Company: SFNC
Filing Date: 2025-09-10
Form Type: 424B5
Source: 0001193125-25-200113
Chunk: 32

Company: SIMMONS FIRST NATIONAL CORP
Filing Date: 2025-09-10
Form: 424B5
Chunk 32
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 (8) | Includes total after-tax, realized loss on securities available-for-sale sold in the Investment Securities Transaction and the impact of the redemption of the Spirit Notes. |

| (9) | Net impact of divested securities, which assumes an average risk weight of 32.9%. |

| (10) | Assumes the issuance of Notes with an aggregate principal amount of $325 million, an underwriting discount 
 of 1%, and $500 thousand of pre-tax offering expenses.                                                     |

| (11) | Assumes the redemption and repayment in full of the 2028 Notes including $631 thousand in unamortized                                                             
 issuance costs, for which we anticipate delivering a redemption notice following this offering, with such redemption expected to be effective on October 1, 2025. |

S-21

CAPITALIZATION The following table sets forth our capitalization as of June 30, 2025:

| • |     | on an actual basis; |

| • |     | on a pro forma basis to give effect to the Common Equity Offering, the Investment Securities Transaction, and the 
 Redemption of the Spirit Notes; and                                                                               |

| • |     | on a pro forma as adjusted basis to give effect to the issuance and sale of the Notes in this offering (after                                                                                                                              
 deducting the underwriting discount and estimated offering expenses) and the redemption of all of the 2028 Notes. As discussed under “Use of Proceeds” above, we may determine not to redeem the 2028 Notes or to redeem only a portion of 
 the 2028 Notes.                                                                                                                                                                                                                            |

This table is unaudited and should be read in conjunction with, and is qualified in its entirety by reference to, the information appearing under “Use of Proceeds” and under “Unaudited Pro Forma Financial Information” appearing elsewhere in this prospectus supplement, as well as our historical financial statements and related notes that are incorporated by reference into this prospectus supplement.

|                                                                                        |     | As of June 30, 2025 |            |   |     |           |            |   |     |                        |            |    |
|:---------------------------------------------------------------------------------------|:----|:--------------------|-----------:|:--|:----|:----------|-----------:|:--|:----|:-----------------------|-----------:|---:|
| ($ in thousands, except share data)                                                    |     | Actual              |            |   |     | Pro Forma |            |   |     | Pro Form