ACNB CORP - Annual Report: 2014 (Form 10-K)

Use these links to rapidly review the document
Table of Contents
ITEM 8—FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA

Table of Contents

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, DC 20549

FORM 10-K

Commission file number 0-11783

ACNB CORPORATION
(Exact name of registrant as specified in its charter)

Registrant's telephone number, including area code: (717) 334-3161

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

Securities registered pursuant to Section 12(g) of the Act: None

         Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes o    No ý

         Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes o    No ý

         Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ý    No o

         Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). Yes ý    No o

         Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of the registrant's knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. ý

         Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer, or a smaller reporting company. See definition of "large accelerated filer," "accelerated filer" and "smaller reporting company" in Rule 12b-2 of the Exchange Act. (Check One)

         Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act). Yes o    No ý

         The aggregate market value of the voting stock held by nonaffiliates of the registrant at June 30, 2014, was approximately $113,225,680.

         The number of shares of the registrant's common stock outstanding on March 6, 2015, was 6,015,650.

         Documents Incorporated by Reference

         Portions of the registrant's 2015 definitive Proxy Statement are incorporated by reference into Part III of this report.

Table of Contents

ACNB CORPORATION

Table of Contents

2

Table of Contents

PART I

FORWARD-LOOKING STATEMENTS

        In addition to historical information, this Form 10-K contains forward-looking statements. Examples of forward-looking statements include, but are not limited to, (a) projections or statements regarding future earnings, expenses, net interest income, other income, earnings or loss per share, asset mix and quality, growth prospects, capital structure, and other financial terms, (b) statements of plans and objectives of management or the Board of Directors, and (c) statements of assumptions, such as economic conditions in the Corporation's market areas. Such forward-looking statements can be identified by the use of forward-looking terminology such as "believes", "expects", "may", "intends", "will", "should", "anticipates", or the negative of any of the foregoing or other variations thereon or comparable terminology, or by discussion of strategy. Forward-looking statements are subject to certain risks and uncertainties such as local economic conditions, competitive factors, and regulatory limitations. Actual results may differ materially from those projected in the forward-looking statements. Such risks, uncertainties and other factors that could cause actual results and experience to differ from those projected include, but are not limited to, the following: the effects of governmental and fiscal policies, as well as legislative and regulatory changes; the effects of new laws and regulations, specifically the impact of the Dodd-Frank Wall Street Reform and Consumer Protection Act; impacts of the new capital and liquidity requirements of the Basel III standards; the effects of changes in accounting policies and practices, as may be adopted by the regulatory agencies, as well as the Financial Accounting Standards Board and other accounting standard setters; ineffectiveness of the business strategy due to changes in current or future market conditions; future actions or inactions of the United States government, including the effects of short-and long-term federal budget and tax negotiations and a failure to increase the government debt limit or a prolonged shutdown of the federal government; the effects of economic deterioration and the prolonged economic malaise on current customers, specifically the effect of the economy on loan customers' ability to repay loans; the effects of competition, and of changes in laws and regulations on competition, including industry consolidation and development of competing financial products and services; the risks of changes in interest rates on the level and composition of deposits, loan demand, and the values of loan collateral, securities, and interest rate protection agreements, as well as interest rate risks; difficulties in acquisitions and integrating and operating acquired business operations, including information technology difficulties; challenges in establishing and maintaining operations in new markets; the effects of technology changes; volatilities in the securities markets; slow economic conditions; the failure of assumptions underlying the establishment of reserves for loan losses and estimations of values of collateral and various financial assets and liabilities; acts of war or terrorism; disruption of credit and equity markets; the ability to manage current levels of impaired assets; the loss of certain key officers; the ability to maintain the value and image of ACNB's brand and protect ACNB's intellectual property rights; continued relationships with major customers; and, potential impacts to ACNB from continually evolving cybersecurity and other technological risks and attacks, including additional costs, reputational damage, regulatory penalties, and financial losses. We caution readers not to place undue reliance on these forward-looking statements. They only reflect management's analysis as of this date. The Corporation does not revise or update these forward-looking statements to reflect events or changed circumstances. Please carefully review the risk factors described in other documents the Corporation files from time to time with the Securities and Exchange Commission, including the Quarterly Reports on Form 10-Q and any Current Reports on Form 8-K.

3

Table of Contents

ITEM 1—BUSINESS

ACNB CORPORATION

        ACNB Corporation (the Corporation or ACNB) is a $1.1 billion financial holding company headquartered in Gettysburg, Pennsylvania. Through its banking and nonbanking subsidiaries, ACNB provides a full range of banking and financial services to individuals and businesses, including commercial and retail banking, trust and investment management, and insurance. ACNB's banking operations are conducted through its primary operating subsidiary, ACNB Bank, with twenty retail banking offices in Adams, Cumberland, Franklin and York Counties, Pennsylvania, as well as one loan production office in York County, Pennsylvania, as of December 31, 2014. The Corporation was formed in 1982, then became the holding company for Adams County National Bank (now ACNB Bank) in 1983.

        On January 5, 2005, ACNB Corporation completed the acquisition of Russell Insurance Group, Inc. (RIG) and RIG began to operate as a separate subsidiary of ACNB Corporation. In accordance with the terms of the acquisition, there was contingent consideration associated with this transaction of up to $3,000,000, payable in 2008 subject to performance criteria for the three-year period subsequent to the acquisition. Due to performance at a higher level than the performance criteria, the liability for this consideration was recorded at December 31, 2006, with a related increase in goodwill. Payment was made in the second quarter of 2008 after it was ascertained that the performance criteria had been met for the full three-year period; after which, the total aggregate purchase price was $8,663,000. In addition, on January 13, 2011, the Corporation entered into another three-year employment agreement with Frank C. Russell, Jr., President & Chief Executive Officer of RIG, effective as of January 1, 2011. That agreement is subject to automatic renewal for successive one-year periods beginning on the third anniversary date of the effective date, subject to the terms and conditions set forth in that agreement, unless either party notifies the other in writing at least 90 days prior to termination of the then current term of the party's desire to terminate the agreement.

        Beginning in 2007, RIG acquired additional books of business and acquired Marks Insurance & Associates, Inc. Details regarding these acquisitions are included in the Notes to Consolidated Financial Statements, Note R—"Acquisitions".

        RIG is managed separately from the banking and related financial services that the Corporation offers and is reported as a separate segment. Financial information on this segment is included in the Notes to Consolidated Financial Statements, Note S—"Segment and Related Information".

        ACNB's major source of operating funds is dividends that it receives from its subsidiaries. ACNB's expenses consist principally of losses from low-income housing investments and interest paid on a term loan used to purchase RIG. Dividends that ACNB pays to stockholders consist of dividends declared and paid to ACNB by the subsidiary bank.

        ACNB and its subsidiaries are not dependent upon a single customer or a small number of customers, the loss of which would have a material adverse effect on the Corporation. ACNB does not depend on foreign sources of funds, nor does it make foreign loans.

        The common stock of ACNB is listed on The NASDAQ Capital Market under the symbol ACNB.

BANKING SUBSIDIARY

ACNB Bank

        On October 4, 2010, the banking subsidiary, then Adams County National Bank, completed the process of converting from a national banking association to a Pennsylvania state-chartered bank and trust company with the filing and effectiveness of its Articles of Conversion with the Pennsylvania Department of State. Accordingly, Adams County National Bank became ACNB Bank (Bank). Reasons

4

Table of Contents

for the conversion included the Corporation's belief that a state bank charter serves the needs of a community bank more effectively. The Pennsylvania Department of Banking and Securities focuses solely on Pennsylvania financial institutions, so there was an anticipation of a better understanding of the Bank and the environment in which it operates, as well as an enhanced level of communication. In addition, the Bank serves customers in four counties—Adams, Cumberland, York and Franklin—and the name of Adams County National Bank no longer served the organization well in expansion beyond Adams County.

        ACNB Bank is a full-service commercial bank operating under charter from the Pennsylvania Department of Banking and Securities. The Bank's principal market area is Adams County, Pennsylvania, which is located in southcentral Pennsylvania. Adams County depends on agriculture, industry and tourism to provide employment for its residents. No single sector dominates the county's economy. At December 31, 2014, ACNB Bank had total assets of $1,077,000,000, total gross loans of $799,000,000, total deposits of $851,000,000, and total equity capital of $92,000,000.

        The main office of the Bank is located at 16 Lincoln Square, Gettysburg, Pennsylvania. In addition to its main office, as of December 31, 2014, the Bank had thirteen branches in Adams County, four branches in York County, one branch in Cumberland County, and one branch in Franklin County, as well as a loan production office in York County, Pennsylvania. ACNB Bank's service delivery channels for its customers also include the ATM network, Customer Contact Center, and Online, Telephone and Mobile Banking. The Bank is subject to regulation and periodic examination by the Pennsylvania Department of Banking and Securities and the Federal Deposit Insurance Corporation (FDIC). The FDIC, as provided by law, insures the Bank's deposits.

        Commercial lending includes commercial mortgages, real estate development and construction loans, accounts receivable and inventory financing, and agricultural and governmental loans. Consumer lending programs include home equity loans and lines of credit, automobile and recreational vehicle loans, manufactured housing loans, and personal lines of credit. Mortgage lending programs include personal residential mortgages, residential construction loans, and investment mortgage loans.

        A trust is a legal fiduciary agreement whereby the ACNB Bank Trust Department is named as trustee of financial assets. As trustee, the Trust Department invests, protects, manages and distributes financial assets as defined in the agreement. Estate settlement governed by the last will and testament of an individual constitutes another part of the Trust Department business. One purpose of having a will is to name an executor to settle the estate. ACNB Bank has the knowledge and expertise to act as executor. Other services include, but are not limited to, those related to testamentary trusts, life insurance trusts, charitable remainder trusts, guardianships, powers of attorney, custodial accounts, and investment management and advisory accounts. Total trust assets under management were $165,000,000 at December 31, 2014.

NONBANKING SUBSIDIARIES

Russell Insurance Group, Inc.

        In January 2005, ACNB Corporation acquired Russell Insurance Group, Inc. (RIG), a full-service insurance agency that offers a broad range of property and casualty, life, and health insurance to both commercial and individual clients. Based in Westminster, Maryland, RIG has served the needs of its clients since its founding as an independent insurance agency by Frank C. Russell, Jr. in 1978. With the acquisition of Marks Insurance & Associates, Inc. as of December 31, 2008, RIG operates a second office location in Germantown, Maryland. Total assets of RIG as of December 31, 2014, were $11,262,000.

5

Table of Contents

BankersRe Insurance Group, SPC

        BankersRe Insurance Group, SPC (formerly Pennbanks Insurance Co., SPC) was organized in 2000 and holds an unrestricted Class "B" Insurer's License under Cayman Islands Insurance Law. The segregated portfolio was novated to a third party during 2012. This entity is not material to ACNB's financial condition or results of operations.

