UNITIL CORP 10-K

Item 9A. Controls and Procedures Disclosure Controls and Procedures Management of the Company, under the supervision and with the participation of the Company’s Chief Executive Officer, Chief Financial Officer, and Chief Accounting Officer, conducted an evaluation of the effectiveness of the design and operation of the Company’s disclosure controls and procedures as of December 31, 2025. Based on this evaluation, the Company’s Chief Executive Officer, Chief Financial Officer, and Chief Accounting Officer concluded as of December 31, 2025 that the Company’s disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) were effective. Management’s Report on Internal Control over Financial Reporting Management is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Exchange Act Rules 13a-15(f) and 15d-15(f). Under the supervision and with the participation of management, including the Chief Executive Officer, Chief Financial Officer, and Chief Accounting Officer, the Company’s management has evaluated the effectiveness of the Company’s internal control over financial reporting as of December 31, 2025, based upon criteria established in the “Internal Control–Integrated Framework” (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based on this evaluation, the Company’s management concluded that the Company’s internal control over financial reporting was effective as of December 31, 2025. There were no material changes in internal control over financial reporting during the year ended December 31, 2025 that materially affected, or are reasonably likely to materially affect, the Company’s internal control over financial reporting. Management continues to evaluate and enhance controls related to significant estimates, including regulatory assets, revenue recognition, and pension and postretirement obligations. Management's assessment of the effectiveness of the Company's internal control over financial reporting as of December 31, 2025 excluded the internal controls of Maine Natural Gas Corporation, which was acquired on October 31, 2025. Maine Natural Gas Corporation's total assets and total revenues represented approximately 4.9% and 1.5%, respectively, of the Company's consolidated total assets and revenues as of and for the year ended December 31, 2025. Deloitte & Touche LLP, an independent registered public accounting firm, has audited the effectiveness of the Company’s internal control over financial reporting as of December 31, 2025, as stated in their report which appears in Part II, Item 8 herein. Changes in Internal Control over Financial Reporting Except as described above, there have been no changes in the Company’s internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) during the fiscal quarter ended December 31, 2025 that have materially affected, or are reasonably likely to materially affect, the Company’s internal control over financial reporting. Item 9B. Other Information (a) On February 9, 2026, the Company issued a press release announcing its results of operations for the year ended December 31, 2025. The press release is furnished with this Annual Report on Form 10-K as Exhibit 99.1. (b) During the quarter ended December 31, 2025, no director or officer (as defined in Rule 16a-1(f) promulgated under the Exchange Act adopted or terminated a Rule10b5-1 trading arrangement (as defined in Item 408(a)(1)(i) of Regulation S-K promulgated under the Exchange Act) or any non-Rule 10b5-1 trading arrangement (as defined in Item 408(c) of Regulation S-K promulgated under the Exchange Act). Item 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections. Not applicable. 92 Table of Contents PART III Item 10. Directors, Executive Officers and Corporate Governance Information required by this Item is set forth in the “Proposal 1: Election of Directors” section and the “Description of Management” section of the Proxy Statement relating to the Annual Meeting of Shareholders to be held April 29, 2026 (the “Proxy Statement”). Information regarding compliance with Section 16(a) of the Securities Exchange Act of 1934, as amended, is set forth in the “Corporate Governance and Policies of the Board—Section 16(a) Beneficial Ownership Reporting Compliance” section of the Proxy Statement. Information regarding the Company’s Audit Committee is set forth in the “Committees of the Board—Audit Committee” section of the Proxy Statement. Information regarding the Company’s Code of Ethics is set forth in the “Corporate Governance and Policies of the Board—Code of Ethics” section of the Proxy