% of their portfolio CHARLOTTE, NC 25,02825.0k $51.9m $51.9m 0.00% Reduced -3.3k -3,330
24 CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.01% of their portfolio SAN FRANCISCO, CA 23,50523.5k $48.7m $48.7m 0.01% Reduced -736 -736
25 Mraz, Amerine & Associates, Inc. 6.61% of their portfolio Modesto, CA 22,21822.2k $46.1m $46.1m 6.61% Added +39 +39
26 Allspring Global Investments Holdings, LLC 0.06% of their portfolio CHARLOTTE, NC 18,11618.1k $37.4m $37.4m 0.06% Reduced -496 -496
27 Gotham Asset Management, LLC 0.09% of their portfolio NEW YORK, NY 17,94017.9k $37.2m $37.2m 0.09% Added +8.9k +8,893
28 BROWN ADVISORY INC 0.06% of their portfolio BALTIMORE, MD 17,72217.7k $36.7m $36.7m 0.06% Reduced -122 -122
29 JANE STREET GROUP, LLC 0.02% of their portfolio NEW YORK, NY 17,22617.2k $35.7m $35.7m 0.02% Added +3.4k +3,418
30 SOUTHEASTERN ASSET MANAGEMENT INC/TN/ 1.85% of their portfolio MEMPHIS, TN 17,10417.1k $35.5m $35.5m 1.85% Reduced -1.8k -1,760
31 UBS Group AG 0.01% of their portfolio ZURICH, V8 16,19816.2k $33.6m $33.6m 0.01% Added +5.8k +5,757
32 VANGUARD FIDUCIARY TRUST CO 0.01% of their portfolio MALVERN, PA 15,31915.3k $31.8m $31.8m 0.01% Added +133 +133
33 RAYMOND JAMES FINANCIAL INC 0.01% of their portfolio ST. PETERSBURG, FL 14,83314.8k $30.8m $30.8m 0.01% Reduced -9.1k -9,118
34 NORTHERN TRUST CORP 0.00% of their portfolio CHICAGO, IL 14,57114.6k $30.2m $30.2m 0.00% Reduced -924 -924
35 WELLINGTON MANAGEMENT GROUP LLP 0.01% of their portfolio Boston, MA 14,53214.5k $30.1m $30.1m 0.01% Reduced -352 -352
36 ENVESTNET ASSET MANAGEMENT INC 0.01% of their portfolio Berwyn, PA 13,83813.8k $28.7m $28.7m 0.01% Reduced -1.7k -1,725
37 Quantinno Capital Management LP 0.03% of their portfolio NEW YORK, NY 12,62412.6k $26.2m $26.2m 0.03% Added +2.8k +2,840
38 ELKHORN PARTNERS LIMITED PARTNERSHIP 21.89% of their portfolio OMAHA, NE 12,32012.3k $25.5m $25.5m 21.89% Reduced -380 -380
39 HORIZON KINETICS ASSET MANAGEMENT LLC 0.29% of their portfolio NEW YORK, NY 12,20612.2k $25.3m $25.3m 0.29% Reduced -906 -906
40 GOLDMAN SACHS GROUP INC 0.00% of their portfolio NEW YORK, NY 12,15112.2k $25.2m $25.2m 0.00% Reduced -3.6k -3,632
41 BOUSSARD & GAVAUDAN GESTION SAS 1.24% of their portfolio PARIS, I0 11,67911.7k $24.5m $24.5m 1.24% First filing
42 VICTORY CAPITAL MANAGEMENT INC 0.01% of their portfolio San Antonio, TX 10,68410.7k $22.2m $22.2m 0.01% Reduced -461 -461
43 FIRST TRUST ADVISORS LP 0.01% of their portfolio Wheaton, IL 10,60410.6k $22.0m $22.0m 0.01% Added +7.5k +7,546
44 Qube Research & Technologies Ltd 0.02% of their portfolio LONDON, X0 9,6739.7k $20.1m $20.1m 0.02% Added +8.7k +8,657
45 SPEECE THORSON CAPITAL GROUP INC 4.08% of their portfolio MINNETONKA, MN 9,2159.2k $19.1m $19.1m 4.08% Reduced -182 -182
46 WELLS FARGO & COMPANY/MN 0.00% of their portfolio SAN FRANCISCO, CA 8,7108.7k $18.1m $18.1m 0.00% Reduced -72 -72
47 Bank of New York Mellon Corp 0.00% of their portfolio NEW YORK, NY 8,4128.4k $17.4m $17.4m 0.00% Reduced -32 -32
