Company: SOJE
Filing Date: 2025-02-26
Form Type: 424B2
Source: 0000092122-25-000026
Chunk: 49

Company: SOUTHERN CO
Filing Date: 2025-02-26
Form: 424B2
Chunk 49
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ordinated Notes

#### Stock Purchase Contracts

#### Stock Purchase Units
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We will provide the specific terms of these securities in supplements to this Prospectus. You should read this Prospectus and the applicable Prospectus Supplement carefully before you invest.

The Southern Company’s common stock is listed on the New York Stock Exchange under the symbol “SO.”

See “Risk Factors” on page 1 for information on certain risks related to the purchase of securities offered by this Prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this Prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

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February 16, 2024

### ABOUT THIS PROSPECTUS
This Prospectus is part of a registration statement filed with the Securities and Exchange Commission (the “Commission”) using a “shelf” registration process under the Securities Act of 1933, as amended (the “1933 Act”). Under the shelf process, The Southern Company (the “Company”) may sell, in one or more transactions,

| l |     | common stock (the “Common Stock”),                            |
| l |     | senior notes (the “Senior Notes”),                            |
| l |     | junior subordinated notes (the “Junior Subordinated Notes”),  |
| l |     | stock purchase contracts (the “Stock Purchase Contracts”), or |
| l |     | stock purchase units (the “Stock Purchase Units”).            |

This Prospectus provides a general description of those securities. Each time the Company sells securities, the Company will provide a prospectus supplement that will contain specific information about the terms of that offering (“Prospectus Supplement”). The Prospectus Supplement may also add, update or change information contained in this Prospectus. You should read this Prospectus and the applicable Prospectus Supplement together with the additional information under the heading “Available Information.”

### RISK FACTORS
Investing in the Company’s securities involves risk. Please see the risk factors described in the Company’s Annual Report on Form 10-K for the year ended December 31, 2023 (the “Form 10-K”), which is incorporated by reference in this 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.

### AVAILABLE INFORMATION
The Company has filed with the Commission a registration statement on Form S-3 (the