SUMMARY

This summary highlights selected information from this joint proxy statement/prospectus. It does not contain all of the information that may be important to you. You should read carefully this entire document and its Annexes and all other documents to which this joint proxy statement/prospectus refers before you decide how to vote. In addition, we incorporate by reference important business and financial information about Farmers into this document. For a description of this information, see “INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE” on page 116. You may obtain the information incorporated by reference into this document without charge by following the instructions in the section entitled “WHERE YOU CAN FIND MORE INFORMATION” in the forepart of this document. Each item in this summary includes a page reference, where applicable, directing you to a more complete description of that item.

The Companies

Farmers National Banc Corp.

Farmers National Banc Corp.

20 South Broad Street

Canfield, Ohio 44406

Phone: (330) 533-3341

Farmers is a one-bank holding company organized in 1983 under the laws of the State of Ohio and registered under the Bank Holding Company Act of 1956, as amended (the “BHCA”). Farmers operates principally through its wholly-owned subsidiaries, Farmers Bank, Farmers Trust Company (“Farmers Trust”) and National Associates, Inc. (“NAI”). Farmers National Insurance, LLC (“Farmers Insurance”) and Farmers of Canfield Investment Co. (“Farmers Investments”) are wholly-owned subsidiaries of Farmers Bank. Farmers and its subsidiaries operate in the domestic banking, trust, retirement consulting, insurance and financial management industries.

Farmers’ principal business consists of owning and supervising its subsidiaries. Although Farmers directs the overall policies of its subsidiaries, including lending practices and financial resources, most day-to-day affairs are managed by their respective officers. Farmers and its subsidiaries had 327 full-time equivalent employees at December 31, 2014. Farmers’ business activities are managed and financial performance is primarily aggregated and reported in three lines of business, the bank segment, the trust segment and the retirement planning/consulting segments.

Farmers Bank is a full-service national banking association engaged in commercial and retail banking mainly in Mahoning, Trumbull, Columbiana and Stark Counties in Ohio. Farmers Bank’s commercial and retail banking services include checking accounts, savings accounts, time deposit accounts, commercial, mortgage and installment loans, home equity loans, home equity lines of credit, night depository, safe deposit boxes, money orders, bank checks, automated teller machines, internet banking, travel cards, “E” Bond transactions, MasterCard and Visa credit cards, brokerage services and other miscellaneous services normally offered by commercial banks.

Farmers Bank faces significant competition in offering financial services to customers. Ohio has a high density of financial service providers, many of which are significantly larger institutions that have greater financial resources than Farmers Bank, and all of which are competitors to varying degrees. Competition for loans comes principally from savings banks, savings and loan associations, commercial banks, mortgage banking companies, credit unions, insurance companies and other financial service companies. The most direct competition for deposits has historically come from savings and loan associations, savings banks, commercial banks and credit unions. Additional competition for deposits comes from non-depository competitors such as the mutual fund industry, securities and brokerage firms and insurance companies.

During 2009, Farmers acquired 100% of the capital stock of Butler Wick Trust Company, a wholly-owned subsidiary of Butler Wick Corporation for approximately $12.1 million and renamed the entity Farmers Trust Company. Farmers Trust offers a full complement of personal and corporate trust services in the areas of estate settlement, trust administration and employee benefit plans. Farmers Trust operates two offices located in Boardman and Howland, Ohio.

During 2013, Farmers completed the acquisition of all of the outstanding stock of the retirement planning consultancy National Associates, Inc. of Cleveland, Ohio. The transaction involved both cash and stock totaling $4.4 million, including up to $1.5 million of future payments, contingent upon NAI meeting income performance targets. The acquisition is part of Farmers’ plan to increase the levels of noninterest income and to complement the existing retirement service currently being offered. NAI operates from its office located in Rocky River, Ohio.

Farmers Insurance was formed during 2009 and offers a variety of insurance products through licensed representatives. Farmers Insurance is a subsidiary of Farmers Bank and does not account for a material portion of the revenue of Farmers.

Farmers of Canfield Investment Company was formed during 2014 with the primary purpose of investing in municipal securities. Farmers Investments is a subsidiary of Farmers Bank and does not account for a material portion of the revenue of Farmers.

Farmers’ common shares are traded on the NASDAQ Stock Market (the “Nasdaq”) under the symbol “FMNB”. Farmers is subject to the reporting requirements under the Securities Exchange Act of 1934, as amended, and, therefore, files reports, proxy statements and other information with the SEC. Further important business and financial information about Farmers is incorporated by reference into this joint proxy statement/prospectus. See “INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE” on page 116 of this joint proxy statement/prospectus.

National Bancshares Corporation

National Bancshares Corporation

112 West Market Street

Orrville, Ohio 44667

Phone: (330) 765-0609

NBOH is a one-bank holding company organized in 1985 under the laws of the State of Ohio and is registered under the BHCA. NBOH operates through its wholly-owned subsidiary, FNB. FNB is a full-service national banking association engaged in banking through a network of 14 offices located in Wayne, Medina, Stark, and Columbiana counties in Ohio.