Statement. Information regarding procedures by which shareholders may recommend nominees to the Company’s Board of Directors is set forth in the “Corporate Governance and Policies of the Board—Nominations” section of the Proxy Statement. Item 11. Executive Compensation Information required by this Item is set forth in the “Compensation Discussion and Analysis” and “Compensation of Named Executive Officers” sections of the Proxy Statement. Item 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters Information required by this Item is set forth in the “Beneficial Ownership” section of the Proxy Statement, as well as the Equity Compensation Plan Information table in Part II, Item 5 of this Form 10-K. Item 13. Certain Relationships and Related Transactions, and Director Independence Information required by this Item is set forth in the “Corporate Governance and Policies of the Board—Transactions with Related Persons” and the “Corporate Governance and Policies of the Board—Director Independence” sections of the Proxy Statement. Item 14. Principal Accountant Fees and Services Information required by this Item is set forth in the “Audit Committee Report—Principal Accountant Fees and Services” and the “Audit Committee Report—Audit Committee Pre-Approval Policy” sections of the Proxy Statement. 93 Table of Contents PART IV Item 15. Exhibits and Financial Statement Schedules (a) (1) and (2)— LIST OF FINANCIAL STATEMENTS AND FINANCIAL STATEMENT SCHEDULES The following financial statements are included herein under Part II, Item 8, Financial Statements and Supplementary Data: • Report of Independent Registered Public Accounting Firm (Deloitte & Touche LLP; PCAOB ID No. 34 ) • Consolidated Statements of Earnings for the years ended December 31, 2025, 2024 and 2023 • Consolidated Balance Sheets—December 31, 2025 and 2024 • Consolidated Statements of Cash Flows for the years ended December 31, 2025, 2024 and 2023 • Consolidated Statements of Changes in Common Stock Equity for the years ended December 31, 2025, 2024 and 2023 • Notes to Consolidated Financial Statements All other schedules for which provision is made in the applicable accounting regulation of the Securities and Exchange Commission are not required under the related instructions, are not applicable, or information required is included in the financial statements or notes thereto and, therefore, have been omitted. (3)— LIST OF EXHIBITS Exhibit Number Description of Exhibit Reference (1) 2.1 (9) Stock Purchase Agreement among Unitil Corporation, PHC Utilities, Inc., and Hearthstone Utilities, Inc. (d/b/a Hope Companies, Inc.) dated July 8, 2024 Exhibit 2.1 to Form 8-K for July 8, 2024 (SEC File No. 1-8858) 2.2 (9) Stock Purchase Agreement between Unitil Corporation and Avangrid Enterprises, Inc. dated March 31, 2025 Exhibit 2.1 to Form 8-K for March 31, 2025 (SEC File No. 1-8858) 2.3 (7)(8) Purchase and Sale Agreement between Unitil Corporation and Aquarion Water Authority, and, solely with respect to Section 9.25 and Section 9.26 thereof, South Central Connecticut Regional Water Authority. Exhibit 2.1 to Form 8-K for May 6, 2025 (SEC File No. 1-8858) 2.4 Amendment No. 1 to Purchase and Sale Agreement, dated as of January 23, 2026, by and among Unitil Corporation, Aquarion Water Authority and South Central Connecticut Regional Water Authority. Exhibit 2.1 to Form 8-K for January 23, 2026 (SEC File No. 1-8858) 3.1 (P) Articles of Incorporation of Unitil Corporation. Exhibit 3.1 to Form S-14 Registration Statement No. 2-93769 dated October 12, 1984 3.2 (P) Articles of Amendment to the Articles of Incorporation of Unitil Corporation filed on March 4, 1992. Exhibit 3.2 to Form 10-K for 1991 (SEC File No. 1-8858) 3.3 Articles of Amendment to the Articles of Incorporation of Unitil Corporation filed on September 23, 2008. Exhibit 3.3 to Form S-3/A Registration Statement No. 333-152823 dated November 25, 2008 3.4 Articles of Amendment to the Articles of Incorporation of Unitil Corporation filed on April 27, 2011. Exhibit 4.4 to Post-Effective Amendment No. 1 to Form S-3 Registration Statement No. 333-168394, dated January 28, 2014 94 Table of Contents Exhibit Number Description of Exhibit Reference (1) 3.5 Fourth Amended and Restated By-Laws of Unitil Corporation. Exhibit 3.1 to Form 8-K dated April 29, 2020 (SEC File No. 1-8858) 4.1 Twelfth Supplemental Indenture of Unitil Energy Systems, Inc., successor to Concord Electric Company, dated as of December 2, 2002, amending and restating the Concord Electric Company Indenture of Mortgage and Deed of