{"transactions":[{"id":873043,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-03-04T01:00:13.000Z","date":"2026-03-03","kind":"purchase","planned":true,"acquired":true,"shares":73185,"price":72.5238,"value":5307654.303,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $72.00 to $72.725."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":58780450,"source":{"system":"sec-edgar","filing":"0001193125-26-089411","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526089411/ownership.xml","form_type":"4"}},{"id":873042,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-03-04T01:00:13.000Z","date":"2026-03-03","kind":"purchase","planned":true,"acquired":true,"shares":38991,"price":71.5961,"value":2791603.5351,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.1095 to $71.9984."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":58707265,"source":{"system":"sec-edgar","filing":"0001193125-26-089411","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526089411/ownership.xml","form_type":"4"}},{"id":873041,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-03-04T01:00:13.000Z","date":"2026-03-02","kind":"purchase","planned":true,"acquired":true,"shares":100897,"price":73.198,"value":7385458.606,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $72.71 to $73.415."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":58668274,"source":{"system":"sec-edgar","filing":"0001193125-26-089411","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526089411/ownership.xml","form_type":"4"}},{"id":873040,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-03-04T01:00:13.000Z","date":"2026-03-02","kind":"purchase","planned":true,"acquired":true,"shares":45103,"price":72.2854,"value":3260288.3962,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.72 to $72.69. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4, 5 and 6."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":58567377,"source":{"system":"sec-edgar","filing":"0001193125-26-089411","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526089411/ownership.xml","form_type":"4"}},{"id":879168,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-28T00:30:41.000Z","date":"2026-02-27","kind":"purchase","planned":true,"acquired":true,"shares":147000,"price":71.6256,"value":10528963.2,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.065 to $72.035."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":58522274,"source":{"system":"sec-edgar","filing":"0001193125-26-083630","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526083630/ownership.xml","form_type":"4"}},{"id":879167,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-28T00:30:41.000Z","date":"2026-02-26","kind":"purchase","planned":true,"acquired":true,"shares":7509,"price":72.114,"value":541504.026,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $72.00 to $72.39."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":58375274,"source":{"system":"sec-edgar","filing":"0001193125-26-083630","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526083630/ownership.xml","form_type":"4"}},{"id":879166,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-28T00:30:41.000Z","date":"2026-02-26","kind":"purchase","planned":true,"acquired":true,"shares":145491,"price":71.646,"value":10423848.186,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.3483 to $71.9977. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4 and 5."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":58367765,"source":{"system":"sec-edgar","filing":"0001193125-26-083630","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526083630/ownership.xml","form_type":"4"}},{"id":883707,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-26T01:02:15.000Z","date":"2026-02-25","kind":"purchase","planned":true,"acquired":true,"shares":14356,"price":71.7704,"value":1030335.8624,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F8","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.70 to $72.07."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":58222274,"source":{"system":"sec-edgar","filing":"0001193125-26-072599","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":6,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526072599/ownership.xml","form_type":"4"}},{"id":883706,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-26T01:02:15.000Z","date":"2026-02-25","kind":"purchase","planned":true,"acquired":true,"shares":154512,"price":71.3917,"value":11030874.3504,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F7","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.7116 to $71.6998."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":58207918,"source":{"system":"sec-edgar","filing":"0001193125-26-072599","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526072599/ownership.xml","form_type":"4"}},{"id":883705,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-26T01:02:15.000Z","date":"2026-02-24","kind":"purchase","planned":true,"acquired":true,"shares":61594,"price":71.2836,"value":4390642.0584,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.0034 to $71.50."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":58053406,"source":{"system":"sec-edgar","filing":"0001193125-26-072599","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526072599/ownership.xml","form_type":"4"}},{"id":883704,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-26T01:02:15.000Z","date":"2026-02-24","kind":"purchase","planned":true,"acquired":true,"shares":103192,"price":70.5232,"value":7277430.0544,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.0004 to $70.9982."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":57991812,"source":{"system":"sec-edgar","filing":"0001193125-26-072599","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526072599/ownership.xml","form_type":"4"}},{"id":883703,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-26T01:02:15.000Z","date":"2026-02-23","kind":"purchase","planned":true,"acquired":true,"shares":16410,"price":71.8041,"value":1178305.281,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.6325 to $72.0067."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":57888620,"source":{"system":"sec-edgar","filing":"0001193125-26-072599","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526072599/ownership.xml","form_type":"4"}},{"id":883702,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-26T01:02:15.000Z","date":"2026-02-23","kind":"purchase","planned":true,"acquired":true,"shares":203590,"price":71.0931,"value":14473844.229,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.635 to $71.63. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4, 5, 6, 7 and 8."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":57872210,"source":{"system":"sec-edgar","filing":"0001193125-26-072599","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526072599/ownership.xml","form_type":"4"}},{"id":892336,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-21T00:34:24.000Z","date":"2026-02-20","kind":"purchase","planned":true,"acquired":true,"shares":160582,"price":70.8046,"value":11369944.2772,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.357 to $71.115."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":57668620,"source":{"system":"sec-edgar","filing":"0001193125-26-061923","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526061923/ownership.xml","form_type":"4"}},{"id":892335,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-21T00:34:24.000Z","date":"2026-02-19","kind":"purchase","planned":true,"acquired":true,"shares":44014,"price":71.4951,"value":3146785.3314,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.0014 to $72.026."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":57508038,"source":{"system":"sec-edgar","filing":"0001193125-26-061923","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526061923/ownership.xml","form_type":"4"}},{"id":892334,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-21T00:34:24.000Z","date":"2026-02-19","kind":"purchase","planned":true,"acquired":true,"shares":300986,"price":70.5273,"value":21227729.9178,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.0699 to $70.9988. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4 and 5."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":57464024,"source":{"system":"sec-edgar","filing":"0001193125-26-061923","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526061923/ownership.xml","form_type":"4"}},{"id":900128,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-18T23:30:03.000Z","date":"2026-02-18","kind":"purchase","planned":true,"acquired":true,"shares":45250,"price":70.9593,"value":3210908.325,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.9003 to $71.435."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":57163038,"source":{"system":"sec-edgar","filing":"0001193125-26-057634","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526057634/ownership.xml","form_type":"4"}},{"id":900127,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-18T23:30:03.000Z","date":"2026-02-18","kind":"purchase","planned":true,"acquired":true,"shares":239750,"price":70.5849,"value":16922729.775,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.9646 to $70.90."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":57117788,"source":{"system":"sec-edgar","filing":"0001193125-26-057634","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526057634/ownership.xml","form_type":"4"}},{"id":900126,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-18T23:30:03.000Z","date":"2026-02-17","kind":"purchase","planned":true,"acquired":true,"shares":281386,"price":71.1935,"value":20032854.191,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.595 to $71.573. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4 and 5."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56878038,"source":{"system":"sec-edgar","filing":"0001193125-26-057634","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526057634/ownership.xml","form_type":"4"}},{"id":906918,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-14T01:30:03.000Z","date":"2026-02-13","kind":"purchase","planned":true,"acquired":true,"shares":280,"price":71.184,"value":19931.52,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F7","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.0038 to $71.5014."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56596652,"source":{"system":"sec-edgar","filing":"0001193125-26-052089","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526052089/ownership.xml","form_type":"4"}},{"id":906917,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-14T01:30:03.000Z","date":"2026-02-13","kind":"purchase","planned":true,"acquired":true,"shares":4314,"price":70.2977,"value":303264.2778,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.00 to $70.9521."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56596372,"source":{"system":"sec-edgar","filing":"0001193125-26-052089","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526052089/ownership.xml","form_type":"4"}},{"id":906916,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-14T01:30:03.000Z","date":"2026-02-13","kind":"purchase","planned":true,"acquired":true,"shares":15406,"price":69.7349,"value":1074335.8694,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.3373 to $69.9996."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56592058,"source":{"system":"sec-edgar","filing":"0001193125-26-052089","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526052089/ownership.xml","form_type":"4"}},{"id":906915,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-14T01:30:03.000Z","date":"2026-02-12","kind":"purchase","planned":true,"acquired":true,"shares":2401,"price":72.7573,"value":174690.2773,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $72.465 to $73.0501."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56576652,"source":{"system":"sec-edgar","filing":"0001193125-26-052089","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526052089/ownership.xml","form_type":"4"}},{"id":906914,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-14T01:30:03.000Z","date":"2026-02-12","kind":"purchase","planned":true,"acquired":true,"shares":17599,"price":71.8808,"value":1265030.1992,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.4623 to $72.46. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4, 5, 6 and7."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56574251,"source":{"system":"sec-edgar","filing":"0001193125-26-052089","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526052089/ownership.xml","form_type":"4"}},{"id":911234,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-12T01:30:04.000Z","date":"2026-02-11","kind":"purchase","planned":true,"acquired":true,"shares":11163,"price":71.4493,"value":797588.5359,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F9","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.0043 to $71.635."