The Southern Company

The full register, from 13F filings

The Register tab above is hand research: a dozen holders, each traced to the filing it came from. This asks the same question of the whole market for the quarter ended 31-mar-2026, where 2,325 managers reported a position. Broad where the research is deep, and shallow in the ways a 13F always is.

Built from 13F filings, which report US listed, long, US custodied positions only. A register from this source is a floor rather than a level: a holder's true position can be far larger, as BlackRock's ASML stake shows at 1.28m shares in a 13F against 26.3m in its 13G/A. Holdings held through derivatives, outside US custody, or below a manager's reporting obligation do not appear. Where a holder is marked as a family, its total sums several separate filing entities and describes something no single filing describes; the constituent entities and their share counts are listed so the total can be checked. That roll-up can legitimately exceed the family's own Schedule 13G, because a 13G is filed by one legal entity: Vanguard reports Alphabet through ten advisory entities, and The Vanguard Group Inc itself reported zero after its January 2026 disaggregation.

What a reader needs to know to read these numbers

• Vogtle nuclear Units 1-4, Plant Hatch, Plant Scherer, Plant Miller, Rocky Mountain (pumped storage), and the Alabama/Mississippi Power Greene County plant are jointly owned facilities where OTHER parties (Oglethorpe Power, MEAG Power, the City of Dalton, PowerSouth Energy Cooperative, and formerly Florida Power & Light) hold undivided interests in Georgia Power's, Alabama Power's, and Mississippi Power's own plants. These are other parties' interests in Southern Company system assets, not Southern Company holdings in others, and are deliberately excluded from the holdings array per the brief. Source: FY2025 10-K, 'Joint Ownership Agreements' note, https://www.sec.gov/Archives/edgar/data/92122/000009212226000006/so-20251231.htm.
• Dalton Pipeline (a Georgia natural gas pipeline facility) is excluded from holdings for a related but distinct reason. Southern Company Gas holds a direct 50% undivided ownership interest in the physical pipeline, jointly with The Williams Companies, Inc., proportionately consolidated on Southern Company Gas' own balance sheet ($273 million plant in service, $36 million accumulated depreciation, $1 million CWIP at 31 December 2025, per the same Joint Ownership Agreements note). This is Southern's own direct fractional ownership of a physical asset, not an equity-method stake in a separate company it does not control, so it is not recorded as a holding, the same logic that excludes Vogtle from the other direction.
• SEGCO (Southern Electric Generating Company) is owned 50% by Alabama Power and 50% by Georgia Power, both wholly owned Southern Company subsidiaries. It sits entirely within the Southern Company system and is not a third-party holding.
• Southern Power's renewable generation portfolio (SP Solar, SP Wind, and various tax-equity and non-tax-equity partnerships with ownership interests from 51% to 100%) is consolidated: Southern Power is the controlling partner in every case, and the noncontrolling interests belong to outside tax-equity and equity partners who hold stakes IN Southern Power's projects. Per the brief, these noncontrolling interests are excluded from holdings; they are the other-direction equivalent of the Vogtle situation. Southern Power sold its remaining equity-method (minority, non-controlling) investments in wind projects during 2023 for $50 million in proceeds and holds no equity-method investments of its own as of the FY2025 10-K or the Q2 FY2026 10-Q.
• Nuclear decommissioning trust funds held by Alabama Power and Georgia Power (purchases of $1,702 million and sales of $1,685 million in 2025, per the FY2025 10-K cash flow statement) are excluded from holdings: they are restricted funds held for a regulatory decommissioning purpose, not strategic equity stakes.
• Southern Company Gas' equity-method investment table separates SNG from an unnamed 'Other' balance of $34 million at both 31 December 2025 and 31 December 2024. The 10-K and Q2 FY2026 10-Q do not name the investee(s) inside 'Other' anywhere that was found, so no holding is recorded for it; the $34 million combined figure is noted here rather than attributed to a specific entity.
• Southern Holdings (Southern Company Holdings, Inc., a wholly owned intermediate holding subsidiary) reports equity-method investments totaling $156 million at 30 June 2026 and $124 million at 31 December 2025, 'primarily related to investments in venture capital funds focused on energy and utility investments' (Q2 FY2026 10-Q, Note E). No individual fund is named and the balance is not split, so per the brief's rule on combined balances, no individual holding is recorded; net earnings from these investments were $45 million (Q2 2026) and $48 million (H1 2026).
• Vanguard disagreement/gap, recorded rather than resolved. The register uses Vanguard's own Form 13F-HR for the quarter ended 31 December 2025 (108,057,413 shares), its most recent 13F-HR on file; Vanguard filed Form 13F-NT (notice, no holdings) for the quarters ended 31 March and 30 June 2026 under CIK 0000102909, so no fresher Vanguard 13F figure is available. Separately, Southern Company's 2026 proxy states that Vanguard reported to the Company on 27 March 2026 that, due to an internal realignment, it no longer has or is deemed to have beneficial ownership of Southern common stock, and that formerly affiliated subsidiaries/business divisions will report beneficial ownership separately going forward. That disclosure concerns Vanguard's Schedule 13G beneficial-ownership reporting, a different regime from the Form 13F-HR institutional-manager reporting used here; whether or how it affects Vanguard's 13F position is not established by any filing checked in this task.
• The register mixes two denominators and two dates, deliberately, rather than mixing the underlying share counts. The BlackRock through Morgan Stanley institutional rows (6 of 7) use 1,150,362,966 shares outstanding as of 30 June 2026 (Q2 FY2026 10-Q cover), matching each manager's own 13F-HR for that quarter. The Vanguard row uses 1,119,391,291 shares outstanding as of 31 January 2026 (FY2025 10-K cover), the closest official share count to Vanguard's 31 December 2025 13F-HR date. The 6 insider rows use the same 1,119,391,291-share, 31 January 2026 count, which is also the denominator the 2026 DEF 14A itself states and uses for its own 5%-holder 'Percentage of Class' column, even though the insider ownership table itself is dated 13 February 2026. Do not compare an institutional row's percentage against an insider row's percentage as if the underlying share counts were identical.
• Individual insider percentages are computed here, not copied from the proxy: the DEF 14A states only that the group as a whole owns less than 1% and gives no individual percentages. Each pct_of_company value in the insider rows is the reported share count divided by the proxy's own 1,119,391,291-share denominator, arithmetic on two filed numbers, not an estimate.
• Southern Company's 2026 proxy separately discloses, from Schedule 13G/A filings, BlackRock at 77,730,437 shares (6.9%, 13G/A filed 26 January 2024) and State Street at 63,785,573 shares (5.7%, 13G/A filed 29 January 2024) as of their respective 13G record dates. Both are materially older and lower than the 30 June 2026 Form 13F-HR figures used in the register (92,990,716 and 64,809,708 shares respectively); recorded here for cross-check, not used as the register figure, consistent with the brief's preference for each manager's own 13F.
• Southern Company has a single class of common stock, one vote per share, and no founder or dual-class control structure. Per the 2026 proxy (ownership table dated 13 February 2026), all 26 current directors and executive officers as a group beneficially own 1,847,604 shares (0.165%), well under 1%, of the 1,119,391,291 shares then outstanding.
• Market capitalization of $106,753,683,245 is the figure published on stockanalysis.com as of 14 August 2026 (4:00 PM ET); it was not independently re-derived from shares outstanding and a separate share price in this research.