Trust dated as of July 15, 1958. Exhibit 4.1 to Form 10-K for 2002 (SEC File No. 1-8858) 4.2 Fitchburg Note Agreement dated January 15, 1999 for the 7.37% Notes due January 15, 2029. Exhibit 4.25 to Form 10-K for 1999 (SEC File No. 1-8858) 4.3 Fitchburg Note Agreement dated June 1, 2001 for the 7.98% Notes due June 1, 2031. Exhibit 4.6 to Form 10-Q for June 30, 2001 (SEC File No. 1-8858) 4.4 Fitchburg Note Agreement dated December 21, 2005 for the 5.90% Notes due December 15, 2030. (2) 4.5 Thirteenth Supplemental Indenture of Unitil Energy Systems, Inc., dated as of September 26, 2006. (2) 4.6 Northern Utilities Note Purchase Agreement, dated as of December 3, 2008, for the 6.95% Senior Notes, Series A due December 3, 2018 and the 7.72% Senior Notes, Series B due December 3, 2038. Exhibit 4.1 to Form 8-K dated December 3, 2008 (SEC File No. 1-8858) 4.7 Fourteenth Supplemental Indenture of Unitil Energy Systems, Inc., dated as of March 2, 2010. Exhibit 4.4 to Form 8-K dated March 2, 2010 (SEC File No. 1-8858) 4.8 Northern Utilities form of Note Purchase Agreement, dated as of October 15, 2014, for the 4.42% Senior Notes, due October 15, 2044. Exhibit 4.1 to Form 8-K dated October 15, 2014 (SEC File No. 1-8858) 4.9 Northern Utilities form of Note issued pursuant to the Note Purchase Agreement, dated as of October 15, 2014, for the 4.42% Senior Notes, due October 15, 2044. Exhibit 4.2 to Form 8-K dated October 15, 2014 (SEC File No. 1-8858) 4.10 Note Purchase Agreement dated August 1, 2016 by and among Unitil Corporation and the several purchasers named therein for the 3.70% Senior Notes, Series 2016, due August 1, 2026. Exhibit 4.1 to Form 8-K dated August 1, 2016 (SEC File No. 1-8858) 4.11 3.70% Senior Note, Series 2016, dated as of August 1, 2016 purchased by Metropolitan Life Insurance Company in the principal amount of $11,200,000. Exhibit 4.2 to Form 8-K dated August 1, 2016 (SEC File No. 1-8858) 4.12 3.70% Senior Note, Series 2016, dated as of August 1, 2016 purchased by Lincoln Benefit Life Company in the principal amount of $4,000,000. Exhibit 4.3 to Form 8-K dated August 1, 2016 (SEC File No. 1-8858) 4.13 3.70% Senior Note, Series 2016, dated as of August 1, 2016 purchased by Lincoln Benefit Life Company in the principal amount of $3,800,000. Exhibit 4.4 to Form 8-K dated August 1, 2016 (SEC File No. 1-8858) 95 Table of Contents Exhibit Number Description of Exhibit Reference (1) 4.14 3.70% Senior Note, Series 2016, dated as of August 1, 2016 purchased by Lincoln Benefit Life Company in the principal amount of $1,000,000. Exhibit 4.5 to Form 8-K dated August 1, 2016 (SEC File No. 1-8858) 4.15 3.70% Senior Note, Series 2016, dated as of August 1, 2016 purchased by United of Omaha Life Insurance Company in the principal amount of $5,000,000. Exhibit 4.6 to Form 8-K dated August 1, 2016 (SEC File No. 1-8858) 4.16 3.70% Senior Note, Series 2016, dated as of August 1, 2016 purchased by United of Omaha Life Insurance Company in the principal amount of $3,000,000. Exhibit 4.7 to Form 8-K dated August 1, 2016 (SEC File No. 1-8858) 4.17 3.70% Senior Note, Series 2016, dated as of August 1, 2016 purchased by Companion Life Insurance Company in the principal amount of $2,000,000. Exhibit 4.8 to Form 8-K dated August 1, 2016 (SEC File No. 1-8858) 4.18 Note Purchase Agreement dated July 14, 2017 by and among Northern Utilities, Inc. and the several purchasers named therein for the 3.52% Senior Notes, Series 2017A, due November 1, 2027 and the 4.32% Senior Notes, Series 2017B, due November 1, 2047. Exhibit 4.1 to Form 8-K dated July 14, 2017 (SEC File No. 1-8858) 4.19 Note Purchase Agreement dated July 14, 2017 by and among Fitchburg Gas and Electric Light Company and the several purchasers named therein for the 3.52% Senior Notes, Series 2017A, due November 1, 2027 and the 4.32% Senior Notes, Series 2017B, due November 1, 2047. Exhibit 4.2 to Form 8-K dated July 14, 2017 (SEC File No. 1-8858) 4.20 Note Purchase Agreement dated July 14, 2017 by and among Granite State Gas Transmission, Inc. and the several purchasers named therein for the 3.72% Senior Notes, Series 2017A, due November 1, 2027. Exhibit 4.3 to Form 8-K dated July 14, 2017 (SEC File No. 1-8858) 4.21 (4) 3.52% Senior Note, Series 2017A, due November 1, 2027, issued by Northern Utilities, Inc. to Great-West Life & Annuity Insurance Company. Exhibit 4.2 to Form 8-K dated November 1, 2017 (SEC File No. 1-8858) 4.22 (4) 4.32% Senior Note, Series 2017B, due November 1, 2047, issued by Northern Utilities, Inc. to The Canada Life Insurance Company