Summary

This summary highlights selected information from this document. It does not contain all of the information that may be important to you. You should carefully read this entire document and the other documents referred to in this document before you decide how to vote. Together these documents will give you a more complete description of the proposed transaction. Page references are included in this summary to direct you to more thorough descriptions of the topics provided elsewhere in these materials.

The Special Meetings of Shareholders

Peoples special meeting of shareholders to be held [—], 2013 (see page 34).

Peoples will hold a special meeting of shareholders on [—], 2013, at [—] a.m., local time, at [—], Hallstead, Pennsylvania 18822.

Penseco special meeting of shareholders to be held [—], 2013 (see page 37).

Penseco will hold a special meeting of shareholders on [—], 2013, at [—] p.m., local time, at [—], Scranton, Pennsylvania 18503.

Peoples record date set at [—], 2013; one vote per share of Peoples common stock (see page 34).

If you owned shares of Peoples common stock at the close of business on [—], 2013, you are entitled to notice of, and to vote at, the special meeting of shareholders. You will have one vote at the special meeting for each share of Peoples common stock you owned on [—], 2013. On [—], 2013, there were [—] shares of Peoples common stock outstanding.

Penseco record date set at [—], 2013; one vote per share of Penseco common stock (see page 37).

If you owned shares of Penseco common stock at the close of business on [—], 2013, you are entitled to notice of, and to vote at, the special meeting of shareholders. You will have one vote at the special meeting for each share of Penseco common stock you owned on [—], 2013. On [—], 2013, there were [—] shares of Penseco common stock outstanding.

The Companies

Peoples Financial Services Corp.

82 Franklin Avenue

Hallstead, PA 18822

(570) 879-2175

Peoples Financial Services Corp., with assets of approximately $689.0 million as of June 30, 2013, is the holding company for Peoples Neighborhood Bank. Peoples stock is quoted on the OTCQB market place under the symbol “PFIS”. For more information, visit Peoples Neighborhood Bank website at www.peoplesnatbank.com. The information on Peoples’ website is not incorporated into this joint proxy statement/prospectus.

Penseco Financial Services Corporation

150 North Washington Avenue

Scranton, PA 18503

(570) 346-7741

Penseco Financial Services Corporation, with assets of approximately $919.7 million as of June 30, 2013, is the holding company for Penn Security Bank and Trust Company. Penseco stock is quoted on the OTCQB market place under the symbol “PFNS”. For more information, visit the Penseco website at www.pennsecurity.com. The information on Penseco’s website is not incorporated into this joint proxy statement/prospectus.

We propose that Penseco merge with and into Peoples (see page 40).

Under the terms of the merger agreement, Penseco will merge with and into Peoples. As soon as practicable but no earlier than the first business day after the merger, Penn Security Bank and Trust Company will merge with and into Peoples Neighborhood Bank, and the resulting institution will be named “Peoples Security Bank and Trust Company.” A copy of the merger agreement is attached to this document as Annex A and a copy of the plan of merger for the banks is attached as Exhibit 3 to the merger agreement.

The boards of directors of Peoples and Penseco are unanimously recommending a vote in favor of the merger and believe that a merger of the two companies will create a stronger and more capable entity than either Peoples or Penseco is likely to be alone.

Both boards of directors of Peoples and Penseco are unanimously recommending its respective shareholders vote in favor of the merger. The reasons we are recommending approval of the merger include the potential revenue and cost synergies and the resulting increase in earnings and expansion of market diversity. Each board of directors believes the merger will provide an opportunity for the combined company to capitalize on its assets in the short-term and strengthen their prospects for continued growth over the long-term. We believe this growth will be sufficient to overcome the costs arising from the merger. Furthermore, since the two companies serve markets that are geographically complementary to the other, the combined entity would have a more diverse market concentration than either of the two companies on their own.

Penseco shareholders will receive shares of Peoples common stock (see page 68).

At the effective time of the merger, each outstanding share of Penseco common stock will be converted into and become the right to receive 1.3636 shares of Peoples common stock. Peoples will not issue fractional shares of its common stock as part of the merger and will instead pay cash for any fractional share of common stock a shareholder of Penseco would have otherwise received in the merger.

Peoples has received an opinion from its financial advisor that the exchange ratio is fair, from a financial point of view, to the shareholders of Peoples (see page 48).

