Item 1.01 Entry into a Material Definitive Agreement. On June 9, 2026, W. R. Berkley Corporation (the “Company”) entered into the First Amendment (the “Amendment”) to that certain Credit Agreement, dated April 1, 2022 (as amended, the “Credit Agreement”), by and among the Company, as borrower, each lender from time to time party to the Credit Agreement, each of M&T Bank, JPMorgan Chase Bank, N.A. and Morgan Stanley Senior Funding, Inc., as Syndication Agents, and Bank of America, N.A., as Administrative Agent, Several L/C Agent and Fronting L/C Issuer. Capitalized terms used but not defined herein have the meanings ascribed to them in the Credit Agreement. The Amendment, among other things, extends the maturity date of the revolving credit facility under the Credit Agreement from April 1, 2027 to June 9, 2031, subject to the terms and conditions of the Credit Agreement. The foregoing description of the Amendment is qualified in its entirety by reference to the full text of the Amendment, which is filed as Exhibit 10.1 to this Current Report on Form 8-K and incorporated herein by reference. Item 2.03 Creation of a Direct Financial Obligation or an Obligation Under an Off-Balance Sheet Arrangement of a Registrant. The information set forth in Item 1.01 of this report is incorporated herein by reference. Item 9.01 Financial Statements and Exhibits. (d) Exhibits Exhibit 10.1 First Amendment to Credit Agreement, dated as of June 9, 2026, by and among the Company, Bank of America, N.A., as Administrative Agent, and the lenders party thereto.* Exhibit 104 Cover Page Interactive Data File (the cover page XBRL tags are embedded within the Inline XBRL document) * Schedules have been omitted pursuant to Item 601(a)(5) of Regulation S-K. The Company hereby undertakes to furnish supplementally copies of any of the omitted schedules upon request by the SEC. 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: June 11, 2026