Mitsui Sumitomo (WRB) adds 630,000 W.R. Berkley shares via plan

Rhea-AI Filing Summary

Mitsui Sumitomo Insurance Co., Ltd., a 10% owner of W. R. Berkley Corporation, reported open-market purchases of the company’s common stock over two days in January 2026 under a pre-arranged Rule 10b5‑1 trading plan adopted on October 3, 2025. On January 20, 2026, it bought 265,006 shares at a weighted average price of $67.7506 and 44,994 shares at $68.0772. On January 21, 2026, it purchased 59,002 shares at $66.9526 and 260,998 shares at $67.6032, for an aggregate 630,000 shares across both days. Following these transactions, the reporting persons show beneficial ownership of 53,891,504 shares. The filing notes that the shares are held directly by Mitsui Sumitomo Insurance Co., Ltd., and that MS&AD Insurance Group Holdings, Inc. may be deemed to beneficially own them 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)
01/20/2026

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	01/20/2026		P(1)		265,006	A	$67.7506(2)	53,526,510	D(3)
Common Stock	01/20/2026		P(1)		44,994	A	$68.0772(4)	53,571,504	D(3)
Common Stock	01/21/2026		P(1)		59,002	A	$66.9526(5)	53,630,506	D(3)
Common Stock	01/21/2026		P(1)		260,998	A	$67.6032(6)	53,891,504	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 $67.00 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.

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 $68.00 to $68.2013.

5. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $66.5523 to $67.40.

6. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $67.41 to $68.13.

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	01/21/2026
	MS&AD INSURANCE GROUP HOLDINGS, INC., By: /s/ Hironori Morimoto, Name: Hironori Morimoto, Title: Authorized Signatory	01/21/2026
	** Signature of Reporting Person	Date
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FAQ

What insider transactions did WRB report in this Form 4?

The Form 4 reports that Mitsui Sumitomo Insurance Co., Ltd., a 10% owner of W. R. Berkley Corporation (WRB), purchased common stock in four open-market transactions on January 20 and 21, 2026, totaling 630,000 shares at weighted average prices between $66.9526 and $68.0772.

Who are the reporting persons in the WRB Form 4 filing?

The reporting persons are Mitsui Sumitomo Insurance Co., Ltd. (MSI) and MS&AD Insurance Group Holdings, Inc., each listed as a 10% owner of W. R. Berkley Corporation.

At what prices did Mitsui Sumitomo buy WRB common stock?

The purchases were reported at weighted average prices of $67.7506 and $68.0772 on January 20, 2026, and $66.9526 and $67.6032 on January 21, 2026. Each reflects multiple trades within the stated price ranges.

How many WRB shares are beneficially owned after these transactions?

After the reported purchases, the filing shows beneficial ownership of 53,891,504 shares of W. R. Berkley Corporation common stock by the reporting persons.

Were the WRB share 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 adopted on October 3, 2025, which pre-specified the trading instructions.

How are the WRB shares held and what does MS&AD disclaim?

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

What do the weighted average prices in the WRB Form 4 mean?

Each reported price is a weighted average of multiple trades executed within stated ranges (for example, between $67.00 and $67.9998). The reporting persons undertake to provide the exact number of shares at each price within those ranges upon request.