Company: SOJE
Filing Date: 2025-11-04
Form Type: 424B2
Source: 0000092122-25-000092
Chunk: 1

Company: SOUTHERN CO
Filing Date: 2025-11-04
Form: 424B2
Chunk 1
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 of these securities or passed upon the adequacy or accuracy of this Prospectus Supplement or the accompanying Prospectus. Any representation to the contrary is a criminal offense.

|                                                |     | Per Corporate 
 Unit          |        |     | Total |               |
|:-----------------------------------------------|:----|:--------------|-------:|:----|:------|--------------:|
| Public offering price                          |     | $             | 50.000 |     | $     | 1,750,000,000 |
| Underwriting discounts and commissions         |     | $             |  0.875 |     | $     |    30,625,000 |
| Proceeds, before expenses, to Southern Company |     | $             | 49.125 |     | $     | 1,719,375,000 |

The Company has granted the underwriters the option to purchase from the Company, within the 13-day period beginning on the date the Company first issues the Equity Units, up to an additional 5,000,000 Corporate Units at the public offering price per Corporate Unit, less the underwriting discounts and commissions, solely for the purpose of covering over-allotments.

The underwriters expect to deliver the Corporate Units to purchasers in book-entry form only on or about November 6, 2025 through the book-entry facilities of The Depository Trust Company for the accounts of its participants, including Euroclear Bank SA/NV (“Euroclear”), as operator of the Euroclear system, or Clearstream Banking, S.A., Luxembourg (“Clearstream”).

<div align='center'>Joint Book-Running Managers</div>

| BofA Securities |     |      |                         |     | J.P. Morgan         |                |     |            |     | Mizuho                 |
| Citigroup       |     |      | Goldman Sachs & Co. LLC |     |                     | Morgan Stanley |     |            |     | Wells Fargo Securities |
| Barclays        |     | MUFG |                         |     | RBC Capital Markets |                |     | Scotiabank |     | Truist Securities      |

November 3, 2025

(continued from cover)

• The purchase contract will obligate you to purchase from the Company on December 15, 2028, or if such day is not a business day, on the following business day (the “purchase contract settlement date”), for a price of $50 in cash, the following number of shares of the Company’s common