Business Combination Prospectus (Form 425)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d)

OF THE SECURITIES EXCHANGE ACT OF 1934

January 12, 2026

Date of Report (Date of earliest event reported)

Middlefield Banc Corp.

(Exact name of registrant as specified in its charter)

Ohio

(State or other jurisdiction of incorporation)

001-36613

(Commission File Number)

34-1585111

(I.R.S. Employer Identification Number)

15985 East High Street

Middlefield, Ohio 44062

(Address of principal executive offices, including zip code)

(440) 632-1666

(Registrant's telephone number, including area code)

(not applicable)

(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:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (17 CFR §230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2).

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 revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

ITEM 5.02(e): Material Compensatory Plan

At a meeting of the Compensation Committee of the Board of Directors of The Middlefield Banking Company held on January 12, 2026, the nonemployee directors approved bonuses to be payable on February 6, 2026 in the amount of $49,935.08 for President and Chief Executive Ronald L. Zimmerly, Jr., $22,827.52 for Chief Financial Officer, Executive Vice President and Treasurer Michael C. Ranttila, and $18,547.49 for Executive Vice President and Chief Banking Officer Michael L. Cheravitch.

At the same meeting, the Compensation Committee took action to establish award levels and plan performance goals under the Bank's Annual Incentive Plan for 2026 for Mr. Zimmerly, Chief Financial Officer Michael C. Ranttila, and Executive Vice President Michael L. Cheravitch.

The Annual Incentive Plan (the "Plan") is a short-term cash incentive plan that rewards Bank employees with additional cash compensation if specified objectives are achieved. For achievement of the 2026 plan performance goals, assuming receipt of shareholder and regulatory approvals for the pending merger with Farmers National Banc Corp., distributions under the Plan are expected to be made in cash to the executives and employees in the first quarter of 2026 on a pro rata basis due to the anticipated closing of the merger in March 2026. For 2026, the executives' performance measures under the Plan relate to maintaining service levels during the merger transition, completing all required integration tasks with Farmers National Banc Corp. and The Farmers National Bank of Canfield, and timely submission of regulatory disclosures.

The foregoing description of the Annual Incentive Plan does not purport to be complete and is qualified in its entirety by reference to the Annual Incentive Plan, which is filed as Exhibit 10.22 to the Form 8-K Current Report filed by Middlefield Banc Corp. (the "Company") on June 13, 2024, and is incorporated herein by reference.

Forward-Looking Statements

This current report on Form 8-K contains "forward-looking statements" within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. These forward-looking statements are not statements of historical fact, but rather statements based on the Company's current expectations, beliefs and assumptions regarding the future of the Company's business, future plans and strategies, projections, anticipated events and trends, its intended results and future performance, the economy and other future conditions. Forward-looking statements are preceded by terms such as "will," "would," "should," "could," "may," "expect," "estimate," "believe," "anticipate," "intend," "plan" "project," or variations of these words, or similar expressions.

Forward-looking statements are not a guarantee of future performance and actual future results could differ materially from those contained in forward-looking information. Because forward-looking statements relate to the future, they are subject to inherent uncertainties, risks and changes in circumstances that are difficult to predict and many of which are outside of the Company's control. Numerous uncertainties, risks, and changes could cause or contribute to the Company's actual results, performance, and achievements to be materially different from those expressed or implied by the forward-looking statements. Factors that may cause or contribute to these differences include, without limitation, risks that the proposed merger transaction will not close when expected or at all because required regulatory, shareholder or other approvals or conditions to closing are delayed or not received or satisfied on a timely basis or at all; risks that the benefits from the transaction may not be fully realized or may take longer to realize than expected, including as a result of changes in general economic and market conditions, interest and exchange rates, monetary policy, laws and regulations and their enforcement, and the degree of competition in the geographic and business areas in which the Company and Farmers

National Banc Corp. ("Farmers") operate; uncertainties regarding the ability of Farmers to promptly and effectively integrate the Company with its businesses in accordance with expectations; changes in business and operational strategies that may occur prior to the closing of the proposed merger with Farmers; uncertainties regarding the reaction to the transaction of the companies' respective customers, employees, and contractual counterparties; and risks relating to the diversion of management time on merger-related issues; and other factors disclosed periodically in the Company's filings with the SEC.

