Unitil Corp 2025年度报告

ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGEACT OF 1934For the fiscal year ended December 31, 2025 OR (Exact name of registrant as specified in its charter) New Hampshire(State or other jurisdiction of Name of each exchange of which registered New York Stock Exchange Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.Yes☒No☐ Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during thepreceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.Yes☒No☐ Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T(§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).Yes☒No☐ Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerginggrowth company. See the definitions of “large accelerated filer”, “accelerated filer”, “smaller reporting company” and “emerging growth company” in Rule 12b-2 of theExchange Act.Large accelerated filer☒Accelerated filer☐Non-accelerated filer☐Smaller reporting company☐ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revisedfinancial accounting standards provided pursuant to Section 13(a) of the Exchange Act☐ financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 762(b)) by the registered public accounting firm that prepared or issued its audit report☒If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflectthe correction of an error to previously issued financial statements.☐Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b).☐ Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act).Yes☐No☒ Based on the closing price of the registrant’s common stock on June 30, 2025, the aggregate market value of common stock held by non-affiliates of the registrant was$832,805,747.The number of shares of the registrant’s common stock outstanding was 17,983,994 as of February 6, 2026. Documents Incorporated by Reference: Portions of the Proxy Statement relating to the 2026 Unitil Corporation Annual Meeting of Shareholders to be held on April 29, 2026 are incorporated by reference into UNITIL CORPORATIONFORM 10-KFor the Fiscal Year Ended December 31, 2025Table of Contents Description PART I 1.BusinessUnitil CorporationOperationsRates and RegulationEmployeesAvailable InformationInvestor Information1A.Risk Factors 1B.Unresolved Staff Comments1C.Cybersecurity2.Properties3.Legal Proceedings4.Mine Safety Disclosures PART II 5.Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities206.Reserved217.Management’s Discussion and Analysis of Financial Condition and Results of Operations (MD&A)227A.Quantitative and Qualitative Disclosures about Market Risk368.Financial Statements and Supplementary Data379.Changes in and Disagreements with Accountants on Accounting and Financial Disclosure929A.Controls and Procedures929B.Other Information929C.Disclosure Regarding Foreign Jurisdictions that Prevent Inspections92 PART III 10.Directors, Executive Officers and Corporate Governance11.Executive Compensation12.Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters13.Certain Relationships and Related Transactions, and Director Independence14.Principal Accountant Fees and Services PART IV SIGNATURES In this Annual Report on Form 10-K, the “Company”, “Unitil”, “we”, “us”, “our” and similar terms refer to UnitilCorporation and its subsidiaries, unless the context requires otherwise. CAUTIONARY STATEMENT This report and the documents incorporated by reference into this report contain statements that may constitute “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, Section 21E of the SecuritiesExchange Act of 1934, as amended (the “Exchange Act”), and the Private Securities Litigation Reform Act of 1995. All statements,other than statements of historical fact, included or incorporated by reference into this report, including, without limitation, statement