of Canada. Exhibit 4.3 to Form 8-K dated November 1, 2017 (SEC File No. 1-8858) 4.23 (4) 3.52% Senior Note, Series 2017A, due November 1, 2027, issued by Fitchburg Gas and Electric Light Company to Great-West Life & Annuity Insurance Company. Exhibit 4.5 to Form 8-K dated November 1, 2017 (SEC File No. 1-8858) 4.24 (4) 4.32% Senior Note, Series 2017B, due November 1, 2047, issued by Fitchburg Gas and Electric Light Company to The Great-West Life Assurance Company. Exhibit 4.6 to Form 8-K dated November 1, 2017 (SEC File No. 1-8858) 4.25 (4) 3.72% Senior Note, Series 2017A, due November 1, 2027, issued by Granite State Gas Transmission, Inc. to Thrivent Financial for Lutherans. Exhibit 4.8 to Form 8-K dated November 1, 2017 (SEC File No. 1-8858) 4.26 Bond Purchase Agreement dated November 30, 2018 by and among Unitil Energy Systems, Inc. and the several purchasers named therein for the $30,000,000 aggregate principal amount of first mortgage bonds, Series Q, due November 30, 2048. Exhibit 4.1 to Form 8-K dated November 30, 2018 (SEC File No. 1-8858) 96 Table of Contents Exhibit Number Description of Exhibit Reference (1) 4.27 Fifteenth Supplemental Indenture dated November 29, 2018 by and between Unitil Energy Systems, Inc. and U.S. Bank National Association (as trustee). Exhibit 4.2 to Form 8-K dated November 30, 2018 (SEC File No. 1-8858) 4.28 (4) First Mortgage Bond, Series Q, 4.18%, due November 30, 2048, issued by Unitil Energy Systems, Inc. to United of Omaha Life Insurance Company. Exhibit 4.3 to Form 8-K dated November 30, 2018 (SEC File No. 1-8858) 4.29 Note Purchase Agreement dated September 12, 2019 by and among Northern Utilities, Inc. and the several purchasers named therein. Exhibit 4.1 to Form 8-K dated September 12, 2019 (SEC File No. 1-8858) 4.30 (4) 4.04% Senior Note, Series 2019, due September 12, 2049, issued by Northern Utilities, Inc. to Pacific Life Insurance Company. Exhibit 4.2 to Form 8-K dated September 12, 2019 (SEC File No. 1-8858) 4.31 Note Purchase Agreement dated December 18, 2019 by and among Unitil Corporation and the several purchasers named therein. Exhibit 4.1 to Form 8-K dated December 18, 2019 (SEC File No. 1-8858) 4.32 (4) 3.43% Senior Note, Series 2019, due December 18, 2029, issued by Unitil Corporation to CHIMEFISH & CO, as nominee for American Equity Investment Life Insurance Company. Exhibit 4.2 to Form 8-K dated December 18, 2019 (SEC File No. 1-8858) 4.33 Note Purchase Agreement dated September 15, 2020 by and among Northern Utilities, Inc. and the several purchasers named therein. Exhibit 4.1 to Form 8-K dated September 15, 2020 (SEC File No. 1-8858) 4.34 (4) 3.78% Senior Note, Series 2020, due September 15, 2040, issued by Northern Utilities, Inc. to Metropolitan Life Insurance Company. Exhibit 4.2 to Form 8-K dated September 15, 2020 (SEC File No. 1-8858) 4.35 Note Purchase Agreement dated September 15, 2020 by and among Fitchburg Gas and Electric Light Company and the several purchasers named therein. Exhibit 4.3 to Form 8-K dated September 15, 2020 (SEC File No. 1-8858) 4.36 (4) 3.78% Senior Note, Series 2020A, due September 15, 2040, issued by Fitchburg Gas and Electric Light Company to Brighthouse Life Insurance Company of NY. Exhibit 4.4 to Form 8-K dated September 15, 2020 (SEC File No. 1-8858) 4.37 Bond Purchase Agreement dated September 15, 2020 by and among Unitil Energy Systems, Inc., U.S. Bank National Association (as trustee), and the several purchasers named therein. Exhibit 4.5 to Form 8-K dated September 15, 2020 (SEC File No. 1-8858) 4.38 Sixteenth Supplemental Indenture dated September 15, 2020 by and between Unitil Energy Systems, Inc. and U.S. Bank National Association (as trustee). Exhibit 4.6 to Form 8-K dated September 15, 2020 (SEC File No. 1-8858) 4.39 (4) First Mortgage Bond, Series R, 3.58%, due September 15, 2040, issued by Unitil Energy Systems, Inc. to CUDD and CO (as nominee for Symetra Life Insurance Company). Exhibit 4.7 to Form 8-K dated September 15, 2020 (SEC File No. 1-8858) 97 Table of Contents Exhibit Number Description of Exhibit Reference (1) 4.40 (5) Bond Purchase Agreement dated August 21, 2024 by and among Unitil Energy Systems, Inc., U.S. Bank Trust Company, National Association (as trustee) and the several purchasers named therein. Exhibit 4.11 to Form 8-K for August 21, 2024 (SEC File No. 1-8858) 4.41 Seventeenth Supplemental Indenture dated August 21, 2024 by and between Unitil Energy Systems, Inc. and U.S. Bank Trust Company, National Association (as trustee) Exhibit 4.12 to Form 8-K for August 21, 2024 (SEC File No. 1-8858) 4.42 (4) First Mortgage Bond, Series S, 5.69%, due August 21, 2054, issued by Unitil Energy Systems, Inc. to Metlife Reinsurance Company of Hamilton, Ltd. Exhibit 4.13 to Form 8-K for August 21, 2024 (SEC File No. 1-8858) 4.43 (5) Note Purchase Agreement dated July 6, 2023 by and among Fitchburg Gas and Electric Light Company and the several purchasers named therein. Exhibit 4.1 to Form 8-K dated July 6, 2023 (SEC File No. 1-8858) 4.44 (4) 5.70% Senior Note, Series 2023A, due July 2, 2033, issued by Fitchburg Gas and Electric Light Company to MetLife Reinsurance Company of Hamilton, Ltd. Exhibit 4.2 to Form 8-K dated July 6, 2023 (SEC File No. 1-8858) 4.45 (4) 5.96% Senior Note, Series 2023B, due July 2, 2053, issued by Fitchburg Gas and Electric Light Company to Mutual of Omaha Insurance Company Exhibit 4.3 to Form 8-K dated July 6, 2023 (SEC File No. 1-8858) 4.46 (5) Note Purchase Agreement dated August 21, 2024 by and among Unitil Corporation and the several purchasers named therein. Exhibit 4.1 to Form 8-K for August 21, 2024 (SEC File No. 1-8858) 4.47 (4) 5.99% Senior Note, Series 2024, due August 21, 2034, issued by Unitil Corporation to Metropolitan Tower Life Insurance Company Exhibit 4.2 to Form 8-K for August 21, 2024 (SEC File No. 1-8858) 4.48 (5) Note Purchase Agreement dated August 21, 2024 by and among Northern Utilities, Inc. and the several purchasers named therein. Exhibit 4.3 to Form 8-K for August 21, 2024 (SEC File No. 1-8858) 4.49 (4) 5.54% Senior Note, Series 2024A, due August 21, 2034, issued by Northern Utilities, Inc. to Metropolitan Life Insurance Company Exhibit 4.4 to Form 8-K for August 21, 2024 (SEC File No. 1-8858) 4.50 (4) 5.74% Senior Note, Series 2024B, due August 21, 2039, issued by Northern Utilities, Inc.to Modern Woodmen of America. Exhibit 4.5 to Form 8-K for August 21, 2024 (SEC File No. 1-8858) 4.51 (5) Note Purchase Agreement dated August 21, 2024 by and among Fitchburg Gas and Electric Light Company and the several purchasers named therein Exhibit 4.6 to Form 8-K for August 21, 2024 (SEC File No. 1-8858) 4.52 (4) 5.54% Senior Note, Series 2024A, due August 21, 2034, issued by Fitchburg Gas and Electric Light Company to Metlife Reinsurance Company of Hamilton, Ltd. Exhibit 4.7 to Form 8-K for August 21, 2024 (SEC File No. 1-8858) 4.53 (4) 5.99% Senior Note, Series 2024B, due August 21, 2044, issued by Fitchburg Gas and Electric Light Company to Metlife Reinsurance Company of Hamilton, Ltd. Exhibit 4.8 to Form 8-K for August 21, 2024 (SEC File No. 1-8858) 98 Table of Contents Exhibit Number Description of Exhibit Reference (1) 4.54 (5) Note Purchase Agreement dated August 21, 2024 by and among Granite State Gas Transmission, Inc. and the several purchasers named therein. Exhibit 4.9 to Form 8-K for August 21, 2024 (SEC File No. 1-8858) 4.55 (4) 5.74% Senior Note, Series 2024, due August 21, 2034, issued by Granite State Gas Transmission, Inc. to Metropolitan Life Insurance Company Exhibit 4.10 to Form 8-K for August 21, 2024 (SEC File No. 1-8858) 4.56 Amended and Restated Note issued to Bank of America, N.A. Exhibit 4.2 to Form 8-K dated July 25, 2018 (SEC File No. 1-8858) 4.57 Loan Agreement dated December 18, 2020 between Unitil Realty Corp. and TD Bank, N.A. Exhibit 4.48 to Form 10-K for 2020 (SEC File No. 1-8858) 4.58 Mortgage and Security Agreement dated December 18, 2020 between Unitil Realty Corp. and TD Bank, N.A. Exhibit 4.49 to Form 10-K for 2020 (SEC File No. 1-8858) 4.59 Mortgage Loan Note dated December 18, 2020 issued to TD Bank, N.A. Exhibit 4.50 to Form 10-K for 2020 (SEC File No. 1-8858) 4.60 Description of Registrant’s Securities Exhibit 4.50 to Form 10-K for 2021 (SEC File No. 1-8858) 4.61 (5) Third Amended and Restated Credit Agreement dated September 29, 2022 among Unitil Corporation, Bank of America, N.A., as administrative agent, and the Lenders Exhibit 4.1 to Form 8-K dated September 29, 2022 (SEC File No. 1-8858) 4.62 First Amendment to Third Amended and Restated Credit Agreement between Unitil and Bank of America, N.A., as administrative agent, dated July 18, 2024 Exhibit 4.1 to Form 8-K for July 18, 2024 (SEC File No. 1-8858) 4.63 Second Amended and Restated Note issued to Citizens Bank, N.A. Exhibit 4.2 to Form 8-K dated September 29, 2022 (SEC File No. 1-8858) 4.64 Second Amended and Restated Note issued to TD Bank, N.A. Exhibit 4.3 to Form 8-K dated September 29, 2022 (SEC File No. 1-8858) 4.65 (5) Second Amendment to Third Amended and Restated Credit Agreement dated January 29, 2025 among Unitil