UNITIL CORP

Electric Distribution Utility Operations

Unitil’s electric distribution operations are conducted through two of the Company’s utilities, Unitil Energy and Fitchburg. Revenue from Unitil’s electric utility operations was $236.4 million in 2025, which represents about 44% of Unitil’s total operating revenue. The Company’s GAAP (as defined below) Electric Gross Margin was $82.7 million in 2025. The Company’s Electric Adjusted Gross Margin (a non-GAAP financial measure) was $114.6 million in 2025, or 37% of Unitil’s total Adjusted Gross Margin. See “Results of Operations” in Part II, Item 7 (Management’s Discussion and Analysis of Financial Condition and Results of Operations) for a discussion of the non-GAAP financial measures presented in this Annual Report on Form 10-K, including a reconciliation of the non-GAAP financial measures to the most comparable GAAP financial measures for the periods presented.

The primary business of Unitil’s electric utility operations is the local distribution of electricity to customers in its service territory in New Hampshire and Massachusetts. All of Unitil Energy’s and Fitchburg’s electric customers are entitled to purchase their supply of electricity from third-party competitive suppliers, while Unitil Energy and Fitchburg remain their electric distribution company. Both Unitil Energy and Fitchburg supply electricity to those customers who do not obtain their supply from third-party competitive suppliers, with the approved costs associated with electricity supply being recovered on a pass-through basis under regulated reconciling rate mechanisms that are periodically adjusted.

Unitil Energy distributes electricity to approximately 79,400 customers in New Hampshire in the capital city of Concord as well as parts of thirteen surrounding towns, and all or part of nineteen towns in the southeastern and seacoast regions of New Hampshire, including the towns of Hampton, Exeter, Atkinson and Plaistow. Unitil Energy’s service territory consists of approximately 408 square miles. Unitil Energy’s service territory encompasses retail and recreation centers for the central and southeastern parts of the state and includes the Hampton Beach recreational area. These areas serve diversified commercial and industrial businesses, including manufacturing firms engaged in the production of electronic components, wire and plastics, as well as firms engaged in the aviation, defense, healthcare and education sectors. Unitil Energy’s 2025 electric operating revenue was $157.3 million, of which approximately 55% was derived from residential sales and 45% from commercial and industrial (C&I) sales.

Fitchburg is engaged in the distribution of both electricity and natural gas in the greater Fitchburg area of north central Massachusetts. Fitchburg’s service territory encompasses approximately 170 square miles. Electricity is distributed by Fitchburg to approximately 30,700 customers in the communities of Fitchburg, Ashby, Townsend and Lunenburg. Fitchburg’s industrial customers include paper manufacturing and paper products companies, rubber and plastics manufacturers, precision machining and molding, non-lethal ballistics manufacturing, specialty chemicals compounding, cannabis growing and processing facilities, printing, and educational institutions. Fitchburg’s 2025 electric operating revenue was $79.1 million, of which approximately 59% was derived from residential sales and 41% from C&I sales.

Natural Gas Operations

Unitil’s natural gas operations include gas distribution utility operations and interstate gas transmission pipeline operations. Revenue from Unitil’s gas operations was $299.6 million in 2025, which represents about 56% of Unitil’s total operating revenue. The Company’s GAAP Gas Gross Margin was $142.3 million in 2025. The Company’s Gas Adjusted Gross

Margin (a non-GAAP financial measure) was $199.1 million in 2025, or 63% of Unitil’s total Adjusted Gross Margin. See “Results of Operations” in Part II, Item 7 (Management’s Discussion and Analysis of Financial Condition and Results of Operations) for a discussion of the non-GAAP financial measures presented in this Annual Report on Form 10-K, including a reconciliation of the non-GAAP financial measures to the most comparable GAAP financial measures for the periods presented.

Natural Gas Distribution Utility Operations

Unitil’s natural gas distribution operations are conducted through four of the Company’s operating utilities, Northern Utilities, Fitchburg, Bangor and Maine Natural. The primary business of Unitil’s natural gas utility operations is the local distribution of natural gas to customers in its service territories in New Hampshire, Massachusetts and Maine. Northern Utilities’, Bangor’s and Maine Natural’s C&I customers and Fitchburg’s residential and C&I customers are able to purchase their natural gas supply from third-party competitive suppliers, while Northern Utilities, Bangor, Maine Natural or Fitchburg remains their gas distribution company. Northern Utilities, Fitchburg, Bangor and Maine Natural supply gas to those customers who do not obtain their supply from third-party competitive suppliers, with the approved costs associated with this gas supply recovered on a pass-through basis under regulated reconciling rate mechanisms that are periodically adjusted.