48 SEI INVESTMENTS CO 0.01% of their portfolio OAKS, PA 8,1088.1k $16.8m $16.8m 0.01% Reduced -3.0k -2,990
49 GW&K Investment Management, LLC 0.13% of their portfolio BOSTON, MA 7,8397.8k $16.3m $16.3m 0.13% Reduced -87 -87
50 THOMPSON SIEGEL & WALMSLEY LLC 0.29% of their portfolio RICHMOND, VA 7,6567.7k $15.9m $15.9m 0.29% Added +447 +447
51 ARROWSTREET CAPITAL, LIMITED PARTNERSHIP 0.01% of their portfolio BOSTON, MA 7,2847.3k $15.1m $15.1m 0.01% Added +5.4k +5,371
52 CITADEL ADVISORS LLC 0.01% of their portfolio MIAMI, FL 7,1367.1k $14.8m $14.8m 0.01% Added +4.5k +4,533
53 HOTCHKIS & WILEY CAPITAL MANAGEMENT LLC 0.04% of their portfolio Los Angeles, CA 6,7886.8k $14.1m $14.1m 0.04% Added +740 +740
54 ROYCE & ASSOCIATES LP 0.11% of their portfolio New York, NY 6,7816.8k $14.1m $14.1m 0.11% Added +321 +321
55 HRT FINANCIAL LP 0.03% of their portfolio NEW YORK, NY 6,7606.8k $14.0m $14.0m 0.03% Added +4.4k +4,385
56 D. E. Shaw & Co., Inc. 0.01% of their portfolio New York, NY 6,6186.6k $13.7m $13.7m 0.01% Reduced -2.3k -2,292
57 Edgestream Partners, L.P. 0.41% of their portfolio Princeton, NJ 6,5786.6k $13.6m $13.6m 0.41% Added +3.4k +3,448
58 AQR CAPITAL MANAGEMENT LLC 0.00% of their portfolio Greenwich, CT 5,4505.5k $11.3m $11.3m 0.00% Reduced -2.3k -2,288
59 JPMORGAN CHASE & CO 0.00% of their portfolio NEW YORK, NY 5,4105.4k $11.5m $11.5m 0.00% Added +2.8k +2,843
60 California Public Employees Retirement System 0.01% of their portfolio Sacramento, CA 5,2485.2k $10.9m $10.9m 0.01% Reduced -1.2k -1,166
61 Williams Jones Wealth Management, LLC. 0.12% of their portfolio NEW YORK, NY 5,1935.2k $10.8m $10.8m 0.12% Reduced -1 -1
62 Swiss National Bank 0.01% of their portfolio ZURICH, V8 4,8264.8k $10.0m $10.0m 0.01% Reduced -210 -210
63 WINMILL & CO. INC 2.20% of their portfolio WALPOLE, NH 4,8004.8k $10.0m $10.0m 2.20% New
64 FRANKLIN RESOURCES INC 0.00% of their portfolio San Mateo, CA 4,1784.2k $8.7m $8.7m 0.00% Reduced -620 -620
65 Phocas Financial Corp. 1.17% of their portfolio ALAMEDA, CA 4,0784.1k $8.5m $8.5m 1.17% Reduced -214 -214
66 RHUMBLINE ADVISERS 0.01% of their portfolio BOSTON, MA 3,8983.9k $8.1m $8.1m 0.01% Reduced -234 -234
67 Creative Planning 0.00% of their portfolio OVERLAND PARK, KS 3,8613.9k $8.0m $8.0m 0.00% Reduced -188 -188
68 Nuveen, LLC 0.00% of their portfolio CHARLOTTE, NC 3,6793.7k $7.6m $7.6m 0.00% Reduced -630 -630
69 Invesco Ltd. 0.00% of their portfolio ATLANTA, GA 3,4973.5k $7.3m $7.3m 0.00% Added +530 +530
70 LEE DANNER & BASS INC 0.39% of their portfolio NASHVILLE, TN 3,2533.3k $6.7m $6.7m 0.39% Added +50 +50
71 AMERIPRISE FINANCIAL INC 0.00% of their portfolio MINNEAPOLIS, MN 2,8522.9k $5.9m $5.9m 0.00% Reduced -14 -14
72 CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.01% of their portfolio WEST SACRAMENTO, CA 2,7612.8k $5.7m $5.7m 0.01% Reduced -126 -126
73 NEW YORK STATE COMMON RETIREMENT FUND 0.01% of their portfolio ALBANY, NY 2,5322.5k $5.2m $5.2m 0.01% Added +19 +19
74 Triad Investment Management 5.65% of their portfolio NEWPORT BEACH, CA 2,4712.5k $5.1m $5.1m 5.65% Reduced -42 -42
