Company: SFNC
Filing Date: 2025-09-10
Form Type: 424B5
Source: 0001193125-25-200113
Chunk: 80

Company: SIMMONS FIRST NATIONAL CORP
Filing Date: 2025-09-10
Form: 424B5
Chunk 80
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, we will provide you with a prospectus supplement that will describe the specific amounts, prices and terms of the securities being offered. You should read this prospectus, the
information incorporated by reference in this prospectus, the accompanying prospectus supplement, including any information incorporated by reference therein, and any free writing prospectus carefully before you invest in the securities described in
the applicable prospectus supplement.

Our common stock is listed on the Nasdaq Global Select Market and trades under the ticker symbol
“SFNC.”

We may offer and sell these securities to or through one or more underwriters, dealers and agents, directly to
purchasers or through a combination of these methods, on a continuous or delayed basis from time to time. The names of any underwriters, dealers or agents involved in the distribution of our securities, their compensation and any option they hold to
acquire additional securities will be described in the applicable prospectus supplement. Net proceeds from the sale of securities will be set forth in the applicable prospectus supplement.

This prospectus may not be used to sell securities unless accompanied by the applicable prospectus supplement.

Investing in our securities involves certain risks. See “ Risk Factors” beginning on page 4 of this prospectus and contained in our Annual Report on Form 10-Kfor the year ended December 31, 2023, which is incorporated herein by reference, as well as any risk factors included in, or incorporated by reference into, the applicable prospectus supplement, to read about factors you should consider before buying any securities issued by us.

These securities are not savings accounts, deposits
or other obligations of any of our bank and non-bank subsidiaries and are not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Neither the U.S. Securities and Exchange Commission, any state securities commission, the Federal Deposit Insurance Corporation, the Board of
Governors of the Federal Reserve System nor any other regulatory body has approved or disapproved of these securities or determined if this prospectus is accurate or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is May 17, 2024.

TABLE OF CONTENTS

|                                     |     | Page |   |
| About This Prospectus               |     |      | 1 |
| Where You Can Find More Information |     |      | 2 |
| The Company                         |     |      | 3 |
| Risk Factors                        |     |      | 4 |
| Use of Proceeds                     |     |