FNB makes commercial real estate loans, commercial loans, residential real estate and home equity loans, and consumer loans. A significant portion of FNB’s lending consists of origination of conventional loans secured by 1-4 family real estate located in FNB’s market area. The bank’s residential mortgage loans generally are originated with loan documentation permitting sale to Federal Home Loan Mortgage Corporation. Deposits, repayment of mortgage-backed securities and repayment of loan principal are FNB’s primary sources of funds for lending activities and other general business purposes. These funds are supplemented by FHLB borrowings.

The banking industry in FNB’s market areas is highly competitive. In addition to competing with other commercial and savings banks and savings and loan associations, FNB competes with credit unions, finance companies, leasing companies, mortgage companies, insurance companies, brokerage and investment banking

firms, asset-based non-bank lenders and many other financial service firms. Competition is based on interest rates offered on deposit accounts, interest rates charged on loans and leases, fees and service charges, the quality and scope of the services rendered, the convenience of banking facilities and, in the case of loans to commercial borrowers, relative lending limits, as well as other factors.

At December 31, 2014, FNB had 111 full-time equivalent employees. NBOH’s common shares are traded in the OTCQX marketplace under the symbol “NBOH.”

The Merger Agreement (page 71)

The Merger Agreement provides that, if all of the conditions are satisfied or waived, NBOH will be merged with and into Farmers, with Farmers surviving. Thereafter, at a later time specified by Farmers Bank in its certificate of merger filed with the Office of the Comptroller of the Currency (the “OCC”), FNB will be merged with and into Farmers Bank. The Merger Agreement is attached to this joint proxy statement/prospectus as Annex B and is incorporated in this joint proxy statement/prospectus by reference. We encourage you to read the Merger Agreement carefully, as it is the legal document that governs the Merger.

What NBOH shareholders will receive in the Merger (page 71)

Under the terms of the Merger Agreement, shareholders of NBOH will be entitled to receive from Farmers, after the Merger is completed, Merger consideration payable in the form of a combination of cash and Farmers common shares to be calculated as set forth in the Merger Agreement. At the effective time of the Merger, each NBOH common share will be converted into the right to receive either: (i) 4.034 Farmers common shares, or (ii) $32.15 in cash, subject to adjustment under certain circumstances set forth in the Merger Agreement. Following the Merger, NBOH sharesholders will own approximately 28.1% of the outstanding Farmers common shares. Additionally, while NBOH has historically paid a $0.10 per share quarterly dividend, Farmers currently pays a $0.03 per share quarterly dividend. On a per share equivalent basis, NBOH shareholders would receive a 21.0% increase in dividends.

Farmers will not issue any fractional common shares in connection with the Merger. Instead, each holder of NBOH common shares who would otherwise be entitled to receive a fraction of a Farmers common share (after taking into account all NBOH common shares owned by such holder at the effective time of the Merger) will receive cash, without interest, in an amount equal to the Farmers fractional common share to which such holder would otherwise be entitled multiplied by the volume-weighted average, rounded to the nearest one tenth of a cent, of the closing sale prices of Farmers common shares based on information reported by the Nasdaq for the five (5) trading days immediately preceding the effective time.

What holders of NBOH Stock Options will receive (page 72)

At the effective time of the Merger, each outstanding and unexercised employee and director option to purchase NBOH common shares, whether vested or unvested, will vest in full and cease to represent an option to purchase NBOH common shares. Instead, each holder of an option will be entitled to receive cash in an amount equal to (a) the difference between $32.15 and the exercise price of the option, multiplied by (b) the total number of NBOH common shares for which the option was exercisable.

As of May 7, 2015, there were outstanding NBOH stock options to purchase 142,471 shares, 100% of which were vested. As of May 7, 2015, all 142,471 NBOH common shares, or 100%% of all outstanding option shares, are held by directors and executive officers of NBOH. The average exercise price of the outstanding NBOH stock options is $16.56. Accordingly, the maximum aggregate cash payment to the holders of NBOH stock options will be approximately $2.2 million.

Exchange of NBOH common shares (page 72)

Once the Merger is complete, Computershare Investor Services, as exchange agent (the “Exchange Agent”), will mail you transmittal materials and instructions for exchanging your NBOH share certificates for Farmers’ common shares to be issued by book-entry transfer.

NBOH special meeting of shareholders (page 37)

A special meeting of shareholders of NBOH will be held at 10:00 a.m., local time, on June 12, 2015, at the Operations Center of the First National Bank of Orrville at 1444 N. Main Street, Orrville, Ohio 44667, for the purpose of considering and voting on the following matters:

You are entitled to vote at the special meeting if you owned NBOH common shares as of the close of business on May 8, 2015. As of May 7, 2015, a total of 2,233,694 NBOH common shares were outstanding and eligible to be voted at the NBOH special meeting.