MARKET AREA ECONOMIC FEATURES AND CONDITIONS

        ACNB Corporation, headquartered in Gettysburg, Pennsylvania, is the financial holding company for the wholly-owned subsidiaries of ACNB Bank, Gettysburg, Pennsylvania, and Russell Insurance Group, Inc., Westminster, Maryland. ACNB Bank serves its marketplace via a network of twenty retail banking offices located throughout Adams County, Pennsylvania, as well as in Dillsburg, Hanover and Spring Grove, York County, Pennsylvania, in Newville, Cumberland County, Pennsylvania, and in Chambersburg, Franklin County, Pennsylvania. In addition, the Bank operates a loan office in York, York County, Pennsylvania. Russell Insurance Group, Inc. offers a broad range of commercial and personal insurance lines with licenses in 36 states, including Pennsylvania and Maryland, through offices in Westminster, Carroll County, and Germantown, Montgomery County, Maryland. Accordingly, ACNB Corporation's major operations are in the more rural areas of the Harrisburg-Carlisle MSA and the York-Hanover MSA, along with all of Adams County, Pennsylvania, and parts of Franklin County, Pennsylvania. Approximately 60% of the population resides in areas designated rural. Major types of employers include those focused on manufacturing, education, healthcare, agriculture, tourism, and transportation/warehousing, as well as local governments. A material amount of land surrounding Gettysburg is under the control of the National Park Service, limiting certain types of development. Unemployment figures in the bank's market recently, and historically, have been better than those for Pennsylvania and the United States. Per capita and household incomes are generally under Pennsylvania averages.

COMPETITION

        The financial services industry in ACNB's market area is highly competitive, including competition for similar products and services from commercial banks, credit unions, finance and mortgage companies, and other nonbank providers of financial services. Several of ACNB's competitors have legal lending limits that exceed those of ACNB's subsidiary bank, as well as funding sources in the capital markets that exceed ACNB's availability. The high level of competition has resulted from changes in the legal and regulatory environment, as well as from the economic climate, customer expectations, and service alternatives via the Internet. There are 80 publicly-traded banks in Pennsylvania, 20 have higher market share than ACNB. In addition, there are 18 thrift institutions and numerous credit unions in Pennsylvania, some with higher market share. Banks, thrifts, credit unions, and other financial service providers in northern Maryland are also competition.

SUPERVISION AND REGULATION

Regulation of Bank Holding Company and Subsidiaries

        BANK HOLDING COMPANY ACT OF 1956—ACNB is a financial holding company and is subject to the regulations of the Board of Governors of the Federal Reserve System under the Bank Holding Company Act of 1956. Bank holding companies are required to file periodic reports with and are subject to examination by the Federal Reserve. The Federal Reserve has issued regulations under the Bank Holding Company Act that require a financial holding company to serve as a source of financial and managerial strength to its subsidiary bank. As a result, the Federal Reserve may require ACNB to stand ready to use its resources to provide adequate capital funds to the Bank during periods of financial stress or adversity.

6

Table of Contents

        In addition, the Federal Reserve may require a financial holding company to end a nonbanking business if the nonbanking business constitutes a serious risk to the financial soundness and stability of any banking subsidiary of the financial holding company.

        The Bank Holding Company Act prohibits ACNB from acquiring direct or indirect control of more than 5% of the outstanding voting stock of any bank, or substantially all of the assets of any bank, or merging with another bank holding company, without the prior approval of the Federal Reserve. The Bank Holding Company Act allows interstate bank acquisitions and interstate branching by acquisition and consolidation in those states that had not elected to opt out by the required deadline. The Pennsylvania Department of Banking and Securities also must approve any similar consolidation. Pennsylvania law permits Pennsylvania financial holding companies to control an unlimited number of banks.

        Further, the Bank Holding Company Act restricts ACNB's nonbanking activities to those that are determined by the Federal Reserve Board to be financial in nature, incidental to such financial activity, or complementary to a financial activity. The Bank Holding Company Act does not place territorial restrictions on the activities of nonbanking subsidiaries of financial holding companies.

        GRAMM-LEACH-BLILEY ACT OF 1999 (GLBA)—The Gramm-Leach-Bliley Act of 1999 eliminated many of the restrictions placed on the activities of bank holding companies that become financial holding companies. Among other things, the Gramm-Leach-Bliley Act repealed certain Glass-Steagall Act restrictions on affiliations between banks and securities firms, and amended the Bank Holding Company Act to permit bank holding companies that are financial holding companies to engage in activities, and acquire companies engaged in activities, that are: financial in nature (including insurance underwriting, insurance company portfolio investment, financial advisory, securities underwriting, dealing and market-making, and merchant banking activities); incidental to financial activities; or, complementary to financial activities if the Federal Reserve determines that they pose no substantial risk to the safety or soundness of depository institutions or the financial system in general.

        REGULATION W—Transactions between a bank and its "affiliates" are quantitatively and qualitatively restricted under the Federal Reserve Act. The Federal Deposit Insurance Act applies Sections 23A and 23B to insured nonmember banks in the same manner and to the same extent as if they were members of the Federal Reserve System. The Federal Reserve has also issued Regulation W, which codifies prior regulations under Sections 23A and 23B of the Federal Reserve Act, and interpretative guidance with respect to affiliate transactions. Regulation W incorporates the exemption from the affiliate transaction rules, but expands the exemption to cover the purchase of any type of loan or extension of credit from an affiliate. Affiliates of a bank include, among other entities, the bank's holding company and companies that are under common control with the bank. ACNB Corporation and Russell Insurance Group, Inc. are considered to be affiliates of ACNB Bank.

        USA PATRIOT ACT OF 2001—In October 2001, the USA Patriot Act of 2001 was enacted in response to the terrorist attacks in New York, Pennsylvania and Washington, D.C., which occurred on September 11, 2001. The Patriot Act is intended to strengthen U.S. law enforcement's and the intelligence communities' abilities to work cohesively to combat terrorism on a variety of fronts. The impact of the Patriot Act on financial institutions of all kinds is significant and wide ranging. The Patriot Act contains sweeping anti-money laundering and financial transparency laws and imposes various regulations, including standards for verifying client identification at account opening, and rules to promote cooperation among financial institutions, regulators and law enforcement entities in identifying parties that may be involved in terrorism or money laundering.

        SARBANES-OXLEY ACT OF 2002 (SOA)—In 2002, the Sarbanes-Oxley Act of 2002 became law. The stated goals of the SOA are to increase corporate responsibility, to provide for enhanced penalties for accounting and auditing improprieties at publicly-traded companies, and to protect

7

Table of Contents

investors by improving the accuracy and reliability of corporate disclosures pursuant to the securities law.

        The SOA is the most far-reaching U.S. securities legislation enacted in some time. The SOA generally applies to all companies, both U.S. and non-U.S., that file or are required to file periodic reports with the Securities and Exchange Commission (SEC) under the Securities Exchange Act of 1934, or the Exchange Act.

        The SOA includes very specific additional disclosure requirements and corporate governance rules, as well as requires the SEC and securities exchanges to adopt extensive additional disclosure, corporate governance, and other related rules. The SOA represents significant federal involvement in matters traditionally left to state regulatory systems, such as the regulation of the accounting profession, and to state corporate law, such as the relationship between a board of directors and management and between a board of directors and its committees.

        The SOA addresses, among other matters:

•

Audit committees for all reporting companies;



•

Certification of financial statements by the chief executive officer and the chief financial officer;



•

The forfeiture of bonuses or other incentive-based compensation and profits from the sale of an issuer's securities by directors and senior officers in the twelve-month period following initial publication of any financial statements that later require restatement;



•

A prohibition on insider trading during pension plan blackout periods;



•

Disclosure of off-balance sheet transactions;



•

A prohibition on personal loans to directors and officers;



•

Expedited filing requirements for SEC Forms 4;



•

Disclosure of a code of ethics and filing an SEC Form 8-K for a change or waiver of such code;



•

"Real time" filing of periodic reports;



•

Formation of a public accounting oversight board;



•

Auditor independence; and,



•

Increased criminal penalties for violations of securities laws.

        The SEC has been delegated the task of enacting rules to implement various provisions of the SOA with respect to, among other matters, disclosure in periodic filings pursuant to the Exchange Act.

        AMERICAN JOBS CREATION ACT OF 2004—In 2004, the American Jobs Creation Act was enacted as the first major corporate tax act in years. The act addresses a number of areas of corporate taxation including executive deferred compensation restrictions. The impact of the act on ACNB is not material.

        BANK SECRECY ACT (BSA)—Under the Bank Secrecy Act, banks and other financial institutions are required to report to the Internal Revenue Service currency transactions of more than $10,000 or multiple transactions of which a bank is aware in any one day that aggregate in excess of $10,000 and to report suspicious transactions under specified criteria. Civil and criminal penalties are provided under the BSA for failure to file a required report, for failure to supply information required by the BSA, or for filing a false or fraudulent report.

        DODD-FRANK WALL STREET REFORM AND CONSUMER PROTECTION ACT (DODD-FRANK)—In 2010, the Dodd-Frank Wall Street Reform and Consumer Protection Act was

8

Table of Contents

signed into law. Dodd-Frank was intended to effect a fundamental restructuring of federal banking regulation. Among other things, Dodd-Frank created the Financial Stability Oversight Council to identify systemic risks in the financial system and gives federal regulators new authority to take control of and liquidate financial firms. Dodd-Frank additionally created a new independent federal regulator to administer federal consumer protection laws. Dodd-Frank has had and will continue to have a significant impact on ACNB's business operations as its provisions take effect. It is expected that, as various implementing rules and regulations are released, they will increase ACNB's operating and compliance costs and could increase the Bank's interest expense. Among the provisions that are likely to affect ACNB are the following:

Holding Company Capital Requirements

        Dodd-Frank requires the Federal Reserve to apply consolidated capital requirements to bank holding companies that are no less stringent than those currently applied to depository institutions. Under these standards, trust preferred securities will be excluded from Tier 1 capital unless such securities were issued prior to May 19, 2010, by a bank holding company with less than $15 billion in assets as of December 31, 2009. Dodd-Frank additionally requires that bank regulators issue countercyclical capital requirements so that the required amount of capital increases in times of economic expansion, consistent with safety and soundness. For further information, please refer to Regulatory Capital Changes in Management's Discussion and Analysis.

Deposit Insurance

        Dodd-Frank permanently increases the maximum deposit insurance amount for banks, savings institutions and credit unions to $250,000 per depositor. Dodd-Frank also broadens the base for FDIC insurance assessments. Assessments are now based on the average consolidated total assets less tangible equity capital of a financial institution. Dodd-Frank requires the FDIC to increase the reserve ratio of the Deposit Insurance Fund from 1.15% to 1.35% of insured deposits by 2020 and eliminates the requirement that the FDIC pay dividends to insured depository institutions when the reserve ratio exceeds certain thresholds. Dodd-Frank also eliminated the federal statutory prohibition against the payment of interest on business checking accounts.