In connection with the merger, the board of directors of Peoples received a written opinion from Peoples’ financial advisor, Boenning & Scattergood, Inc., as to the fairness, from a financial point of view, of the exchange ratio to the shareholders of Peoples. The full text of the opinion of Boenning & Scattergood, dated as of June 28, 2013, is included in this document as Annex B. We encourage you to read this opinion carefully in its entirety for a description of the procedures followed, assumptions made, matters considered, and limitations of the review undertaken by Boenning & Scattergood. The opinion of Boenning & Scattergood is directed to Peoples’ board of directors and does not constitute a recommendation to you or any other shareholder as to how to vote with respect to the merger or any other matter relating to the proposed merger. Boenning & Scattergood will receive a fee for its services, including rendering the fairness opinion, in connection with the merger.

Penseco has received an opinion from its financial advisor that the exchange ratio is fair, from a financial point of view, to the shareholders of Penseco (see page 59).

In connection with the merger, the board of directors of Penseco received a written opinion from Penseco’s financial advisor, Griffin Financial Group, LLC, as to the fairness of the exchange ratio, from a financial point of view, to the shareholders of Penseco. The full text of the opinion of Griffin, dated as of June 28, 2013, is included in this document as Annex C. We encourage you to read this opinion carefully in its entirety for a description of the procedures followed, assumptions made, matters considered, and limitations of the review undertaken by Griffin. The opinion of Griffin is directed to Penseco’s board of directors and does not constitute a recommendation to you or any other shareholder as to how to vote with respect to the merger, the form of consideration to be received in the merger, or any other matter relating to the proposed merger. Griffin will receive a fee for its services, including rendering the fairness opinion, in connection with the merger.

Peoples engaged Penseco’s financial consultant to assist management in preparing pro forma financial information.

In connection with the evaluation of a potential transaction with Peoples, Penseco engaged Cedar Hill Advisors, LLC to assist it in preparing certain financial modeling. Subsequently, in connection with the preparation of this joint proxy statement/prospectus, related registration statement and other regulatory applications, Peoples engaged Cedar Hill to assist management in the preparation of certain pro forma financial information related to the merger presented elsewhere in this document. Peoples and Penseco are aware of the potential conflicts that might arise from each of them engaging Cedar Hill in the same transaction, albeit for different purposes.

Peoples Shareholder Vote Required (see page 35).

Approval and Adoption of the Merger Agreement. Since Peoples’ board of directors unanimously approved the merger agreement and merger, Peoples’ articles of incorporation require the approval and adoption of the merger agreement and the merger by an affirmative vote, in person or by proxy, of at least a majority of the outstanding shares of Peoples common stock on the record date.

Approval and Adoption of the Amendment to the Articles of Incorporation. The affirmative vote of a majority of the shares of Peoples common stock voted at the special meeting of shareholders is required to approve and adopt the amendment to Peoples’ articles of incorporation to increase the number of authorized shares of common stock from 12,500,000 to 25,000,000.

Advisory (Non-binding) Vote Regarding Golden Parachute Compensation. The affirmative vote of a majority of the votes cast by the holders of Peoples common stock entitled to vote on that matter at a shareholders’ meeting at which a quorum is present, is required to approve on an advisory (non-binding) basis, golden parachute compensation payable to the named executive officers of Peoples and Penseco in connection with the merger.

Discretionary Authority to Adjourn the Special Meeting. The affirmative vote of the holders of a majority of the votes cast by the holders of Peoples common stock entitled to vote on the adjournment proposal is required to approve the proposal to grant discretionary authority to the Peoples board of directors to adjourn the special meeting if necessary to solicit additional proxies from Peoples shareholders in the event a quorum is present at our special meeting but there are insufficient votes to adopt the merger agreement.

Each holder of shares of Peoples common stock outstanding on the record date will be entitled to one vote for each share held of record. The vote required for approval and adoption of the merger agreement is a

percentage of all outstanding shares of Peoples common stock. Therefore, abstentions will have the same effect as a vote against the merger agreement and the merger. Brokers who hold Peoples common stock as nominees on your behalf will not have authority to vote your shares with respect to the merger agreement or the merger unless you provide voting instructions in accordance with the directions provided by your broker. Failure to provide your broker with voting instructions will have the same effect as a vote against the merger agreement.

Penseco Shareholder Vote Required (see page 37).

Approval and Adoption of the Merger Agreement. Penseco’s articles of incorporation require the approval and adoption of the merger agreement and the merger by an affirmative vote of at least 75% of the shares of Penseco common stock outstanding on the record date.