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56556652,"source":{"system":"sec-edgar","filing":"0001193125-26-047258","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":7,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526047258/ownership.xml","form_type":"4"}},{"id":911233,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-12T01:30:04.000Z","date":"2026-02-11","kind":"purchase","planned":true,"acquired":true,"shares":3578,"price":70.5048,"value":252266.1744,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F8","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.00 to $70.9925."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56545489,"source":{"system":"sec-edgar","filing":"0001193125-26-047258","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":6,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526047258/ownership.xml","form_type":"4"}},{"id":911232,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-12T01:30:04.000Z","date":"2026-02-11","kind":"purchase","planned":true,"acquired":true,"shares":9289,"price":69.5877,"value":646400.1453,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F7","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.28 to $69.9981."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56541911,"source":{"system":"sec-edgar","filing":"0001193125-26-047258","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526047258/ownership.xml","form_type":"4"}},{"id":911231,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-12T01:30:04.000Z","date":"2026-02-10","kind":"purchase","planned":true,"acquired":true,"shares":12082,"price":69.9211,"value":844786.7302,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.5057 to $70.185."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56532622,"source":{"system":"sec-edgar","filing":"0001193125-26-047258","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526047258/ownership.xml","form_type":"4"}},{"id":911230,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-12T01:30:04.000Z","date":"2026-02-10","kind":"purchase","planned":true,"acquired":true,"shares":21884,"price":69.0872,"value":1511904.2848,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.53 to $69.505."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56520540,"source":{"system":"sec-edgar","filing":"0001193125-26-047258","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526047258/ownership.xml","form_type":"4"}},{"id":911229,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-12T01:30:04.000Z","date":"2026-02-09","kind":"purchase","planned":true,"acquired":true,"shares":4048,"price":70.3195,"value":284653.336,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.0059 to $70.925."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56498656,"source":{"system":"sec-edgar","filing":"0001193125-26-047258","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526047258/ownership.xml","form_type":"4"}},{"id":911228,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-12T01:30:04.000Z","date":"2026-02-09","kind":"purchase","planned":true,"acquired":true,"shares":35952,"price":69.2744,"value":2490553.2288,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.0015 to $69.9972. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4, 5, 6, 7, 8 and 9."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56494608,"source":{"system":"sec-edgar","filing":"0001193125-26-047258","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526047258/ownership.xml","form_type":"4"}},{"id":917174,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-07T01:46:48.000Z","date":"2026-02-06","kind":"purchase","planned":true,"acquired":true,"shares":4306,"price":71.3915,"value":307411.799,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.0012 to $71.8345."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56458656,"source":{"system":"sec-edgar","filing":"0001193125-26-041641","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526041641/ownership.xml","form_type":"4"}},{"id":917173,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-07T01:46:48.000Z","date":"2026-02-06","kind":"purchase","planned":true,"acquired":true,"shares":15694,"price":70.4608,"value":1105811.7952,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.1381 to $70.9994."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56454350,"source":{"system":"sec-edgar","filing":"0001193125-26-041641","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526041641/ownership.xml","form_type":"4"}},{"id":917172,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-07T01:46:48.000Z","date":"2026-02-05","kind":"purchase","planned":true,"acquired":true,"shares":13472,"price":71.2528,"value":959917.7216,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.0009 to $71.60."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56438656,"source":{"system":"sec-edgar","filing":"0001193125-26-041641","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526041641/ownership.xml","form_type":"4"}},{"id":917171,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-07T01:46:48.000Z","date":"2026-02-05","kind":"purchase","planned":true,"acquired":true,"shares":6528,"price":70.7889,"value":462109.9392,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.4471 to $70.9964. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4, 5 and 6."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56425184,"source":{"system":"sec-edgar","filing":"0001193125-26-041641","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526041641/ownership.xml","form_type":"4"}},{"id":920693,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-05T00:45:14.000Z","date":"2026-02-04","kind":"purchase","planned":true,"acquired":true,"shares":22415,"price":70.2528,"value":1574716.512,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F8","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.00 to $70.63."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56418656,"source":{"system":"sec-edgar","filing":"0001193125-26-038028","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":6,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526038028/ownership.xml","form_type":"4"}},{"id":920692,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-05T00:45:14.000Z","date":"2026-02-04","kind":"purchase","planned":true,"acquired":true,"shares":2585,"price":69.765,"value":180342.525,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F7","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.4645 to $69.995."