Corporate Governance

        Dodd-Frank requires publicly-traded companies to give stockholders a non-binding vote on executive compensation at least every three years, a non-binding vote regarding the frequency of the vote on executive compensation at least every six years, and a non-binding vote on "golden parachute" payments in connection with approvals of mergers and acquisitions unless previously voted on by stockholders. The SEC has finalized the rules implementing these requirements which took effect on January 21, 2011. Additionally, Dodd-Frank directs the federal banking regulators to promulgate rules prohibiting excessive compensation paid to executives of depository institutions and their holding companies with assets in excess of $1.0 billion, regardless of whether the company is publicly traded. Dodd-Frank also gives the SEC authority to prohibit broker discretionary voting on elections of directors and executive compensation matters.

Prohibition Against Charter Conversions of Troubled Institutions

        Dodd-Frank prohibits a depository institution from converting from a state to a federal charter, or vice versa, while it is the subject of a cease and desist order or other formal enforcement action or a memorandum of understanding with respect to a significant supervisory matter unless the appropriate federal banking agency gives notice of the conversion to the federal or state authority that issued the enforcement action and that agency does not object within 30 days. The notice must include a plan to address the significant supervisory matter. The converting institution must also file a copy of the

9

Table of Contents

conversion application with its current federal regulator, which must notify the resulting federal regulator of any ongoing supervisory or investigative proceedings that are likely to result in an enforcement action and provide access to all supervisory and investigative information relating thereto.

Interstate Branching

        Dodd-Frank authorizes national and state banks to establish branches in other states to the same extent as a bank chartered by that state would be permitted. Previously, banks could only establish branches in other states if the host state expressly permitted out-of-state banks to establish branches in that state. Accordingly, banks are able to enter new markets more freely.

Limits on Interstate Acquisitions and Mergers

        Dodd-Frank precludes a bank holding company from engaging in an interstate acquisition—the acquisition of a bank outside its home state—unless the bank holding company is both well capitalized and well managed. Furthermore, a bank may not engage in an interstate merger with another bank headquartered in another state unless the surviving institution will be well capitalized and well managed. The previous standard in both cases was adequately capitalized and adequately managed.

Limits on Interchange Fees

        Dodd-Frank amended the Electronic Fund Transfer Act to, among other things, give the Federal Reserve the authority to establish rules regarding interchange fees charged for electronic debit transactions by payment card issuers having assets over $10 billion and to enforce a new statutory requirement that such fees be reasonable and proportional to the actual cost of a transaction to the issuer.

Consumer Financial Protection Bureau

        Dodd-Frank created the independent federal agency called the Consumer Financial Protection Bureau (CFPB), which is granted broad rulemaking, supervisory and enforcement powers under various federal consumer financial protection laws, including the Equal Credit Opportunity Act, Truth in Lending Act, Real Estate Settlement Procedures Act, Fair Credit Reporting Act, Fair Debt Collection Act, Consumer Financial Privacy provisions of the Gramm-Leach-Bliley Act, and certain other statutes. The CFPB has examination and primary enforcement authority with respect to depository institutions with $10 billion or more in assets. Smaller institutions are subject to rules promulgated by the CFPB, but continue to be examined and supervised by federal banking regulators for consumer compliance purposes. The CFPB has authority to prevent unfair, deceptive or abusive practices in connection with the offering of consumer financial products. Dodd-Frank authorizes the CFPB to establish certain minimum standards for the origination of residential mortgages including a determination of the borrower's ability to repay. In addition, Dodd-Frank allows borrowers to raise certain defenses to foreclosure if they receive any loan other than a "qualified mortgage" as defined by the CFPB. Dodd-Frank permits states to adopt consumer protection laws and standards that are more stringent than those adopted at the federal level and, in certain circumstances, permits state attorneys general to enforce compliance with both the state and federal laws and regulations.

        ABILITY-TO-REPAY AND QUALIFIED MORTGAGE RULE—Pursuant to Dodd-Frank as highlighted above, the CFPB issued a final rule on January 10, 2013 (effective on January 10, 2014), amending Regulation Z as implemented by the Truth in Lending Act, requiring mortgage lenders to make a reasonable and good faith determination based on verified and documented information that a consumer applying for a mortgage loan has a reasonable ability to repay the loan according to its terms. Mortgage lenders are required to determine the consumers' ability to repay in one of two ways. The first alternative requires the mortgage lender to consider the following eight underwriting factors

10

Table of Contents

when making the credit decision: (1) current or reasonably expected income or assets; (2) current employment status; (3) the monthly payment on the covered transaction; (4) the monthly payment on any simultaneous loan; (5) the monthly payment for mortgage-related obligations; (6) current debt obligations, alimony, and child support; (7) the monthly debt-to-income ratio or residual income; and, (8) credit history. Alternatively, the mortgage lender can originate "qualified mortgages", which are entitled to a presumption that the creditor making the loan satisfied the ability-to-repay requirements. In general, a "qualified mortgage" is a mortgage loan without negative amortization, interest-only payments, balloon payments, or terms exceeding 30 years. In addition, to be a qualified mortgage, the points and fees paid by a consumer cannot exceed 3% of the total loan amount. Loans which meet these criteria will be considered qualified mortgages and, as a result, generally protect lenders from fines or litigation in the event of foreclosure. Qualified mortgages that are "higher-priced" (e.g., subprime loans) garner a rebuttable presumption of compliance with the ability-to-repay rules, while qualified mortgages that are not "higher-priced" (e.g., prime loans) are given a safe harbor of compliance. The impact of the final rule, and the subsequent amendments thereto, on the Corporation's lending activities and the Corporation's statements of income and condition are uncertain at this time; however, management will continue to monitor the implementation of the rule for any potential effects on the Corporation's business.

        FEDERAL DEPOSIT INSURANCE CORPORATION ACT OF 1991—Under the Federal Deposit Insurance Corporation Act of 1991, any depository institution, including the subsidiary bank, is prohibited from paying any dividends, making other distributions or paying any management fees if, after such payment, it would fail to satisfy the minimum capital requirement.

        FEDERAL RESERVE ACT—A subsidiary bank of a bank holding company is subject to certain restrictions and reporting requirements imposed by the Federal Reserve Act, including:

•

Extensions of credit to the bank holding company, its subsidiaries, or principal shareholders;



•

Investments in the stock or other securities of the bank holding company or its subsidiaries; and,



•

Taking such stock or securities as collateral for loans.

        COMMUNITY REINVESTMENT ACT OF 1977 (CRA)—Under the Community Reinvestment Act of 1977, the FDIC is required to assess the record of all financial institutions regulated by it to determine if these institutions are meeting the credit needs of the community, including low- and moderate-income neighborhoods, which they serve and to take this record into account in its evaluation of any application made by any of such institutions for, among other things, approval of a branch or other deposit facility, office relocation, merger, or acquisition of bank shares. The Financial Institutions Reform, Recovery and Enforcement Act of 1989 amended the CRA to require, among other things, that the FDIC make publicly available the evaluation of a bank's record of meeting the credit needs of its entire community, including low- and moderate-income neighborhoods. This evaluation includes a descriptive rating like "outstanding", "satisfactory", "needs to improve" or "substantial noncompliance" and a statement describing the basis for the rating. These ratings are publicly disclosed.

        FEDERAL DEPOSIT INSURANCE CORPORATION IMPROVEMENT ACT OF 1991 (FDICIA)—The Federal Deposit Insurance Corporation Improvement Act requires that institutions be classified, based on their risk-based capital ratios into one of five defined categories, as follows and as

11

Table of Contents

illustrated below: well capitalized, adequately capitalized, undercapitalized, significantly undercapitalized, or critically undercapitalized.

        In the event an institution's capital deteriorates to the undercapitalized category or below, FDICIA prescribes an increasing amount of regulatory intervention, including the institution of a capital restoration plan and a guarantee of the plan by a parent institution and the placement of a hold on increases in assets, number of branches, or lines of business. If capital reaches the significantly or critically undercapitalized levels, further material restrictions can be imposed, including restrictions on interest payable on accounts, dismissal of management, and, in critically undercapitalized situations, appointment of a receiver. For well capitalized institutions, FDICIA provides authority for regulatory intervention when the institution is deemed to be engaging in unsafe or unsound practices or receives a less than satisfactory examination report rating for asset quality, management, earnings or liquidity. All but well capitalized institutions are prohibited from accepting brokered deposits without prior regulatory approval. Under FDICIA, financial institutions are subject to increased regulatory scrutiny and must comply with certain operational, managerial and compensation standards established by Federal Reserve Board regulations.

        JUMPSTART OUR BUSINESS STARTUPS (JOBS) ACT—In 2012, the JOBS Act became law. The JOBS Act is aimed at facilitating capital raising by smaller companies and banks and bank holding companies by implementing the following changes:

•

Raising the threshold requiring registration under the Securities Exchange Act of 1934 (Exchange Act) for banks and bank holding companies from 500 to 2,000 holders of record;



•

Raising the threshold for triggering deregistration under the Exchange Act for banks and bank holding companies from 300 to 1,200 holders of record;



•

Raising the limit for Regulation A offerings from $5 million to $50 million per year and exempting some Regulation A offerings from state blue sky laws;



•

Permitting advertising and general solicitation in Rule 506 and Rule 144A offerings;



•

Allowing private companies to use "crowd funding" to raise up to $1 million in any 12-month period, subject to certain conditions; and,



•

Creating a new category of issuer, called an "Emerging Growth Company", for companies with less than $1 billion in annual gross revenue, which will benefit from certain changes that reduce the cost and burden of carrying out an equity initial public offering (IPO) and complying with public company reporting obligations for up to five years.

12

Table of Contents

While the JOBS Act was not expected to have any immediate application to the Corporation, and since 2012 has had no material impact, management will continue to monitor the implementation rules for potential effects which might benefit the Corporation.

Dividends

        ACNB is a legal entity separate and distinct from its subsidiary bank. ACNB's revenues, on a parent company only basis, result primarily from dividends paid to the Corporation by its subsidiaries. Federal and state laws regulate the payment of dividends by ACNB's subsidiary bank. For further information, please refer to Regulation of Bank below.

Regulation of Bank

        The operations of the subsidiary bank are subject to statutes applicable to banks chartered under the banking laws of Pennsylvania, to state nonmember banks, and to banks whose deposits are insured by the FDIC. The subsidiary bank's operations are also subject to regulations of the Pennsylvania Department of Banking and Securities, Federal Reserve, and FDIC.

