WRB

SEC source: 0000011544-26-000044 · form4.xml · nonDerivative · entry 2

Welt Philip S · CIK 0001764818 · EVP & Secretary

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 214,033

F2 · shares: Represents payment of tax liability by withholding securities incident to the vesting of RSUs.

F3 · balance_after: Includes 139,750 shares of common stock underlying RSUs, all of which have vested (the receipt of which has been deferred) and does not include unvested shares of common stock underlying performance-based RSUs.

SEC source: 0000011544-26-000044 · form4.xml · nonDerivative · entry 1

Welt Philip S · CIK 0001764818 · EVP & Secretary

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 214,625

F1 · shares: Represents the vesting of tranches of performance-based restricted stock units ("RSUs") granted in 2021, 2022 and 2023 under the W. R. Berkley Corporation 2018 Stock Incentive Plan for the three-year performance period ending June 30, 2026 (consisting of 5,550 shares; 4,181 shares; and 4,355 shares, respectively).

SEC source: 0000011544-26-000043 · form4.xml · nonDerivative · entry 2

Baio Richard Mark · CIK 0001463038 · EVP & CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 227,611

F2 · shares: Represents payment of tax liability by withholding securities incident to the vesting of RSUs.

F3 · balance_after: Includes 224,986 shares of common stock underlying RSUs, all of which have vested (the receipt of which has been deferred) and does not include unvested shares of common stock underlying performance-based RSUs.

SEC source: 0000011544-26-000043 · form4.xml · nonDerivative · entry 1

Baio Richard Mark · CIK 0001463038 · EVP & CFO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 228,261

F1 · shares: Represents the vesting of tranches of performance-based restricted stock units ("RSUs") granted in 2021, 2022 and 2023 under the W. R. Berkley Corporation 2018 Stock Incentive Plan for the three-year performance period ending June 30, 2026 (consisting of 5,550 shares; 4,181 shares; and 4,355 shares, respectively).

SEC source: 0000011544-26-000042 · form4.xml · nonDerivative · entry 2

BERKLEY WILLIAM R JR · CIK 0001236253 · Director · Chairman, President and CEO · 10% owner

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 4,650,314

F2 · shares: Represents payment of tax liability by withholding securities incident to the vesting of RSUs.

F3 · balance_after: Includes 3,275,694 shares of common stock underlying RSUs, all of which have vested (the receipt of which has been deferred) and does not include unvested shares of common stock underlying performance-based RSUs.

SEC source: 0000011544-26-000042 · form4.xml · nonDerivative · entry 1

BERKLEY WILLIAM R JR · CIK 0001236253 · Director · Chairman, President and CEO · 10% owner

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 4,654,453

F1 · shares: Represents the vesting of tranches of performance-based restricted stock units ("RSUs") granted in 2021, 2022 and 2023 under the W. R. Berkley Corporation 2018 Stock Incentive Plan for the three-year performance period ending June 30, 2026 (consisting of 38,841 shares; 29,264 shares; and 30,488 shares, respectively).

SEC source: 0000011544-26-000041 · form4.xml · nonDerivative · entry 2

SHIEL JAMES G · CIK 0001236251 · EVP - Investments

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 810,633

F2 · shares: Represents payment of tax liability by withholding securities incident to the vesting of RSUs.

F3 · balance_after: Includes 660,468 shares of common stock underlying RSUs, all of which have vested (the receipt of which has been deferred) and does not include unvested shares of common stock underlying performance-based RSUs.

SEC source: 0000011544-26-000041 · form4.xml · nonDerivative · entry 1

SHIEL JAMES G · CIK 0001236251 · EVP - Investments

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 811,283

F1 · shares: Represents the vesting of tranches of performance-based restricted stock units ("RSUs") granted in 2021, 2022 and 2023 under the W. R. Berkley Corporation 2018 Stock Incentive Plan for the three-year performance period ending June 30, 2026 (consisting of 5,550 shares; 4,181 shares; and 4,355 shares, respectively).

