Company: SFNC
Filing Date: 2025-09-10
Form Type: 424B5
Source: 0001193125-25-200113
Chunk: 59

Company: SIMMONS FIRST NATIONAL CORP
Filing Date: 2025-09-10
Form: 424B5
Chunk 59
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 have the meanings set forth above, under the heading “—Interest.” Determinations and Decisions We and the calculation agent are expressly authorized to make certain determinations, decisions, and elections under the terms of the Notes, including with respect to the use of Three-Month Term SOFR as the S-38

Benchmark for the floating rate period and under the benchmark transition provisions. Any determination, decision, or election that may be made by us or by the calculation agent under the terms of the Notes, including any determination with respect to the use of Three-Month Term SOFR as the Benchmark for the floating rate period, any determination under the benchmark transition provisions, any determination of a tenor, rate, or adjustment or of the occurrence or non-occurrenceof an event, circumstance, or date and any decision to take or refrain from taking any action or any selection:

| • |     | will be conclusive and binding on the holders of the Notes and the Trustee absent manifest error; |

| • |     | if made by us, will be made in our sole discretion; |

| • |     | if made by the calculation agent, will be made after consultation with us, and the calculation agent will not 
 make any such determination, decision or election to which we reasonably object; and                          |

| • |     | notwithstanding anything to the contrary in the Indenture, shall become effective without consent from the 
 holders of the Notes or the Trustee.                                                                       |

If the calculation agent fails to make any determination, decision or election that it is required to make under the terms of the Notes, then we will make that determination, decision or election on the same basis as described above. The Indenture provides that the Trustee will have no liability relating to any delay caused by the calculation agent’s failure to timely or appropriately determine the rate of interest borne by the Notes. Calculation Agent Wilmington Trust, National Association will initially act as calculation agent for the Notes. Paying Agent We may appoint one or more financial institutions to act as our paying agents, at whose designated offices the Notes in non-globalform may be surrendered for payment at their maturity. We call each of those offices a paying agent. We may add, replace or terminate paying agents from time to time. We may also choose to act as our own paying agent. Initially, we have appointed the Trustee, at its principal corporate trust office at 1100 North Market Street, Rodney Square North, Wilmington, DE 19890, as the paying agent for the Notes