Company: SFNC
Filing Date: 2025-07-23
Form Type: 424B5
Source: 0001193125-25-162761
Chunk: 24

Company: SIMMONS FIRST NATIONAL CORP
Filing Date: 2025-07-23
Form: 424B5
Chunk 24
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 net proceeds from this offering, and investors will
be relying on the judgment of our board of directors and management with regard to the use of these net proceeds. Please see “Risk Factors — Risks Related to an Investment in Our Common Stock and the Offering — Our management will
have broad discretion in allocating the net proceeds of the offering. Our failure to effectively utilize such net proceeds may have an adverse effect on our financial performance and the value of our common stock.” Pending the use of the net
proceeds from this offering as described above, we may invest the net proceeds in cash or short-term marketable securities.

The foregoing
represents our intentions based upon our present plans and business conditions. The occurrence of unforeseen events or changed business conditions, however, could result in the application of the net proceeds of the offering in a manner other than
as described in this prospectus supplement.

S-21

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

| • |     | on an actual basis; and |

| • |     | on an as adjusted basis to reflect the sale of 16,220,000 shares of our common stock offered by us at the public                                                                                                               
 offering price of $18.50 per share in this offering, after deducting the underwriting discount and our estimated offering expenses (assuming the underwriters’ option to purchase additional shares from us is not exercised). |

This table should be read in conjunction with, and is qualified in its entirety by reference to, the information appearing under “Use of Proceeds” included 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              |            |   |     | As          
 Adjusted(1) |            |   |
| Cash and cash equivalents                                                     |     | $                   |    644,462 |   |     | $           |    928,772 |   |
| Liabilities:                                                                  |     |                     |            |   |     |             |            |   |
| Deposits                                                                      |     |                     | 21,824,