        The Pennsylvania Department of Banking and Securities, which has primary supervisory authority over banks chartered in Pennsylvania, regularly examines banks in such areas as reserves, loans, investments, management practices, and other aspects of operations. The subsidiary bank is also subject to examination by the FDIC for safety and soundness, as well as consumer compliance. These examinations are designed for the protection of the subsidiary bank's depositors rather than ACNB's stockholders. The subsidiary bank must file quarterly and annual reports to the Federal Financial Institutions Examination Council, or FFIEC.

Monetary and Fiscal Policy

        ACNB and its subsidiary bank are affected by the monetary and fiscal policies of government agencies, including the Federal Reserve and FDIC. Through open market securities transactions and changes in its discount rate and reserve requirements, the Board of Governors of the Federal Reserve exerts considerable influence over the cost and availability of funds for lending and investment. The nature of monetary and fiscal policies on future business and earnings of ACNB cannot be predicted at this time. From time to time, various federal and state legislation is proposed that could result in additional regulation of, and restrictions on, the business of ACNB and the subsidiary bank, or otherwise change the business environment. Management cannot predict whether any of this legislation will have a material effect on the business of ACNB.

ACCOUNTING POLICY DISCLOSURE

        Disclosure of the Corporation's significant accounting policies is included in Note A—"Summary of Significant Accounting Policies" in the Notes to Consolidated Financial Statements. Some of these policies are particularly sensitive requiring significant judgments, estimates and assumptions to be made by management. Additional information is contained in Management's Discussion and Analysis for the most sensitive of these issues, including the provision and allowance for loan losses which is located in Note D—"Loans" in the Notes to Consolidated Financial Statements.

        Management, in determining the allowance for loan losses, makes significant judgments. Consideration is given to a variety of factors in establishing this estimate. In estimating the allowance for loan losses, management considers current economic conditions, diversification of the loan portfolio, delinquency statistics, results of internal loan review, financial and managerial strengths of borrowers, adequacy of collateral if collateral dependent or present value of future cash flows, and other relevant factors.

13

Table of Contents

STATISTICAL DISCLOSURES

        The following statistical disclosures are included in Management's Discussion and Analysis, Item 7 hereof, and are incorporated by reference in this Item 1:

•

Interest Rate Sensitivity Analysis



•

Interest Income and Expense, Volume and Rate Analysis



•

Investment Portfolio



•

Loan Maturity and Interest Rate Sensitivity



•

Loan Portfolio



•

Allocation of Allowance for Loan Losses



•

Deposits



•

Short-Term Borrowings

AVAILABLE INFORMATION

        The Corporation's reports, proxy statements, and other information are available for inspection and copying at the SEC Office of Investor Education and Advocacy at 100 F Street, N.E., Washington, DC 20549, at prescribed rates. The public may obtain information from the Office of Investor Education and Advocacy by calling the Commission at 1-800-SEC-0330. The Corporation is an electronic filer with the Commission. The Commission maintains a website that contains reports, proxy and information statements, and other information regarding registrants that file electronically with the Commission. The address of the Commission's website is http://www.sec.gov.

        Upon a shareholder's written request, a copy of the Corporation's Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, and Current Reports on Form 8-K, as required to be filed with the SEC pursuant to Securities Exchange Act Rule 13a-1, may be obtained, without charge, from Lynda L. Glass, Executive Vice President, Secretary & Chief Governance Officer, ACNB Corporation, 16 Lincoln Square, P.O. Box 3129, Gettysburg, PA 17325, or visit our website at http://www.acnb.com and click on "ACNB Corporation".

EMPLOYEES

        As of December 31, 2014, ACNB had 297 full-time equivalent employees. None of these employees are represented by a collective bargaining agreement, and ACNB believes it enjoys good relations with its personnel.

ITEM 1A—RISK FACTORS

ACNB IS SUBJECT TO INTEREST RATE RISK.

        ACNB's earnings and cash flows are largely dependent upon its net interest income. Net interest income is the difference between interest income earned on interest-earning assets, such as loans and securities, and interest expense paid on interest-bearing liabilities, such as deposits and borrowed funds. Interest rates are highly sensitive to many factors that are beyond ACNB's control, including general economic conditions and policies of various governmental and regulatory agencies and, in particular, the Board of Governors of the Federal Reserve System. Changes in monetary policy, including changes in interest rates, could influence not only the amount of interest ACNB receives on loans and securities and the amount of interest it pays on deposits and borrowings, but such changes could also affect (i) ACNB's ability to originate loans and obtain deposits, (ii) the fair value of ACNB's financial assets and liabilities, and (iii) the average duration of ACNB's mortgage-backed securities portfolio. If the

14

Table of Contents

interest rates paid on deposits and other borrowings increase at a faster rate than the interest rates received on loans and other investments, ACNB's net interest income, and therefore earnings, could be adversely affected. Earnings could also be adversely affected if the interest rates received on loans and other investments fall more quickly than the interest rates paid on deposits and other borrowings.

        Although management believes it has implemented effective asset and liability management strategies to reduce the potential effects of changes in interest rates on ACNB's results of operations, any substantial, unexpected or prolonged change in market interest rates could have a material adverse effect on ACNB's financial condition and results of operations.

ACNB IS SUBJECT TO CREDIT RISK.

        As of December 31, 2014, approximately 45% of ACNB's loan portfolio consisted of commercial and industrial, construction, and commercial real estate loans. These types of loans are generally viewed as having more risk of default than residential real estate loans or consumer loans. These types of loans are also typically larger than residential real estate loans and consumer loans. Because ACNB's loan portfolio contains a significant number of commercial and industrial, construction, and commercial real estate loans with relatively large balances, the deterioration of one or a few of these loans could cause a significant increase in non-performing loans. An increase in non-performing loans could result in a net loss of earnings from these loans, an increase in the provision for loan losses, and an increase in loan charge-offs, all of which could have a material adverse effect on ACNB's financial condition and results of operations.

ACNB'S ALLOWANCE FOR LOAN LOSSES MAY BE INSUFFICIENT.

        ACNB maintains an allowance for loan losses, which is a reserve established through a provision for loan losses charged to expense, that represents management's best estimate of probable losses that have been incurred within the existing portfolio of loans. The allowance, in the judgment of management, is necessary to reserve for estimated loan losses and risks inherent in the loan portfolio. The level of the allowance reflects management's continuing evaluation of the following: industry concentrations; specific credit risks; loan loss experience; current loan portfolio quality; present economic, political and regulatory conditions; and, unidentified losses inherent in the current loan portfolio. The determination of the appropriate level of the allowance for loan losses inherently involves a high degree of subjectivity and requires ACNB to make significant estimates of current credit risks and future trends, all of which may undergo material changes. Changes in economic conditions affecting borrowers, new information regarding existing loans, identification of additional problem loans, and other factors, both within and outside of ACNB's control, may require an increase in the allowance for loan losses. In addition, bank regulatory agencies periodically review ACNB's allowance for loan losses and may require an increase in the provision for loan losses or the recognition of further loan charge-offs, based on judgments different than those of management. Further, if charge-offs in future periods exceed the allowance for loan losses, ACNB will need additional provisions to increase the allowance for loan losses. Any increases in the allowance for loan losses will result in a decrease in net income, and possibly capital, and may have a material adverse effect on ACNB's financial condition and results of operations.

COMPETITION FROM OTHER FINANCIAL INSTITUTIONS MAY ADVERSELY AFFECT ACNB'S PROFITABILITY.

        ACNB's banking subsidiary faces substantial competition in originating both commercial and consumer loans. This competition comes principally from other banks, credit unions, mortgage banking companies, and other lenders. Many of its competitors enjoy advantages, including greater financial resources with higher lending limits, wider geographic presence, more branch office locations, the ability to offer a wider array of services or more favorable pricing alternatives, and lower origination

15

Table of Contents

and operating costs. This competition could reduce the Corporation's net income by decreasing the number and size of loans that its banking subsidiary originates and the interest rates it may charge on these loans.

        In attracting business and consumer deposits, its banking subsidiary faces substantial competition from other insured depository institutions such as banks, savings institutions, and credit unions, as well as institutions offering uninsured investment alternatives, including money market funds. Many of ACNB's competitors enjoy advantages, including greater financial resources, wider geographic presence, more aggressive marketing campaigns, better brand recognition, more branch office locations, the ability to offer a wider array of services or more favorable pricing alternatives, and lower origination and operating costs. These competitors may offer higher interest rates than ACNB, which could decrease the deposits that it attracts or require it to increase its rates to retain existing deposits or attract new deposits. Increased deposit competition could adversely affect the subsidiary's ability to generate the funds necessary for lending operations. As a result, it may need to seek other sources of funds that may be more expensive to obtain and could increase its cost of funds.

        ACNB's banking subsidiary also competes with nonbank providers of financial services, such as brokerage firms, consumer finance companies, credit unions, insurance agencies, and governmental organizations which may offer more favorable terms. Some of its nonbank competitors are not subject to the same extensive regulations that govern ACNB's banking operations. As a result, such nonbank competitors may have advantages over ACNB's banking subsidiary in providing certain products and services. This competition may reduce or limit ACNB's margins on banking services, reduce its market share, and adversely affect its earnings and financial condition.

THE BASEL III CAPITAL REQUIREMENTS MAY REQUIRE ACNB TO MAINTAIN HIGHER LEVELS OF CAPITAL, WHICH COULD REDUCE ACNB'S PROFITABILITY.

        Basel III targets higher levels of base capital, certain capital buffers, and a migration toward common equity as the key source of regulatory capital. Although the new capital requirements are phased in over the next decade and may change substantially before final implementation, Basel III signals a growing effort by domestic and international bank regulatory agencies to require financial institutions, including depository institutions, to maintain higher levels of capital. The direction of the Basel III implementation activities or other regulatory viewpoints could require additional capital to support our business risk profile prior to final implementation of the Basel III standards. If ACNB and the subsidiary bank are required to maintain higher levels of capital, ACNB and the subsidiary bank may have fewer opportunities to invest capital into interest-earning assets, which could limit the profitable business operations available to ACNB and the subsidiary bank and adversely impact ACNB's financial condition and results of operations.

THE CORPORATION'S OPERATIONS OF ITS BUSINESS, INCLUDING ITS TRANSACTIONS WITH CUSTOMERS, ARE INCREASINGLY DONE VIA ELECTRONIC MEANS, AND THIS HAS INCREASED ITS RISKS RELATED TO CYBERSECURITY.