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56396241,"source":{"system":"sec-edgar","filing":"0001193125-26-038028","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526038028/ownership.xml","form_type":"4"}},{"id":920691,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-05T00:45:14.000Z","date":"2026-02-03","kind":"purchase","planned":true,"acquired":true,"shares":31653,"price":68.8688,"value":2179904.1264,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.40 to $69.37."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56393656,"source":{"system":"sec-edgar","filing":"0001193125-26-038028","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526038028/ownership.xml","form_type":"4"}},{"id":920690,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-05T00:45:14.000Z","date":"2026-02-03","kind":"purchase","planned":true,"acquired":true,"shares":8347,"price":67.7486,"value":565497.5642,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.0009 to $68.7067."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56362003,"source":{"system":"sec-edgar","filing":"0001193125-26-038028","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526038028/ownership.xml","form_type":"4"}},{"id":920689,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-05T00:45:14.000Z","date":"2026-02-02","kind":"purchase","planned":true,"acquired":true,"shares":13159,"price":68.4171,"value":900300.6189,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $67.43 to $67.9942."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56353656,"source":{"system":"sec-edgar","filing":"0001193125-26-038028","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526038028/ownership.xml","form_type":"4"}},{"id":920688,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-02-05T00:45:14.000Z","date":"2026-02-02","kind":"purchase","planned":true,"acquired":true,"shares":237062,"price":67.7086,"value":16051136.1332,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $67.43 to $67.9942. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4, 5, 6, 7 and 8."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56340497,"source":{"system":"sec-edgar","filing":"0001193125-26-038028","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526038028/ownership.xml","form_type":"4"}},{"id":927634,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-31T00:30:03.000Z","date":"2026-01-30","kind":"purchase","planned":true,"acquired":true,"shares":195000,"price":68.3611,"value":13330414.5,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $67.83 to $68.645."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":56103435,"source":{"system":"sec-edgar","filing":"0001193125-26-032269","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526032269/ownership.xml","form_type":"4"}},{"id":927633,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-31T00:30:03.000Z","date":"2026-01-29","kind":"purchase","planned":true,"acquired":true,"shares":27718,"price":68.5605,"value":1900359.939,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.4004 to $69.015."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":55908435,"source":{"system":"sec-edgar","filing":"0001193125-26-032269","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526032269/ownership.xml","form_type":"4"}},{"id":927632,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-31T00:30:03.000Z","date":"2026-01-29","kind":"purchase","planned":true,"acquired":true,"shares":262282,"price":68.0816,"value":17856578.2112,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $67.43 to $68.40. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4 and 5."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":55880717,"source":{"system":"sec-edgar","filing":"0001193125-26-032269","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526032269/ownership.xml","form_type":"4"}},{"id":929693,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-29T01:30:13.000Z","date":"2026-01-28","kind":"purchase","planned":true,"acquired":true,"shares":28577,"price":67.8935,"value":1940192.5495,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F11","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $67.8011 to $68.015."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":55618435,"source":{"system":"sec-edgar","filing":"0001193125-26-027858","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":9,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526027858/ownership.xml","form_type":"4"}},{"id":929692,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-29T01:30:13.000Z","date":"2026-01-28","kind":"purchase","planned":true,"acquired":true,"shares":280354,"price":67.5756,"value":18945089.7624,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F10","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $66.87 to $67.80."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":55589858,"source":{"system":"sec-edgar","filing":"0001193125-26-027858","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":8,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526027858/ownership.xml","form_type":"4"}},{"id":929691,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-29T01:30:13.000Z","date":"2026-01-27","kind":"purchase","planned":true,"acquired":true,"shares":2671,"price":69.0351,"value":184392.7521,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F9","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.00 to $69.37."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":55309504,"source":{"system":"sec-edgar","filing":"0001193125-26-027858","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":7,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526027858/ownership.xml","form_type":"4"}},{"id":929690,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-29T01:30:13.000Z","date":"2026-01-27","kind":"purchase","planned":true,"acquired":true,"shares":8582,"price":68.561,"value":588390.502,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F8","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.25 to $68.99."