American Electric Power Company, Inc.

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 1,899 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

• Direction trap, resolved per the brief. In December 2025 AEPTCo and Midwest Transmission Holdings, LLC (a subsidiary that owns all of IMTCo and OHTCo) signed an agreement with Olympus BidCo L.P., a special purpose entity controlled by Kohlberg Kravis Roberts & Co. (KKR) and the Public Sector Pension Investment Board, under which the Investor agreed to acquire a 19.9% noncontrolling equity interest in Midwest Transmission Holdings for $2.82 billion. This is the KKR/PSP consortium's stake IN an AEP transmission subsidiary, not an AEP holding in KKR or PSP, so it is deliberately excluded from the holdings array. Source: FY2025 10-K.
• Transource Energy, LLC is 86.5% owned by AEP (via AEPTHCo) and is a consolidated VIE, not an equity method investment: AEP controls and consolidates it, with the remaining 13.5% reported as a noncontrolling interest. Transource Energy is therefore excluded from holdings as a majority-owned, consolidated subsidiary, consistent with the brief's exclusion of wholly/majority owned subsidiaries. The 13.5% non-AEP interest in Transource is other parties' stake in an AEP entity, not an AEP holding.
• Midcontinent Grid Solutions, LLC, Grid Growth Ventures, LLC and Valley Link Transmission Company, LLC are each recorded using AEP's own effective 'owned by AEP' percentage as stated directly in the FY2025 10-K and/or Q2 FY2026 10-Q glossary (43.25%, 43.25% and 31.14% respectively). Each of these is a sub-tier joint venture in which the direct partner is Transource Energy, LLC (86.5% AEP-owned and consolidated) rather than AEP itself; AEP's stated percentage is already the look-through figure, so it should not be further multiplied by Transource's 86.5% ownership.
• Prairie Wind Transmission, LLC and Pioneer Transmission, LLC (Indiana) ownership percentages (25% and 50%) come from the AEPTHCo Joint Ventures summary table in the FY2025 10-K's MD&A rather than from Note 18 (Equity Method Investments in Unconsolidated Entities), which names only ETT and GWAI with dollar figures. No carrying value could be attributed to either investee individually; both sit within AEP's undifferentiated $4,402 million 'Deferred Charges and Other Noncurrent Assets' balance at 31 December 2025 ($3,873 million at 31 December 2024) alongside unrelated items, so no value_usd is recorded for either.
• Pioneer Transmission, LLC (Indiana) is the same joint venture in which Duke Energy Corporation held the other 50% interest before selling it in November 2024 (per Duke Energy's own FY2025 10-K, referenced in this research project's duke-energy.json). AEP's 50% stake is a separate, continuing holding unaffected by Duke's exit; the identity of Duke's replacement co-owner was not disclosed in AEP's FY2025 10-K and was not researched further here.
• Nuclear decommissioning trust funds are excluded from holdings by decision, per the brief: they are restricted funds held for a regulatory decommissioning purpose, not strategic equity stakes, even though the trusts hold securities. Indiana Michigan Power's (I&M's) Spent Nuclear Fuel and Decommissioning Trusts balance was $4,916 million at 31 December 2025 and $4,395 million at 31 December 2024, per the FY2025 10-K balance sheet.
• AEP's 'Competitive Contracted Renewables Portfolio' (unregulated wind and solar assets held via AEP Renewables) was fully divested via sale process initiated in 2022 and completed in 2023; the FY2025 10-K shows no remaining balance and describes only the historical loss on sale. This is a full divestiture, not the 'minority interest in the renewables portfolio' pattern flagged as a possible direction trap; no current AEP-held minority renewables stake was found within the research performed.
• AEP has a single class of common stock, $6.50 par value per share (900,000,000 shares authorized, 545,549,444 issued and 1,186,815 held in treasury as of 30 June 2026 per the Q2 FY2026 10-Q balance sheet). AEP has no dual-class structure and no founder or control block; the entire 21-person director and executive officer group beneficially owns well under 1% of outstanding shares.
• The register mixes two denominators and two dates, deliberately, rather than mixing the underlying counts. The 10 institutional 13F rows use 544,397,352 shares outstanding as of 30 July 2026 (Q2 FY2026 10-Q cover page), matching each manager's own 13F-HR share counts. The 21 insider rows use 542,930,331 shares outstanding as of 27 February 2026, the denominator AEP's 2026 DEF 14A itself states and uses for its own 5%-holder percentage column. Each row's pct_denominator states which count it uses.
• Vanguard's most recent 13F-HR on file (CIK 0000102909) covers the quarter ended 31 December 2025 (52,496,895 shares); Vanguard filed Form 13F-NT (notice, no holdings) for the quarters ended 31 March and 30 June 2026, so no fresher Vanguard 13F figure exists under that CIK. AEP's 2026 proxy separately reports Vanguard at 49,224,906 shares (9.06%) as of a Schedule 13G/A dated 13 February 2024 (data as of 29 December 2023), which is both older and materially lower than the 13F figure used here; both are recorded rather than reconciled.
• BlackRock and State Street disagreement, recorded rather than resolved. The register uses each manager's own Form 13F-HR for the quarter ended 30 June 2026 (BlackRock 51,024,057 shares; State Street 30,783,142 shares). AEP's 2026 proxy reports BlackRock at 40,248,240 shares (7.41%) as of a Schedule 13G/A filed 17 April 2025 (data as of 31 March 2025) and State Street at 28,190,434 shares (5.19%) as of a Schedule 13G/A filed 30 January 2024 (data as of 31 December 2023), both older and lower than the 30 June 2026 13F figures used here.
• Individual insider percentages in the register are computed here, not copied verbatim from the proxy: the DEF 14A does not print a per-person percentage column for the Share Ownership of Directors and Executive Officers table (only a footnote stating the 21-person group is under 1.0%). Each pct_of_company value is the proxy's own reported 'Shares' figure divided by the proxy's own 542,930,331-share denominator, simple arithmetic on two filed numbers rather than an estimate.
• Market capitalization of $68.38 billion is the figure published on the source page as of 14 August 2026, precise to the figure shown there; it was not independently re-derived from shares outstanding and a separate share price in this research. Cross-check: $68.38 billion divided by 544,397,352 shares implies a share price of roughly $125.6, a plausible order of magnitude for AEP in mid-August 2026.