Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the 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 past90 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 RegulationS-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 emerginggrowth company. See definition of “large accelerated filer,” “accelerated filer”, “smaller reporting company” and “emerging growth company” in Rule 12b-2 of theExchange Act. Smaller reporting company☒Emerging growth 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.☐ Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control overfinancial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its auditreport. 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 ofthe 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☒ The aggregate market value of the voting and non-voting common equity held by non-affiliates of the Registrant, computed by reference to the last sale price onJune 30, 2025, as reported by the NASDAQ Capital Market ($15.34), was approximately $80.0 million. As of March 25, 2026, there were 4,876,213 shares outstanding of the Registrant’s voting common stock and 1,380,283 shares of the Registrant’s Series Anonvoting common stock. DOCUMENTS INCORPORATED BY REFERENCE: Proxy Statement for the 2026 Annual Meeting of Shareholders of the Registrant (Part III). TABLE OF CONTENTS FORM 10-K ANNUAL REPORTFOR THE YEAR ENDEDDECEMBER 31, 2025PATHFINDER BANCORP, INC. PART I Item 1.BusinessItem 1A.Risk FactorsItem 1B.Unresolved Staff CommentsItem 1C.CybersecurityItem 2.PropertiesItem 3.Legal ProceedingsItem 4.Mine Safety Disclosure PART II Item 5.Market for Registrant's Common Equity, Related Stockholder Matters and Issuer Purchases of EquitySecurities25Item 6.Reserved25Item 7.Management's Discussion and Analysis of Financial Condition and Results of Operations26Item 7A.Quantitative and Qualitative Disclosures About Market Risk53Item 8.Financial Statements and Supplementary Data54Item 9.Changes In and Disagreements With Accountants on Accounting and Financial Disclosure115Item 9AControls and Procedures115Item 9B.Other Information115Item 9C.Disclosure Regarding Foreign Jurisdictions that Prevent Inspections115 PART III Item 10.Directors, Executive Officers and Corporate Governance115Item 11.Executive Compensation116Item 12.Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters116Item 13.Certain Relationships and Related Transactions, and Director Independence116Item 14.Principal Accounting Fees and Services116 PART IVItem 15. Exhibits and Financial Statement Schedules117Item 16.Form 10-K Summary119 PART I FORWARD-LOOKING STATEMENTS Certain statements contained herein are “forward looking statements” within the meaning of Section 27A of the Securities Act of1933 and Section 21E of the Securities Exchange Act of 1934. These forward-looking statements concern the financial condition,results of operations, plans, objectives, future performance and business of Pathfinder Bancorp, Inc. (the “Company”) and itssubsidiaries, including, but not limited to, Pathfinder Bank (the "Bank"). Forward-looking statements are generally identified by use of the words “believes,” “expect,” “intend,” “anticipate,” “estimate,”“project” or similar expressions, or future or conditional verbs, such as “will,” “would,” “should,” “could,” or “may