Company: SOJE
Filing Date: 2025-11-03
Form Type: 424B5
Source: 0000092122-25-000088
Chunk: 43

Company: SOUTHERN CO
Filing Date: 2025-11-03
Form: 424B5
Chunk 43
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| December 14, 2028 (one business day prior to the purchase contract settlement date)         |     | If the final remarketing has not been successful, last day for holders of Corporate Units who have elected to settle the related purchase contracts with separate cash on the purchase contract settlement date to pay the purchase price.                                                                                                                     |
| December 15, 2028 (or if such day is not a business day, the following business day)        |     | Purchase contract settlement date and settlement date for any successful final remarketing of the RSNs.                                                                                                                                                                                                                                                        |

<div align='center'>S-27</div>

### RISK FACTORS
Investing in the Equity Units involves risk. In addition to the factors described below, please see the risk factors in the Annual Report on Form 10-K of the Company for the year ended December 31, 2024 , which is incorporated by reference in this Prospectus Supplement and the accompanying Prospectus. Before making an investment decision, you should carefully consider these risks as well as other information contained or incorporated by reference in this Prospectus Supplement and the accompanying Prospectus.

The Corporate Units consist of a purchase contract to acquire the Company’s common stock and an interest in Series 2025B RSNs and Series 2025C RSNs issued by the Company. When considering an investment in the Corporate Units, you are making an investment decision with respect to the Company’s common stock and the RSNs as well as the Corporate Units. You can create Treasury Units from Corporate Units by substituting Treasury securities for both series of RSNs; you would be making an investment decision with respect to the Company’s common stock and the RSNs as well as the Treasury Units in such case. You should carefully review the information in this Prospectus Supplement and the accompanying Prospectus about these securities.

See “Available Information” on page S-1.

#### Risks Relating to the Equity Units
You assume the risk that the market value of the Company’s common stock may decline.

The number of shares of the Company’s common stock that you will receive upon the settlement of a purchase contract is not fixed but instead will depend on the average of the VWAP of the Company’s common stock on each trading day of the 20 consecutive scheduled trading day period ending on the third scheduled trading day immediately preceding the purchase contract settlement date (subject to adjustment as described herein if a market disruption event occurs), which is referred to as the applicable market value. There can be