        The Corporation is exposed to the risk of cyber-attacks in the normal course of business. In addition, the Corporation is exposed to cyber-attacks on vendors and merchants that affect the Corporation and its customers. In general, cyber incidents can result from deliberate attacks or unintentional events. The Corporation has observed an increased level of attention in the industry focused on cyber-attacks that include, but are not limited to, gaining unauthorized access to digital systems for purposes of misappropriating assets or sensitive information, corrupting data, or causing operational disruption. To combat against these attacks, policies and procedures are in place to prevent or limit the effect of the possible security breach of its information systems. While ACNB maintains insurance coverage that may, subject to policy terms and conditions including significant self-insured deductibles, cover certain aspects of cyber risks, such insurance coverage may be insufficient to cover

16

Table of Contents

all losses. While the Corporation has not incurred any material losses related to cyber-attacks, nor is it aware of any specific or threatened cyber incidents as of the date of this report, it may incur substantial costs and suffer other negative consequences if it falls victim to successful cyber-attacks. Such negative consequences could include remediation costs that may include liability for stolen assets or information and repairing system damage that may have been caused; deploying additional personnel and protection technologies, training employees, and engaging third-party experts and consultants; lost revenues resulting from unauthorized use of proprietary information or the failure to retain or attract customers following an attack; disruption or failures of physical infrastructure, operating systems or networks that support ACNB's business and customers resulting in the loss of customers and business opportunities; additional regulatory scrutiny and possible regulatory penalties; litigation; and, reputational damage adversely affecting customer or investor confidence.

ACNB'S CONTROLS AND PROCEDURES MAY FAIL OR BE CIRCUMVENTED.

        Management regularly reviews and updates ACNB's internal controls, disclosure controls and procedures, as well as corporate governance policies and procedures. Any system of controls, however well designed and operated, is based in part on certain assumptions and can provide only reasonable, not absolute, assurances that the objectives of the system are met. Any failure or circumvention of ACNB's controls and procedures or failure to comply with regulations related to controls and procedures could have a material adverse effect on ACNB's business, financial condition, and results of operations.

ACNB'S ABILITY TO PAY DIVIDENDS DEPENDS PRIMARILY ON DIVIDENDS FROM ITS BANKING SUBSIDIARY, WHICH ARE SUBJECT TO REGULATORY LIMITS AND THE BANKING SUBSIDIARY PERFORMANCE.

        ACNB is a financial holding company and its operations are conducted by its subsidiaries. Its ability to pay dividends depends on its receipt of dividends from its subsidiaries. Dividend payments from its banking subsidiary are subject to legal and regulatory limitations, generally based on net profits and retained earnings, imposed by the various banking regulatory agencies. The ability of its subsidiaries to pay dividends is also subject to their profitability, financial condition, capital expenditures, and other cash flow requirements. There is no assurance that its subsidiaries will be able to pay dividends in the future or that ACNB will generate adequate cash flow to pay dividends in the future. ACNB's failure to pay dividends on its common stock could have a material adverse effect on the market price of its common stock.

ACNB'S PROFITABILITY DEPENDS SIGNIFICANTLY ON ECONOMIC CONDITIONS IN THE COMMONWEALTH OF PENNSYLVANIA AND THE STATE OF MARYLAND.

        ACNB's success depends primarily on the general economic conditions of the Commonwealth of Pennsylvania, the State of Maryland, and the specific local markets in which ACNB operates. Unlike larger national or other regional banks that are more geographically diversified, ACNB provides banking and financial services to customers primarily in the southcentral Pennsylvania and northern Maryland region of the country. The local economic conditions in these areas have a significant impact on the demand for ACNB's products and services, as well as the ability of ACNB's customers to repay loans, the value of the collateral securing the loans, and the stability of ACNB's deposit funding sources. A significant decline in general economic conditions caused by inflation, recession, acts of terrorism, outbreak of hostilities or other international or domestic occurrences, unemployment, changes in securities markets, or other factors could impact these local economic conditions and, in turn, have a material adverse effect on ACNB's financial condition and results of operations.

17

Table of Contents

THE EARNINGS OF FINANCIAL SERVICES COMPANIES ARE SIGNIFICANTLY AFFECTED BY GENERAL BUSINESS AND ECONOMIC CONDITIONS.

        ACNB's operations and profitability are impacted by general business and economic conditions in the United States and abroad. These conditions include short-term and long-term interest rates, inflation, money supply, political issues, legislative and regulatory changes, fluctuations in both debt and equity capital markets, broad trends in industry and finance, and the strength of the U.S. economy and the local economies in which ACNB operates, all of which are beyond ACNB's control. Deterioration in economic conditions could result in an increase in loan delinquencies and non-performing assets, decreases in loan collateral values, and a decrease in demand for ACNB's products and services, among other things, any of which could have a material adverse impact on ACNB's financial condition and results of operations.

        The regulatory environment for the financial services industry is being significantly impacted by financial regulatory reform initiatives in the United States and elsewhere, including Dodd-Frank and regulations promulgated to implement it.

        Dodd-Frank, which was signed into law on July 21, 2010, comprehensively reforms the regulation of financial institutions, products and services. Dodd-Frank requires various federal regulatory agencies to implement numerous rules and regulations. Because the federal agencies are granted broad discretion in drafting these rules and regulations, many of the details and the impact of Dodd-Frank may not be known for many months or years.

        While much of how the Dodd-Frank and other financial industry reforms will change ACNB's current business operations depends on the specific regulatory reforms and interpretations, many of which have yet to be released or finalized, it is clear that the reforms, both under Dodd-Frank and otherwise, will have a significant effect on the entire industry. Although Dodd-Frank and other reforms will affect a number of the areas in which ACNB does business, it is not clear at this time the full extent of the adjustments that will be required and the extent to which ACNB will be able to adjust its businesses in response to the requirements. Although it is difficult to predict the magnitude and extent of these effects at this stage, ACNB believes compliance with Dodd-Frank and implementing its regulations and initiatives will negatively impact revenue and increase the cost of doing business, both in terms of transition expenses and on an ongoing basis, and it may also limit ACNB's ability to pursue certain business opportunities.

NEW LINES OF BUSINESS OR NEW PRODUCTS AND SERVICES MAY SUBJECT ACNB TO ADDITIONAL RISKS.

        From time to time, ACNB may implement new lines of business or offer new products and services within existing lines of business. There are substantial risks and uncertainties associated with these efforts, particularly in instances where the markets are not fully developed. In developing and marketing new lines of business and/or new products and services, ACNB may invest significant time and resources. Initial timetables for the introduction and development of new lines of business and/or new products or services may not be achieved and price and profitability targets may not prove feasible. External factors, such as compliance with regulations, competitive alternatives, and shifting market preferences, may also impact the successful implementation of a new line of business and/or a new product or service. Furthermore, any new line of business and/or new product or service could have a significant impact on the effectiveness of ACNB's system of internal controls. Failure to successfully manage these risks in the development and implementation of new lines of business and new products or services could have a material adverse effect on ACNB's business, financial condition, and results of operations.

18

Table of Contents

ACNB MAY NOT BE ABLE TO ATTRACT AND RETAIN SKILLED PEOPLE.

        ACNB's success depends, in large part, on its ability to attract and retain key people. Competition for the best people in most activities engaged in by ACNB can be intense, and ACNB may not be able to hire people or to retain them. The unexpected loss of services of one or more of ACNB's key personnel could have a material adverse impact on ACNB's business because the Corporation would no longer have the benefit of their skills, knowledge of ACNB's market, as well as years of industry experience, and it would be difficult to promptly find qualified replacement personnel. ACNB currently has employment agreements, including covenants not to compete, with the following named executive officers: its President & Chief Executive Officer; Executive Vice President, Secretary & Chief Governance Officer; Executive Vice President, Treasurer & Chief Financial Officer; the Executive Vice President of Banking Services of ACNB Bank; and, the President & Chief Executive Officer of Russell Insurance Group, Inc.

ACNB IS SUBJECT TO CLAIMS AND LITIGATION PERTAINING TO FIDUCIARY RESPONSIBILITY.

        From time to time, customers make claims and take legal action pertaining to ACNB's performance of its fiduciary responsibilities. Whether customer claims and legal action related to ACNB's performance of its fiduciary responsibilities are founded or unfounded, if such claims and legal actions are not resolved in a manner favorable to ACNB, they may result in significant financial liability and/or adversely affect the market perception of ACNB and its products and services, as well as impact customer demand for those products and services. Any financial liability or reputation damage could have a material adverse effect on ACNB's business, which, in turn, could have a material adverse effect on ACNB's financial condition and results of operations.

THE TRADING VOLUME IN ACNB'S COMMON STOCK IS LESS THAN THAT OF OTHER LARGER FINANCIAL SERVICES COMPANIES.

        ACNB's common stock trades on NASDAQ, and the trading volume in its common stock is less than that of other larger financial services companies. A public trading market having the desired characteristics of depth, liquidity and orderliness depends on the presence in the marketplace of willing buyers and sellers of ACNB's common stock at any given time. This presence depends on the individual decisions of investors and general economic and market conditions over which ACNB has no control. Given the lower trading volume of ACNB's common stock, significant sales of ACNB's common stock, and the expectation of these sales, could cause ACNB's stock price to fall.

ACNB OPERATES IN A HIGHLY REGULATED ENVIRONMENT AND MAY BE ADVERSELY AFFECTED BY CHANGES IN FEDERAL, STATE AND LOCAL LAWS AND REGULATIONS.

        ACNB, primarily through its banking subsidiary, is subject to extensive regulation, supervision and/or examination by federal and state banking authorities. Any change in applicable regulations or federal, state or local legislation could have a substantial impact on ACNB and its operations. Additional legislation and regulations that could significantly affect ACNB's powers, authority and operations may be enacted or adopted in the future, which could have a material adverse effect on its financial condition and results of operations. Further, regulators have significant discretion and authority to prevent or remedy unsafe or unsound practices or violations of laws by banks and bank and financial holding companies in the performance of their supervisory and enforcement duties. The exercise of regulatory authority may have a negative impact on ACNB's financial condition and results of operations.

19

Table of Contents

        Like other financial holding companies and financial institutions, ACNB must comply with significant anti-money laundering and anti-terrorism laws. Under these laws, ACNB is required, among other things, to enforce a customer identification program and file currency transaction and suspicious activity reports with the federal government. Government agencies have substantial discretion to impose significant monetary penalties on institutions which fail to comply with these laws or make required reports. While ACNB has policies and procedures designed to prevent any such violations, there can be no assurance that such violations will not occur.

THE SOUNDNESS OF OTHER FINANCIAL INSTITUTIONS MAY ADVERSELY AFFECT ACNB.

        Financial services institutions are interrelated as a result of trading, clearing, counterparty, or other relationships. ACNB has exposure to many different industries and counterparties, and routinely executes transactions with counterparties in the financial services industry, including commercial banks, brokers and dealers, investment banks, and institutional clients. Many of these transactions expose ACNB to credit risk in the event of a default by a counterparty or client. In addition, ACNB's credit risk may be exacerbated when the collateral held by ACNB cannot be realized upon or is liquidated at prices not sufficient to recover the full amount of the credit exposure due to ACNB. Any such losses could have a material adverse effect on ACNB's financial condition and results of operations.