Advisory (Non-binding) Vote Regarding Golden Parachute Compensation. In accordance with Penseco’s bylaws, the affirmative vote of a majority of Penseco shares represented, in person or by proxy, at the special meeting is required to approve, on an advisory basis, the compensation of Penseco’s named executive officers that is based on or related to the proposed merger.

Discretionary Authority to Adjourn the Special Meeting. In accordance with Penseco’s bylaws, the affirmative vote of a majority of Penseco shares represented, in person or by proxy, at the special meeting is required to approve the proposal to adjourn the special meeting, if necessary, to solicit additional proxies in the event that there are not sufficient votes at the time of the special meeting to approve the proposal to approve and adopt the merger agreement.

Each holder of shares of Penseco common stock outstanding on the record date will be entitled to one vote for each share held of record. The vote required for approval and adoption of the merger agreement is a percentage of all outstanding shares of Penseco common stock. Therefore, abstentions will have the same effect as a vote against the merger agreement and the merger. Brokers who hold Penseco common stock as nominees on your behalf will not have authority to vote your shares with respect to the merger agreement or the merger unless you provide voting instructions in accordance with the directions provided by your broker. Failure to provide your broker with voting instructions will have the same effect as a vote against the merger agreement.

Peoples directors and executive officers have agreed to vote in favor of the merger (see page 35).

On [—], 2013, the directors and executive officers of Peoples had sole or shared voting power over [—] shares, or [—] %, of the outstanding shares of Peoples common stock. These directors and officers of Peoples have agreed to vote these shares of Peoples common stock in favor of approving and adopting of the merger agreement.

Penseco directors and executive officers have agreed to vote in favor of the merger (see page 37).

On [—], 2013, the directors and executive officers of Penseco had sole or shared voting power over [—] shares, or [—] %, of the outstanding shares of Penseco common stock. These directors and officers of Penseco have agreed with Peoples to vote these shares of Penseco common stock in favor of approving and adopting the merger agreement.

Peoples and Penseco directors and management may have interests in the merger that differ from your interests (see page 81).

The directors and certain officers of each of Peoples and Penseco and their subsidiaries have interests in the merger as directors and employees that are different from or in addition to yours as a Peoples or Penseco

shareholder. These interests include, among others, provisions in the merger agreement regarding the resulting Peoples and Peoples Security Bank and Trust Company boards, as well as change in control agreements, employment agreements, supplemental executive retirement plans, deferred compensation plans, indemnification, insurance, stock options, restricted stock plans, and eligibility to participate in various employee benefit plans. For purposes of the Peoples agreements and plans generally, and for certain Penseco agreements and plans, the completion of the transactions contemplated by the merger agreement will constitute a change in control. These additional interests may create potential conflicts of interest and cause some of these persons to view the proposed transaction differently than you may view it as a shareholder.

Each of Peoples’ and Penseco’s board of directors was aware of these interests and considered them in approving and recommending the merger agreement.

Peoples and Penseco must obtain regulatory approval and satisfy other conditions before the merger is complete (see page 75).

Peoples’ and Penseco’s obligations to complete the merger and the bank merger are subject to various conditions that are usual and customary for this kind of transaction. These conditions include obtaining approval from the Federal Reserve Board, the FDIC and the Pennsylvania Department of Banking and Securities. As of the date of this document, appropriate applications for approval have been filed or will be filed as soon as possible. In addition to the required regulatory approvals, the merger will only be completed if certain conditions are met. See “Proposal—The Merger—Terms of the Merger—Conditions to Merger”.

Amendment or termination of the merger agreement is possible (see page 77).

Peoples and Penseco can agree to amend the merger agreement in any way, except that, after approval by Peoples and Penseco shareholders at their special meetings, Peoples and Penseco cannot change the amount of Peoples common stock Penseco shareholders will receive in the transaction from what is provided in the merger agreement.

Peoples and Penseco may agree to terminate the merger agreement and not complete the merger at any time before the merger is completed. Each company also may unilaterally terminate the merger agreement in certain circumstances. These include the failure to complete the merger by March 31, 2014, unless the terminating company’s breach is the reason the merger has not been completed.

Rights of Penseco shareholders differ from those of Peoples shareholders (see page 164).