Because of the risks and uncertainties inherent in forward-looking statements, readers are cautioned not to place undue reliance on them, whether included in this report or made elsewhere from time to time by the Company or Farmers or on the Company or Farmers' behalf. The Company and Farmers disclaim any obligation and do not intend to update or revise any forward-looking statements contained in this communication, which speak only as of the date hereof, whether as a result of new information, future events or otherwise, except as required by federal securities laws.

Additional factors which could affect future results of the Company can be found in the Company's Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, and the Current Reports on Form 8-K, in each case filed with the SEC and available on the SEC's website at https://www.sec.gov.

Information about the Merger and Where to Find It

In connection with the proposed merger of the Company with and into Farmers with Farmers as the surviving entity (the "Merger") pursuant to that certain Agreement and Plan of Merger, dated as of October 22, 2025, by and between the Company and Farmers (the "Merger Agreement"), Farmers filed a registration statement on Form S-4 with the SEC to register the shares of Farmers' common stock that will be issued to the Company's shareholders in connection with the Merger (the "Registration Statement"). The Registration Statement was declared effective on December 15, 2025, and included a joint proxy statement of the Company and Farmers that also constitutes a prospectus of Farmers. The definitive joint proxy statement has been sent to the shareholders of Farmers and the Company seeking their approval of the proposed Merger. This communication is not a substitute for the joint proxy statement/prospectus or Registration Statement or for any other document that the Company or Farmers may file with the SEC and send to the Company's shareholders in connection with the proposed merger transaction.

INVESTORS AND SECURITY HOLDERS ARE URGED TO CAREFULLY READ THE REGISTRATION STATEMENT AND ACCOMPANYING JOINT PROXY STATEMENT/PROSPECTUS REGARDING THE PROPOSED MERGER TRANSACTION AND ANY OTHER RELEVANT DOCUMENTS FILED WITH THE SEC, AS WELL AS ANY AMENDMENTS OR SUPPLEMENTS TO THOSE DOCUMENTS, BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION.

Investors and security holders are able to obtain free copies of the Registration Statement on Form S-4 and other documents containing information about the Company, Farmers, and the proposed merger transaction filed with the SEC through the website maintained by the SEC at http://www.sec.gov. Copies of the documents filed with the SEC by the Company will be available free of charge on the Company's website at https://www.middlefieldbank.bank or may be obtained from the Company by written request to Middlefield Banc Corp., 15985 East High Street, Middlefield, Ohio 44062, Attention: Investor Relations. Copies of the documents filed with the SEC by Farmers will be available free of charge on Farmers' website at https://www.farmersbankgroup.com or may be obtained from Farmers by written request to Farmers National Banc Corp., 20 South Broad Street, Canfield, Ohio 44406, Attention: Investor Relations.

Participants in the Solicitation

The respective directors and executive officers of the Company and Farmers and other persons may be deemed to be participants in the solicitation of proxies from Farmers shareholders and Company shareholders with respect to the Merger. Information regarding the directors and executive officers of the Company is available in its proxy statement filed with the SEC on April 4, 2025. Information regarding the directors and executive officers of Farmers, is set forth in the proxy statement for Farmers' 2025 annual meeting of shareholders, as filed with the SEC on March 18, 2025 and in certain of its Current Reports on Form 8-K, which are filed with the SEC. Additional information regarding the interests of those participants and other persons who may be deemed participants may be obtained by reading the joint proxy statement/prospectus included in the Registration Statement and other relevant documents regarding the proposed merger transaction filed with the SEC when they become available. Copies of these documents may be obtained free of charge from the sources described above.

No Offer or Solicitation

This communication shall not constitute an offer to sell or the solicitation of an offer to buy any securities nor shall there be any sale of securities in any jurisdiction in which the offer, solicitation or sale is unlawful before registration or qualification of the securities under the securities laws of the jurisdiction. No offer of securities shall be made except by means of a prospectus satisfying the requirements of Section 10 of the Securities Act of 1933, as amended, and otherwise in accordance with applicable law.

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.