SEC source: 0001193125-26-257711 · ownership.xml · nonDerivative · entry 1

BERKLEY WILLIAM R · CIK 0000918186 · Director · Executive Chairman · 10% owner

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 17,366,375

F1 · shares: Represents award granted pursuant to the terms of the W. R. Berkley Corporation 2009 Directors Stock Plan, as amended and restated.

F2 · balance_after: Includes 7,618,901 shares of common stock underlying Restricted Stock Units ("RSUs"), all of which have vested (the receipt of which has been deferred) and does not include shares of common stock underlying unvested performance-based RSUs.

SEC source: 0001193125-26-257689 · ownership.xml · nonDerivative · entry 1

Ferre Maria Luisa · CIK 0001289698 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 59,234

F1 · shares: Represents award granted pursuant to the terms of the W. R. Berkley Corporation 2009 Directors Stock Plan, as amended and restated.

SEC source: 0001193125-26-257685 · ownership.xml · nonDerivative · entry 1

Mattson Marie Angela · CIK 0002026387 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 9,667

F1 · shares: Represents award granted pursuant to the terms of the W. R. Berkley Corporation 2009 Directors Stock Plan, as amended and restated.

SEC source: 0001193125-26-257667 · ownership.xml · nonDerivative · entry 1

BERKLEY WILLIAM R JR · CIK 0001236253 · Director · President and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 4,555,860

F1 · shares: Represents award granted pursuant to the terms of the W. R. Berkley Corporation 2009 Directors Stock Plan, as amended and restated.

F2 · balance_after: Includes 3,181,240 shares of common stock underlying Restricted Stock Units ("RSUs"), all of which have vested (the receipt of which has been deferred) and does not include shares of common stock underlying unvested performance-based RSUs.

SEC source: 0001193125-26-257662 · ownership.xml · nonDerivative · entry 1

Mosley Daniel Lynn · CIK 0001961594 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 14,885

F1 · shares: Represents award granted pursuant to the terms of the W. R. Berkley Corporation 2009 Directors Stock Plan, as amended and restated.

SEC source: 0001193125-26-257656 · ownership.xml · nonDerivative · entry 1

Farrell Mary C · CIK 0001355414 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 19,378

F1 · shares: Represents award granted pursuant to the terms of the W. R. Berkley Corporation 2009 Directors Stock Plan, as amended and restated.

SEC source: 0001193125-26-257653 · ownership.xml · nonDerivative · entry 1

Rusbuldt Robert Alan · CIK 0002071104 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 5,866

F1 · shares: Represents award granted pursuant to the terms of the W. R. Berkley Corporation 2009 Directors Stock Plan, as amended and restated.

SEC source: 0001193125-26-257649 · ownership.xml · nonDerivative · entry 1

Augostini Christopher L · CIK 0001550828 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 109,859

F1 · shares: Represents award granted pursuant to the terms of the W. R. Berkley Corporation 2009 Directors Stock Plan, as amended and restated.

SEC source: 0001193125-26-257637 · ownership.xml · nonDerivative · entry 1

BLAYLOCK RONALD E · CIK 0001214686 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 121,990

F1 · shares: Represents award granted pursuant to the terms of the W. R. Berkley Corporation 2009 Directors Stock Plan, as amended and restated.

SEC source: 0001193125-26-257636 · ownership.xml · nonDerivative · entry 1

Talisman Jonathan · CIK 0001794251 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 33,180

F1 · shares: Represents award granted pursuant to the terms of the W. R. Berkley Corporation 2009 Directors Stock Plan, as amended and restated.