MARKET VOLATILITY MAY HAVE MATERIALLY ADVERSE EFFECTS ON ACNB'S LIQUIDITY AND FINANCIAL CONDITION.

        The capital and credit markets have experienced extreme volatility and disruption. Over the last several years, in some cases, the markets have exerted downward pressure on stock prices, security prices, and credit capacity for certain issuers without regard to those issuers' underlying financial strength. If the market disruption and volatility returns, there can be no assurance that ACNB will not experience adverse effects, which may be material, on its liquidity, financial condition, and profitability.

ACNB MAY NEED OR BE COMPELLED TO RAISE ADDITIONAL CAPITAL IN THE FUTURE WHICH COULD DILUTE SHAREHOLDERS OR BE UNAVAILABLE WHEN NEEDED OR AT UNFAVORABLE TERMS.

        ACNB's regulators or market conditions may require it to increase its capital levels. If ACNB raises capital through the issuance of additional shares of its common stock or other securities, it would likely dilute the ownership interests of current investors and would likely dilute the per share book value and earnings per share of its common stock. Furthermore, it may have an adverse impact on ACNB's stock price. New investors may also have rights, preferences and privileges senior to ACNB's current shareholders, which may adversely impact its current shareholders. ACNB's ability to raise additional capital will depend on conditions in the capital markets at that time, which are outside its control, and on its financial performance. Accordingly, ACNB cannot be assured of its ability to raise additional capital on terms and time frames acceptable to it or to raise additional capital at all. If ACNB cannot raise additional capital in sufficient amounts when needed, its ability to comply with regulatory capital requirements could be materially impaired. Additionally, the inability to raise capital in sufficient amounts may adversely affect ACNB's operations, financial condition, and results of operations.

ACNB'S FUTURE ACQUISITIONS COULD DILUTE SHAREHOLDER OWNERSHIP AND MAY CAUSE IT TO BECOME MORE SUSCEPTIBLE TO ADVERSE ECONOMIC EVENTS.

        ACNB may use its common stock to acquire other companies or make investments in banks and other complementary businesses in the future. ACNB may issue additional shares of common stock to pay for future acquisitions, which would dilute current investors' ownership interest in ACNB. Future business acquisitions could be material to ACNB, and the degree of success achieved in acquiring and

20

Table of Contents

integrating these businesses into ACNB could have a material effect on the value of ACNB's common stock. In addition, any acquisition could require it to use substantial cash or other liquid assets or to incur debt. In those events, ACNB could become more susceptible to economic downturns and competitive pressures.

PENNSYLVANIA BUSINESS CORPORATION LAW AND VARIOUS ANTI-TAKEOVER PROVISIONS UNDER ACNB'S ARTICLES AND BYLAWS COULD IMPEDE THE TAKEOVER OF ACNB.

        Various Pennsylvania laws affecting business corporations may have the effect of discouraging offers to acquire ACNB, even if the acquisition would be advantageous to shareholders. In addition, ACNB has various anti-takeover measures in place under its articles of incorporation and bylaws, including a supermajority vote requirement for mergers, a staggered Board of Directors, and the absence of cumulative voting. Any one or more of these measures may impede the takeover of ACNB without the approval of the Board of Directors and may prevent shareholders from taking part in a transaction in which they could realize a premium over the current market price of ACNB common stock.

IF ACNB CONCLUDES THAT THE DECLINE IN VALUE OF ANY OF ITS INVESTMENT SECURITIES IS AN OTHER-THAN-TEMPORARY IMPAIRMENT, ACNB IS REQUIRED TO WRITE DOWN THE VALUE OF THAT SECURITY THROUGH A CHARGE TO EARNINGS.

        ACNB reviews its investment securities portfolio at each quarter-end to determine whether the fair value is below the current carrying value. When the fair value of any of its investment securities has declined below its carrying value, ACNB is required to assess whether the decline is an other-than-temporary impairment. If ACNB determines that the decline is an other-than-temporary impairment, it is required to write down the value of that security through a charge to earnings for credit related impairment. Non-credit related reductions in the value of a security do not require a write down of the value through earnings unless ACNB intends to, or is required to, sell the security. Changes in the expected cash flows related to the credit related piece of the investment of a security in ACNB's investment portfolio or a prolonged price decline may result in ACNB's conclusion in future periods that an impairment is other than temporary, which would require a charge to earnings to write down the security to fair value. Due to the complexity of the calculations and assumptions used in determining whether an asset has an impairment that is other than temporary, the impairment disclosed may not accurately reflect the actual impairment in the future.

ACNB IS SUBJECT TO POTENTIAL IMPAIRMENT OF GOODWILL AND INTANGIBLES.

        RIG has certain long-lived assets including purchased intangible assets subject to amortization, such as insurance books of business, and associated goodwill assets which are reviewed for impairment annually or whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to estimated undiscounted cash flows expected to be generated by the asset. If the carrying amount of an asset exceeds its future cash flows, an impairment charge is recognized by the amount by which the carrying amount of the asset exceeds the fair value of the asset. Assets to be disposed of would be separately presented in the statement of condition and reported at the lower of the carrying amount or fair value less costs to sell, and are no longer depreciated.

        Goodwill, which has an indefinite useful life, is evaluated for impairment annually and is evaluated for impairment more frequently if events and circumstances indicate that the asset might be impaired. During the quarter ended June 30, 2012, the Corporation changed its method of applying ASC Topic 350, Intangibles—Goodwill and Other, such that the annual goodwill impairment testing date was changed from December 31 to October 1. This new testing date is preferable, because it allows the Corporation more time to accurately complete its impairment testing process, in order to incorporate

21

Table of Contents

the results in the annual consolidated financial statements. An impairment loss is recognized to the extent that the carrying amount exceeds the asset's fair value. The goodwill impairment analysis currently used by the Corporation is a two-step test. The first step, used to identify potential impairment, involves comparing the reporting unit's estimated fair value to its carrying value, including goodwill. If the estimated fair value of the reporting unit exceeds its carrying value, goodwill is considered not to be impaired. If the carrying value exceeds estimated fair value, there is an indication of potential impairment and the second step is performed to measure the amount of impairment. If required, the second step involves calculating an implied fair value of goodwill for the reporting unit for which the first step indicated potential impairment. The implied fair value of goodwill is determined in a manner similar to the amount of goodwill calculated in a business combination, by measuring the excess of the estimated fair value of the reporting unit to a group of likely buyers whose cash flow estimates could differ from those of the reporting entity, as determined in the first step, over the aggregate estimated fair values of the individual assets, liabilities and identifiable intangibles as if the reporting unit was being acquired in a business combination. If the implied fair value of goodwill exceeds the carrying value of goodwill assigned to the reporting unit, there is no impairment. If the carrying value of goodwill assigned to the reporting unit exceeds the implied fair value of the goodwill, an impairment charge is recorded for the excess. Subsequent reversal of goodwill impairment losses is not permitted. ACNB performs an annual evaluation to determine if there is goodwill impairment.

ACNB IS SUBJECT TO ENVIRONMENTAL LIABILITY RISK ASSOCIATED WITH LENDING ACTIVITIES.

        A significant portion of ACNB's banking subsidiary loan portfolio is secured by real property. During the ordinary course of business, ACNB may foreclose on and take title to properties securing certain loans. In doing so, there is a risk that hazardous or toxic substances could be found on these properties. If hazardous or toxic substances are found, ACNB may be liable for remediation costs, as well as for personal injury and property damage. Environmental laws may require ACNB to incur substantial expense and may materially reduce the affected property's value or limit ACNB's ability to use or sell the affected property. In addition, future laws or more stringent interpretations or enforcement policies with respect to existing laws may increase ACNB's exposure to environmental liability. Although ACNB has policies and procedures to perform an environmental review before initiating any foreclosure action on real property, these reviews may not be sufficient to detect all potential environmental hazards. The remediation costs and any other financial liabilities associated with an environmental hazard could have a material adverse effect on ACNB's financial condition and results of operations.

THE SEVERITY AND DURATION OF A FUTURE DOWNTURN AND THE COMPOSITION OF THE BANKING SUBSIDIARY'S LOAN PORTFOLIO COULD IMPACT THE LEVEL OF LOAN CHARGE-OFFS AND THE PROVISION FOR LOAN LOSSES AND MAY AFFECT ACNB'S NET INCOME OR LOSS.

        Lending money is a substantial part of ACNB's business through its banking subsidiary. However, every loan that ACNB makes carries a certain risk of non-payment. ACNB cannot assure that its allowance for loan losses will be sufficient to absorb actual loan losses. ACNB also cannot assure that it will not experience significant losses in its loan portfolio that may require significant increases to the allowance for loan losses in the future.

        Although ACNB evaluates every loan that it makes against its underwriting criteria, ACNB may experience losses by reasons of factors beyond its control. Some of these factors include changes in market conditions affecting the value of real estate and unexpected problems affecting the creditworthiness of ACNB's borrowers.

22

Table of Contents

        ACNB determines the adequacy of its allowance for loan losses by considering various factors, including:

•

An analysis of the risk characteristics of various classifications of loans;



•

Previous loan loss experience;



•

Specific loans that would have loan loss potential;



•

Delinquency trends;



•

Estimated fair value of the underlying collateral;



•

Current economic conditions;



•

The views of ACNB's regulators;



•

Reports of internal auditors;



•

Reports of external auditors;



•

Reports of loan reviews conducted by independent organizations; and,



•

Geographic and industry loan concentrations.

        Local economic conditions could impact the loan portfolio of ACNB. For example, an increase in unemployment, a decrease in real estate values, or increases in interest rates, as well as other factors, could weaken the economies of the communities ACNB serves. Weakness in the market areas served by ACNB could depress the Corporation's earnings and, consequently, its financial condition because:

•

Borrowers may not be able to repay their loans;



•

The value of the collateral securing ACNB's loans to borrowers may decline; and/or,



•

The quality of ACNB's loan portfolio may decline.

        Although, based on the aforementioned procedures implemented by ACNB, management believes the current allowance for loan losses is adequate, ACNB may have to increase its provision for loan losses should local economic conditions deteriorate which could negatively impact its financial condition and results of operations.

CHANGES IN REAL ESTATE VALUES MAY ADVERSELY IMPACT ACNB'S BANKING SUBSIDIARY LOANS THAT ARE SECURED BY REAL ESTATE.

        A significant portion of ACNB's banking subsidiary loan portfolio consists of residential and commercial mortgages, as well as consumer loans, secured by real estate. These properties are concentrated in Adams County, Pennsylvania. Real estate values and real estate markets generally are affected by, among other things, changes in national, regional or local economic conditions, fluctuations in interest rates, the availability of loans to potential purchasers, changes in the tax laws and other government statutes, regulations and policies, and acts of nature. If real estate prices decline, particularly in ACNB's market area, the value of the real estate collateral securing ACNB's loans could be reduced. This reduction in the value of the collateral could increase the number of non-performing loans and could have a material adverse impact on ACNB's financial condition and results of operations.

