[Form 4] BERKLEY W R CORP Insider Trading Activity

Rhea-AI Filing Summary

Mitsui Sumitomo Insurance Co., Ltd. (MSI)MS&AD Insurance Group Holdings, Inc., reported open-market purchases of W. R. Berkley Corporation common stock. On December 18, 2025, MSI bought 204,350 shares at a weighted average price of $69.3815 per share under a Rule 10b5-1 purchase plan adopted on October 3, 2025. On December 19, 2025, it acquired another 204,000 shares at a weighted average of $69.503.

On December 22, 2025, MSI purchased 39,940 shares at a weighted average price of $69.9716 and 162,060 shares at a weighted average of $70.3257. Following these transactions, MSI is shown as beneficially owning 49,211,938 W. R. Berkley shares in direct form. MS&AD may be deemed to beneficially own these securities through its 100% ownership of MSI but expressly disclaims beneficial ownership except to the extent of its pecuniary interest.

12/22/2025 - 08:45 PM

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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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)
12/18/2025

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	12/18/2025		P(1)		204,350	A	$69.3815(2)	48,805,938	D(3)
Common Stock	12/19/2025		P(1)		204,000	A	$69.503(4)	49,009,938	D(3)
Common Stock	12/22/2025		P(1)		39,940	A	$69.9716(5)	49,049,878	D(3)
Common Stock	12/22/2025		P(1)		162,060	A	$70.3257(6)	49,211,938	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 $68.82 to $69.60. 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 $69.36 to $69.955.

5. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $69.23 to $70.1973.

6. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.20 to $70.64.

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	12/22/2025
	MS&AD INSURANCE GROUP HOLDINGS, INC., By: /s/ Hironori Morimoto, Name: Hironori Morimoto, Title: Authorized Signatory	12/22/2025
	** 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).
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FAQ

What insider activity did WRB report in this Form 4 filing?

The filing shows that Mitsui Sumitomo Insurance Co., Ltd. (MSI) reported multiple open-market purchases of W. R. Berkley common stock on December 18, 19, and 22, 2025, increasing its directly held position.

How many W. R. Berkley (WRB) shares were purchased and at what prices?

MSI bought 204,350 shares at a weighted average $69.3815 on December 18, 204,000 shares at $69.503 on December 19, and on December 22 purchased 39,940 shares at $69.9716 and 162,060 shares at $70.3257, all as weighted average prices.

How many WRB shares does the reporting person beneficially own after these transactions?

After the reported purchases, the Form 4 lists MSI as beneficially owning 49,211,938 shares of W. R. Berkley common stock in direct ownership.

Was the WRB insider buying done under a Rule 10b5-1 trading 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, and the Form 4 includes the Rule 10b5-1 checkbox reference.

Who are the reporting persons in this WRB Form 4 filing and what is their relationship to the issuer?

The reporting persons are Mitsui Sumitomo Insurance Co., Ltd. and MS&AD Insurance Group Holdings, Inc.. The relationship section shows the reporting person as a Director of W. R. Berkley Corporation, and the explanatory footnote describes MSI as a wholly owned subsidiary of MS&AD.

Does MS&AD claim beneficial ownership of the WRB shares reported in this filing?

The filing explains that because MSI is wholly owned by MS&AD, MS&AD may be deemed to beneficially own the reported securities, but MS&AD expressly disclaims beneficial ownership except to the extent of its pecuniary interest.

Were any derivative securities of WRB reported in this Form 4?

No derivative securities are shown in Table II of the filing; only non-derivative common stock transactions are reported.