Upon the terms and subject to the conditions of the merger agreement, Guaranty will merge with and into Bar Harbor, with Bar Harbor as the survivingcorporation. We refer to this transaction as the merger. Immediately following the merger, Woodsville Guaranty Savings Bank, a New Hampshire-chartered bank and wholly owned subsidiary of Guaranty, willmerge with and into Bar Harbor Bank & Trust, a Maine-chartered bank and wholly owned subsidiary of Bar Harbor, with Bar Harbor Bank & Trust as theresulting bank. We refer to this transaction as the bank merger. Shareholders of Guaranty will receive 1.85 shares of Bar Harbor common stock, par value $2.00 per share, in exchange for each share of Guarantycommon stock, par value $0.20 per share, that they own (other than any shares as to which statutory appraisal rights have been properly exercised andperfected). Guaranty shareholders will also receive cash in lieu of fractional shares of Bar Harbor common stock they would otherwise have received in themerger. Bar Harbor common stock currently trades on the NYSE American, under the symbol “BHB.” Guaranty common stock is quoted on the OTC ExpertMarket under the symbol “GUAA”; however, the shares do not have an active trading market and are not traded frequently. The shares of Bar Harbor commonstock issued pursuant to the merger will be registered under the Securities Act of 1933, as amended, and will trade on the NYSE American at closing. The value of the merger consideration will fluctuate as the market price of Bar Harbor common stock fluctuates before the completion of the merger. Based on the closing price of Bar Harbor common stock as reported on NYSE American of $29.31 as of March11, 2025, the last full trading day prior tothe announcement of the merger, the implied value of the merger consideration was approximately $54.22 per share of Guaranty common stock and the impliedaggregate transaction value was approximately $39.6million. Based on the closing price of Bar Harbor common stock as reported on the NYSE American of $29.50 as of April30, 2025, the last practicable date beforethe date of this proxy statement/prospectus, the implied value of the merger consideration was approximately $54.58 per share of Guaranty common stock andthe implied aggregate transaction value was approximately $39.8million. We urge you to obtain current market quotations for shares of Bar Harbor commonstock. We cannot complete the merger unless we obtain the necessary approval from the shareholders of Guaranty as described in the attached proxy statement/prospectus. Accordingly, Guaranty will hold a special meeting of its shareholders in connection with the merger at 9:00a.m., local time, on June12, 2025, whichwe refer to as the special meeting. Guaranty shareholders will be asked to vote to approve the merger agreement, which we refer to as the merger proposal, andto approve one or more adjournments of the special meeting, if necessary or appropriate, as determined by Guaranty, including adjournments to permit furthersolicitation of proxies in favor of the merger proposal, which we refer to as the adjournment proposal. Approval of the merger proposal requires the affirmativevote of holders of two-thirds of the outstanding shares of common stock of Guaranty entitled to vote at the special meeting. The adjournment proposal will beapproved if a majority of the shares present in person or represented by proxy at the special meeting and entitled to vote on the matter are voted in favor of theadjournmentproposal. Guaranty’s board of directors has unanimously adopted and approved the merger agreement, has unanimously determined that the merger agreement and thetransactions contemplated thereby, including the merger, are advisable and in the best interests of Guaranty and its shareholders, and unanimously recommends thatGuaranty shareholders vote “FOR” the merger proposal and “FOR” the adjournment proposal. YOUR VOTE IS VERY IMPORTANT.We cannot complete the merger unless Guaranty’s shareholders approve the merger proposal. Regardless ofwhether you plan to attend the special meeting, please vote as soon as possible. If you hold stock in your name as a shareholder of record of Guaranty, pleasesubmit a proxy to have your shares voted as promptly as possible by signing and returning the accompanying proxy card in the enclosed postage-paid returnenvelope. You may also cast your vote at the special meeting. If you hold your stock in “street name” through a bank or broker, please follow the instructions onthe voting instruction card furnished by the record holder. The attached proxy statement/prospectus contains a more complete description of the merger agreement and the special meeting. You should read this entireproxy statement/prospectus carefully because it contains important information about the merger. In particular, you should read the information under the sectionentitled “Risk Factors” beginning on page19. You may also obtain infor