Unitil Corporation

Item 1.01 Entry into a Material Definitive Agreement. On October 21, 2026, Maine Natural Gas Corporation (“Maine Natural”), a natural gas distribution utility subsidiary of Unitil Corporation (the “Company” or the “Registrant”), entered into a Note Purchase Agreement with Lincoln National Reinsurance Company (Barbados) Limited, The Lincoln National Life Insurance Company, and CoBank, ACB (the “Note Purchase Agreement”) pursuant to which it issued and sold $40,000,000 of 5.95% Senior Unsecured Notes, due October 21, 2031 (the “Notes”). The Note Purchase Agreement and the Notes collectively contain customary representations and warranties, covenants and events of default for a transaction of this type. The Notes may or will become immediately due and payable upon an event of default, as described in the Note Purchase Agreement. The foregoing summary of the Note Purchase Agreement and the Notes does not purport to be complete and is subject to, and qualified in its entirety by, the full text of such documents, the executed copies or forms of which are attached hereto as exhibits to this Current Report on Form 8-K. Certain of the purchasers of the Notes (or their affiliates) are holders of other indebtedness of the Company or its subsidiaries. Maine Natural plans to use the net proceeds from this long-term financing to refinance existing debt of the Company (on a consolidated basis) and/or for general corporate purposes. Maine Natural offered the Notes principally to institutional investors in an offering made pursuant to the exemption from registration requirements under Section 4(a)(2) of the Securities Act of 1933, as amended (“Act”). The Notes have not been and will not be registered under the Act, or any state securities laws, and may not be offered or sold in the United States absent registration or an applicable exemption from the registration requirements of the Act and applicable state securities laws. The Company intends this notice to comply with Rule 135c of the Act and, accordingly, this notice does not constitute an offer to sell or the solicitation of an offer to buy any security and shall not constitute an offer, solicitation or sale of any securities in any jurisdiction in which such offer, solicitation or sale would be unlawful. The Note Purchase Agreement and a Note have been attached as exhibits to this Current Report on Form 8-K to provide investors with information regarding their terms. The representations, warranties and covenants contained in such documents were made only for purposes of such documents and as of specific dates, were solely for the benefit of the parties to such documents, and are subject to limitations agreed upon by the parties to such documents. Moreover, the representations and warranties contained in such documents were made for the purpose of allocating contractual risk between the parties to such documents instead of establishing matters as facts, and may be subject to standards of materiality applicable to the parties to such documents that differ from those applicable to investors generally. Investors (other than the parties to such documents) are not third-party beneficiaries under such documents and should not rely on the representations, warranties and covenants contained therein or any descriptions thereof as characterizations of the actual state of facts or condition of the Company or any of its subsidiaries or affiliates.

Item 1.02 Termination of a Material Definitive Agreement. As previously reported, on June 30, 2026, the Company entered into an Amended and Restated Credit Agreement dated as of June 30, 2026 among the following parties (the “Credit Agreement”): the Company; The Bank of Nova Scotia, as agent; and The Bank of Nova Scotia, as lender. On October 22, 2026, the Company repaid all outstanding amounts under the Credit Agreement, without premium or penalty. The Company may not reborrow any portion of the repaid amounts under the Credit Agreement. The Credit Agreement was scheduled to terminate on June 30, 2027, and all amounts outstanding under its tranche A loan (which related to the Company’s acquisition of Maine Natural Gas Corporation) were due and payable on October 31, 2026 and under its tranche B loan (which related to the Company’s acquisition of Aquarion Water Company of New Hampshire, Inc. (“AWC-NH”) and Abenaki Water Co., Inc. (“Abenaki”)) were due and payable on June 30, 2027. The Credit Agreement had a borrowing limit of $86.0 million with respect to its tranche A loan and $50.0 million with respect to its tranche B loan. The Credit Agreement generally provided Unitil with the ability to elect from one of two options with respect to interest on outstanding amounts. The Credit Agreement contained customary terms, conditions, restrictions and events of default for credit facilities of this type, including affirmative and negative covenants. The foregoing summary of the Credit Agreement and the transactions contemplated thereby does not purport to be complete and is subject to, and qualified in its entirety by, the full text of the Credit Agreement included as Exhibit 4.3 to this Form 8-K. Neither Unitil nor any of its controlled affiliates has any material relationship with The Bank of Nova Scotia, other than with respect to (i) the Credit Agreement, (ii) the debt commitment letter dated May 6, 2025 between Unitil and The Bank of Nova Scotia relating to the acquisition of Aquarion Water Company of Massachusetts, Inc. (“AWC-MA”), AWC-NH, and Abenaki, (iii) advice provided by The Bank of Nova Scotia or its affiliates in connection with the acquisition of AWC-MA, AWC-NH, and Abenaki, (iv) the debt commitment letter dated March 31, 2025 between the Company and The Bank of Nova Scotia relating to the acquisition of Maine Natural Gas Corporation, a Maine corporation, (vi) advice provided by The Bank of Nova Scotia or its affiliates in connection with the acquisition of Maine Natural Gas Corporation, (v) the debt commitment letter dated July 8, 2024 between the Company and The Bank of Nova Scotia relating to the acquisition of Bangor Natural Gas Company, a Maine corporation, (vi) advice provided by The Bank of Nova Scotia or its affiliates in connection with the acquisition of Bangor Natural Gas Company, and (vii) other customary banking and investment banking relationships.