Duke Energy Corporation, together with its subsidiaries, operates as an energy company in the United States. It operates through two segments: Electric Utilities and Infrastructure (EU&I), and Gas Utilities and Infrastructure (GU&I). The EU&I segment generates, transmits, distributes, and sells electricity in the Carolinas, Florida, and the Midwest. It generates electricity through coal, hydroelectric, natural gas, oil, solar and wind sources, renewables, and nuclear fuel. This segment also engages in the wholesale of electricity to municipalities, electric cooperative utilities, and load-serving entities. The GU&I segment distributes natural gas to residential, commercial, industrial, and power generation natural gas customers; and invests in pipeline transmission projects, renewable natural gas projects, and natural gas storage facilities. The company was formerly known as Duke Energy Holding Corp. and changed its name to Duke Energy Corporation in April 2006. Duke Energy Corporation was founded in 1904 and is headquartered in Charlotte, North Carolina.

American Electric Power Company, Inc., an electric public utility holding company, engages in the generation, transmission, and distribution of electricity for sale to retail and wholesale customers in the United States. It operates through Vertically Integrated Utilities, Transmission and Distribution Utilities, AEP Transmission Holdco, and Generation & Marketing segments. The company generates electricity using coal and lignite, natural gas, renewable, nuclear, hydro, solar, wind, and other energy sources. It also supplies and markets electric power at wholesale to other electric utility companies, rural electric cooperatives, municipalities, and other market participants. American Electric Power Company, Inc. was incorporated in 1906 and is headquartered in Columbus, Ohio.

Entergy Corporation, together with its subsidiaries, engages in the production and retail distribution of electricity in the United States. It generates, transmits, distributes, and sells electric power in portions of Arkansas, Louisiana, Mississippi, and Texas, including the City of New Orleans; and distributes natural gas. It also engages in the ownership of interests in non-nuclear power plants that sell electric power to wholesale customers, as well as provides decommissioning services to other nuclear power plant owners. It generates electricity through gas, nuclear, coal, hydro, and solar power sources. The company sells energy to retail power providers, utilities, electric power co-operatives, power trading organizations, and other power generation companies. The company's power plants have approximately 24,000 megawatts of electric generating capacity. It delivers electricity to 3 million utility customers in Arkansas, Louisiana, Mississippi, and Texas. Entergy Corporation was founded in 1913 and is headquartered in New Orleans, Louisiana.

CenterPoint Energy, Inc. operates as a public utility holding company in the United States. The company operates through two segments, Electric and Natural Gas. The Electric segment includes electric transmission and distribution services to electric customers and electric generation assets, as well as optimizes assets in the wholesale power market. The Natural Gas segment engages in the intrastate natural gas sales, and natural gas transportation and distribution for residential, commercial, industrial and institutional customers in Indiana, Louisiana, Minnesota, Mississippi, Ohio, and Texas; permanent pipeline connections through interconnects with various interstate and intrastate pipeline companies; and provides maintenance and repair services of home appliances to customers in Minnesota and home repair protection plans to natural gas customers in Indiana, Mississippi, Ohio, and Texas through a third party. It serves approximately 2,534,730 metered customers; owned 348 substations with transformer capacity of 79,719 megavolt amperes; and owned and operated 217 miles of intrastate pipeline in Louisiana and Texas. The company was founded in 1866 and is headquartered in Houston, Texas.

Alliant Energy Corporation operates as a utility holding company that provides regulated electricity and natural gas services in the United States. It operates in three segments: Utility Electric Operations, Utility Gas Operations, and Utility Other. The company, through its subsidiary, Interstate Power and Light Company (IPL), primarily generates and distributes electricity, and distributes and transports natural gas to retail customers in Iowa; sells electricity to wholesale customers in Minnesota, Illinois, and Iowa; and generates and distributes steam in Cedar Rapids, Iowa. Alliant Energy Corporation, through its other subsidiary, Wisconsin Power and Light Company (WPL), generates and distributes electricity, and distributes and transports natural gas to retail customers in Wisconsin; and sells electricity to wholesale customers in Wisconsin. It serves retail customers in the farming, agriculture, industrial manufacturing, chemical, packaging, and food industries, as well as wholesale customers comprising municipalities and rural electric cooperatives. In addition, the company owns and operates a short-line rail freight service in Iowa; a Mississippi River barge, rail, and truck freight terminal in Illinois; freight brokerage services; wind turbine blade recycling services; and a rail-served warehouse in Iowa. Further, it holds interests in a natural gas-fired electric generating unit near Sheboygan Falls, Wisconsin; and a wind farm located in Oklahoma. The company was formerly known as Interstate Energy Corp. and changed its name to Alliant Energy Corporation in May 1999. Alliant Energy Corporation was incorporated in 1981 and is headquartered in Madison, Wisconsin.

Evergy, Inc., together with its subsidiaries, engages in the generation, transmission, distribution, and sale of electricity in the United States. The company generates electricity through coal, landfill gas, uranium, and natural gas and oil sources, as well as solar, wind, other renewable sources. It serves residences, commercial firms, industrials, municipalities, and other electric utilities. The company was incorporated in 2017 and is headquartered in Kansas City, Missouri.

The AES Corporation, together with its subsidiaries, operates as a diversified power generation and utility company in the United States and internationally. The company owns and/or operates power plants to generate and sell power to customers, such as utilities, industrial users, and other intermediaries; owns and/or operates utilities to generate or purchase, distribute, transmit, and sell electricity to end-user customers in the residential, commercial, industrial, and governmental sectors; and generates and sells electricity on the wholesale market. It uses various fuels and technologies to generate electricity, such as coal, gas, hydro, wind, solar, and biomass, as well as renewables comprising energy storage and landfill gas. The company owns and/or operates a generation portfolio of approximately 34,596 megawatts and distributes power to 2.6 million customers. The company was formerly known as Applied Energy Services, Inc. and changed its name to The AES Corporation in April 2000. The AES Corporation was incorporated in 1981 and is headquartered in Arlington, Virginia.

MGE Energy, Inc., through its subsidiaries, operates as a public utility holding company primarily in the United States. It operates through Regulated Electric Utility Operations; Regulated Gas Utility Operations; Nonregulated Energy Operations; Transmission Investments; and All Other segments. The company generates, purchases, and distributes electricity and natural gas in Wisconsin and Iowa; owns and leases electric generating capacity; and plans, constructs, operates, maintains, and expands transmission facilities to provide transmission power services. It generates electricity from coal-fired, gas-fired, and renewable energy sources. As of December 31, 2023, the company owned and operated 835 miles of overhead electric distribution lines; 1,330 miles of underground electric distribution cables; 49 substations with an installed capacity of 1.2 million kVA; and gas facilities, including 3,066 miles of distribution mains, as well as supplied electric service to approximately 163,000 customers. MGE Energy, Inc. founded in 2001 and is headquartered in Madison, Wisconsin.