Mitsui Sumitomo boosts W. R. Berkley (WRB) stake with planned share purchases

Rhea-AI Filing Summary

Mitsui Sumitomo Insurance Co., Ltd. (MSI), a 10% owner of W. R. Berkley Corporation, reported multiple open-market purchases of WRB common stock on February 2–4, 2026. The trades, all coded "P", were executed under a pre-arranged Rule 10b5-1 purchase plan adopted on October 3, 2025.

Individual transactions included purchases such as 237,062 shares at a weighted average price of $67.7086 on February 2, 2026 and 22,415 shares at $70.2528 on February 4, 2026. Following the final reported transaction, MSI directly held 56,418,656 WRB common shares. MSI is a wholly owned subsidiary of MS&AD Insurance Group Holdings, Inc., which may be deemed to beneficially own these securities but expressly disclaims beneficial ownership except to the extent of its pecuniary interest.

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

OMB Number:			3235-0287
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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)
02/02/2026

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	02/02/2026		P(1)		237,062	A	$67.7086(2)	56,340,497	D(3)
Common Stock	02/02/2026		P(1)		13,159	A	$68.4171(4)	56,353,656	D(3)
Common Stock	02/03/2026		P(1)		8,347	A	$67.7486(5)	56,362,003	D(3)
Common Stock	02/03/2026		P(1)		31,653	A	$68.8688(6)	56,393,656	D(3)
Common Stock	02/04/2026		P(1)		2,585	A	$69.765(7)	56,396,241	D(3)
Common Stock	02/04/2026		P(1)		22,415	A	$70.2528(8)	56,418,656	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 $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.

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 $67.43 to $67.9942.

5. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.0009 to $68.7067.

6. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.40 to $69.37.

7. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.4645 to $69.995.

8. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.00 to $70.63.

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	02/04/2026
	MS&AD INSURANCE GROUP HOLDINGS, INC., By: /s/ Hironori Morimoto, Name: Hironori Morimoto, Title: Authorized Signatory	02/04/2026
	** Signature of Reporting Person	Date
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FAQ

What insider activity was reported in the WRB Form 4 filing?

The filing reports that Mitsui Sumitomo Insurance Co., Ltd. made several open-market purchases of W. R. Berkley (WRB) common stock on February 2–4, 2026 under a Rule 10b5-1 purchase plan, increasing its direct holdings to 56,418,656 shares after the final trade.

Who are the reporting persons in the WRB Form 4 and what is their role?

The reporting persons are Mitsui Sumitomo Insurance Co., Ltd. and its parent MS&AD Insurance Group Holdings, Inc., each listed as a 10% owner of W. R. Berkley (WRB). MSI directly holds the shares, while MS&AD may be deemed a beneficial owner through its wholly owned subsidiary relationship.

Were the WRB insider share purchases pre-planned under Rule 10b5-1?

Yes. The filing states that all reported W. R. Berkley (WRB) purchases were effected under a Rule 10b5-1 purchase plan adopted on October 3, 2025, indicating the trades followed a pre-established trading program rather than discretionary timing decisions during February 2026.

What prices were paid for the WRB shares in the reported transactions?

Each transaction is reported using a weighted average price. Examples include $67.7086 and $68.4171 on February 2, 2026 and $69.7650 and $70.2528 on February 4, 2026, with underlying individual trades executed within specified price ranges disclosed in the footnotes.

How many WRB shares did Mitsui Sumitomo hold after the latest reported trade?

After the final reported purchase on February 4, 2026, Mitsui Sumitomo Insurance Co., Ltd. directly held 56,418,656 shares of W. R. Berkley (WRB) common stock, according to the Form 4’s post-transaction beneficial ownership column for the non-derivative securities table.

How does MS&AD describe its beneficial ownership of WRB shares?

The filing explains that the shares are held directly by Mitsui Sumitomo Insurance Co., Ltd., a wholly owned subsidiary of MS&AD Insurance Group Holdings, Inc. MS&AD may be deemed to beneficially own the reported securities but expressly disclaims beneficial ownership except to the extent of its pecuniary interest.