What changed in this filing

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Item 1. Business

2026-02-09 compared with 2025-02-10 · 62 added, 39 removed, 146 unchanged (41% of the section changed)

13 unchanged sentences

Natural Gas Distribution Utility

Bangor Natural Gas Company (Bangor)

Natural Gas Distribution Utility

Maine Natural Gas Corporation (Maine Natural)

Natural Gas Distribution Utility

Granite State Gas Transmission, Inc.

13 unchanged sentences

Non-regulated Energy Services

Unitil Water Corp.

(Unitil Water)

Non-regulated Company

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 three wholly-owned distribution utilities:

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 three distribution utilities serve approximately 109,400 electric customers and 89,100 natural gas customers.

Together, Unitil’s five distribution utilities serve approximately 110,100 electric customers and 105,000 natural gas customers.

Customers Served as of December 31, 2025

3 unchanged sentences

Northern Utilities

Maine Natural

Total Natural Gas

Total Customers Served

Unitil had an investment in Net Utility Plant of $1,539.6 million at December 31, 2024.

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 fifth 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 three other wholly-owned non-utility subsidiaries:

Unitil Service, Unitil Realty, and Unitil Resources.

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 for future use in Kingston, New Hampshire.

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.

On January 31, 2025, Unitil Corporation acquired Bangor Natural Gas Company, a natural gas distribution utility.

Bangor Natural Gas Company was incorporated under the laws of the State of Maine in 1998.

Electric Distribution Utility Operations

7 unchanged sentences

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 78,900 customers in New Hampshire in the capital city of Concord as well as parts of 12 surrounding towns, and all or part of 18 towns in the southeastern and seacoast regions of New Hampshire, including the towns of Hampton, Exeter, Atkinson and Plaistow.

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.

11 unchanged sentences

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 $166.9 million in 2024, or 61% of Unitil’s total Adjusted Gross Margin.

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 two of the Company’s operating utilities, Northern Utilities and Fitchburg.

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’ C&I customers and Fitchburg’s residential and C&I customers are entitled to purchase their natural gas supply from third-party competitive suppliers, while Northern Utilities or Fitchburg remains their gas distribution company.

Both Northern Utilities and Fitchburg 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 72,700 customers in 47 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’, 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.

3 unchanged sentences

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, 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

5 unchanged sentences

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.

Accordingly, the results of operations are historically most favorable in the first and fourth

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 and Northern Utilities 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.

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

Revenue decoupling is the term given to the elimination of the dependency of a utility’s distribution revenue on the volume of electricity or gas sales.

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 Massachusetts Department of Public Utilities (MDPU) and New Hampshire Public Utilities Commission (NHPUC).

Fitchburg has been subject to revenue decoupling since 2011.

Unitil Energy has been subject to revenue decoupling since June 1, 2022.

As a result of Unitil Energy now being subject to revenue decoupling, as of June 1, 2022, revenue decoupling now applies to substantially all of Unitil’s total annual electric sales volumes.

Substantially all of Northern Utilities’ gas sales volumes in New Hampshire have been subject to decoupling

since August 1, 2022.

The Company's electric and gas sales in New Hampshire and Massachusetts are now largely decoupled.

Northern Utilities’ gas sales volumes in Maine are not subject to revenue decoupling.

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, and the holding company, are included in the Company’s consolidated results of 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.

7 unchanged sentences

Fitchburg is subject to regulation by the MDPU;

and Northern Utilities is regulated by the NHPUC and Maine Public Utilities Commission (MPUC).

Northern Utilities is regulated by the NHPUC and Maine Public Utilities Commission (MPUC);

and Bangor and Maine Natural are regulated by the MPUC.

Granite State, Unitil’s interstate natural gas transmission pipeline, is subject to regulation by the FERC with regard to its rates and operations.

Because Unitil’s primary operations are subject to rate regulation, the regulatory treatment of various matters could significantly affect the Company’s operations and financial position.

Unitil’s distribution utilities deliver electricity and/or natural gas to all customers in their service territory, at rates established under cost of service regulation.

Unitil Energy, Fitchburg, Northern Utilities and Maine Natural’s non-Augusta service areas deliver electricity and/or natural gas to all customers in their service territory, at rates established under cost of service regulation.

