W. R. Berkley discloses MSI gaining 12.5% ownership stake

W. R. Berkley Corporation reported a significant change in ownership of its common stock.

Rhea-AI Filing Summary

W. R. Berkley Corporation reported a significant change in ownership of its common stock. The company announced that Mitsui Sumitomo Insurance Co., Ltd. (MSI) has acquired beneficial ownership of at least 12.5% of W. R. Berkley’s outstanding common stock. This stake was obtained under MSI’s previously announced agreements with a company owned by members of the Berkley family and related trusts, indicating that the transaction involves a transfer from long‑standing family-related holders rather than a new share issuance by the company. The announcement was made through a press release dated December 5, 2025, which is filed as an exhibit and incorporated by reference.

Insights

Equity Ownership & Governance Analyst

MSI now holds at least 12.5% of W. R. Berkley’s common stock.

The company disclosed that Mitsui Sumitomo Insurance Co., Ltd. has acquired beneficial ownership of at least 12.5% of W. R. Berkley’s outstanding common stock. The stake comes from agreements with an entity owned by members of the Berkley family and related trusts, indicating a shift in who holds a sizable block of shares rather than the creation of new shares.

This type of transaction can be important for corporate governance because it changes the balance among major shareholders. The filing does not describe any changes to management, board composition, or strategic arrangements tied to MSI’s ownership; it is limited to noting the beneficial ownership level and its source.

Investors may pay particular attention to any future disclosures that describe MSI’s intentions or any formal agreements between MSI and W. R. Berkley, especially if additional filings reference this ownership position or related governance developments.

8-K Event Classification

2 items: 8.01, 9.01

2 items

Item 8.01 Other Events Other

Voluntary disclosure of events the company deems important to shareholders but not covered by other items.

Item 9.01 Financial Statements and Exhibits Exhibits

Financial statements, pro forma financial information, or exhibit attachments filed with this report.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What ownership change did W. R. Berkley (WRB) disclose in this 8-K?

The company disclosed that Mitsui Sumitomo Insurance Co., Ltd. (MSI) has acquired beneficial ownership of at least 12.5% of W. R. Berkley’s outstanding common stock.

How did MSI acquire its stake in W. R. Berkley (WRB)?

MSI acquired its stake pursuant to previously announced agreements with a company owned by members of the Berkley family and trusts for their benefit.

Does the disclosed transaction involve new shares issued by W. R. Berkley (WRB)?

The disclosure states that MSI acquired beneficial ownership of at least 12.5% of the outstanding common stock through agreements with a Berkley family-owned company and related trusts, indicating a transfer of existing shares.

Where can investors find more details on MSI’s 12.5% stake in W. R. Berkley?

Additional details are contained in the company’s press release dated December 5, 2025, which is filed as Exhibit 99.1 and incorporated by reference.

What securities of W. R. Berkley are listed on the New York Stock Exchange?

Listed securities include Common Stock (symbol WRB) and several subordinated debentures: 5.700% due 2058 (WRB-PE), 5.100% due 2059 (WRB-PF), 4.250% due 2060 (WRB-PG), and 4.125% due 2061 (WRB-PH).

Who signed this W. R. Berkley (WRB) 8-K related to MSI’s ownership?

The report was signed on behalf of W. R. Berkley Corporation by Richard M. Baio, Executive Vice President – Chief Financial Officer.

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Accepted by SEC EDGAR 12/05/2025 - 09:17 AM Learn about SEC filing dates

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): December 5, 2025

Commission File Number 1-15202

W. R. BERKLEY CORPORATION

(Exact name of registrant as specified in its charter)

Delaware		22-1867895
(State or other jurisdiction of incorporation or organization)		(I.R.S. Employer Identification No.)

475 Steamboat Road		Greenwich		Connecticut		06830
(Address of principal executive offices)						(Zip Code)

(203) 629-3000

(Registrant’s telephone number, including area code)

None

(Former name, former address and former fiscal year, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class		Trading Symbol(s)		Name of each exchange on which registered
Common Stock, par value $.20 per share		WRB		New York Stock Exchange
5.700% Subordinated Debentures due 2058		WRB-PE		New York Stock Exchange
5.100% Subordinated Debentures due 2059		WRB-PF		New York Stock Exchange
4.250% Subordinated Debentures due 2060		WRB-PG		New York Stock Exchange
4.125% Subordinated Debentures due 2061		WRB-PH		New York Stock Exchange

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 8.01 Other Events

On December 5, 2025, W. R. Berkley Corporation (the “Company”) issued a press release announcing that the Company has been informed by representatives of Mitsui Sumitomo Insurance Co., Ltd. (“MSI”) that MSI has acquired beneficial ownership of at least 12.5% of the Company’s outstanding common stock (the “Common Stock”) pursuant to MSI’s previously announced agreements with a company owned by members of the Berkley family and trusts for their benefit. The press release is attached as Exhibit 99.1 and incorporated by reference.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits.

Exhibit No.		Description
99.1		Press Release, issued December 5, 2025.
104		Cover Page Interactive Data File (embedded within the Inline XBRL document).

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

W. R. BERKLEY CORPORATION
By:		/s/ Richard M. Baio
		Name:   Richard M. Baio
		Title:   Executive Vice President – Chief Financial Officer

Date: December 5, 2025