Hanover Insurance Group Inc — Current Report (Form 8-K)

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): August 19, 2025

THE HANOVER INSURANCE GROUP, INC.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (508) 855-1000

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:

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

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 under 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. ☐

The information set forth below in Item 8.01 is incorporated by reference into this Item 2.03.

On August 19, 2025, The Hanover Insurance Group, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Goldman Sachs & Co. LLC, J.P. Morgan Securities LLC and Morgan Stanley & Co. LLC, as representatives of the several underwriters named in Schedule I thereto (collectively, the “Underwriters”), pursuant to which the Company agreed to sell and the Underwriters agreed to purchase, upon the terms and subject to the conditions set forth therein, $500 million aggregate principal amount of the Company’s 5.500% Notes due 2035 (the “Notes”). The Notes were registered on Form S-3 under the Securities Act of 1933 (Registration Statement File No. 333-289677) (the “Registration Statement”) and were issued pursuant to an indenture dated as of April 8, 2016 (the “Base Indenture”) between the Company and U.S. Bank Trust Company National Association, as successor in interest to U.S. Bank National Association (the “Trustee”), as supplemented by the third supplemental indenture dated as of August 21, 2025 between the Company and the Trustee (the “Third Supplemental Indenture”).

On August 21, 2025, the Company completed the issuance and sale of the Notes. The Notes, which are senior unsecured obligations of the Company, will mature in 2035 and will bear interest at the rate of 5.500% per year, with interest payable semi-annually on March 1 and September 1 of each year, beginning on March 1, 2026. The Company may redeem the Notes in whole or in part on the terms set forth in the Third Supplemental Indenture. The Company plans to use the net proceeds from the issuance of the Notes to (i) repay its outstanding 7 5/8% Senior Debentures due 2025, (ii) repay or redeem its outstanding 4.500% Notes due 2026 and (iii) for general corporate purposes.

The foregoing summaries of the Underwriting Agreement, the Base Indenture and the Third Supplemental Indenture do not purport to be complete and are qualified in their entirety by references to such documents. The Underwriting Agreement and the Third Supplemental Indenture are filed hereto as Exhibits 1.1 and 4.2, respectively. The Base Indenture is filed as Exhibit 4.1 to the Company’s Current Report on Form 8-K (File No. 001-13754), filed with the SEC on April 8, 2016.

A copy of the opinion of Ropes & Gray LLP relating to the validity of the Notes is filed as Exhibit 5.1 hereto.

(d) Exhibits.

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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.

Date: August 21, 2025

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