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":55306833,"source":{"system":"sec-edgar","filing":"0001193125-26-027858","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":6,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526027858/ownership.xml","form_type":"4"}},{"id":929689,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-29T01:30:13.000Z","date":"2026-01-27","kind":"purchase","planned":true,"acquired":true,"shares":325960,"price":67.4036,"value":21970877.456,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F7","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $67.00 to $67.82."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":55298251,"source":{"system":"sec-edgar","filing":"0001193125-26-027858","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526027858/ownership.xml","form_type":"4"}},{"id":929688,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-29T01:30:13.000Z","date":"2026-01-27","kind":"purchase","planned":true,"acquired":true,"shares":11987,"price":66.8658,"value":801520.3446,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $66.03 to $66.9994."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":54972291,"source":{"system":"sec-edgar","filing":"0001193125-26-027858","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526027858/ownership.xml","form_type":"4"}},{"id":929687,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-29T01:30:13.000Z","date":"2026-01-27","kind":"purchase","planned":true,"acquired":true,"shares":800,"price":65.8618,"value":52689.44,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $65.77 to $65.975."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":54960304,"source":{"system":"sec-edgar","filing":"0001193125-26-027858","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526027858/ownership.xml","form_type":"4"}},{"id":929686,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-29T01:30:13.000Z","date":"2026-01-26","kind":"purchase","planned":true,"acquired":true,"shares":76389,"price":67.877,"value":5185056.153,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $67.4004 to $68.19."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":54959504,"source":{"system":"sec-edgar","filing":"0001193125-26-027858","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526027858/ownership.xml","form_type":"4"}},{"id":929685,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-29T01:30:13.000Z","date":"2026-01-26","kind":"purchase","planned":true,"acquired":true,"shares":293611,"price":66.8554,"value":19629480.8494,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $66.45 to $67.40. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4, 5, 6, 7, 8, 9, 10 and 11."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":54883115,"source":{"system":"sec-edgar","filing":"0001193125-26-027858","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526027858/ownership.xml","form_type":"4"}},{"id":933028,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-24T00:30:03.000Z","date":"2026-01-23","kind":"purchase","planned":true,"acquired":true,"shares":166919,"price":67.1803,"value":11213668.4957,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $67.00 to $67.9353."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":54589504,"source":{"system":"sec-edgar","filing":"0001193125-26-021399","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526021399/ownership.xml","form_type":"4"}},{"id":933027,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-24T00:30:03.000Z","date":"2026-01-23","kind":"purchase","planned":true,"acquired":true,"shares":201081,"price":66.7699,"value":13426158.2619,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $66.5195 to $66.9993."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":54422585,"source":{"system":"sec-edgar","filing":"0001193125-26-021399","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526021399/ownership.xml","form_type":"4"}},{"id":933026,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-24T00:30:03.000Z","date":"2026-01-22","kind":"purchase","planned":true,"acquired":true,"shares":330000,"price":67.4505,"value":22258665.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $67.09 to $67.66. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4 and 5."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":54221504,"source":{"system":"sec-edgar","filing":"0001193125-26-021399","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526021399/ownership.xml","form_type":"4"}},{"id":934885,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-22T00:30:03.000Z","date":"2026-01-21","kind":"purchase","planned":true,"acquired":true,"shares":260998,"price":67.6032,"value":17644299.9936,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $67.41 to $68.13."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":53891504,"source":{"system":"sec-edgar","filing":"0001193125-26-018358","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526018358/ownership.xml","form_type":"4"}},{"id":934884,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-22T00:30:03.000Z","date":"2026-01-21","kind":"purchase","planned":true,"acquired":true,"shares":59002,"price":66.9526,"value":3950337.3052,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $66.5523 to $67.40."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":53630506,"source":{"system":"sec-edgar","filing":"0001193125-26-018358","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526018358/ownership.xml","form_type":"4"}},{"id":934883,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-22T00:30:03.000Z","date":"2026-01-20","kind":"purchase","planned":true,"acquired":true,"shares":44994,"price":68.0772,"value":3063065.5368,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.00 to $68.2013."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":53571504,"source":{"system":"sec-edgar","filing":"0001193125-26-018358","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526018358/ownership.xml","form_type":"4"}},{"id":934882,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-22T00:30:03.000Z","date":"2026-01-20","kind":"purchase","planned":true,"acquired":true,"shares":265006,"price":67.7506,"value":17954315.5036,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $67.00 to $67.9998. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4, 5 and 6."