Farmers special meeting of shareholders (page 41)

A special meeting of shareholders of Farmers will be held at 10:00 a.m., local time, on June 12, 2015, at Farmers’ main office at 20 South Broad Street, Canfield, Ohio 44406, for the purpose of considering and voting on the following matters:

You are entitled to vote at the special meeting if you owned Farmers common shares as of the close of business on May 8, 2015. As of May 7, 2015, a total of 18,408,612 Farmers common shares were outstanding and eligible to be voted at the Farmers special meeting.

Required vote (pages 37, 41)

The adoption and approval of the Merger Agreement by Farmers will require the affirmative vote of the holders of at least 12,272,408 Farmers common shares, which, as of May 7, 2015, is not less than two-thirds of the Farmers common shares outstanding and entitled to vote at the Farmers special meeting. A quorum, consisting of the holders of 6,136,204 of the outstanding Farmers common shares, must be present in person or

by proxy at the Farmers special meeting before any action, other than the adjournment of the special meeting, can be taken. The affirmative vote of the holders of a majority of the Farmers common shares represented, in person or proxy, at the special meeting is required to adjourn the special meeting, if necessary, to solicit additional proxies.

The adoption and approval of the Merger Agreement by NBOH will require the affirmative vote of the holders of at least 1,489,130 NBOH common shares, which is two-thirds of the NBOH common shares outstanding and entitled to vote at the NBOH special meeting. A quorum, consisting of the holders of 1,116,847 of the outstanding NBOH common shares, must be present in person or by proxy at the NBOH special meeting before any action, other than the adjournment of the special meeting, can be taken. The affirmative vote of the holders of a majority of the NBOH common shares represented, in person or proxy, at the special meeting is required to adjourn the special meeting, if necessary, to solicit additional proxies.

As of May 7, 2015, directors, executive officers and greater than 5% beneficial owners of Farmers owned an aggregate of 2,105,217 Farmers common shares, an amount equal to approximately 11.44% of the outstanding Farmers common shares. As of the same date, directors, executive officers and greater than 5% beneficial owners of NBOH beneficially owned an aggregate of 749,333 NBOH common shares, an amount equal to approximately 33.55% of the outstanding NBOH common shares. As of May 7, 2015, prior to giving effect to the Merger, the directors, executive officers and greater than 5% beneficial owners of Farmers owned 1.86%, 0.42% and 9.16%, respectively, of the outstanding Farmers common shares, and after giving effect to the Merger, the directors, executive officers and greater than 5% beneficial owners of Farmers would own 1.37%, 0.30% and 6.46%, respectively, of the outstanding Farmers common shares.

All directors and executive officers of Farmers have indicated that they will vote in favor of the adoption and approval of the Merger Agreement, although none of them have entered into formal commitments. Certain of the directors of NBOH, who, collectively, beneficially own 535,729 NBOH common shares, entered into the Voting Agreements, pursuant to which they are required, up to a collective maximum of 19.9% of NBOH’s outstanding common shares and subject to certain other terms and conditions, to vote their shares in favor of the adoption and approval of the Merger Agreement. No non-director executive officer of NBOH nor any other NBOH shareholder included in the table on page 89 of this joint proxy statement/prospectus has executed a voting agreement with Farmers nor has any such person committed to Farmers or NBOH that such person will vote in favor of any of the matters being presented to the NBOH shareholders at the NBOH special meeting. Excluding such committed shares held by NBOH directors, the adoption and approval of the Merger Agreement will require the affirmative vote of the holders of at least 1,044,625 NBOH common shares, or 58.4% of the non-committed outstanding shares.

As of the date of this joint proxy statement/prospectus, Farmers and its directors, executive officers and affiliates beneficially owned no NBOH common shares, and NBOH and its directors, executive officers and affiliates beneficially owned no Farmers common shares. Farmers Trust acts as trustee with respect to 310,383 Farmers common shares. FNB acts as trustee for no NBOH common shares. Farmers Trust will vote the shares it holds as trustee with respect to which it has voting power in accordance with its fiduciary duties at the time of the Farmers special meeting, but expects at this time that it will vote the shares in favor of all of the proposals presented for a vote.

Recommendation to NBOH shareholders (page 40)

The board of directors of NBOH approved the Merger Agreement by a vote of eight to two. The board of directors of NBOH believes that the Merger is in the best interests of NBOH and its shareholders, and, as a result, the board of directors recommend that NBOH shareholders vote “FOR” the adoption and approval of the Merger Agreement and “FOR” the proposal to adjourn the special meeting, if necessary and appropriate, to solicit additional proxies.