Northern Utilities distributes natural gas to approximately 73,200 customers in fifty New Hampshire and southern Maine communities, from Plaistow, New Hampshire in the south to the city of Portland, Maine and then extending to Lewiston-Auburn, Maine to the north. Northern Utilities has a diversified customer base both in Maine and New Hampshire. Commercial businesses include healthcare, education, government and retail. Northern Utilities’ industrial base includes manufacturers in the auto, housing, paper, printing, textile, pharmaceutical, electronics, wire and food production industries as well as a military installation. Northern Utilities’ 2025 gas operating revenue was $191.3 million, of which approximately 37% was derived from residential firm sales and 63% from C&I firm sales.

Fitchburg distributes natural gas to approximately 16,400 customers in the communities of Fitchburg, Lunenburg, Townsend, Ashby, Gardner and Westminster, all located in Massachusetts. Fitchburg’s industrial customers include paper manufacturing and paper products companies, rubber and plastics manufacturers, cannabis growing and processing facilities, printing, and educational institutions. Fitchburg’s 2025 gas operating revenue was $59.5 million, of which approximately 59% was derived from residential firm sales and 41% from C&I firm sales.

Bangor distributes natural gas to approximately 8,900 customers in ten communities in the Bangor area of central Maine. Bangor’s commercial customers include healthcare, education, retail and hospitality. Bangor’s industrial customers include manufacturers in outdoor products, electronics, and food production industries. Bangor’s 2025 gas operating revenue from the date of acquisition was $27.9 million, of which approximately 39% was derived from residential firm sales and 61% from C&I firm sales.

Maine Natural distributes natural gas to approximately 6,500 customers in nine communities in the greater Portland region of Maine, as well as the capital city of Augusta. Maine Natural’s commercial customers include healthcare, education, government and retail. Maine Natural’s industrial customers include shipbuilding, construction, aggregate and materials production, and paving. Maine Natural’s 2025 gas operating revenue from the date of acquisition was $8.3 million, of which approximately 28% was derived from residential firm sales and 72% from C&I firm sales.

Gas Transmission Pipeline Operations

Granite State is an interstate natural gas transmission pipeline company, operating 85 miles of underground gas transmission pipeline primarily located in Maine and New Hampshire. Granite State provides Northern Utilities with interconnection to major natural gas pipelines and access to domestic natural gas supplies in the south and Canadian natural gas supplies in the north. Granite State had operating revenue of $12.6 million in 2025. Granite State derives its revenues principally from the transportation services provided to Northern Utilities and to third-party suppliers under FERC-approved rates.

Seasonality

The Company’s results of operations are expected to reflect the seasonal nature of the natural gas business. Annual gas revenues are substantially realized during the colder weather seasons of the year as a result of higher sales of natural gas used for heating-related purposes. Accordingly, the results of operations are historically most favorable in the first and fourth quarters. Fluctuations in seasonal weather conditions may have a significant effect on the result of operations. Sales of electricity are generally less sensitive to weather than natural gas sales, but may also be affected by weather conditions and the temperature in the winter and summer seasons.

Unitil Energy, Fitchburg, Northern Utilities, Bangor and Maine Natural have a well-diversified customer mix and are not dependent on a single customer, or a few customers, for their electric and natural gas sales.

Revenue Decoupling

The Company’s electric and gas sales in Massachusetts and New Hampshire are largely decoupled. Revenue decoupling eliminates the dependency of distribution revenue on the volume of electricity or gas sold. The difference between distribution revenue amounts billed to customers and the targeted revenue decoupling amounts is recognized as an increase or a decrease in Accrued Revenue, which forms the basis for resetting rates for future cash recoveries from, or credits to, customers. These revenue decoupling targets may be adjusted as a result of rate cases and other authorized adjustments that the Company files with the MDPU and NHPUC.

Non-Regulated and Other Non-Utility Operations

The results of Unitil’s other non-utility subsidiaries, Unitil Service, Unitil Resources, Unitil Realty, Unitil Water and the holding company, are included in the Company’s consolidated results of operations. The results of these non-utility operations are principally derived from income earned on short-term investments and real property owned for Unitil’s and its subsidiaries’ use and are reported, after intercompany eliminations, in Other segment income. For segment information, see Note 2 (Segment Information) to the Consolidated Financial Statements included in Part II, Item 8 (Financial Statements and Supplementary Data) of this report.