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":53526510,"source":{"system":"sec-edgar","filing":"0001193125-26-018358","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526018358/ownership.xml","form_type":"4"}},{"id":938208,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-17T00:00:49.000Z","date":"2026-01-16","kind":"purchase","planned":true,"acquired":true,"shares":58691,"price":68.7857,"value":4037101.5187,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.6711 to $69.055."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":53261504,"source":{"system":"sec-edgar","filing":"0001193125-26-015569","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526015569/ownership.xml","form_type":"4"}},{"id":938207,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-17T00:00:49.000Z","date":"2026-01-16","kind":"purchase","planned":true,"acquired":true,"shares":241309,"price":68.031,"value":16416492.579,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $67.68 to $68.67."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":53202813,"source":{"system":"sec-edgar","filing":"0001193125-26-015569","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526015569/ownership.xml","form_type":"4"}},{"id":938206,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-17T00:00:49.000Z","date":"2026-01-15","kind":"purchase","planned":true,"acquired":true,"shares":68093,"price":69.4472,"value":4728868.1896,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.00 to $69.775."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":52961504,"source":{"system":"sec-edgar","filing":"0001193125-26-015569","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526015569/ownership.xml","form_type":"4"}},{"id":938205,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-17T00:00:49.000Z","date":"2026-01-15","kind":"purchase","planned":true,"acquired":true,"shares":166907,"price":68.675,"value":11462338.225,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.31 to $68.9978. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4, 5 and 6."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":52893411,"source":{"system":"sec-edgar","filing":"0001193125-26-015569","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526015569/ownership.xml","form_type":"4"}},{"id":939817,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-15T02:36:18.000Z","date":"2026-01-14","kind":"purchase","planned":true,"acquired":true,"shares":208272,"price":69.2333,"value":14419357.8576,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F7","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.00 to $69.74."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":52726504,"source":{"system":"sec-edgar","filing":"0001193125-26-013375","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526013375/ownership.xml","form_type":"4"}},{"id":939816,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-15T02:36:18.000Z","date":"2026-01-14","kind":"purchase","planned":true,"acquired":true,"shares":21728,"price":68.8019,"value":1494927.6832,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.245 to $68.9988."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":52518232,"source":{"system":"sec-edgar","filing":"0001193125-26-013375","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526013375/ownership.xml","form_type":"4"}},{"id":939815,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-15T02:36:18.000Z","date":"2026-01-13","kind":"purchase","planned":true,"acquired":true,"shares":206499,"price":68.1479,"value":14072473.2021,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.00 to $68.965."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":52496504,"source":{"system":"sec-edgar","filing":"0001193125-26-013375","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526013375/ownership.xml","form_type":"4"}},{"id":939814,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-15T02:36:18.000Z","date":"2026-01-13","kind":"purchase","planned":true,"acquired":true,"shares":118501,"price":67.8241,"value":8037223.6741,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $67.57 to $67.9993."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":52290005,"source":{"system":"sec-edgar","filing":"0001193125-26-013375","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526013375/ownership.xml","form_type":"4"}},{"id":939813,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-15T02:36:18.000Z","date":"2026-01-12","kind":"purchase","planned":true,"acquired":true,"shares":256041,"price":68.7344,"value":17598824.5104,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.42 to $69.30. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4, 5, 6 and 7."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":52171504,"source":{"system":"sec-edgar","filing":"0001193125-26-013375","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526013375/ownership.xml","form_type":"4"}},{"id":942874,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-10T01:00:04.000Z","date":"2026-01-09","kind":"purchase","planned":true,"acquired":true,"shares":8150,"price":70.1162,"value":571447.03,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F8","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.0011 to $70.4398."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":51915463,"source":{"system":"sec-edgar","filing":"0001193125-26-009283","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":6,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526009283/ownership.xml","form_type":"4"}},{"id":942873,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-10T01:00:04.000Z","date":"2026-01-09","kind":"purchase","planned":true,"acquired":true,"shares":105674,"price":69.5648,"value":7351190.6752,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F7","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.00 to $69.9974."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":51907313,"source":{"system":"sec-edgar","filing":"0001193125-26-009283","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526009283/ownership.xml","form_type":"4"}},{"id":942872,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-10T01:00:04.000Z","date":"2026-01-09","kind":"purchase","planned":true,"acquired":true,"shares":161176,"price":68.4816,"value":11037590.3616,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.36 to $68.9975."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":51801639,"source":{"system":"sec-edgar","filing":"0001193125-26-009283","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526009283/ownership.xml","form_type":"4"}},{"id":942871,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-10T01:00:04.000Z","date":"2026-01-08","kind":"purchase","planned":true,"acquired":true,"shares":151511,"price":70.3161,"value":10653662.6271,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.00 to $70.555."