Entry into a Material Definitive Agreement. 1. Amendment No. 4 to Purchase and Sale Agreement. As previously reported, on May 6, 2025, Unitil Corporation, a New Hampshire corporation (“ Unitil ” or the “ Company ”), entered into a Purchase and Sale Agreement (as amended, the “ Purchase Agreement ”) by and between the Company and Aquarion Water Authority, a public corporation and political subdivision of the state of Connecticut (“ AWA ” or “ Seller ”), and, solely with respect to Section 9.25…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The disclosure in

Other Events. On June 30, 2026, Unitil and Seller completed Unitil’s acquisition of all of the outstanding shares of capital stock of AWC-NH and Abenaki from Seller pursuant to the Purchase Agreement. Pursuant to the Purchase Agreement, as consideration for the shares of capital stock of AWC-NH and Abenaki, Unitil paid Seller $42.1 million in cash for the stock, plus approximately $0.6 million for estimated working capital and reimbursable capital expenditures.

Regulation FD Disclosure. A press release announcing the completion of Unitil’s acquisition of AWC-NH and Abenaki is attached as Exhibit 99.1 to this Form 8-K.

Entry into a Material Definitive Agreement. Amendment to Purchase Agreement As previously reported, on May 6, 2025, Unitil Corporation, a New Hampshire corporation (the " Company "), entered into a Purchase and Sale Agreement (the “ Purchase Agreement ”) by and between the Company and Aquarion Water Authority, a public corporation and political subdivision of the state of Connecticut (“ Seller ”), and, solely with respect to Section 9.25 and Section 9.26 thereof, South Central Connecticut Reg…

Entry into a Material Definitive Agreement. On April 30, 2026, Fitchburg Gas and Electric Light Company (“Fitchburg”), an electric and natural gas distribution utility subsidiary of Unitil Corporation (the “Company” or the “Registrant”), entered into a Note Purchase Agreement with State Farm Life Insurance Company, State Farm Life and Accident Assurance Company and CoBank, ACB (the “Note Purchase Agreement”) pursuant to which it issued and sold (i) $23,000,000 of 5.62% Senior Unsecured Notes,…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The disclosure in

Entry into a Material Definitive Agreement Distribution Agreement As previously reported, on June 3, 2025, Unitil Corporation, a New Hampshire corporation (the “ Company ”), entered into a Distribution Agreement (the “ Distribution Agreement ”) with Janney Montgomery Scott LLC and Scotia Capital (USA) Inc., as agents and/or forward sellers, and Janney Montgomery Scott LLC and The Bank of Nova Scotia, as forward purchasers, pursuant to which the Company may sell, from time to time, up to an ag…

Entry into a Material Definitive Agreement The disclosure required by this item is included in

The filing describes amendments to the company's equity compensation practices, which is not a management change.

Entry into a Material Definitive Agreement Amendment to Purchase Agreement On May 6, 2025, Unitil Corporation, a New Hampshire corporation (the “ Company ”), entered into a Purchase and Sale Agreement (the “ Purchase Agreement ”) by and between the Company and Aquarion Water Authority, a public corporation and political subdivision of the state of Connecticut (“ Seller ”), and, solely with respect to Section 9.25 and Section 9.26 thereof, South Central Connecticut Regional Water Authority (“…

General Counsel — Carleton B. Simpson: The filing discloses the internal promotion of Carleton B. Simpson to Senior Vice President and General Counsel, which is a succession event rather than a departure.

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant The disclosure in

Regulation FD Disclosure A press release announcing the completion of Unitil’s acquisition of Maine Natural is attached as Exhibit 99.1 to this Form 8-K.

Entry into a Material Definitive Agreement 1. Credit Agreement On October 31, 2025, Unitil Corporation (“ Unitil ”) entered into a Credit Agreement dated as of October 31, 2025 among the following parties (the “ Credit Agreement ”): Unitil; The Bank of Nova Scotia, as agent; and The Bank of Nova Scotia, as lender (the “ Lender ”). The Credit Agreement has a borrowing limit of $86 million. Subject to certain notice requirements, Unitil may irrevocably reduce or terminate the unutilized portion…

Entry into a Material Definitive Agreement On August 14, 2025, Unitil Corporation (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Wells Fargo Securities, LLC as representative of the several underwriters named therein (the “Underwriters”), pursuant to which the Company agreed to sell 1,393,355 shares of the Company’s common stock, without par value (“Common Stock”), at a public offering price of $46.65 per share (the “Offering”). In connection with t…

Entry into a Material Definitive Agreement On July 8, 2025, Bangor Natural Gas Company (“ Bangor ”), a natural gas distribution utility subsidiary of Unitil Corporation (the “ Company ” or the “ Registrant ”), entered into a Note Purchase Agreement with CoBank, ACB and United of Omaha Life Insurance Company (the “ Note Purchase Agreement ”) pursuant to which it issued and sold (i) $14,000,000 of 5.70% Senior Unsecured Notes, Series 2025A, due July 8, 2030 and (ii) $18,000,000 of 6.31% Senior…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant The disclosure in

Entry into a Material Definitive Agreement On June 3, 2025, Unitil Corporation, a New Hampshire corporation (the “Company”), entered into a Distribution Agreement (the “Distribution Agreement”) with Janney Montgomery Scott LLC and Scotia Capital (USA) Inc. (each, a “Sales Agent” and collectively, the “Sales Agents”), as agents and/or forward sellers, and Janney Montgomery Scott LLC and The Bank of Nova Scotia (each, a “Forward Purchaser” and collectively, the “Forward Purchasers”), as forward…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant The disclosure in

Entry into a Material Definitive Agreement Purchase Agreement On May 6, 2025, Unitil Corporation, a New Hampshire corporation (the “ Company ”), entered into a Purchase and Sale Agreement (the “ Purchase Agreement ”) by and between the Company and Aquarion Water Authority, a public corporation and political subdivision of the state of Connecticut (“ Seller ” or “ AWA ”), and, solely with respect to Section 9.25 and Section 9.26 thereof, South Central Connecticut Regional Water Authority (“ RW…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant The disclosure in

Entry into a Material Definitive Agreement Purchase Agreement On March 31, 2025, Unitil Corporation, a New Hampshire corporation (the “ Company ”), entered into a Stock Purchase Agreement (the “ Purchase Agreement ”) between the Company and Avangrid Enterprises, Inc., a Maine corporation ( Seller ). Neither the Company nor any of its controlled affiliates has any material relationship with Seller, other than with respect to the Purchase Agreement. The following is a brief summary of the mater…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant The disclosure in

Entry into a Material Definitive Agreement 1. Second Amendment to Third Amended and Restated Credit Agreement On January 29, 2025, Unitil Corporation (“ Unitil ”) entered into a Second Amendment to Third Amended and Restated Credit Agreement dated January 29, 2025 among the following parties (the “ Second Amendment ”): Unitil; Bank of America, N.A., as administrative agent; and Bank of America, N.A., Citizens Bank, N.A., and TD Bank, N.A. (each, a “ Lender ”). The Second Amendment further ame…