Corporation; Bank of America, N.A., as administrative agent; and Bank of America, N.A., Citizens Bank, N.A., and TD Bank, N.A. Exhibit 4.1 to Form 8-K dated January 29, 2025 (SEC File No. 1-8858) 4.66 Third Amended and Restated Note issued to Citizens Bank, N.A. Exhibit 4.2 to Form 8-K dated January 29, 2025 (SEC File No. 1-8858) 4.67 Third Amended and Restated Note issued to TD Bank, N.A. Exhibit 4.3 to Form 8-K dated January 29, 2025 (SEC File No. 1-8858) 4.68 (5)(8) Note Purchase Agreement dated July 8, 2025 by and among Bangor Natural Gas Company and the several purchasers named therein. Exhibit 4.1 to Form 8-K for July 8, 2025 (SEC File No. 1-8858) 99 Table of Contents Exhibit Number Description of Exhibit Reference (1) 4.69 5.70% Senior Note, Series 2025A, due July 8, 2030, issued by Bangor Natural Gas Company to CoBank, ACB. Exhibit 4.2 to Form 8-K for July 8, 2025 (SEC File No. 1-8858) 4.70 6.31% Senior Note, Series 2025B, due July 8, 2035, issued by Bangor Natural Gas Company to United of Omaha Life Insurance Company. Exhibit 4.3 to Form 8-K for July 8, 2025 (SEC File No. 1-8858) 4.71 (5) Credit Agreement dated October 31, 2025 among Unitil Corporation, The Bank of Nova Scotia, as agent, and The Bank of Nova Scotia, as lender Exhibit 4.1 to Form 8-K for October 31, 2025 (SEC File No. 1-8858) 10.1 (3) Amended and Restated Form of Severance Agreement between the Company and the persons listed at the end of such Agreement. Exhibit 10.2 to Form 8-K dated June 19, 2008 (SEC File No. 1-8858) 10.2 (3) Amended and Restated Form of Severance Agreement between the Company and the persons listed at the end of such Agreement. Exhibit 10.3 to Form 8-K dated June 19, 2008 (SEC File No. 1-8858) 10.3 (3) Amended and Restated Form of Severance Agreement (Three-Year Term). Exhibit 10.1 to Form 8-K dated July 25, 2018 (SEC File No. 1-8858) 10.4 (3) Amended and Restated Form of Severance Agreement (Two-Year Term). Exhibit 10.2 to Form 8-K dated July 25, 2018 (SEC File No. 1-8858) 10.5 (3) Amended and Restated Form of Severance Agreement (Two-Year Term; Non Pension). Exhibit 10.3 to Form 8-K dated July 25, 2018 (SEC File No. 1-8858) 10.6 (3) Severance Agreement dated March 23, 2020, between the Company and Daniel J. Hurstak. Exhibit 10.1 to Form 8-K dated March 19, 2020 (SEC File No. 1-8858) 10.7 (3) Severance Agreement dated July 29, 2020, between the Company and Robert B. Hevert. Exhibit 10.1 to Form 8-K dated July 29, 2020 (SEC File No. 1-8858) 10.8 (3) Amended and Restated Unitil Corporation Supplemental Executive Retirement Plan effective as of December 31, 2016. Exhibit 10.1 to Form 10-Q for March 31, 2017 (SEC File No. 1-8858) 10.9 (3) Amended and Restated Supplemental Executive Retirement Plan. Exhibit 10.5 to Form 8-K dated July 25, 2018 (SEC File No. 1-8858) 10.10 (3) Unitil Corporation Deferred Compensation Plan. Exhibit 10.6 to Form 8-K dated July 25, 2018 (SEC File No. 1-8858) 10.11 (3) Unitil Corporation Management Incentive Plan (amended and restated as of June 5, 2013). Exhibit 10.2 to Form 8-K dated June 5, 2013 (SEC File No. 1-8858) 100 Table of Contents Exhibit Number Description of Exhibit Reference (1) 10.12 (3) Unitil Corporation Second Amended and Restated 2003 Stock Plan. Appendix 1 to the Proxy Statement filed on Schedule 14A dated March 13, 2012 (SEC File No. 1-8858) 10.13 (3) Unitil Corporation Third Amended and Restated 2003 Stock Plan. Exhibit 10.1 to Form 10-Q for March 31, 2024 (SEC File No. 1-8858) 10.14 (3) Form of Restricted Stock Unit Agreement under the Unitil Corporation Second Amended and Restated 2003 Stock Plan. Exhibit 4.7 to Form S-8 Registration Statement No. 333-184849 dated November 9, 2012 10.15 (3) Form of Restricted Stock Agreement under the Unitil Corporation Second Amended and Restated 2003 Stock Plan. Exhibit 4.8 to Form S-8 Registration Statement No. 333-184849 dated November 9, 2012 10.16 (3) Unitil Corporation Tax Deferred Savings and Investment Plan, as amended and restated effective as of January 1, 2021. Exhibit 10.15 to Form 10-K for 2021 (SEC File No. 1-8858) 10.17 (3) Unitil Corporation Tax Deferred Savings and Investment Plan Trust Agreement. Exhibit 4.2 to Form S-8 Registration Statement No. 333-234391 dated October 31, 2019 10.18 (3) Unitil Corporation Incentive Plan (amended and restated as of January 26, 2015). Exhibit 10.1 to Form 10-Q for March 31, 2015 (SEC File No. 1-8858) 10.19 (3) Employment Agreement between Unitil Corporation and Thomas P. Meissner, Jr. Exhibit 10.1 to Form 8-K for May 1, 2024 (SEC File No. 1-8858) 10.20 (3) Unitil Corporation - Compensation of Directors effective as of January 1, 2025 Exhibit 10.23 to Form 10-K for 2024 (SEC File No. 1-8858) 10.21 Underwriting Agreement dated August 4, 2021 among Unitil Corporation, on the one hand, and RBC Capital Markets, LLC and BofA Securities, Inc., on the other hand, for themselves and as representatives of the several underwriters named therein. Exhibit 1.1 to Form 8-K dated August 3, 2021 (File No. 1-8858) 10.22 (3) Form of Restricted Stock Agreement (Time Vesting) Exhibit 10.1 to Form 8-K dated January 24, 2023 (SEC File No. 1-8858) 10.23 (3) Form of Restricted Stock Agreement (Performance Vesting) Exhibit 10.2 to Form 8-K dated January 24, 2023 (SEC File No. 1-8858) 10.24 (5) Transition Services Agreement dated January 31, 2025 between Bangor Natural Gas Company and Hearthstone Holdings, Inc. (d/b/a Hope Utilities, Inc.), acknowledged by Unitil Corporation Exhibit 10.2 to Form 8-K dated January 29, 2025 (SEC File No. 1-8858) 10.25 Guaranty between Unitil Corporation and Avangrid Networks, Inc., dated March 31. 2025 Exhibit 10.3 to Form 10-Q for March 31, 2025 (SEC File No. 1-8858) 101 Table of Contents Exhibit Number Description of Exhibit Reference (1) 10.26 (6) Debt Commitment Letter between Unitil Corporation and The Bank of Nova Scotia, dated March 31, 2025 Exhibit 10.4 to Form 10-Q for March 31, 2015 (SEC File No. 1-8858) 10.27 Distribution Agreement, dated June 3, 2025, by and among Unitil Corporation, Janney Montgomery Scott LLC and Scotia Capital (USA) Inc. (each as agent and/or forward seller) and Janney Montgomery Scott LLC and The Bank of Nova Scotia (each as forward purchaser). Exhibit 10.1 to Form 8-K for June 3, 2025 (SEC File No. 1-8858) 10.28 Underwriting Agreement, August 14, 2025, by and among Unitil Corporation and Wells Fargo Securities, LLC, Scotia Capital (USA) Inc. and Janney Montgomery Scott LLC. Exhibit 1.1 to Form 8-K for August 14, 2025 (SEC File No. 1-8858) 10.29 (5) Transition Services Agreement dated October 31, 2025 between Maine Natural Gas Company and Avangrid Service Company, as consented to and acknowledged by Unitil Corporation Exhibit 10.2 to Form 8-K for October 31, 2025 (SEC File No. 1-8858) 19.1 Unitil Corporation Corporate Governance Guidelines and Policies of the Board of Directors (includes the Registrant’s insider trading policies and procedures) Exhibit 19.1 to Form 10-K for 2023 (SEC File No. 1-8858) 19.2 Unitil Corporation Insider Trading Policy Exhibit 19.2 to Form 10-K for 2024 (SEC File No. 1-8858) 21.1 Statement Re: Subsidiaries of Registrant . Filed herewith 23.1 Consent of Independent Registered Public Accounting Firm. Filed herewith 31.1 Certification of Chief Executive Officer Pursuant to Rule 13a-14 of the Exchange Act, as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. Filed herewith 31.2 Certification of Chief Financial Officer Pursuant to Rule 13a-14 of the Exchange Act, as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. Filed herewith 31.3 Certification of Chief Accounting Officer Pursuant to Rule 13a-14 of the Exchange Act, as Adopted Pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. Filed herewith 32.1 Certifications of Chief Executive Officer, Chief Financial Officer and Chief Accounting Officer Pursuant to 18 U.S.C. Section 1350, as Adopted Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. Filed herewith 97.1 Executive Compensation Recovery Policy Exhibit 97.1 to Form 10-K for 2023 (SEC File No. 1-8858) 99.1 Unitil Corporation Press Release Dated February 9, 2026 Announcing Earnings For the Year Ended December 31, 2025. Furnished herewith 101.INS Inline XBRL Instance Document – The instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document. Filed herewith 102 Table of Contents Exhibit Number Description of Exhibit Reference (1) 101.SCH Inline XBRL Taxonomy Extension Schema With Embedded Linkbase Documents. Filed herewith 104 Cover Page Interactive Data File – The cover page interactive data file does not appear in the interactive data file because its XBRL tags are embedded within the inline XBRL document. Filed herewith (1) The exhibits referred to in this column by specific designations and dates have heretofore been filed with or furnished to the Securities and Exchange Commission under such designations and are hereby incorporated by reference. (2) In accordance with Item 601(b)(4)(iii)(A) of Regulation S-K, the instrument defining the debt of the Registrant and its subsidiary, described above, has been omitted but will be furnished to the Commission upon request. (3) These