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":51640463,"source":{"system":"sec-edgar","filing":"0001193125-26-009283","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526009283/ownership.xml","form_type":"4"}},{"id":942870,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-10T01:00:04.000Z","date":"2026-01-08","kind":"purchase","planned":true,"acquired":true,"shares":39302,"price":69.6902,"value":2738964.2404,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.0527 to $69.995."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":51488952,"source":{"system":"sec-edgar","filing":"0001193125-26-009283","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526009283/ownership.xml","form_type":"4"}},{"id":942869,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-10T01:00:04.000Z","date":"2026-01-08","kind":"purchase","planned":true,"acquired":true,"shares":4187,"price":68.7913,"value":288029.1731,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.445 to $68.995. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4, 5, 6, 7 and 8."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":51449650,"source":{"system":"sec-edgar","filing":"0001193125-26-009283","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526009283/ownership.xml","form_type":"4"}},{"id":945403,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-08T00:30:04.000Z","date":"2026-01-07","kind":"purchase","planned":true,"acquired":true,"shares":10378,"price":69.2043,"value":718202.2254,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F9","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.00 to $69.445."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":51445463,"source":{"system":"sec-edgar","filing":"0001193125-26-006715","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":7,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526006715/ownership.xml","form_type":"4"}},{"id":945402,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-08T00:30:04.000Z","date":"2026-01-07","kind":"purchase","planned":true,"acquired":true,"shares":254622,"price":68.4677,"value":17433382.7094,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F8","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.07 to $68.9999."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":51435085,"source":{"system":"sec-edgar","filing":"0001193125-26-006715","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":6,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526006715/ownership.xml","form_type":"4"}},{"id":945401,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-08T00:30:04.000Z","date":"2026-01-06","kind":"purchase","planned":true,"acquired":true,"shares":92357,"price":70.2115,"value":6484523.5055,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F7","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.00 to $70.67."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":51180463,"source":{"system":"sec-edgar","filing":"0001193125-26-006715","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526006715/ownership.xml","form_type":"4"}},{"id":945400,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-08T00:30:04.000Z","date":"2026-01-06","kind":"purchase","planned":true,"acquired":true,"shares":122931,"price":69.9278,"value":8596294.3818,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.25 to $69.9999."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":51088106,"source":{"system":"sec-edgar","filing":"0001193125-26-006715","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526006715/ownership.xml","form_type":"4"}},{"id":945399,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-08T00:30:04.000Z","date":"2026-01-05","kind":"purchase","planned":true,"acquired":true,"shares":153686,"price":70.7775,"value":10877510.865,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.60 to $71.0727."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":50965175,"source":{"system":"sec-edgar","filing":"0001193125-26-006715","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526006715/ownership.xml","form_type":"4"}},{"id":945398,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-08T00:30:04.000Z","date":"2026-01-05","kind":"purchase","planned":true,"acquired":true,"shares":35894,"price":70.2323,"value":2520918.1762,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.706 to $70.5996."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":50811489,"source":{"system":"sec-edgar","filing":"0001193125-26-006715","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526006715/ownership.xml","form_type":"4"}},{"id":945397,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-08T00:30:04.000Z","date":"2026-01-05","kind":"purchase","planned":true,"acquired":true,"shares":11350,"price":69.1996,"value":785415.46,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.7 to $69.6978. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4, 5, 6, 7, 8 and 9."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":50775595,"source":{"system":"sec-edgar","filing":"0001193125-26-006715","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526006715/ownership.xml","form_type":"4"}},{"id":956261,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-03T00:00:04.000Z","date":"2026-01-02","kind":"purchase","planned":true,"acquired":true,"shares":237734,"price":69.3477,"value":16486306.1118,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.92 to $69.77."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":50764245,"source":{"system":"sec-edgar","filing":"0001193125-26-001178","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526001178/ownership.xml","form_type":"4"}},{"id":956260,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-03T00:00:04.000Z","date":"2025-12-31","kind":"purchase","planned":true,"acquired":true,"shares":230000,"price":70.2652,"value":16160996.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.08 to $70.785."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":50526511,"source":{"system":"sec-edgar","filing":"0001193125-26-001178","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526001178/ownership.xml","form_type":"4"}},{"id":956259,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2026-01-03T00:00:04.000Z","date":"2025-12-30","kind":"purchase","planned":true,"acquired":true,"shares":205000,"price":70.8284,"value":14519822.