Capital World Investors (SO) discloses 63.0M shares, 5.6% stake

Rhea-AI Filing Summary

The Southern Co. ownership disclosure: Capital World Investors reports beneficial ownership of 63,022,016 shares of Common Stock, representing 5.6% of the 1,125,750,586 shares believed outstanding (positions stated in the filing as of the reporting period). The filer reports 62,527,269 shares of sole voting power and 63,022,016 shares of sole dispositive power. The filing notes certain convertible preferred instruments and exchangeable debt that were converted to common share equivalents in the disclosed total.

Insights

Institutional Ownership Analyst

Large passive stake disclosed: 5.6% of outstanding common stock.

Capital World Investors reports beneficial ownership of 63,022,016 shares, equal to 5.6% of the stated outstanding share count of 1,125,750,586. The position combines direct holdings and common‑share equivalents from convertible preferred stock and exchangeable debt.

This disclosure is a routine Section 13G filing showing an institutional stake; timing and voting/disposition powers are explicitly reported. Subsequent filings would show any material changes to this position.

Corporate Governance Specialist

Voting and dispositive powers are concentrated in sole control.

The filing lists 62,527,269 shares as sole voting power and 63,022,016 as sole dispositive power, indicating the filer exercises direct control over voting and disposition for most reported shares.

Holdings include convertible instruments converted to common equivalents; the filing quantifies those equivalents (for example, 11,846,675 Convertible Preferred Stocks representing 6,359,295 common share equivalents). No transaction intent or trading plan is stated in the excerpt.

Key Figures

Beneficial ownership: 63,022,016 shares Percent of class: 5.6% Shares believed outstanding: 1,125,750,586 shares +4 more

7 metrics

Beneficial ownership 63,022,016 shares reported beneficially owned

Percent of class 5.6% of 1,125,750,586 shares believed outstanding

Shares believed outstanding 1,125,750,586 shares stated as believed to be outstanding in the filing

Sole voting power 62,527,269 shares sole power to vote

Sole dispositive power 63,022,016 shares sole power to dispose

Convertible preferred reported 11,846,675 shares (preferred) convertible preferred stocks representing 6,359,295 common equivalents

Corporate convertible/exchangeable debt 114,000 instruments representing 1,233 common equivalents

Key Terms

Beneficially owned, Sole dispositive power, Convertible Preferred Stocks, CUSIP

4 terms

Beneficially owned financial

"CWI is deemed to be the beneficial owner of 63,022,016 shares"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

Sole dispositive power regulatory

"Sole power to dispose or to direct the disposition of: 63,022,016"

Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.

Convertible Preferred Stocks financial

"Shares reported include 11,846,675 Convertible Preferred Stocks"

CUSIP regulatory

"CUSIP Number(s): 842587107"

A CUSIP is a nine-character alphanumeric code that uniquely identifies a U.S. or Canadian financial security—such as a stock, bond, or fund share—like a Social Security number for an investment. It matters to investors because brokers, exchanges and record-keepers use the CUSIP to match trades, track ownership, settle transactions and pull accurate records, reducing errors and ensuring money and securities go to the right place.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

The Southern Co.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

842587107

(CUSIP Number)

03/31/2026

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 842587107

1

Names of Reporting Persons

Capital World Investors

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 62,527,269.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 63,022,016.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

63,022,016.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

5.6 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: The Southern Co.
(b)	Address of issuer's principal executive offices: 30 Ivan Allen Jr. Blvd. N.W., Atlanta, GA 30308
Item 2.
(a)	Name of person filing: Capital World Investors
(b)	Address or principal business office or, if none, residence: 333 SOUTH HOPE STREET, 55TH FLOOR, LOS ANGELES, CALIFORNIA 90071
(c)	Citizenship: N/A
(d)	Title of class of securities: Common Stock
(e)	CUSIP Number(s): 842587107
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: 63,022,016 ** **Capital World Investors ("CWI") is a division of Capital Research and Management Company ("CRMC"), as well as its investment management subsidiaries and affiliates Capital Bank and Trust Company, Capital International, Inc., Capital International Limited, Capital International Sarl, Capital International K.K., Capital Group Private Client Services, Inc., and Capital Group Investment Management Private Limited (together with CRMC, the "investment management entities"). CWI's divisions of each of the investment management entities collectively provide investment management services under the name "Capital World Investors." CWI is deemed to be the beneficial owner of 63,022,016 shares or 5.6% of the 1,125,750,586 shares believed to be outstanding. Shares reported include 11,846,675 Convertible Preferred Stocks, which represent 6,359,295 Common Stock. Shares reported include 114,000 Corporate Convertible/ Exchangeable Debts, which represent 1,233 Common Stock.
(b)	Percent of class: 5.6 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 62,527,269
	(ii) Shared power to vote or to direct the vote: 0
	(iii) Sole power to dispose or to direct the disposition of: 63,022,016
	(iv) Shared power to dispose or to direct the disposition of: 0
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Capital World Investors

Signature:	Jae Won Chung
Name/Title:	Senior Vice President and Associate General Counsel, Capital Research and Management Company
Date:	05/13/2026

FAQ

What stake does Capital World Investors hold in The Southern Co. (SO)?

Capital World Investors reports beneficial ownership of 63,022,016 shares, representing 5.6% of the company’s 1,125,750,586 shares believed outstanding. The total includes common‑share equivalents from convertible preferred stock and exchangeable debt.

How many votes does Capital World Investors control in SO?

The filing states Capital World Investors has 62,527,269 shares of sole voting power. The report also shows 0 shared voting power, indicating primary voting control is held solely by the filer for the cited shares.

Do the reported holdings include convertible securities for SO?

Yes. The filing includes 11,846,675 Convertible Preferred Stocks representing 6,359,295 common share equivalents, and 114,000 corporate convertible/exchangeable debts representing 1,233 common equivalents included in the total.

When was this Schedule 13G filed and signed?

The signature block shows the filing was signed on 05/13/2026 by Jae Won Chung, Senior Vice President and Associate General Counsel of Capital Research and Management Company, representing Capital World Investors.

Does this Schedule 13G indicate active trading or an intent to change control?

The filing discloses beneficial ownership and voting/dispositive powers; it does not state any trading activity, acquisition intent, or plans to change control within the provided excerpt.