ACNB'S INFORMATION SYSTEMS MAY EXPERIENCE AN INTERRUPTION OR BREACH IN SECURITY.

        ACNB relies heavily on communications and information systems to conduct its business. Any failure, interruption or breach in security of these systems could result in failures or disruptions in

23

Table of Contents

ACNB's customer relationship management, general ledger, deposit, loan and other systems. While ACNB has policies and procedures designed to prevent or limit the effect of the failure, interruption or security breach of its information systems, there can be no assurance that any such failures, interruptions or security breaches will not occur or, if they do occur, that they will be adequately addressed. Although ACNB maintains insurance coverage that may, subject to policy terms and conditions including significant self-insured deductibles, cover certain aspects of cyber risks, such insurance coverage may be insufficient to cover all losses. The occurrence of any failures, interruptions or security breaches of ACNB's information systems could damage ACNB's reputation, adversely affecting customer or investor confidence, result in a loss of customer business, subject ACNB to additional regulatory scrutiny and possible regulatory penalties, or expose ACNB to civil litigation and possible financial liability, any of which could have a material adverse effect on ACNB's financial condition and results of operations.

ACNB CONTINUALLY ENCOUNTERS TECHNOLOGICAL CHANGE.

        The financial services industry is continually undergoing rapid technological change with frequent introductions of new technology-driven products and services. The effective use of technology increases efficiency and enables financial institutions to better serve customers and to reduce costs. ACNB's future success depends, in part, upon its ability to address the needs of its customers by using technology to provide products and services that will satisfy customer demands, as well as to create additional efficiencies in ACNB's operations. Many of ACNB's competitors have substantially greater resources to invest in technological improvements. ACNB may not be able to effectively implement new technology-driven products and services or be successful in marketing these products and services to its customers. Failure to successfully keep pace with technological change affecting the financial services industry could have a material adverse impact on ACNB's business and, in turn, ACNB's financial condition and results of operations.

FINANCIAL SERVICES COMPANIES DEPEND ON THE ACCURACY AND COMPLETENESS OF INFORMATION ABOUT CUSTOMERS AND COUNTERPARTIES.

        In deciding whether to extend credit or enter into other transactions, ACNB may rely on information furnished by or on behalf of customers and counterparties, including financial statements, credit reports, and other financial information. ACNB may also rely on representations of those customers, counterparties or other third parties, such as independent auditors, as to the accuracy and completeness of that information. Reliance on inaccurate or misleading financial statements, credit reports, or other financial information could have a material adverse impact on ACNB's business and, in turn, ACNB's financial condition and results of operations.

CONSUMERS MAY DECIDE NOT TO USE BANKS TO COMPLETE THEIR FINANCIAL TRANSACTIONS.

        Technology and other changes are allowing parties to complete financial transactions that historically have involved banks through alternative methods. For example, consumers can now maintain funds in brokerage accounts or mutual funds that would have historically been held as bank deposits. Consumers can also complete transactions such as paying bills and/or transferring funds directly without the assistance of banks. The process of eliminating banks as intermediaries, known as "disintermediation", could result in the loss of fee income, as well as the loss of customer deposits and the related income generated from those deposits. The loss of these revenue streams and the lower cost deposits as a source of funds could have a material adverse effect on ACNB's financial condition and results of operations.

24

Table of Contents

FUTURE ECONOMIC CONDITIONS MAY ADVERSELY AFFECT SECONDARY SOURCES OF LIQUIDITY.

        In addition to primary sources of liquidity in the form of deposits and principal and interest payments on outstanding loans and investments, ACNB maintains secondary sources that provide it with additional liquidity. These secondary sources include secured and unsecured borrowings from sources such as the Federal Reserve Bank, Federal Home Loan Bank of Pittsburgh, and third-party commercial banks. However, market liquidity conditions have been negatively impacted by past disruptions in the capital markets and could, in the future, have a negative impact on ACNB's secondary sources of liquidity.

SEVERE WEATHER, NATURAL DISASTERS, ACTS OF WAR OR TERRORISM, AND OTHER EXTERNAL EVENTS COULD SIGNIFICANTLY IMPACT ACNB'S BUSINESS.

        The unpredictable nature of events such as severe weather, natural disasters, acts of war or terrorism, and other adverse external events could have a significant impact on ACNB's ability to conduct business. If any of its financial, accounting, network or other information processing systems fail or have other significant shortcomings due to external events, ACNB could be materially adversely affected. Third parties with which ACNB does business could also be sources of operational risk to ACNB, including the risk that the third parties' own network and information processing systems could fail. Any of these occurrences could materially diminish ACNB's ability to operate one or more of the Corporation's businesses, or result in potential liability to clients, reputational damage, and regulatory intervention, any of which could materially adversely affect ACNB. Such events could affect the stability of ACNB's deposit base, impair the ability of borrowers to repay outstanding loans, impair the value of collateral securing loans, impair ACNB's liquidity, cause significant property damage, result in loss of revenue, and/or cause ACNB to incur additional expenses.

        ACNB may be subject to disruptions or failures of the financial, accounting, network and other information processing systems arising from events that are wholly or partially beyond ACNB's control, which may include, for example, computer viruses, electrical or telecommunications outages, natural disasters, disease pandemics, damage to property or physical assets, or terrorist acts. ACNB has developed a comprehensive business continuity plan which includes plans to maintain or resume operations in the event of an emergency, such as a power outage or disease pandemic, and contingency plans in the event that operations or systems cannot be resumed or restored. The business continuity plan is updated as needed, periodically reviewed, and components are regularly tested. ACNB also reviews and evaluates the business continuity plans of critical third-party service providers. While ACNB believes its business continuity plan and efforts to evaluate the business continuity plans of critical third-party service providers help mitigate risks, disruptions or failures affecting any of these systems may cause interruptions in service to customers, damage to ACNB's reputation, and loss or liability to the Corporation.

FUTURE CREDIT DOWNGRADES OF THE UNITED STATES GOVERNMENT DUE TO ISSUES RELATING TO DEBT AND THE DEFICIT MAY ADVERSELY AFFECT ACNB.

        As a result of past difficulties of the federal government to reach agreement over federal debt and issues connected with the debt ceiling, certain rating agencies placed the United States government's long-term sovereign debt rating on their equivalent of negative watch and announced the possibility of a rating downgrade. The rating agencies, due to constraints related to the rating of the United States, also placed government-sponsored enterprises in which ACNB invests and receives lines of credit on negative watch and a downgrade of the United States government's credit rating would trigger a similar downgrade in the credit rating of these government-sponsored enterprises. Furthermore, the credit rating of other entities, such as state and local governments, may also be downgraded should the United States government's credit rating be downgraded. The impact that a credit rating downgrade

25

Table of Contents

may have on the national and local economy could have an adverse effect on ACNB's financial condition and results of operations.

ACNB'S BANKING SUBSIDIARY MAY BE REQUIRED TO PAY HIGHER FDIC INSURANCE PREMIUMS OR SPECIAL ASSESSMENTS WHICH MAY ADVERSELY AFFECT ITS EARNINGS.

        Poor economic conditions and the resulting bank failures have increased the costs of the FDIC and adversely impacted its Deposit Insurance Fund. Additional bank failures may prompt the FDIC to increase its premiums or to issue special assessments. ACNB is generally unable to control the amount of premiums or special assessments that its banking subsidiary is required to pay for FDIC insurance. Any future changes in the calculation or assessment of FDIC insurance premiums may have a material adverse effect on ACNB's financial condition and results of operations.

INCOME TAXATION CHANGES COULD HAVE NEGATIVE EFFECTS ON RESULTS OF OPERATIONS AND ASSET VALUES.

        Discussions of proposed major overhauls of the federal corporate tax code could result in unknown and unpredictable effects on ACNB's results of operations and value of assets. Proposals that would lower the corporate tax rate and, at the same time, reduce certain deductions from taxable income are aimed to increase overall revenue from corporate taxation. For example, reducing the tax deductibility of state and local government investments and loans would increase income tax expense and could perhaps decrease the value of those assets. Lowering tax rates would decrease the value of certain deferred tax assets. In addition, changes to individual income tax laws could have the effect of lowering demand for important sources of lending and revenue to ACNB, such as residential mortgages.

THE INCREASING USE OF SOCIAL MEDIA PLATFORMS PRESENTS NEW RISKS AND CHALLENGES AND THE INABILITY OR FAILURE TO RECOGNIZE, RESPOND TO, AND EFFECTIVELY MANAGE THE ACCELERATED IMPACT OF SOCIAL MEDIA COULD MATERIALLY ADVERSELY IMPACT ACNB'S BUSINESS.

        There has been a marked increase in the use of social media platforms, including weblogs (blogs), social media websites, and other forms of Internet-based communications which allow individuals access to a broad audience of consumers and other interested persons. Social media practices in the banking industry are evolving, which creates uncertainty and risk of noncompliance with regulations applicable to ACNB's business. Consumers value readily available information concerning businesses and their goods and services and often act on such information without further investigation and without regard to its accuracy. Many social media platforms immediately publish the content their subscribers and participants post, often without filters or checks on accuracy of the content posted. Information posted on such platforms at any time may be adverse to ACNB's interests and/or may be inaccurate. The dissemination of information online could harm ACNB's business, prospects, financial condition, and results of operations, regardless of the information's accuracy. The harm may be immediate without affording ACNB an opportunity for redress or correction.

        Other risks associated with the use of social media include improper disclosure of proprietary information, negative comments about ACNB's business, exposure of personally identifiable information, fraud, out-of-date information, and improper use by employees and customers. The inappropriate use of social media by ACNB's customers or employees could result in negative consequences including remediation costs including training for employees, additional regulatory scrutiny and possible regulatory penalties, litigation, or negative publicity that could damage ACNB's reputation adversely affecting customer or investor confidence.

26

Table of Contents

ITEM 1B—UNRESOLVED STAFF COMMENTS

        None.

ITEM 2—PROPERTIES

        ACNB Bank, in addition to its main office in Gettysburg, Adams County, Pennsylvania, had a retail banking office network of nineteen offices at December 31, 2014. Thirteen retail banking offices are located in Adams County, one is located in Cumberland County, one is located in Franklin County, and four are located in York County, Pennsylvania. There is also a loan production office situated in York County, Pennsylvania. Bank offices at sixteen locations are owned, while five are leased. All real estate owned by the subsidiary bank is free and clear of encumbrances. During 2014, RIG had two leased offices located in Carroll County and Montgomery County, Maryland.

