Mitsui Sumitomo boosts W. R. Berkley (WRB) stake with 566,386-share buy

Rhea-AI Filing Summary

Mitsui Sumitomo Insurance Co., Ltd., a 10% owner of W. R. Berkley Corporation, reported open-market purchases of a total of 566,386 shares of common stock on February 17 and 18, 2026, at weighted average prices of about $70–71 per share.

The trades were executed under a pre-arranged Rule 10b5-1 purchase plan adopted on October 3, 2025. The 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 expressly disclaims beneficial ownership except to the extent of its pecuniary interest.

Insights

Equity ownership and governance analyst

Large 10% owner adds 566,386 W. R. Berkley shares via 10b5-1 plan.

Mitsui Sumitomo Insurance Co., Ltd., listed as a 10% owner, executed three open-market purchases of W. R. Berkley common stock totaling 566,386 shares at per-share prices in the low $70s. These were non-derivative transactions that increased its direct shareholdings.

The activity occurred on February 17–18, 2026 under a pre-established Rule 10b5-1 trading plan adopted on October 3, 2025, indicating the purchases were scheduled in advance. The filing notes that the shares are held by MSI, while parent MS&AD Insurance Group Holdings, Inc. may be deemed a beneficial owner but disclaims beneficial ownership beyond its pecuniary interest.

The Rule 10b5-1 framework and the explicit beneficial-ownership disclaimer frame these trades as part of a structured ownership program by a strategic holder rather than discretionary short-term trading. Future company filings may show how this sizable position evolves over subsequent reporting periods.

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)
02/17/2026

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	02/17/2026		P(1)		281,386	A	$71.1935(2)	56,878,038	D(3)
Common Stock	02/18/2026		P(1)		239,750	A	$70.5849(4)	57,117,788	D(3)
Common Stock	02/18/2026		P(1)		45,250	A	$70.9593(5)	57,163,038	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 $70.595 to $71.573. 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 and 5.

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 $69.9646 to $70.90.

5. The price reported is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $70.9003 to $71.435.

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	02/18/2026
	MS&AD INSURANCE GROUP HOLDINGS, INC., By: /s/ Hironori Morimoto, Name: Hironori Morimoto, Title: Authorized Signatory	02/18/2026
	** Signature of Reporting Person	Date
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FAQ

What insider transactions did Mitsui Sumitomo report for W. R. Berkley (WRB)?

Mitsui Sumitomo Insurance Co., Ltd. reported buying 566,386 shares of W. R. Berkley common stock. The purchases were non-derivative open-market transactions across three trades at weighted average prices in the low $70s, increasing its already significant ownership stake.

On what dates did the recent W. R. Berkley (WRB) insider share purchases occur?

The reported W. R. Berkley insider purchases occurred on February 17 and 18, 2026. All three transactions involved common stock acquired in open-market trades under a pre-arranged Rule 10b5-1 plan, at weighted average prices slightly above $70 per share.

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

Mitsui Sumitomo bought 566,386 W. R. Berkley shares in total. Individual trades were 281,386 shares at $71.1935, 239,750 shares at $70.5849, and 45,250 shares at $70.9593, all reported as weighted average prices from multiple executions.

Was the W. R. Berkley (WRB) insider buying done under a Rule 10b5-1 plan?

Yes. The filing states the W. R. Berkley share purchases were executed under a Rule 10b5-1 purchase plan adopted on October 3, 2025. Such plans pre-schedule trades, helping separate them from short-term discretionary trading decisions by the reporting holder.

Who is the actual holder of the W. R. Berkley (WRB) shares in this Form 4?

The shares are held directly by Mitsui Sumitomo Insurance Co., Ltd. Because it is wholly owned by MS&AD Insurance Group Holdings, Inc., MS&AD may be deemed a beneficial owner but expressly disclaims beneficial ownership except for its pecuniary interest in the securities.

How did these transactions affect Mitsui Sumitomo’s W. R. Berkley (WRB) holdings?

After the reported transactions, Mitsui Sumitomo’s direct W. R. Berkley holdings rose to over 57 million shares, based on the totals shown after each trade. This reflects a net increase of 566,386 shares through the three open-market purchases disclosed.