75 VANGUARD ASSET MANAGEMENT, Ltd 0.00% of their portfolio London, EC4N 8AF, X0 2,3922.4k $5.0m $5.0m 0.00% Added +67 +67
76 Russell Investments Group, Ltd. 0.00% of their portfolio Seattle, WA 2,3692.4k $4.9m $4.9m 0.00% Added +1.2k +1,227
77 STATE BOARD OF ADMINISTRATION OF FLORIDA RETIREMENT SYSTEM 0.01% of their portfolio TALLAHASSEE, FL 2,3512.4k $4.9m $4.9m 0.01% Added +90 +90
78 PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio BALTIMORE, MD 2,3352.3k $4.8m $4.8m 0.00% Added +124 +124
79 Legal & General Group Plc 0.00% of their portfolio London, X0 2,2572.3k $4.7m $4.7m 0.00% Reduced -151 -151
80 Robeco Institutional Asset Management B.V. 0.01% of their portfolio ROTTERDAM, P7 2,1842.2k $4.5m $4.5m 0.01% Added +5 +5
81 Regency Capital Management Inc.\DE 1.77% of their portfolio HONOLULU, HI 2,1462.1k $4.4m $4.4m 1.77% Added +611 +611
82 DAVENPORT & Co LLC 0.02% of their portfolio RICHMOND, VA 2,1232.1k $4.4m $4.4m 0.02% Unchanged
83 BRADLEY FOSTER & SARGENT INC/CT 0.06% of their portfolio HARTFORD, CT 1,8991.9k $3.9m $3.9m 0.06% Reduced -103 -103
84 PARSONS CAPITAL MANAGEMENT INC/RI 0.18% of their portfolio PROVIDENCE, RI 1,8871.9k $3.9m $3.9m 0.18% Reduced -1 -1
85 Lighthouse Investment Partners, LLC 0.12% of their portfolio Palm Beach Gardens, FL 1,8681.9k $3.9m $3.9m 0.12% New
86 Cerity Partners LLC 0.00% of their portfolio NEW YORK, NY 1,7971.8k $3.7m $3.7m 0.00% Reduced -70 -70
87 Atlantic Union Bankshares Corp 0.06% of their portfolio GLEN ALLEN, VA 1,7651.8k $3.7m $3.7m 0.06% Unchanged
88 MML INVESTORS SERVICES, LLC 0.01% of their portfolio SPRINGFIELD, MA 1,7411.7k $3.6m $3.6m 0.01% Reduced -718 -718
89 AGF MANAGEMENT LTD 0.01% of their portfolio TORONTO, A6 1,6961.7k $3.5m $3.5m 0.01% Reduced -7 -7
90 XTX Topco Ltd 0.04% of their portfolio LONDON, X0 1,6441.6k $3.4m $3.4m 0.04% Added +1.4k +1,394
91 Tidal Investments LLC 0.01% of their portfolio Milwaukee, WI 1,5781.6k $3.3m $3.3m 0.01% Added +230 +230
92 Focus Partners Wealth 0.00% of their portfolio ST LOUIS, MO 1,5531.6k $3.2m $3.2m 0.00% Added +424 +424
93 ExodusPoint Capital Management, LP 0.03% of their portfolio NEW YORK, NY 1,4431.4k $3.0m $3.0m 0.03% Added +832 +832
94 OPPENHEIMER ASSET MANAGEMENT INC. 0.03% of their portfolio NEW YORK, NY 1,3561.4k $2.8m $2.8m 0.03% Reduced -124 -124
95 LPL Financial LLC 0.00% of their portfolio FORT MILL, SC 1,3181.3k $2.7m $2.7m 0.00% Reduced -77 -77
96 HighTower Advisors, LLC 0.00% of their portfolio CHICAGO, IL 1,3161.3k $2.7m $2.7m 0.00% Reduced -131 -131
97 ROYAL BANK OF CANADA 0.00% of their portfolio TORONTO, A6 1,2371.2k $2.6m $2.6m 0.00% Added +42 +42
98 STIFEL FINANCIAL CORP 0.00% of their portfolio ST. LOUIS, MO 1,2351.2k $2.6m $2.6m 0.00% Reduced -59 -59
99 WCM INVESTMENT MANAGEMENT, LLC 0.00% of their portfolio LAGUNA BEACH, CA 1,1971.2k $2.5m $2.5m 0.00% Reduced -4.8k -4,798
100 1834 INVESTMENT ADVISORS CO 0.28% of their portfolio Milwaukee, WI 1,1761.2k $2.4m $2.4m 0.28% Unchanged