Who owns American Transmission Company LLC

American Transmission Company LLC - Profile

American Transmission Company owns, maintains and operates high voltage electric transmission systems in Wisconsin, Michigan, Illinois and Minnesota. Formed in 2001 under Wisconsin legislation that separated transmission from the state's vertically integrated utilities, it was the first multi state transmission only utility in the United States and carries no generation or retail customers of its own: it moves power from generators to the local utilities that distribute it, serving more than five million electricity consumers. The system runs at voltages from 69 kV to 345 kV and covered about 10,081 miles of line and 582 substations as of 2020, and the company employs over 700 people from a base at Waukesha, Wisconsin. Rates and terms of service are set by the Federal Energy Regulatory Commission, state commissions handle routing and siting, and MISO holds operational control of the system as ATC is a transmission owning member.

The disclosed stakes

One row per position. Where a holder reports the same company in two share classes, both rows are shown rather than summed, because the class is part of a position's identity.

Where each figure comes from

A private stake has no ownership form behind it, so the source is always the holder's own filing or disclosure. Anything modelled says so, with the arithmetic.

• WEC Energy Group, Inc., as of 30 Jun 2026. Q2 2026 10-Q Note 19, Investment in Transmission Affiliates: 'At June 30, 2026 and December 31, 2025, our equity investment in ATC was $2,398.1 million and $2,256.9 million, respectively, which approximates our maximum exposure to loss as a result of our involvement with ATC.' ATC is a FERC-regulated, for-profit, transmission-only LLC. Despite the approximate 60% ownership interest, WEC has determined ATC is a VIE for which WEC is not the primary beneficiary (limited voting rights mean WEC lacks power to direct the activities most significant to ATC's economic performance), so ATC is accounted for as an equity method investment rather than consolidated. ATC has no publicly traded shares; the 60% figure is an ownership interest, not a share count, so shares stays null. source
• Alliant Energy Corporation. Alliant Energy's 10-K Note 4 reports one combined equity-method line called 'ATC Holdings' covering BOTH this 16% direct interest in ATC AND the 20% interest in ATC Holdco LLC (below) at a single carrying value: $463 million at 31 Dec 2025, $415 million at 31 Dec 2024. The Q2 2026 10-Q balance sheet updates the same combined 'ATC Holdings' line to $501 million at 30 Jun 2026, confirming the position is still held, but does not re-split it between ATC and ATC Holdco. Because the balance is not disclosed per entity, value_usd is null here per the combined-balance rule; the combined figures ($501m as of 30 Jun 2026, $463m as of 31 Dec 2025) are recorded in notes and unknowns instead of being assigned to either interest. sourcesource 2