Company: CCNE
Filing Date: 2025-03-05
Form Type: 424B3
Source: 0001193125-25-047258
Chunk: 54

Company: CNB FINANCIAL CORP/PA
Filing Date: 2025-03-05
Form: 424B3
Chunk 54
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30

| • |     | the dilution caused by CNB’s issuance of additional shares of its capital stock in connection with the 
 proposed transaction;                                                                                  |

| • |     | uncertainty and changes in general economic conditions, including changes in market interest rates and changes in 
 monetary and fiscal policies of the federal government;                                                           |

| • |     | volatility and disruptions in global capital and credit markets; and |

| • |     | legislative and regulatory changes. |

Additional factors that could cause CNB’s and ESSA’s results to differ materially from those described in the forward-looking statements can be found in the section entitled “Risk Factors” beginning on page 21, and CNB’s and ESSA’s filings with the SEC, including CNB’s Annual Report on Form 10-Kfor the fiscal year ended December 31, 2023 and ESSA’s Annual Report on Form 10-Kfor the fiscal year ended September 30, 2024, as amended. You are cautioned not to place undue reliance on forward-looking statements, which speak only as of the date of this joint proxy statement/prospectus or the date of any document incorporated by reference into this joint proxy statement/prospectus. All subsequent written and oral forward-looking statements concerning the merger or other matters addressed in this joint proxy statement/prospectus and attributable to CNB or ESSA or any person acting on their behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. Except to the extent required by applicable law or regulation, CNB and ESSA undertake no obligation to update these forward-looking statements to reflect events or circumstances after the date of this joint proxy statement/prospectus or to reflect the occurrence of unanticipated events. 31

INFORMATION ABOUT THE COMPANIES

CNB Financial Corporation

CNB
is a financial holding company registered under the BHC Act. It was incorporated under the laws of the Commonwealth of Pennsylvania in 1983 for the purpose of engaging in the business of a financial holding company. On April 26, 1984, CNB
acquired all of the outstanding capital stock of County National Bank, a national banking chartered institution. In December 2006, County National Bank changed its name to CNB Bank and became a state bank chartered in Pennsylvania and subject to
regulation by the PADOBS and the FDIC. In October 2013, CNB acquired FC Banc Corp. and its subsidiary, The Farmers Citizens Bank