When the merger is complete, Penseco shareholders will automatically become Peoples shareholders. The rights of Penseco shareholders differ from the rights of Peoples shareholders in certain important ways. Many of these differences have to do with provisions in Penseco’s articles of incorporation and bylaws that differ from those of Peoples. See “Comparison of Shareholders’ Rights”.

Material U.S. federal income tax consequences of the merger (see page 88).

The merger is intended to qualify as a “reorganization” within the meaning of Section 368(a) of the Internal Revenue Code of 1986, as amended, and the holders of Penseco common stock generally will not recognize any gain or loss for U.S. federal income tax purposes on the exchange of shares of Penseco common stock for shares of Peoples common stock in the merger, except with respect to any cash received in lieu of fractional shares. This tax treatment may not apply to all Penseco shareholders.

We urge you to consult your tax advisor for a full understanding of the specific tax consequences of the merger to you. Tax matters are very complicated and, in many cases, tax consequences of the merger will depend on your particular facts and circumstances. See “Proposal—The Merger—Material U.S. Federal Income Tax Consequences,” beginning at page 88.

Peoples and Penseco shareholders are entitled to dissenters’ rights (see page 89).

As a Peoples or Penseco shareholder, you have the right under Pennsylvania law to dissent from the merger and to demand and receive a cash payment for the statutorily determined “fair value” of your common stock in the event that the merger is completed. The statutorily determined “fair value” could be more or less than the value of the merger consideration. In order to assert dissenters’ rights, shareholders must precisely follow the process described in “Proposal—The Merger—Rights of Dissenting Shareholders” and in Annex D. These sources describe provisions of Pennsylvania law related to dissenters’ rights. You also are encouraged to consult with your own legal advisor as to your dissenters’ rights under Pennsylvania law. Failure to strictly comply with these procedures will result in the loss of these dissenters’ rights and your ability to receive cash for the statutorily determined “fair value” of your common stock of either Peoples or Penseco.

Peoples will pursue a Nasdaq listing of its common stock (see page 90).

Peoples and Penseco have agreed to use their commercially reasonable best efforts to obtain a listing for trading of Peoples common stock as soon as practical after the effective time of the merger.

Peoples and Penseco will maintain a significant presence in their communities (see page 75).

For at least three years after the effective time of the merger, the headquarters and loan operations of the companied company and bank will be located in Scranton, Pennsylvania, and the deposit operations and data processing of the companied company and bank will be located in Hallstead, Pennsylvania.

Market Price and Dividend Information

Peoples

As of June 30, 2013, there were 3,087,206 shares of Peoples common stock outstanding, which were held by approximately 1,053 holders of record and outstanding options that were exercisable on that date (or within 60 days of that date) for 5,800 additional shares of Peoples common stock. The number of shareholders does not reflect the number of individuals or institutional investors holding stock in nominee name through banks, brokerage firms, and others.

Additionally, a substantial source of Peoples’ income from which it can pay dividends is the receipt of dividends from Peoples Neighborhood Bank. The availability of dividends from Peoples Neighborhood Bank is limited by various statutes and regulations. It also is possible, depending on the financial condition of Peoples Neighborhood Bank, and other factors, that the applicable regulatory authorities could assert that payment of dividends or other payments is an unsafe or unsound banking practice. In the event that Peoples Neighborhood Bank is unable to pay dividends to Peoples, Peoples may not be able to pay dividends on its common stock.

Peoples common stock is listed on the OTCQB market place under the symbol “PFIS”. The following table shows, for the indicated periods, the high and low sales prices per share for Peoples common stock as reported on

the OTCQB market place and dividends declared per share of Peoples common stock. These prices may include retail markups, markdowns, or commissions.

On June 28, 2013, the last full trading day before the public announcement of the execution of the merger agreement, and on August 8, 2013, the latest practicable trading day before the printing of this document, the high, low and closing sales prices for Peoples common stock were as follows:

Penseco

As of June 30, 2013, there were 3,285,145 shares of Penseco common stock outstanding which were held by approximately 1,001 holders of record. The number of shareholders does not reflect the number of individuals or institutional investors holding stock in nominee name through banks, brokerage firms, and others.

Penseco common stock is listed on the OTCQB market place under the symbol “PFNS”. The following table shows, for the indicated periods, the high and low sales prices per share for Penseco common stock as

reported on the OTCQB market place and dividends declared per share of Penseco common stock. These prices may include retail markups, markdowns, or commissions.

