UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D. C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): August 12, 2015

Palmetto Bancshares, Inc.

(Exact name of registrant as specified in its charter)

800.725.2265

Registrant’s telephone number

N/A

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

SECTION 8 – OTHER EVENTS

Item 8.01. Other Events

On August 12, 2015, Palmetto Bancshares, Inc. (the “Company”) will hold a special meeting of its shareholders (the “Special Meeting”). During the Special Meeting, an informational update will be presented by the Company. A copy of the presentation is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

CAUTIONARY STATEMENTS REGARDING FORWARD-LOOKING INFORMATION

This Current Report on Form 8-K contains “forward-looking statements” as defined in the Private Securities Litigation Reform Act of 1995. In general, forward-looking statements usually use words such as “may,” “believe,” “expect,” “anticipate,” “intend,” “will,” “should,” “plan,” “estimate,” “predict,” “continue” and “potential” or the negative of these terms or other comparable terminology, including statements related to the expected timing of the closing of the proposed merger of the Company with and into United Community Banks, Inc. (“United”), the holding company for United Community Bank, Blairsville, Georgia (the “Merger”), the expected returns and other benefits of the Merger to shareholders, expected improvement in operating efficiency resulting from the Merger, estimated expense reductions resulting from the transactions and the timing of achievement of such reductions, the impact on and timing of the recovery of the impact on tangible book value, and the effect of the Merger on United’s capital ratios. Forward-looking statements represent management’s beliefs, based upon information available at the time the statements are made, with regard to the matters addressed; they are not guarantees of future performance. Forward-looking statements are subject to numerous assumptions, risks and uncertainties that change over time and could cause actual results or financial condition to differ materially from those expressed in or implied by such statements.

Factors that could cause or contribute to such differences include, but are not limited to, the possibility that expected benefits may not materialize in the time frames expected or at all, or may be more costly to achieve; that the Merger may not be timely completed, if at all; that prior to completion of the Merger or thereafter, the parties’ respective businesses may not perform as expected due to transaction-related uncertainties or other factors; that the parties are unable to implement successful integration strategies; that the required shareholder or other closing conditions are not satisfied in a timely manner, or at all; reputational risks and the reaction of the parties’ customers to the Merger; diversion of management time to Merger-related issues; and other factors and risk influences contained in the cautionary language included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2014 and other documents subsequently filed by the Company with the Securities and Exchange Commission (the “SEC”). Consequently, no forward-looking statement can be guaranteed. Neither the Company nor United undertakes any obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise. For any forward-looking statements made in this Current Report on Form 8-K, the exhibits hereto, or any related documents, the Company and United claim protection of the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995.

ADDITIONAL INFORMATION ABOUT THE MERGER AND WHERE TO FIND IT

This communication is being made in respect of the Merger involving the Company and United Community Banks, Inc. (“United”). This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval. United filed a registration statement on Form S-4, as amended, with the Securities and Exchange Commission that was declared effective by the Securities and Exchange Commission on July 10, 2015 to register the shares of United’s common stock that will be issued to the Company’s shareholders in connection with the transaction. The registration statement includes a proxy statement/prospectus and other relevant materials in connection with the proposed merger transaction involving United and the Company. The proxy statement/prospectus was mailed to the Company’s shareholders on or about July 13, 2015. INVESTORS AND SECURITY HOLDERS ARE URGED TO READ THE REGISTRATION STATEMENT, PROXY STATEMENT/PROSPECTUS (AND ANY OTHER DOCUMENTS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION IN CONNECTION WITH THE TRANSACTION OR INCORPORATED BY REFERENCE INTO THE PROXY STATEMENT/PROSPECTUS) BECAUSE SUCH DOCUMENTS CONTAIN IMPORTANT INFORMATION REGARDING THE PROPOSED MERGER TRANSACTION. Investors and security holders may obtain free copies of these documents and other documents filed with the Securities and Exchange Commission on its website at http://www.sec.gov. Investors and security holders may also obtain free copies of the documents filed with the Securities and Exchange Commission by United on its website at http://www.ucbi.com and by the Company on its website at http://www.palmettobank.com.

PARTICIPANTS IN THE MERGER SOLICITATION

United and the Company, and certain of their respective directors, executive officers and other members of management and employees may be deemed to be participants in the solicitation of proxies from the shareholders of the Company in respect of the proposed merger transaction. Information regarding the directors and executive officers of United and the Company and other persons who may be deemed participants in the solicitation of the shareholders of the Company in connection with the proposed transaction is included in the proxy statement/prospectus for the Company’s special meeting of shareholders which was mailed to the Company’s shareholders on or about July 13, 2015. Information about United’s directors and executive officers can also be found in United’s definitive proxy statement in connection with its 2015 annual meeting of shareholders, as filed with the Securities and Exchange Commission on March 31, 2015, and other documents subsequently filed by United with the Securities and Exchange Commission. Information about the Company’s directors and executive officers can also be found in the Company’s definitive proxy statement in connection with its 2015 annual meeting of shareholders, as filed with the Securities and Exchange Commission on April 1, 2015, and other documents subsequently filed by the Company with the Securities and Exchange Commission. Additional information regarding the interests of such participants is included in the proxy statement/prospectus and other relevant documents regarding the proposed merger transaction filed with the Securities and Exchange Commission.

SECTION 9 – FINANCIAL STATEMENTS AND EXHIBITS

Item 9.01. Financial Statements and Exhibits

(d) Exhibits

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Date: August 12, 2015

INDEX TO EXHIBITS