FINANCIAL INSTITUTIONS INC

Expectations for our directors, officers and employees are memorialized in our Code of Business Conduct and Ethics Policy (“Code of Ethics”) that is annually approved by our Board of Directors. The Code of Ethics is applicable to all employees and covers professional conduct, including, but not limited to, conflicts of interest, safeguarding of confidential information, protecting company assets, anti-trust compliance, fair and responsible banking, and financial responsibility. New and existing employees and directors (on an annual basis) are required to acknowledge receipt of and compliance with the Code of Ethics.

Additionally, we have a code of ethics for the CEO, CFO and senior financial officers that sets additional and heightened expectations for honest and ethical conduct and compliance with applicable laws, rules and regulations applicable to financial related matters (this code of ethics and the Code of Ethics collectively are referred to as “Ethics Codes”). Each applicable employee and director must annually review and affirm their intent to comply with the Ethics Codes.

Current versions of these codes may be viewed on our website atwww.FISI-Investors.com by clicking on “Governance,” then on “Governance Documents.” Exceptions or an amendment to any provision of the Ethics Codes must be approved by the Chief Compliance Officer (“CCO”) and are reported to and ratified or approved by the Board. We intend to notify shareholders of any exceptions or amendments granted on our website atwww.FISI-Investors.com. We did not grant any exceptions or approve any amendments during 2024 and our investor website includes the current versions of the Ethics Codes.

6 Financial Institutions, Inc.