In reaching this decision, the board of directors of NBOH considered many factors, which are described in the section captioned “THE MERGER – Background of the Merger” and “THE MERGER – NBOH’s Reasons for the Merger” beginning on page 46 and page 49, respectively, of this joint proxy statement/prospectus.

Opinion of NBOH’s Financial Advisor (page 51)

In connection with the Merger, NBOH’s financial advisor, Boenning & Scattergood, Inc. (“Boenning”), delivered a written opinion, dated January 27, 2015, to the NBOH board of directors as to the fairness, from a financial point of view, of the Merger consideration in the Merger to be received by the holders of NBOH common shares. The full text of the opinion, which describes the procedures followed, assumptions made, matters considered, and qualifications and limitations on the review undertaken by Boenning in preparing the opinion, is attached as Annex C to this document. The opinion was for the information of, and was directed to, the NBOH board (in its capacity as such) in connection with its consideration of the financial terms of the Merger. The opinion did not address the underlying business decision of NBOH to engage in the Merger or enter into the Merger Agreement or constitute a recommendation to the NBOH board in connection with the Merger, and it does not constitute a recommendation to any holder of NBOH common shares or any shareholder of any other entity as to how to vote in connection with the Merger or any other matter.

Recommendation to Farmers shareholders (page 44)

The board of directors of Farmers unanimously approved the Merger Agreement. The board of directors of Farmers believes that the Merger is in the best interests of Farmers and its shareholders, and, as a result, the directors unanimously recommend that Farmers shareholders vote “FOR” the adoption and approval of the Merger Agreement, “FOR” the approval of the issuance of up to 7,668,359 common shares in connection with the Merger, and “FOR” the proposal to adjourn the special meeting, if necessary and appropriate, to solicit additional proxies.

In reaching this decision, the board of directors of Farmers considered many factors which are described in the section captioned “THE MERGER – Background of the Merger” and “THE MERGER – Farmers’ Reasons for the Merger” beginning on page 46 and page 58, respectively, of this joint proxy statement/prospectus.

Opinion of Farmers’ Financial Advisor (page 59)

At the request of Farmers’ board of directors on January 27, 2015, Sterne, Agee & Leach, Inc. (“Sterne Agee”) rendered its opinion that, as of January 27, 2015, from a financial point of view, the Merger consideration to be paid by Farmers pursuant to the Merger Agreement was fair, based upon and subject to the qualifications, assumptions and other matters considered in connection with the preparation of its opinion. The full text of Sterne Agee’s written opinion, which sets forth the assumptions made, procedures followed, matters considered and limitations on the review undertaken in connection with the opinion, is attached to this document as Annex D. The opinion was provided for the information of Farmers’ board of directors (solely in its capacity as such) in connection with, and for purposes of, its consideration of the Merger and the opinion only addressed whether the Merger consideration to be paid by Farmers in the Merger pursuant to the Merger Agreement was fair, from a financial point of view, to Farmers. The opinion did not address any other term or aspect of the Merger Agreement or the Merger contemplated thereby. The opinion does not constitute a recommendation to the board or to any holder of Farmers common shares as to how the board, such shareholder or any other person should vote or otherwise act with respect to the Merger or any other matter.

Material U.S. federal income tax consequences of the Merger (page 66)

Farmers and NBOH intend that the Merger will be treated as a reorganization within the meaning of Section 368(a) of the Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”), and it is a condition to the obligation of NBOH to complete the Merger that it receives a legal opinion to that effect. If treated as a reorganization, for U.S. federal income tax purposes (i) no gain or loss will be recognized by Farmers or NBOH as a result of the Merger, (ii) NBOH shareholders will recognize gain (but not loss) in an amount not to exceed any cash received in exchange for NBOH common shares in the Merger (other than any cash received in lieu of a fractional Farmers common share, as discussed below under the section entitled “THE MERGER – Material U.S. Federal Income Tax Consequences of the Merger – Cash in Lieu of Fractional Shares” beginning on page 69) and (iii) NBOH shareholders who exercise dissenters’ rights and receive solely cash in exchange for NBOH common shares in the Merger will, generally, recognize gain or loss equal to the difference between the amount of cash received and their tax basis in their shares.

All NBOH shareholders should read carefully the description under the section captioned “THE MERGER – Material U.S. Federal Income Tax Consequences of the Merger” beginning on page 66 of this joint proxy statement/prospectus and should consult their own tax advisors concerning these matters. All NBOH shareholders should consult their tax advisors as to the specific tax consequences of the Merger to them, including the applicability and effect of the alternative minimum tax and any state, local, foreign or other tax laws.

Interests of directors and executive officers of NBOH (page 65)

Officers and directors of NBOH have employment and other compensation agreements or economic interests that give them interests in the Merger that are somewhat different from, or in addition to, their interests as NBOH shareholders. These interests and agreements include:

Each of Farmers’ and NBOH’s board of directors was aware of these interests and considered them in approving the Merger Agreement. See “THE MERGER – Interests of NBOH Directors and Executive Officers in the Merger” beginning on page 65 of this joint proxy statement/prospectus.

