W.R. Berkley Corp (WRB) director Mitsui Sumitomo discloses stock purchases

Rhea-AI Filing Summary

Mitsui Sumitomo Insurance Co., Ltd., a director of W.R. Berkley Corporation, reported a series of open‑market purchases of WRB common stock in late December 2025. On December 23, 2025, it bought 232,546 shares at a weighted average price of $70.3106 and 2,027 shares at $71.1535. Additional purchases of 220,000 shares were made on December 24 and December 26, and 205,000 shares on December 29, at weighted average prices between $70.5093 and $70.7726. After these transactions, Mitsui Sumitomo reported beneficial ownership of 50,091,511 WRB shares held directly. The trades were executed under a Rule 10b5‑1 purchase plan adopted on October 3, 2025, and the filing notes that prices reflect weighted averages over multiple trades within stated ranges.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

X

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

MITSUI SUMITOMO INSURANCE CO LTD

(Last) (First) (Middle)

9, KANDA-SURUGADAI 3-CHOME, CHIYODA-KU

(Street)

TOKYO M0

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
BERKLEY W R CORP [ WRB ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
12/23/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

	Form filed by One Reporting Person
X	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	12/23/2025		P(1)		232,546	A	$70.3106(2)	49,444,484	D(3)
Common Stock	12/23/2025		P(1)		2,027	A	$71.1535(4)	49,446,511	D(3)
Common Stock	12/24/2025		P(1)		220,000	A	$70.5093(5)	49,666,511	D(3)
Common Stock	12/26/2025		P(1)		220,000	A	$70.558(6)	49,886,511	D(3)
Common Stock	12/29/2025		P(1)		205,000	A	$70.7726(7)	50,091,511	D(3)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

1. Name and Address of Reporting Person^*

MITSUI SUMITOMO INSURANCE CO LTD

(Last) (First) (Middle)

9, KANDA-SURUGADAI 3-CHOME, CHIYODA-KU

(Street)

TOKYO M0

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

MS&AD Insurance Group Holdings, Inc.

(Last) (First) (Middle)

TOKYO SUMITOMO TWIN BUILDING WEST TOWER,

27-2, SHINKAWA 2-CHOME, CHUO-KU,

(Street)

TOKYO M0

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

Explanation of Responses:

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

2. 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.

3. 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.

4. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $71.06 to $71.18.

5. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.13 to $70.64.

6. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.30 to $70.9844.

7. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.535 to $70.989.

Remarks:

MSI, the Issuer and WR Berkley & Others LLC ("WRBO") are party to certain agreements described in, and filed as exhibits to, the Reporting Persons' Schedule 13D filed with the U.S. Securities and Exchange Commission on December 11, 2025. The Reporting Persons disclaim beneficial ownership of the securities of the Issuer owned by WRBO and disclaim that the Reporting Persons and WRBO constitute a "group" within the meaning of Rule 13d-5(b)(1) under the Securities Exchange Act of 1934, as amended.

	MITSUI SUMITOMO INSURANCE CO., LTD., By: /s/ Hironori Morimoto, Name: Hironori Morimoto, Title: Authorized Signatory	12/29/2025
	MS&AD INSURANCE GROUP HOLDINGS, INC., By: /s/ Hironori Morimoto, Name: Hironori Morimoto, Title: Authorized Signatory	12/29/2025
	** Signature of Reporting Person	Date
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FAQ

What insider transactions were reported in W.R. Berkley (WRB) stock?

The reporting person disclosed multiple open‑market purchases of W.R. Berkley common stock on December 23, 24, 26 and 29, 2025, including blocks of 232,546, 2,027, 220,000, 220,000 and 205,000 shares.

Who reported these W.R. Berkley (WRB) insider purchases?

The transactions were reported by Mitsui Sumitomo Insurance Co., Ltd. (MSI) and its parent MS&AD Insurance Group Holdings, Inc., with MSI identified as holding the shares directly and MS&AD potentially deemed a beneficial owner through its wholly owned subsidiary.

At what prices were the recent WRB shares purchased?

The filing reports weighted average purchase prices of $70.3106, $71.1535, $70.5093, $70.558 and $70.7726 per share, with underlying trade prices ranging from $70.13 to $71.18 across the different transaction dates.

How many W.R. Berkley (WRB) shares are now beneficially owned after these trades?

Following the reported transactions, the Form 4 states that 50,091,511 shares of W.R. Berkley common stock are beneficially owned, held directly by Mitsui Sumitomo Insurance Co., Ltd.

Were the WRB insider purchases made under a Rule 10b5-1 plan?

Yes. The explanation notes that the purchases reported were effected pursuant to a Rule 10b5‑1 purchase plan adopted on October 3, 2025, which is intended to satisfy the affirmative defense conditions of Rule 10b5‑1(c).

What ownership and group status does MS&AD disclose regarding its WRB holdings?

The filing states that the shares are held directly by MSI, a wholly owned subsidiary of MS&AD, so MS&AD may be deemed to beneficially own the securities but expressly disclaims beneficial ownership except to the extent of its pecuniary interest. It also notes that the reporting persons disclaim that they and WR Berkley & Others LLC constitute a group under Rule 13d‑5(b)(1).