FISI Financial Institutions Inc

Vote the Blue Proxy Card FOR ALL Four Financial Institutions, Inc.’s (FISI) Director Nominees

ISS Recognizes that the Board’s Strategy is Driving Profitable Growth and Shareholder Value Creation

Company Urges Shareholders to Follow ISS’ Recommendation and Vote the BLUE Proxy Card Today

WARSAW, N.Y., May 23, 2016 – Financial Institutions, Inc. (Nasdaq: FISI), the parent company of Five Star Bank, Scott Danahy Naylon and Courier Capital, today announced that Institutional Shareholders Services (“ISS”), a leading independent proxy advisory firm, has issued a report recommending that Financial Institutions shareholders vote on the BLUE proxy card FOR ALL four of the Company’s director nominees – Martin Birmingham, Samuel Gullo, Kim VanGelder and James Wyckoff – at the 2016 Annual Meeting of Shareholders to be held on June 3, 2016. ISS’ clients include institutional investors, mutual funds, pension funds and other fiduciaries. In its May 20, 2016 report, ISS stated:

ISS ultimately concluded that:

Commenting on the ISS report and its recommendation, FISI issued the following statement:

“We are very pleased that ISS has carefully reviewed the voting alternatives and has recommended that shareholders vote FOR ALL four of FISI’s highly-qualified and very experienced director nominees on the BLUE proxy card. We are also pleased that in making its recommendation, ISS recognized that the Board’s strategic plan has been producing superior returns for shareholders over the last three years. We believe that, our strategic plan will continue to drive growth and profitability and create superior value for shareholders. We strongly urge all shareholders to follow the recommendation of ISS and vote TODAY on the BLUE proxy card FOR ALL four of FISI’s director nominees to ensure that FISI is best positioned to continue executing on its successful strategic plan that has delivered increased growth, increased profitability, and achieved a 66% increase in total shareholder returns.”

Shareholders are reminded that, no matter how many or how few shares they own, their vote is extremely important for the future of FISI. FISI is asking that shareholders follow ISS’ recommendation and VOTE TODAY each and every BLUE proxy card they receive for the FISI Board’s four highly-qualified and very experienced nominees: Martin Birmingham, Samuel Gullo, Kim VanGelder and James Wyckoff . Shareholders may also vote by phone or Internet by following the instructions on the BLUE proxy card they have received.

Shareholders are also urged NOT to sign or return any white proxy card or voting instruction form that they may receive from Clover Partners. Even a WITHHOLD vote with respect to Clover Partners’ proposed director nominees on its white proxy card or voting instruction form will cancel any BLUE proxy card or voting instruction form previously given to FISI. Shareholders are also reminded that if they do sign a white proxy card that is sent to them by Clover Partners they have the right to change their vote by voting the BLUE proxy card.

Only the latest dated proxy card or voting instruction form voted will be counted, so shareholders are urged to vote TODAY each and every BLUE proxy card they have received! If you have any questions on how to vote your shares, please call Morrow & Co., LLC at (203) 658-9400 or toll free at 800-662-5200 or by email at votefisi@morrowco.com.

For additional information about the Annual Meeting, shareholders are encouraged to visit www.votefisi.com.

About Financial Institutions, Inc.

Financial Institutions, Inc. provides diversified financial services through its subsidiaries, Five Star Bank, Scott Danahy Naylon and Courier Capital. Five Star Bank provides a wide range of consumer and commercial banking services to individuals, municipalities and businesses through a network of over 50 offices and more than 60 ATMs

throughout Western and Central New York State. Scott Danahy Naylon provides a broad range of insurance services to personal and business clients across 44 states. Courier Capital provides customized investment management, investment consulting and retirement plan services to individuals, businesses, institutions, foundations and retirement plans. Financial Institutions, Inc. and its subsidiaries employ approximately 700 individuals. The Company’s stock is listed on the Nasdaq Global Select Market under the symbol FISI and is a member of the NASDAQ OMX ABA Community Bank Index. Additional information is available at the Company’s website: www.fiiwarsaw.com .