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.6 to $71.145. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4 and 5."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":50296511,"source":{"system":"sec-edgar","filing":"0001193125-26-001178","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312526001178/ownership.xml","form_type":"4"}},{"id":959169,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-12-30T00:00:04.000Z","date":"2025-12-29","kind":"purchase","planned":true,"acquired":true,"shares":205000,"price":70.7726,"value":14508383.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F7","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.535 to $70.989."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":50091511,"source":{"system":"sec-edgar","filing":"0001193125-25-335622","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312525335622/ownership.xml","form_type":"4"}},{"id":959168,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-12-30T00:00:04.000Z","date":"2025-12-26","kind":"purchase","planned":true,"acquired":true,"shares":220000,"price":70.558,"value":15522760.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.30 to $70.9844."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":49886511,"source":{"system":"sec-edgar","filing":"0001193125-25-335622","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312525335622/ownership.xml","form_type":"4"}},{"id":959167,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-12-30T00:00:04.000Z","date":"2025-12-24","kind":"purchase","planned":true,"acquired":true,"shares":220000,"price":70.5093,"value":15512046.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.13 to $70.64."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":49666511,"source":{"system":"sec-edgar","filing":"0001193125-25-335622","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312525335622/ownership.xml","form_type":"4"}},{"id":959166,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-12-30T00:00:04.000Z","date":"2025-12-23","kind":"purchase","planned":true,"acquired":true,"shares":2027,"price":71.1535,"value":144228.1445,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.06 to $71.18."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":49446511,"source":{"system":"sec-edgar","filing":"0001193125-25-335622","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312525335622/ownership.xml","form_type":"4"}},{"id":959165,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-12-30T00:00:04.000Z","date":"2025-12-23","kind":"purchase","planned":true,"acquired":true,"shares":232546,"price":70.3106,"value":16350448.7876,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.1731 to $70.99. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4, 5, 6 and 7."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":49444484,"source":{"system":"sec-edgar","filing":"0001193125-25-335622","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312525335622/ownership.xml","form_type":"4"}},{"id":961690,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-12-23T01:45:03.000Z","date":"2025-12-22","kind":"purchase","planned":true,"acquired":true,"shares":162060,"price":70.3257,"value":11396982.942,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.20 to $70.64."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":49211938,"source":{"system":"sec-edgar","filing":"0001193125-25-329220","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312525329220/ownership.xml","form_type":"4"}},{"id":961689,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-12-23T01:45:03.000Z","date":"2025-12-22","kind":"purchase","planned":true,"acquired":true,"shares":39940,"price":69.9716,"value":2794665.704,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.23 to $70.1973."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":49049878,"source":{"system":"sec-edgar","filing":"0001193125-25-329220","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312525329220/ownership.xml","form_type":"4"}},{"id":961688,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-12-23T01:45:03.000Z","date":"2025-12-19","kind":"purchase","planned":true,"acquired":true,"shares":204000,"price":69.503,"value":14178612.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.36 to $69.955."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":49009938,"source":{"system":"sec-edgar","filing":"0001193125-25-329220","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312525329220/ownership.xml","form_type":"4"}},{"id":961687,"issuer":{"id":3183,"kind":"organization","name":"BERKLEY W R CORP"},"owners":[{"id":63839,"kind":"organization","name":"Mitsui Sumitomo Insurance Co Ltd","position":1,"cik":"0001142206","reported_name":"MITSUI SUMITOMO INSURANCE CO LTD","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}},{"id":63840,"kind":"organization","name":"MS&AD Insurance Group Holdings, Inc.","position":2,"cik":"0001431048","reported_name":"MS&AD Insurance Group Holdings, Inc.","relationship":{"director":false,"officer":false,"ten_percent_owner":true,"other":false}}],"security":"Common Stock","published_at":"2025-12-23T01:45:03.000Z","date":"2025-12-18","kind":"purchase","planned":true,"acquired":true,"shares":204350,"price":69.3815,"value":14178109.525,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.82 to $69.60. The Reporting Persons undertake to provide to W.R. Berkley Corporation (the \"Issuer\"), any security holder of the Issuer, or the staff of the U.S. Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in this footnote and in footnotes 4, 5 and 6."},{"field":"ownership.direct","element":"directOrIndirectOwnership","label":"F3","text":"The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. (\"MSI\"). Because MSI is a wholly-owned subsidiary of MS&AD Insurance Group Holdings, Inc. (\"MS&AD\"), MS&AD may be deemed to beneficially own the reported securities. MS&AD expressly disclaims beneficial ownership of the reported securities, except to the extent of its pecuniary interest therein."}],"balance_after":48805938,"source":{"system":"sec-edgar","filing":"0001193125-25-329220","document":"ownership.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/11544/000119312525329220/ownership.xml","form_type":"4"}}]}