Under this regulatory structure, Unitil’s distribution utilities are provided the opportunity to recover the cost of providing distribution service to their customers based on a test year, and to earn a reasonable return on their capital investment in utility assets.

In addition, the Company’s distribution utilities and its natural gas transmission pipeline company may recover certain base rate costs, including capital project spending and enhanced reliability and vegetation management programs, through annual step adjustments and cost tracking rate mechanisms.

The Company's electric and gas sales in New Hampshire and Massachusetts are now largely decoupled.

Bangor and Maine Natural’s Augusta Service Area deliver natural gas to their customers at rates established under alternative rate plans, which provide multi-year rate changes designed to approximate market-based rates.

The Company's electric and gas sales in New Hampshire and Massachusetts are largely decoupled.

Also see Note 1 (Summary of Significant Accounting Policies), Note 6 (Energy Supply) and Note 8 (Commitments and Contingencies) to the accompanying Consolidated Financial Statements for additional information regarding rates and regulation.

1 unchanged sentence

The Company considers its relationship with employees to be good and has not experienced any major labor disruptions.

The Company strives to be the employer of choice in the communities it serves—regardless of race, religion, color, gender, or sexual orientation.

The Company strives to be the employer of choice in the communities it serves.

The Company works diligently to attract the best talent from a diverse range of sources to meet the current and future demands of the Company’s business.

7 unchanged sentences

CBA Expiration

Unitil Energy

Northern Utilities NH Division

Northern Utilities ME Division

Maine Natural

Granite State

Unitil Energy

Unitil Service

1 unchanged sentence

The Company expects to negotiate new agreements prior to their expiration dates.

RECENT DEVELOPMENTS

Acquisition of Bangor Natural Gas Company

On January 31, 2025, the Company acquired all issued and outstanding shares of Bangor for $71.4 million, which includes an estimated working capital adjustment.

Through this acquisition, the Company expanded its service territory to include approximately 8,500 customers in the greater Bangor area of central Maine.

Acquisition of Maine Natural Gas Corporation

On March 31, 2025, the Company entered into a Stock Purchase Agreement (the Avangrid Purchase Agreement) between the Company and Avangrid Enterprises, Inc.

Pursuant to, and subject to the terms and conditions of, the Avangrid Purchase Agreement, the Company agreed to acquire all of the issued and outstanding shares of capital stock of Maine Natural from Avangrid for $86.0 million in cash, subject to certain adjustments as provided in the Avangrid Purchase Agreement.

The MPUC issued an order on September 12, 2025 approving the merger of Maine Natural into the Company.

The transaction closed on October 31, 2025.

AVAILABLE INFORMATION

The Internet address for the Company’s website is unitil.com .

On the Investors section of the Company’s website, the Company makes available, free of charge, its Securities and Exchange Commission (SEC) reports, including annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K and other reports, as well as amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Exchange Act as soon as reasonably practical after the Company electronically files such material with, or furnishes such material to, the SEC.

reports filed or furnished pursuant to Section 13(a) or 15(d) of the Exchange Act as soon as reasonably practical after the Company electronically files such material with, or furnishes such material to, the SEC.

The Company’s current Code of Ethics was approved by Unitil’s Board of Directors (the “Board”) on January 15, 2004.

10 unchanged sentences

Providence, RI 02940-3078

www.computershare.com/investor

computershare.com/investor

Investor Relations

1 unchanged sentence

800-999-6501 and ask for the Investor Relations Representative;

visit the Investors page at www.unitil.com ;

visit the Investors page at unitil.com ;

or contact the transfer agent, Computershare, at the number listed above.

2 unchanged sentences

The following services and programs are available to shareholders of record:

• Online Account Access is available at www.computershare.com/investor .

• Online Account Access is available at computershare.com/investor .

• Dividend Reinvestment and Stock Purchase Plan:

5 unchanged sentences

Compared sentence by sentence after normalising whitespace, quotation marks, case and digits, so re-formatting and restated figures do not read as changed language. Wording changes appear as one removal and one addition. The current filing and the prior one are authoritative.

What changed 10-K

Item 1. Business