Safe Harbor Statement

This press release may contain forward-looking statements as defined by Section 21E of the Securities Exchange Act of 1934, as amended, and is subject to the safe harbors created by such laws. These forward-looking statements can generally be identified as such by the context of the statements, including words such as “believe,” “expect,” “anticipate,” “plan,” “may,” “would,” “intend,” “estimate,” “guidance” and other similar expressions, whether in the negative or affirmative. Similarly, statements that describe the objectives, plans or goals of Financial Institutions, Inc. (“FISI”) are forward-looking. Such forward-looking statements include, but are not limited to, statements regarding the anticipated proxy contest by Clover Partners, L.P. and the other participants in its solicitation, FISI’s ability to continue to execute on and implement its strategic growth plan, FISI’s opportunities for continued growth, FISI’s initiatives to improve its financial and operational performance and increase its growth and profitability, FISI’s future stock price and dividend growth, FISI’s future returns to shareholders, FISI’s ability to continue to strengthen its balance sheet and grow its core business, FISI’s ability to continue to strengthen its regulatory compliance procedures, FISI’s ability to continue to profitably grow its commercial lending business, FISI’s ability to enhance its competitive position through diversified income streams, FISI’s ability to leverage its client base to offer its clients additional fee-based products, FISI’s future returns from its existing fee-based platforms and the effect of those platforms on overall shareholder value, FISI’s ability to continue to maintain expense discipline, FISI’s plans to continue to return cash to its shareholders through cash dividends and future increases that may be made thereto, FISI’s actions taken or contemplated to enhance its long-term prospects and create and return value for its shareholders, FISI’s future operational and financial performance, FISI’s future growth and profitability, the effect that the election of FISI’s nominees to the FISI Board will have on FISI’s execution of its long-term plan and long-term shareholder value, and the future effect of FISI’s strategic growth plan on FISI’s growth, profitability and total shareholder returns. Such forward-looking statements are not guarantees of future operational or financial performance and are based on current expectations, estimates, forecasts and projections and management’s current beliefs and assumptions, all of which involve a number of significant risks and uncertainties, any one or more of which could cause actual results to differ materially from those described in FISI’s forward-looking statements. There are a number of important risks and uncertainties that could cause FISI’s actual events or results to differ materially from those indicated or implied by such forward-looking statements,

including, but not limited to: FISI’s ability to implement its strategic plan, FISI’s ability to redeploy investment assets into loan assets, whether FISI experiences greater credit losses than expected, whether FISI experiences breaches of its, or third party, information systems, the attitudes and preferences of FISI’s customers, FISI’s ability to successfully integrate and profitably operate SDN and Courier Capital, the competitive environment, fluctuations in the fair value of securities in its investment portfolio, changes in the regulatory environment and FISI’s compliance with regulatory requirements, changes in interest rates, general economic and credit market conditions nationally and regionally, and the actions of activist investors, including the amount of related costs incurred by FISI and the disruption caused to FISI’s business activities by these actions. Consequently, all forward-looking statements made herein are qualified by these cautionary statements and the cautionary language in FISI’s Annual Report on Form 10-K, its Quarterly Reports on Form 10-Q and other documents filed with the SEC. Except as required by law, FISI undertakes no obligation to revise these statements, whether to reflect new information or the occurrence of unanticipated events or otherwise, following the date of this press release.

Important Additional Information And Where To Find It

Financial Institutions, Inc. (“FISI”) its directors and certain of its executive officers are deemed to be participants in the solicitation of proxies from FISI’s shareholders in connection with the matters to be considered at FISI’s 2016 Annual Meeting of Shareholders. On April 19, 2016, FISI filed a definitive proxy statement and accompanying definitive BLUE proxy card with the Securities and Exchange Commission (“ SEC ”) in connection with the solicitation of proxies from FISI’s shareholders in connection with the matters to be considered at FISI’s 2016 Annual Meeting of Shareholders. Information regarding the names of FISI’s directors and executive officers and their respective interests in FISI by security holdings or otherwise can be found in such definitive proxy statement, including the schedules and appendices thereto. INVESTORS AND SHAREHOLDERS ARE STRONGLY ENCOURAGED TO READ ANY SUCH PROXY STATEMENT AND THE ACCOMPANYING BLUE PROXY CARD AND OTHER DOCUMENTS FILED BY FINANCIAL INSTITUTIONS WITH THE SEC CAREFULLY AND IN THEIR ENTIRETY WHEN THEY BECOME AVAILABLE AS THEY WILL CONTAIN IMPORTANT INFORMATION. Shareholders may obtain the definitive proxy statement, any amendments or supplements to the proxy statement, the accompanying BLUE proxy card, and other documents filed by FISI with the SEC for no charge at the SEC’s website at www.sec.gov . Copies will also be available at no charge at the Investor Relations section of FISI’s corporate website at www.fiiwarsaw.com, by writing to FISI’s Corporate Secretary at Financial Institutions, Inc., 220 Liberty Street, Warsaw, New York 14569, or by calling FISI’s Corporate Secretary at (585) 786-1100.

Disclaimer

Financial Institutions, Inc. has neither sought nor obtained the consent from any third party to use any statements or information contained in this press release that have been obtained or derived from statements made or published by such third parties. Any

such statements or information should not be viewed as indicating the support of such third parties for the views expressed herein.

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