Dissenters’ rights of NBOH shareholders (page 45)

Under Ohio law, NBOH shareholders who do not vote in favor of the adoption and approval of the Merger Agreement and deliver a written demand for payment for the fair cash value of their NBOH common shares prior to the NBOH special meeting, will be entitled, if and when the Merger is completed, to receive the fair cash value of their NBOH common shares. The right to make this demand is known as “dissenters’ rights.” NBOH shareholders’ right to receive the fair cash value of their NBOH common shares, however, is contingent upon

strict compliance with the procedures set forth in Section 1701.85 of the OGCL. An NBOH shareholder’s failure to vote against the adoption and approval of the Merger Agreement will not constitute a waiver of such shareholder’s dissenters’ rights, so long as such shareholder does not vote in favor of the Merger Agreement or return an unmarked proxy card.

For additional information regarding dissenters’ rights, see “DISSENTERS’ RIGHTS” on page 45 of this joint proxy statement/prospectus and the complete text of Section 1701.85 of the OGCL attached to this joint proxy statement/prospectus as Annex A. If NBOH shareholders should have any questions regarding dissenters’ rights, such shareholders should consult with their own legal advisers.

Certain differences in shareholder rights (page 84)

When the Merger is completed, NBOH shareholders (other than those exercising dissenters’ rights or receiving only cash) will receive Farmers common shares and, therefore, will become Farmers shareholders. As Farmers shareholders, the former NBOH shareholders’ rights will be governed by Farmers’ Amended Articles of Incorporation and Regulations, as well as Ohio law. Notably, NBOH shareholders will own less of the combined company and as such will have decreased voting power. For a summary of significant differences, see “COMPARISON OF CERTAIN RIGHTS OF NBOH AND FARMERS SHAREHOLDERS” beginning on page 89 of this joint proxy statement/prospectus.

Regulatory approvals required for the Merger (page 65)

The Merger cannot be completed until Farmers receives necessary regulatory approvals, which include the approval of the Federal Reserve and the approval of the OCC. Farmers has received such approval to consummate the Merger from the OCC, but has not yet received such approval from the Federal Reserve.

Conditions to the Merger (page 80)

As more fully described in this joint proxy statement/prospectus and in the Merger Agreement, the completion of the Merger depends on the adoption and approval of the Merger Agreement by Farmers’ and NBOH’s shareholders and receipt of the required regulatory approvals, in addition to satisfaction of, or where legally permissible, waiver of, other customary conditions. Although Farmers and NBOH anticipate the closing of the Merger will occur in the second quarter of 2015, neither Farmers nor NBOH can be certain when, or if, the conditions to the Merger will be satisfied or, where permissible, waived, or that the Merger will be completed. See “THE MERGER AGREEMENT – Conditions to Consummation of the Merger” beginning on page 80 of this joint proxy statement/prospectus.

Termination; Termination Fee (page 81)

The Merger Agreement may be terminated at any time prior to the effective time of the Merger, whether before or after approval of the Merger by NBOH shareholders:

If the Merger Agreement is terminated under certain circumstances, including circumstances involving alternative acquisition proposals, NBOH may be required to pay Farmers a termination fee of $2.5 million. See “THE MERGER AGREEMENT – Termination; Termination Fee” beginning on page 81.

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA FOR FARMERS

The following table summarizes financial results achieved by Farmers for the periods and at the dates indicated and should be read in conjunction with “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” Farmers’ Consolidated Financial Statements and the notes to the Consolidated Financial Statements contained in reports that Farmers has previously filed with the SEC. Historical financial information for Farmers can be found in its Annual Report on Form 10-K for the fiscal year ended December 31, 2014. The selected operating data presented below are not necessarily indicative of the results that may be expected for future periods. See “WHERE YOU CAN FIND MORE INFORMATION” in the forepart of this document for instructions on how to obtain the information that has been incorporated by reference. You should not assume the results of operations for past periods noted below indicate results for any future period.

The information below has been derived from Farmers’ Consolidated Financial Statements.

SELECTED HISTORICAL FINANCIAL AND OTHER DATA OF

FARMERS NATIONAL BANC CORP.

SELECTED HISTORICAL FINANCIAL AND OTHER DATA OF

FARMERS NATIONAL BANC CORP.

Note: All performance ratios are based on average balance sheet amounts where applicable.

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA FOR NBOH

The following table summarizes financial results achieved by NBOH for the periods and at the dates indicated and should be read in conjunction with “INFORMATION ABOUT NBOH – NBOH Management’s Discussion and Analysis of Results of Operations and Financial Condition,” and NBOH’s Consolidated Financial Statements and the notes to the Consolidated Financial Statements included in this joint proxy statement/prospectus. The selected operating data presented below are not necessarily indicative of the results that may be expected for future periods. You should not assume the results of operations for past periods noted below indicate results for any future period.

The information below has been derived from NBOH’s Consolidated Financial Statements.

SELECTED HISTORICAL FINANCIAL AND OTHER DATA OF

NATIONAL BANCSHARES CORPORATION

SELECTED HISTORICAL FINANCIAL AND OTHER DATA OF

NATIONAL BANCSHARES CORPORATION

SUMMARY SELECTED PRO FORMA CONDENSED COMBINED DATA

The following table shows selected financial information on a pro forma combined basis giving effect to the Merger (which is known as “pro forma” information) as if the Merger had become effective as of the date presented, in the case of the balance sheet information, and at the beginning of the period presented, in the case of the income statement information. The pro forma information reflects the acquisition method of accounting.

Farmers anticipates that the Merger will provide the combined company with financial benefits that include reduced operating expenses and greater revenue. The pro forma information, while helpful in illustrating the financial characteristics of Farmers following the Merger under one set of assumptions, does not reflect these benefits and, accordingly, does not attempt to predict or suggest future results. The pro forma information also does not necessarily reflect what the historical results of Farmers would have been had the companies been combined during these periods.

The exchange ratio of 4.034 was used in preparing this selected pro forma information. You should read this summary pro forma information in conjunction with the information under “Unaudited Pro Forma Condensed Combined Consolidated Financial Information Related to the Merger” and with the historical information in this document on which it is based.

UNAUDITED PRO FORMA CONDENSED COMBINED CONSOLIDATED

FINANCIAL INFORMATION RELATING TO THE MERGER

The unaudited pro forma condensed combined consolidated financial information has been prepared using the acquisition method of accounting, giving effect to the proposed Merger. The unaudited pro forma condensed combined consolidated balance sheet combines the historical financial information of Farmers and NBOH as of December 31, 2014, and assumes that the Merger was completed on that date. The unaudited pro forma condensed combined consolidated income statement combines the historical financial information of Farmers and NBOH and give effect to the Merger as if it had been completed as of January 1, 2014. The unaudited pro forma condensed combined consolidated financial information is presented for illustrative purposes only and is not necessarily indicative of the results of operations or financial condition had the Merger been completed on the dates described above, nor is it necessarily indicative of the results of operations in future periods or the future financial position of the combined entities. The financial information should be read in conjunction with the accompanying Notes to Unaudited Pro Forma Condensed Combined Consolidated Financial Information. Certain reclassifications have been made to NBOH’s historical financial information in order to conform to Farmers’ presentation of financial information.

The actual value of Farmers common shares to be recorded as consideration in the Merger will be based on the closing price of Farmers common shares at the time of the Merger completion date. The proposed Merger is expected to be completed in the second quarter of 2015, but there can be no assurance that the Merger will be completed as anticipated. For purposes of the pro forma financial information, NBOH’s outstanding shares, as of January 26, 2015 in the amount of 2,230,494, were used and the fair value of Farmers common shares to be issued in connection with the Merger was based on FMNB’s closing price of $7.50 as of January 26, 2015.

The pro forma financial information includes estimated adjustments, including adjustments to record assets and liabilities of NBOH at its fair value, and represents the pro forma estimates by Farmers based on available fair value information as of the date of the Merger Agreement. In some cases, where noted, more recent information has been used to support estimated adjustments in the pro forma financial information.

The pro forma adjustments included herein are subject to change depending on changes in interest rates and the components of assets and liabilities, and as additional information becomes available and additional analyses are performed. The final allocation of the purchase price for the Merger will be determined after it is completed and after completion of thorough analyses to determine the fair value of NBOH’s tangible and identifiable intangible assets and liabilities as of the date the Merger is completed. Increases or decreases in the estimated fair values of the net assets as compared with the information shown in the unaudited pro forma condensed combined consolidated financial information may change the amount of the purchase price allocated to goodwill and other assets and liabilities and may impact Farmers’ statement of income due to adjustments in yield and/or amortization of the adjusted assets or liabilities. Any changes to NBOH’s shareholders’ equity, including results of operations from December 31, 2014, through the date the Merger is completed, will also change the purchase price allocation, which may include the recording of a lower or higher amount of goodwill. The final adjustments may be materially different from the unaudited pro forma adjustments presented herein.

Farmers anticipates that the Merger will provide the combined company with financial benefits that include reduced operating expenses. Farmers expects to realize cost savings of approximating 25% of the anticipated non-interest expense of NBOH. These cost savings are not included in these pro forma statements and there can be no assurance that expected cost savings will be realized. The pro forma information, while helpful in illustrating the financial characteristics of the combined company under one set of assumptions, does not reflect the benefits of expected cost savings or opportunities to earn additional revenue and, accordingly, does not attempt to predict or suggest future results. It also does not necessarily reflect what the historical results of the combined company would have been had the companies been combined during these periods.

The unaudited pro forma condensed combined consolidated financial information has been derived from and should be read in conjunction with the historical consolidated financial statements and the related notes of Farmers and NBOH, which, in the case of Farmers, are incorporated in this joint proxy statement/prospectus by reference and, in the case of NBOH, included in this joint proxy statement/prospectus. See “Where You Can Find More Information” in the forepart of this document.

The unaudited pro forma shareholders’ equity and net income are qualified by the statements set forth under this caption and should not be considered indicative of the market value of Farmers’ common shares or the actual or future results of operations of Farmers for any period. Actual results may be materially different than the pro forma information presented.

UNAUDITED PRO FORMA CONDENSED COMBINED CONSOLIDATED BALANCE SHEET

UNAUDITED PRO FORMA CONDENSED COMBINED CONSOLIDATED INCOME STATEMENT

Notes to Unaudited Pro Forma Condensed Combined Consolidated Balance Sheet

As of December 31, 2014

(In thousands, except share and per share amounts)

Basis of Presentation

The unaudited pro forma condensed combined consolidated financial information has been prepared using the acquisition method of accounting giving effect to the Merger involving Farmers and NBOH, with Farmers as the accounting acquirer. The unaudited pro forma condensed combined consolidated financial information is presented for illustrative purposes only and is not necessarily indicative of the financial position had the Merger been consummated at December 31, 2014 or the results of operations had the Merger been consummated at January 1, 2014, nor is it necessarily indicative of the results of operations in future periods or the future financial position of the combined entities. The Merger, which is currently expected to be completed in the first half of 2015, provides for the issuance of 7,198,250 shares of Farmers common stock and cash consideration totaling $16.6 million which includes payout of 145,671 options with an average exercise price of $16.49. Based on NBOH’s 2,230,494 outstanding shares as of January 26, 2015, the 80% maximum stock conversion at the 4.034 exchange rate and Farmers’ closing stock price on January 26, 2015, the value of the aggregate Merger consideration would be approximately $70.6 million. Certain NBOH stock transactions may occur prior to close of the Merger which are not considered in the assumptions for these pro forma adjustments.

Under the acquisition method of accounting, the assets and liabilities of NBOH will be recorded at the respective fair values on the Merger date. The fair value on the Merger date represents management’s best estimates based on available information and facts and circumstances in existence on the Merger date. The pro forma allocation of purchase price reflected in the unaudited pro forma condensed combined consolidated financial information is subject to adjustment and may vary from the actual purchase price allocation that will be recorded at the time the Merger is completed. Adjustments may include, but not be limited to, changes in (1) the aggregate value of the Merger consideration paid if the price of Farmers common stock varies from the assumed $7.50 per share; (2) total Merger-related expenses if consummation and/or implementation costs vary from currently estimated amounts; and (3) the underlying values of assets and liabilities if market conditions differ from current assumptions. The following table sets forth the impact on the purchase price, as well as the goodwill generated, if the market price increased or decreased by 10%, 20% or 30% from the assumed market price of $7.50 per share.

Estimated Merger and Integration Costs

The plan to integrate Farmers and NBOH’s operations is still being developed. Over the next several months, the specific details of these plans will continue to be refined. Farmers and NBOH are currently in the process of assessing the two companies’ personnel, benefit plans, premises, equipment, computer systems, attorneys and service contracts to determine where they may take advantage of redundancies or where it will be beneficial or necessary to convert to one system. Certain decisions arising from these assessments may involve involuntary termination of Farmers and NBOH’s employees, changing information systems, canceling contracts between Farmers or NBOH and certain service providers and selling or otherwise disposing of certain premises, furniture and equipment owned by Farmers or NBOH. Farmers and NBOH expect to incur merger-related expenses including or related to system conversion costs, legal fees, accounting fees, investment banking fees, employee retention and severance agreements, communications to customers, and others. To the extent there are costs associated with these actions, the costs will be recorded based on the nature and timing of these integration

actions. Most acquisition and restructuring costs are recognized separately from a business combination and generally will be expensed as incurred. Farmers estimates Merger-related costs to total approximately $3.5 million on an after-tax basis. A significant portion of such costs are expected to be incurred in the years ending December 31, 2015. Merger costs are expected to have no material impact on the combined company’s liquidity, while merger costs specifically related to a reduction in staff levels, termination of contracts, and a reduction in operating space requirements are expected to lower operating expenses and therefore improve earnings in future periods. Farmers’ statements regarding its estimated Merger and integration costs and any cost savings that may be achieved are forward-looking statements, should not be relied upon, and are not reflected in the accompanying pro forma financial information.

Pro Forma Adjustments

The following pro forma adjustments have been reflected in the unaudited condensed combined consolidated financial statements presented for Farmers and NBOH. All taxable adjustments were calculated using a 35% tax rate to arrive at deferred tax asset or liability adjustments. All adjustments are based on current assumptions and valuations, which are subject to change. The adjustments are presented in thousands, with the exception of per share amounts.

A – Adjustments to available for sale securities: Farmers expects to sell investment securities available for sale to provide cash for buyer and seller deal expenses and for purposes of cashing out stock options.

B – Loans, including loans held for sale, net of deferred fees and costs were adjusted to reflect the estimated fair value of NBOH’s portfolio, including consideration of credit, liquidity and interest rates resulting in a discount on NBOH’s portfolio.

C – To remove NBOH’s allowance at Merger date as the credit risk is contemplated in the fair value adjustment in B above.

D – Adjustment to reflect estimated fair value of acquired premises and equipment based on third party estimates. Premises and equipment were adjusted to remove NBOH’s purchase accounting adjustment on buildings related to a previous acquisition. The adjustment will be accreted into income over the useful life of the premises.

E – Adjustment to goodwill

F – Preliminary estimated fair value of the core deposit intangible to be recorded calculated at 1.5% of NBOH’s non-time deposits. The acquired core deposit intangible will be amortized over 10 years using the sum-of-the-years-digits method. The actual amount of such core deposit intangible asset will be determined at the completion of the transaction and will be based on an independent third party appraisal.

G – Adjustment to current and deferred income taxes based on the pro forma fair value adjustments of acquired assets and assumed liabilities and on a calculation of future tax benefits.

H – Negative adjustment of $74 to reflect the estimated fair value of foreclosed and repossessed assets based on third party estimates adjusted for estimated costs to sell. Subsequent to the completion of the transaction, Farmers will finalize its determination of the fair value of the acquired foreclosed and repossessed property which could significantly change the estimated purchase accounting adjustments.

I – Adjustments to the fair value of time deposits to reflect the current market rate of interest for similar products. The adjustment will be accreted into income over the estimated lives of the deposits.

J – Adjustment to common shares

K – NBOH’s additional paid-in-capital of $5,005 was eliminated.

L – Adjustments to retained earnings

M – To reflect the elimination of NBOH other comprehensive income.

N – To reflect the elimination of NBOH treasury stock.

O – Farmers has evaluated the acquired loan portfolio to estimate the necessary interest rate and credit risk fair value adjustments. Subsequently, the fair value adjustment will be accreted into earnings using the level yield method. For purposes of the pro forma impact, the net discount accretion was estimated using a period of 4.6 years.

P – Adjustment to reflect lost interest due to sale of securities to provide cash for the transaction.

Q – Adjustment to reflect the estimated fair value of time deposits based on the current market rate of interest for comparable deposits. The fair value adjustment will be accreted into earnings as a reduction of the cost of funds over 1.2 years.

R – Adjustment to amortize the acquired core deposit intangible asset over 10 years by the sum of the years’ digits method

S – Adjustment to reflect the income tax effect of pro forma adjustments at NBOH’s assumed income tax rate of 35%.

T – Preliminary Purchase Accounting Allocation: The unaudited pro forma condensed combined financial information reflects the issuance of 7,198,250 of Farmers common shares totaling $54.0 million and cash consideration totaling $16.6 million for a total consideration of $70.6 million. The Merger will be accounted for using the acquisition method of accounting: accordingly Farmers cost to acquire NBOH will be allocated to the assets (including identifiable intangible assets) and liabilities of NBOH at their respective estimated fair values as of the merger date. Accordingly, the pro forma purchase price was preliminarily allocated to the assets acquired and liabilities assumed based on their estimated fair values as summarized in the following table:

UNAUDITED COMPARATIVE PER SHARE DATA

The following table summarizes selected share and per share information about Farmers and NBOH giving effect to the Merger (which is referred to as “pro forma” information). The data in the table should be read together with the financial information and the financial statements of Farmers and NBOH incorporated by reference or included in this joint proxy statement/prospectus. The pro forma information is presented as an illustration only. The data does not necessarily indicate the combined financial position per share or combined results of operations per share that would have been reported if the Merger had occurred when indicated, nor is the data a forecast of the combined financial position or combined results of operations for any future period.

The information about book value per share and shares outstanding assumes that the Merger took place as of the dates presented and is based on the assumptions set forth in the preceding unaudited pro forma condensed combined consolidated balance sheet. The information about dividends and earnings per share assumes that the Merger took place as of the periods presented and is based on the assumptions set forth in the preceding unaudited pro forma condensed combined consolidated income statement. No pro forma adjustments have been included to reflect potential effects of the Merger related to integration expenses, cost savings or operational synergies which are expected to be obtained by combining the operations of Farmers and NBOH, or the costs of combining the companies and their operations. It is further assumed that Farmers will pay a cash dividend after the completion of the Merger at the annual rate of $0.12 per common share. The actual payment of dividends is subject to numerous factors, and no assurance can be given that Farmers will pay dividends following the completion of the Merger or that dividends will not be reduced in the future.