Mitsui Sumitomo boosts W.R. Berkley (WRB) holdings with 10b5-1 stock purchases

Rhea-AI Filing Summary

Mitsui Sumitomo Insurance Co., Ltd., a 10% owner of W.R. Berkley Corporation, reported a series of open-market purchases of W.R. Berkley common stock executed under a Rule 10b5-1 purchase plan adopted on October 3, 2025.

On January 5–7, 2026, Mitsui Sumitomo recorded multiple buy transactions, including 153,686 shares at a weighted average price of $70.7775 on January 5 and 254,622 shares at a weighted average price of $68.4677 on January 7. Following the final reported trade, Mitsui Sumitomo is shown as beneficially owning 51,445,463 W.R. Berkley common shares directly.

The filing notes that these prices are weighted averages for numerous trades within stated price ranges and that additional detail is available on request. It also states that Mitsui Sumitomo is a wholly owned subsidiary of MS&AD Insurance Group Holdings, Inc., which may be deemed to beneficially own the 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
Estimated average burden
hours per response:			0.5

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)
01/05/2026

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	01/05/2026		P(1)		11,350	A	$69.1996(2)	50,775,595	D(3)
Common Stock	01/05/2026		P(1)		35,894	A	$70.2323(4)	50,811,489	D(3)
Common Stock	01/05/2026		P(1)		153,686	A	$70.7775(5)	50,965,175	D(3)
Common Stock	01/06/2026		P(1)		122,931	A	$69.9278(6)	51,088,106	D(3)
Common Stock	01/06/2026		P(1)		92,357	A	$70.2115(7)	51,180,463	D(3)
Common Stock	01/07/2026		P(1)		254,622	A	$68.4677(8)	51,435,085	D(3)
Common Stock	01/07/2026		P(1)		10,378	A	$69.2043(9)	51,445,463	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 $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.

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 $69.706 to $70.5996.

5. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.60 to $71.0727.

6. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.25 to $69.9999.

7. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.00 to $70.67.

8. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $68.07 to $68.9999.

9. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.00 to $69.445.

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	01/07/2026
	MS&AD INSURANCE GROUP HOLDINGS, INC., By: /s/ Hironori Morimoto, Name: Hironori Morimoto, Title: Authorized Signatory	01/07/2026
	** Signature of Reporting Person	Date
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FAQ

Who reported the recent insider transactions in W.R. Berkley (WRB) stock?

The transactions were reported by Mitsui Sumitomo Insurance Co., Ltd. ("Mitsui Sumitomo" or "MSI"), a 10% owner of W.R. Berkley Corporation, with MS&AD Insurance Group Holdings, Inc. also listed as a reporting person through its ownership of MSI.

What type of W.R. Berkley (WRB) transactions were disclosed in this Form 4?

The filing discloses open-market purchases of W.R. Berkley common stock, coded as transaction type "P" (purchase) in the non-derivative securities table, across several trades on January 5, 6, and 7, 2026.

How many W.R. Berkley (WRB) shares did Mitsui Sumitomo hold after these purchases?

After the final reported transaction on January 7, 2026, Mitsui Sumitomo is shown as beneficially owning 51,445,463 shares of W.R. Berkley common stock directly.

On what dates did Mitsui Sumitomo buy W.R. Berkley (WRB) shares and at what prices?

The purchases occurred on January 5, 6, and 7, 2026. Examples include 153,686 shares at a weighted average price of $70.7775 on January 5, 122,931 shares at $69.9278 on January 6, and 254,622 shares at $68.4677 on January 7. Prices are reported as weighted averages for multiple trades within specified ranges.

Were the W.R. Berkley (WRB) insider purchases made under a Rule 10b5-1 plan?

Yes. The filing states that the purchases were effected pursuant to a Rule 10b5-1 purchase plan that was adopted on October 3, 2025.

How does MS&AD Insurance Group Holdings, Inc. relate to the W.R. Berkley (WRB) shares?

The filing explains that the shares are held directly by Mitsui Sumitomo Insurance Co., Ltd., which is 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.

What do the weighted average prices mean in the W.R. Berkley (WRB) insider trades?

For each reported price, the filing notes that it is a weighted average of multiple individual trades executed within a stated range (for example, from $68.07 to $68.9999). The reporting persons undertake to provide full details of the number of shares purchased at each separate price within those ranges upon request.