exhibits represent a management contract or compensatory plan. (4) This Note or Bond (each, an “Instrument”) is substantially identical in all material respects to other Instruments that are otherwise required to be filed as exhibits, except as to the registered payee of such Instrument, the identifying number of such Instrument, and the principal amount of such Instrument. In accordance with instruction no. 2 to Item 601 of Regulation S-K, the registrant has filed a copy of only one of such Instruments, with a schedule identifying the other Instruments omitted and setting forth the material details in which such Instruments differ from the Instrument that was filed. The registrant acknowledges that the Securities and Exchange Commission may at any time in its discretion require filing of copies of any Instruments so omitted. (5) In accordance with Item 601(a)(5) of Regulation S-K, this exhibit omits certain of its schedules and exhibits. This exhibit’s table of contents, or the cover page of its omitted schedules and exhibits, includes a brief description of the subject matter of all of its omitted schedules and exhibits. The Registrant acknowledges that it must provide a copy of any omitted schedules or exhibits to the Securities and Exchange Commission or its staff upon request. (6) In accordance with Item 601(a)(5) of Regulation S-K, this exhibit omits certain of its schedules and exhibits. These schedules and exhibits consist of Annex I to Exhibit B (Interest), which describes the interest rates applicable to the loan facility. The Registrant acknowledges that it must provide a copy of any omitted schedules or exhibits to the Securities and Exchange Commission or its staff upon request. (7) Certain schedules and exhibits to the Purchase and Sale Agreement have been omitted pursuant to Item 601(a)(5) of Regulation S-K. These schedules and exhibits consist of (i) the Seller Disclosure Schedule (as such term is defined in the Purchase and Sale Agreement) and (ii) the Operating Agreement (as such term is defined in the Purchase and Sale Agreement). Unitil Corporation hereby undertakes to furnish supplementally copies of any of the omitted schedules and exhibits upon request by the Securities and Exchange Commission or its staff. (8) Certain information has been excluded from this exhibit pursuant to Item 601(b)(2)(ii) of Regulation S-K. (9) Certain schedules and exhibits to the Stock Purchase Agreement have been omitted pursuant to Item 601(a)(5) of Regulation S-K. These schedules and exhibits consist of (i) the Disclosure Schedules (as such term is defined in the Stock Purchase Agreement), (ii) the Transition Services Agreement (as such term is defined in the Stock Purchase Agreement), (iii) the Allocation Schedule (as such term is defined in the Stock Purchase Agreement), and (iv) the Target Working Capital (as such term is defined in the Stock Purchase Agreement). Unitil Corporation hereby undertakes to furnish supplementally copies of any of the omitted schedules and exhibits upon request by the Securities and Exchange Commission or its staff. (P) Paper exhibit. (P) 103 Table of Contents SIGNATURES Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, as amended, the Registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized. U NITIL C ORPORATION Date February 9, 2026 By / S / T HOMAS P. M EISSNER , J R . Thomas P. Meissner, Jr. Chairman of the Board of Directors and Chief Executive Officer Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, this report has been signed below by the following persons on behalf of the Registrant and in the capacities and on the dates indicated. Signature Capacity Date /S/ THOMAS P. MEISSNER, JR. Principal Executive Officer; Director February 9, 2026 Thomas P. Meissner, Jr. /S/ DANIEL J. HURSTAK Daniel J. Hurstak Principal Financial Officer February 9, 2026 /S/ TODD R. DIGGINS Todd R. Diggins Principal Accounting Officer February 9, 2026 /S/ ANNE L. ALONZO Anne L. Alonzo Director February 9, 2026 /S/ NEVEEN F. AWAD Neveen F. Awad Director February 9, 2026 /S/ WINFIELD S. BROWN Winfield S. Brown Director February 9, 2026 /S/ MARK H. COLLIN Mark H. Collin Director February 9, 2026 /S/ SUZANNE FOSTER Suzanne Foster Director February 9, 2026 /S/ MICHAEL B. GREEN Michael B. Green Director February 9, 2026 /S/ KATHERINE KOUNTZE Katherine Kountze Director February 9, 2026 /S/ JANE LEWIS-RAYMOND Jane Lewis-Raymond Director February 9, 2026 /S/ JUSTINE VOGEL Director February 9, 2026 Justine Vogel /S/ DAVID A. WHITELEY Director February 9, 2026 David A. Whiteley 104