ITEM 3—LEGAL PROCEEDINGS

        As of December 31, 2014, there were no material pending legal proceedings, other than ordinary routine litigation incidental to the business, to which ACNB or its subsidiaries are a party or by which any of their property is the subject, which could have a material adverse effect on ACNB or its subsidiaries or their results of operations. In addition, no material proceedings are pending or are known to be threatened or contemplated against the Corporation or its subsidiaries by governmental authorities.

ITEM 4—MINE SAFETY DISCLOSURES

        Not Applicable.

27

Table of Contents

PART II

ITEM 5—MARKET FOR THE REGISTRANT'S COMMON EQUITY, RELATED STOCKHOLDER MATTERS AND ISSUER PURCHASES OF EQUITY SECURITIES

        ACNB Corporation's common stock trades on NASDAQ under the symbol ACNB. At December 31, 2014 and 2013, there were 20,000,000 shares of common stock authorized, 6,078,250 and 6,053,911 shares issued, respectively, and 6,015,650 and 5,991,311 shares outstanding, respectively. As of December 31, 2014, ACNB had approximately 2,323 stockholders of record. At December 31, 2014 and 2013, there were 62,600 shares of treasury stock purchased by the Corporation through the common stock repurchase program approved in October 2008. There have been no shares purchased during the most recent quarter and 57,400 shares can still be purchased under the program. ACNB is restricted as to the amount of dividends that it can pay to stockholders by virtue of the restrictions on the banking subsidiary's ability to pay dividends to ACNB under the Pennsylvania Banking Code, the Federal Deposit Insurance Corporation Act, and the regulations of the FDIC. For further information, please refer to Notes J—"Regulatory Restrictions on Dividends" and N—"Regulatory Matters" in the Notes to Consolidated Financial Statements.

        On May 5, 2009, stockholders approved and ratified the ACNB Corporation 2009 Restricted Stock Plan, effective as of February 24, 2009, in which awards shall not exceed, in the aggregate, 200,000 shares of common stock. As of December 31, 2014, there were no shares of common stock granted as restricted stock awards to either employees or directors. The Corporation's Registration Statement under the Securities Act of 1933 on Form S-8 for the ACNB Corporation 2009 Restricted Stock Plan was filed with the Securities and Exchange Commission on January 4, 2013.

        On May 5, 2009, stockholders approved and adopted the amendment to the Articles of Incorporation of ACNB Corporation to authorize up to 20,000,000 shares of preferred stock, par value $2.50 per share. As of December 31, 2014, there were no issued or outstanding shares of preferred stock.

        On January 24, 2011, the ACNB Corporation Dividend Reinvestment and Stock Purchase Plan was introduced for stockholders of record. This plan provides registered holders of ACNB Corporation common stock with a convenient way to purchase additional shares of common stock by permitting participants in the plan to automatically reinvest cash dividends on all or a portion of the shares owned and to make quarterly voluntary cash payments under the terms of the plan. Participation in the plan is voluntary, and there are eligibility requirements to participate in the plan. As of December 31, 2014, there were 87,307 shares of common stock issued through the ACNB Corporation Dividend Reinvestment and Stock Purchase Plan.

        There have been no unregistered sales of stock in 2014, 2013 or 2012.

28

Table of Contents

        The following table reflects the quarterly high and low prices of ACNB's common stock and the cash dividends on the common stock for the periods indicated.

        The Corporation has added the Mid-Atlantic Custom Peer Group—Asset $700M-$2B to the performance graph below, which management believes better represents the Corporation's performance versus other financial institutions of similar size.

29

Table of Contents

30

Table of Contents

Mid-Atlantic Custom Peer Group—Asset <$1B

31

Table of Contents

Mid-Atlantic Custom Peer Group—Asset $700M-$2B

32

Table of Contents

ITEM 6—SELECTED FINANCIAL DATA

33

Table of Contents

ITEM 7—MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

INTRODUCTION

        The following is management's discussion and analysis of the significant changes in the financial condition, results of operations, comprehensive income, capital resources, and liquidity presented in its accompanying consolidated financial statements for ACNB Corporation (the Corporation or ACNB), a financial holding company. Please read this discussion in conjunction with the consolidated financial statements and disclosures included herein. Current performance does not guarantee, assure or indicate similar performance in the future.

CRITICAL ACCOUNTING POLICIES

        The accounting policies that the Corporation's management deems to be most important to the portrayal of its financial condition and results of operations, and that require management's most difficult, subjective or complex judgment, often result in the need to make estimates about the effect of such matters which are inherently uncertain. The following policies are deemed to be critical accounting policies by management:

        The allowance for loan losses represents management's estimate of probable losses inherent in the loan portfolio. Management makes numerous assumptions, estimates and adjustments in determining an adequate allowance. The Corporation assesses the level of potential loss associated with its loan portfolio and provides for that exposure through an allowance for loan losses. The allowance is established through a provision for loan losses charged to earnings. The allowance is an estimate of the losses inherent in the loan portfolio as of the end of each reporting period. The Corporation assesses the adequacy of its allowance on a quarterly basis. The specific methodologies applied on a consistent basis are discussed in greater detail under the caption, Allowance for Loan Losses, in a subsequent section of this Management's Discussion and Analysis of Financial Condition and Results of Operations.

        The evaluation of securities for other-than-temporary impairment requires a significant amount of judgment. In estimating other-than-temporary impairment losses, management considers various factors including the length of time the fair value has been below cost, the financial condition of the issuer, and the Corporation's intent to sell, or requirement to sell, the security before recovery of its value. Declines in fair value that are determined to be other than temporary are charged against earnings.

        Accounting Standards Codification (ASC) Topic 350, Intangibles—Goodwill and Other, requires that goodwill is not amortized to expense, but rather that it be assessed or tested for impairment at least annually. Impairment write-downs are charged to results of operations in the period in which the impairment is determined. The Corporation did not identify any impairment on its outstanding goodwill from its most recent testing, which was performed as of October 1, 2014. If certain events occur which might indicate goodwill has been impaired, the goodwill is tested for impairment when such events occur. During the quarter ended June 30, 2012, the Corporation changed its method of applying ASC Topic 350 such that the annual goodwill impairment testing date was changed from December 31 to October 1. This new testing date is preferable under the circumstances, because it allows the Corporation more time to accurately complete its impairment testing process in order to incorporate the results in the annual consolidated financial statements. Other acquired intangible assets with finite lives, such as customer lists, are required to be amortized over the estimated lives. These intangibles are generally amortized using the straight line method over estimated useful lives of ten years.

34

Table of Contents

EXECUTIVE OVERVIEW

        The primary source of the Corporation's revenues is net interest income derived from interest earned on loans and investments, less deposit and borrowing funding costs. Revenues are influenced by general economic factors, including market interest rates, the economy of the markets served, stock market conditions, as well as competitive forces within the markets.

        The Corporation's overall strategy is to increase loan growth in local markets, while maintaining a reasonable funding base by offering competitive deposit products and services. The year 2014 continued to be challenging for financial institutions with new expensive compliance regulations, slowly recovering housing markets, lingering wage stagnation, and slow uneven growth. ACNB continued to be profitable and well capitalized despite the aftershocks of the unprecedented challenge to the United States economy in recent years past. Lower provision for loan losses offset increased expenses resulting in increased net income of $10,290,000, or $1.71 per share, in 2014, compared to $9,315,000, or $1.56 per share, in 2013 and $8,886,000, or $1.49 per share, in 2012. Returns on average equity were 9.32%, 9.00% and 8.91% in 2014, 2013 and 2012, respectively.

        Because funding costs were near practical floors, they could not be decreased at the same increments as earning asset decreases; therefore, the Corporation's net interest margin decreased to 3.47% in 2014, compared to 3.48% and 3.56% in 2013 and 2012, respectively. Net interest income was $33,880,000 in 2014, as compared to $33,612,000 in 2013 and $34,344,000 in 2012.

        Other income was $11,904,000, $11,703,000 and $11,867,000 in 2014, 2013 and 2012, respectively. The largest source of other income is commissions from insurance sales from Russell Insurance Group, Inc. (RIG), which increased by 3.6% in 2014 to $4,839,000, boosted by higher contingent commissions and stable commercial insurance volume despite the continued weak economic conditions. In 2014, a $62,000 gain was recognized on sold or called investments compared to net gains of $0 in 2013 and $7,000 in 2012. Income from fiduciary activities totaled $1,418,000 for 2014, as compared to $1,299,000 for 2013 and $1,224,000 for 2012. Trust fiduciary income increased from increased estate settlements and new account relationships. Service charges on deposit accounts decreased 5.7% to $2,118,000 for 2014 due to changes in customer behaviors, while revenue from ATM and debit card transactions increased 8.1% to $1,550,000 due to higher volume.

        Other expenses increased to $32,264,000, or by 0.8%, in 2014, as compared to $32,015,000 in 2013. Other expenses totaled $30,331,000 in 2012. The largest component of other expenses is salaries and employee benefits, which increased 3.0% to $19,516,000 in 2014 compared to $18,950,000 in 2013, due to an increase in employees, merit increases, and the increased cost of benefits, offset by lower pension expense. Compared to 2013, occupancy expense increased 4.8% in 2014 due to harsh winter expenses and new locations, and equipment expense decreased 2.1% from temporary variance in expenditures. Professional services expense increased 4.6% despite lower problem loan-related legal expenses in 2014, due to higher compliance and corporate governance. Marketing and corporate relations expense increased by 48.2% due to website redesign, product specific campaigns and brand awareness activities. FDIC and regulatory expense decreased by 2.6%; however, it is still a significant expense as the result of a requirement of all FDIC-insured banks to restore and maintain the Deposit Insurance Fund due to protecting depositors' accounts. In 2014, foreclosed real estate expenses decreased $230,000 or 39.9% resulting from higher final sale losses in 2013. A more thorough discussion of the Corporation's results of operations is included in the following pages.

RESULTS OF OPERATIONS

Net Interest Income

        The primary source of ACNB's traditional banking revenue is net interest income, which represents the difference between interest income on earning assets and interest expense on liabilities

35

Table of Contents

used to fund those assets. Earning assets include loans, securities, and interest bearing deposits with banks. Interest bearing liabilities include deposits and borrowings.

        Net interest income is affected by changes in interest rates, volume of interest bearing assets and liabilities, and the composition of those assets and liabilities. The "interest rate spread" and "net interest margin" are two common statistics related to changes in net interest income. The interest rate spread represents the difference between the yields earned on interest earning assets and the rates paid for interest bearing liabilities. The net interest margin is defined as the percentage of net interest income to average earning assets, which also considers the Corporation's net non-interest bearing funding sources, the largest of which are non-interest bearing demand deposits and stockholders' equity.

        The following table includes average balances, rates, interest income and expense, interest rate spread, and net interest margin:

Table 1—Average Balances, Rates and Interest Income and Expense