On June 28, 2013, the last full trading day before the public announcement of the execution of the merger agreement, and on August 8, 2013, the latest practicable trading day before the printing of this document, the high, low and closing sales prices for Penseco common stock were as follows:

Pursuant to the merger agreement, Peoples and Penseco have agreed to coordinate with one another with respect to regular quarterly dividends to ensure that holders of Penseco common stock do not receive two dividends, or fail to receive one dividend, for any quarter with respect to their shares of Penseco common stock and any shares of Peoples common stock received in the merger. In addition, Peoples and Penseco have agreed that for at least five years after the merger, Peoples will pay a quarterly cash dividend in an amount no less than $.31 per share, provided that sufficient funds are legally available for payment of dividends and that Peoples and the combined bank remains “well-capitalized” in accordance with applicable regulatory guidelines. The post-merger quarterly dividend may only be reduced below $.31 per share upon the approval of 80% of the board of directors.

Comparative Market Value

The following table sets forth the market value per share of Peoples and Penseco common stock and the equivalent market value per share of Penseco common stock on June 28, 2013 (the date of the public announcement of the merger) and August 8, 2013 (the latest practicable trading day prior to the date of this document). The equivalent market value is based upon an assumed exchange ratio of 1.3636 shares of Peoples common stock multiplied by the closing sales price of Peoples common stock on the specified date.

Advisory (Non-binding) Votes on Golden Parachute Compensation (Pages 171 and 172)

In accordance with SEC rules, Peoples and Penseco are providing shareholders with the opportunity to vote to approve on an advisory (non-binding) basis, certain payments that will or may be made to certain named executive officers in connection with the merger, as reported in the Summary of Golden Parachute Arrangements tables on pages 83 and 85, and the associated narrative discussions.

Adjournment or Postponement Proposals (Page 173)

You are being asked to approve a proposal to grant the Peoples and Penseco boards of directors discretionary authority to adjourn or postpone the special meetings, if necessary, to solicit additional proxies from their shareholders for the merger proposal in the event a quorum is present at the special meeting but there are insufficient votes to adopt the merger agreement.

Selected Historical Consolidated Financial Data of Peoples

The following is a summary of consolidated financial information with respect to Peoples as of and for the six months ended June 30, 2013 and 2012, and as of and for the fiscal years ended December 31, 2012, 2011, 2010, 2009 and 2008. The results for the six months ended June 30, 2013 are not necessarily indicative of the results to be expected for the full year. This information is derived from, and should be read in conjunction with, Peoples’ consolidated financial statements and the accompanying notes and “Management’s Discussion and Analysis of Financial Condition and Results of Operations of Peoples Financial Services Corp. for the Six Months Ended June 30, 2013 and 2012”, “Management’s Discussion and Analysis of Financial Condition and Results of Operations of Peoples Financial Services Corp. for the Years Ended December 31, 2012 and 2011”, and “Management’s Discussion and Analysis of Financial Condition and Results of Operations of Peoples Financial Services Corp. for the Years Ended December 31, 2011 and 2010”, each of which can be found elsewhere in this joint proxy statement/prospectus. In the opinion of management of Peoples, all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of results for or as of the six month interim periods have been made.

Note: Average balances were calculated using average daily balances. Average balances for loans include nonaccrual loans. Tax-equivalent adjustments were calculated using the prevailing statutory rate of 34.0 percent.

Selected Historical Consolidated Financial Data of Penseco

The following selected financial information for the fiscal years ended December 31, 2012, 2011, 2010, 2009 and 2008 is derived from audited consolidated financial statements of Penseco. The financial information as of and for the six months ended June 30, 2013 and 2012 is derived from unaudited financial statements. The results of operations for the six months ended June 30, 2013 are not necessarily indicative of the results of operations for the full year or any other interim period. Penseco’s management prepared the unaudited information on the same basis as it prepared Penseco’s audited consolidated financial statements. In the opinion of Penseco’s management, this information reflects all adjustments, consisting of only normal recurring adjustments, necessary for a fair presentation of this data for those dates. You should read this information in conjunction with Penseco’s consolidated financial statements and related notes included in Penseco’s Annual Report on Form 10-K for the year ended December 31, 2012, and Penseco’s Quarterly Report on Form 10-Q for the quarter ended June 30, 2013, which are incorporated by reference herein and from which this information is derived. Please see “Where You Can Find More Information” on page 174.

(in thousands, except per share amounts)

RESULTS OF OPERATIONS: