Large WRB (NYSE: WRB) holder adds 553,654 shares under 10b5-1 plan

Rhea-AI Filing Summary

BERKLEY W R CORP reported substantial insider-related buying of its common stock by Mitsui Sumitomo Insurance Co., Ltd. over three days. The reporting group purchased a total of 553,654 shares in open-market transactions on February 23, 24 and 25, 2026 at prices generally around the low-$70 range per share.

These trades were executed under a pre-arranged Rule 10b5-1 purchase plan adopted on October 3, 2025, meaning the buying followed a preset schedule rather than day-to-day discretion. The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd.; its parent, 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
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)
02/23/2026

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	02/23/2026		P(1)		203,590	A	$71.0931(2)	57,872,210	D(3)
Common Stock	02/23/2026		P(1)		16,410	A	$71.8041(4)	57,888,620	D(3)
Common Stock	02/24/2026		P(1)		103,192	A	$70.5232(5)	57,991,812	D(3)
Common Stock	02/24/2026		P(1)		61,594	A	$71.2836(6)	58,053,406	D(3)
Common Stock	02/25/2026		P(1)		154,512	A	$71.3917(7)	58,207,918	D(3)
Common Stock	02/25/2026		P(1)		14,356	A	$71.7704(8)	58,222,274	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 $70.635 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.

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 $71.6325 to $72.0067.

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

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

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

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

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	02/25/2026
	MS&AD INSURANCE GROUP HOLDINGS, INC., By: /s/ Hironori Morimoto, Name: Hironori Morimoto, Title: Authorized Signatory	02/25/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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FAQ

What insider transactions did WRB report for Mitsui Sumitomo Insurance?

BERKLEY W R CORP reported that Mitsui Sumitomo Insurance Co., Ltd. bought 553,654 WRB common shares in open-market trades. The purchases occurred on February 23–25, 2026 at prices generally in the low-$70 range and were executed under a pre-set Rule 10b5-1 trading plan.

Over what dates were the recent WRB insider share purchases made?

The reported insider-related purchases in WRB common stock occurred on February 23, 24 and 25, 2026. Multiple open-market trades were executed each day, with weighted average prices in the low-$70s, as part of a Rule 10b5-1 purchase plan adopted earlier.

How many WRB shares did Mitsui Sumitomo Insurance acquire in total?

Mitsui Sumitomo Insurance Co., Ltd. acquired a total of 553,654 WRB common shares in these transactions. Individual trades ranged from about 14,356 to 203,590 shares, all reported as open-market purchases under a Rule 10b5-1 trading plan filed on the Form 4.

At what prices were the WRB insider purchases executed?

The WRB insider-related purchases were executed at weighted average prices mainly around $70–$72 per share. Footnotes state the trades occurred in multiple transactions within ranges such as $70.0004–$72.07, with exact breakdowns available upon request from the reporting persons.

Who is considered the holder of the WRB shares bought in this Form 4?

The WRB shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. Its parent, MS&AD Insurance Group Holdings, Inc., may be deemed a beneficial owner but explicitly disclaims beneficial ownership, except for its pecuniary interest, according to the ownership footnote included in the Form 4.

Was the WRB insider buying discretionary or under a trading plan?

The WRB insider-related buying was executed under a Rule 10b5-1 purchase plan adopted on October 3, 2025. Such plans pre-set trading parameters, so these transactions followed the established schedule rather than being made at the day-to-day discretion of the reporting entities.