SEC source: 0001193125-26-089411 · ownership.xml · nonDerivative · entry 4

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 58,780,450

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F6 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $72.00 to $72.725.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-089411 · ownership.xml · nonDerivative · entry 3

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 58,707,265

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F5 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.1095 to $71.9984.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-089411 · ownership.xml · nonDerivative · entry 2

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 58,668,274

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F4 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $72.71 to $73.415.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-089411 · ownership.xml · nonDerivative · entry 1

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 58,567,377

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F2 · price: 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.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-083630 · ownership.xml · nonDerivative · entry 3

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 58,522,274

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F5 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.065 to $72.035.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-083630 · ownership.xml · nonDerivative · entry 2

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 58,375,274

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F4 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $72.00 to $72.39.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-083630 · ownership.xml · nonDerivative · entry 1

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 58,367,765

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F2 · price: 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.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-072599 · ownership.xml · nonDerivative · entry 6

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 58,222,274

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F8 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.70 to $72.07.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-072599 · ownership.xml · nonDerivative · entry 5

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 58,207,918

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F7 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.7116 to $71.6998.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-072599 · ownership.xml · nonDerivative · entry 4

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 58,053,406

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F6 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.0034 to $71.50.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-072599 · ownership.xml · nonDerivative · entry 3

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 57,991,812

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F5 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.0004 to $70.9982.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-072599 · ownership.xml · nonDerivative · entry 2

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 57,888,620

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F4 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.6325 to $72.0067.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-072599 · ownership.xml · nonDerivative · entry 1

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 57,872,210

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F2 · price: 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.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-061923 · ownership.xml · nonDerivative · entry 3

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 57,668,620

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F5 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.357 to $71.115.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-061923 · ownership.xml · nonDerivative · entry 2

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 57,508,038

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F4 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.0014 to $72.026.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-061923 · ownership.xml · nonDerivative · entry 1

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 57,464,024

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F2 · price: 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.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-057634 · ownership.xml · nonDerivative · entry 3

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 57,163,038

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F5 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.9003 to $71.435.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-057634 · ownership.xml · nonDerivative · entry 2

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 57,117,788

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F4 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.9646 to $70.90.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-057634 · ownership.xml · nonDerivative · entry 1

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 56,878,038

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F2 · price: 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.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-052089 · ownership.xml · nonDerivative · entry 5

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 56,596,652

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F7 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.0038 to $71.5014.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-052089 · ownership.xml · nonDerivative · entry 4

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 56,596,372

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F6 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.00 to $70.9521.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-052089 · ownership.xml · nonDerivative · entry 3

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 56,592,058

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F5 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.3373 to $69.9996.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-052089 · ownership.xml · nonDerivative · entry 2

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 56,576,652

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F4 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $72.465 to $73.0501.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-052089 · ownership.xml · nonDerivative · entry 1

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 56,574,251

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F2 · price: 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.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-047258 · ownership.xml · nonDerivative · entry 7

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 56,556,652

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F9 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.0043 to $71.635.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-047258 · ownership.xml · nonDerivative · entry 6

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 56,545,489

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F8 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.00 to $70.9925.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-047258 · ownership.xml · nonDerivative · entry 5

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 56,541,911

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F7 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.28 to $69.9981.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-047258 · ownership.xml · nonDerivative · entry 4

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 56,532,622

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F6 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.5057 to $70.185.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-047258 · ownership.xml · nonDerivative · entry 3

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 56,520,540

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F5 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.53 to $69.505.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-047258 · ownership.xml · nonDerivative · entry 2

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 56,498,656

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F4 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.0059 to $70.925.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-047258 · ownership.xml · nonDerivative · entry 1

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 56,494,608

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F2 · price: 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.

F3 · ownership.direct: 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.

SEC source: 0001193125-26-041641 · ownership.xml · nonDerivative · entry 4

MITSUI SUMITOMO INSURANCE CO LTD · CIK 0001142206 · 10% owner

MS&AD Insurance Group Holdings, Inc. · CIK 0001431048 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 56,458,656

F1 · kind: The purchases reported on this Form 4 were effected pursuant to a Rule 10b5-1 purchase plan, adopted October 3, 2025.

F6 · price: The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.0012 to $71.8345.

F3 · ownership.direct: 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.