OGE Energy is a holding company for Oklahoma Gas & Electric, a regulated utility with electricity generation, transmission, and distribution service for 900,000 customers in Oklahoma and western Arkansas. In December 2021, OGE divested its 25.5% stake in Enable Midstream Partners, an oil and gas services company it created in 2013 through a unit exchange merger with Energy Transfer. OGE sold its 95.4 million limited partner units of Energy Transfer throughout 2022. OGE sold its retail gas business in 1928 and no longer has any gas operations.

NiSource is one of the nation's largest natural gas distribution companies with 2.4 million customers in Kentucky, Maryland, Ohio, Pennsylvania, and Virginia. NiSource also serves 1.4 million gas and electric customers in Indiana. The regulated electric utility owns 4 gigawatts of generation capacity, including coal, natural gas, and renewable energy.

FirstEnergy is an investor-owned holding company with operations across five mid-Atlantic and Midwestern states. FirstEnergy also owns and operates one of the nation's largest electric transmission systems.

American Electric Power is one of the largest regulated utilities in the United States, providing electricity generation, transmission, and distribution to more than 5 million customers in 11 states. About 39% of AEP's capacity is coal, with the remainder from a mix of natural gas (28%), renewable energy and hydro (23%), nuclear (7%), and demand response (3%). Vertically integrated utilities, transmission and distribution, and generation and marketing support earnings.