UNITIL CORP

In this Annual Report on Form 10-K, the “Company”, “Unitil”, “we”, and “our” refer to Unitil Corporation and its subsidiaries, unless the context requires otherwise. Unitil is a public utility holding company incorporated under the laws of the State of New Hampshire in 1984. The following companies are wholly-owned subsidiaries of Unitil:

Unitil and its subsidiaries are subject to regulation as a holding company system by the Federal Energy Regulatory Commission (FERC) under the Energy Policy Act of 2005.

Unitil’s principal business is the local distribution of electricity and natural gas to approximately 215,100 customers throughout its service territories in the states of New Hampshire, Massachusetts and Maine. Unitil is the parent company of five wholly-owned distribution utilities: i) Unitil Energy, which provides electric service in the southeastern seacoast and state capital regions of New Hampshire, including the capital city of Concord, ii) Fitchburg, which provides both electric and natural gas service in the greater Fitchburg area of north central Massachusetts, iii) Northern Utilities, which provides natural gas service in southeastern New Hampshire and portions of southern and central Maine, including the city of Portland, which is the largest city in northern New England, iv) Bangor, which provides natural gas service in the Bangor area of central Maine, and v) Maine Natural, which provides natural gas service in southern and central Maine, including the greater Portland region, as well as the capital city of Augusta. In addition, Unitil is the parent company of Granite State, an interstate natural gas transmission pipeline company that provides interstate natural gas pipeline access and transportation services to Northern Utilities in its New Hampshire and Maine service territory. Together, Unitil’s five distribution utilities serve approximately 110,100 electric customers and 105,000 natural gas customers.

Unitil had an investment in Net Utility Plant of $1.8 billion at December 31, 2025. The Company’s total operating revenue was $536.0 million in 2025. Unitil’s operating revenue is substantially derived from regulated electric and natural gas distribution utility operations. A seventh utility subsidiary, Unitil Power, formerly functioned as the full requirements wholesale power supply provider for Unitil Energy, but ceased being the wholesale supplier of Unitil Energy with the implementation of industry restructuring and divested its long-term power supply contracts.

Unitil has four other wholly-owned non-utility subsidiaries: Unitil Service, Unitil Realty, Unitil Resources and Unitil Water. Unitil Service provides, at cost, a variety of administrative and professional services, including regulatory, financial, accounting, human resources, engineering, operations, technology and energy supply management services on a centralized basis to its affiliated Unitil companies. Unitil Realty owns and manages the Company’s corporate office in Hampton, New Hampshire and land in Kingston, New Hampshire on which Unitil Energy’s solar facility is located, which became operational in May 2025. Unitil Resources is the Company’s wholly-owned non-regulated subsidiary which currently does not have any activity. Unitil Water currently does not have any activity. For segment information relating to each segment’s revenue, earnings and assets, see Note 2 (Segment Information) to the Consolidated Financial Statements included in Part II, Item 8 (Financial Statements and Supplementary Data) of this report. All of the Company’s revenues are attributable to customers in the United States of America and all its long-lived assets are located in the United States of America.