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.

FirstEnergy Corp., through its subsidiaries, generates, transmits, and distributes electricity in the United States. It operates through Regulated Distribution and Regulated Transmission segments. The company owns and operates coal-fired, nuclear, hydroelectric, wind, and solar power generating facilities. It operates 24,080 circuit miles of overhead and underground transmission lines; and electric distribution systems, including 274,518 miles of overhead pole line and underground conduit carrying primary, secondary, and street lighting circuits. The company serves approximately 6 million customers in Ohio, Pennsylvania, West Virginia, Maryland, New Jersey, and New York. FirstEnergy Corp. was incorporated in 1996 and is headquartered in Akron, Ohio.

NRG Energy, Inc., together with its subsidiaries, operates as an energy and home services company in the United States and Canada. It operates through Texas; East; West/Services/Other; Vivint Smart Home; and Corporate Activities segments. The company produces and sells electricity generated using coal, oil, solar, and battery storage; natural gas; and a cloud-based home platform, including hardware, software, sales, installation, customer service, technical support, and professional monitoring solutions. It offers retail electricity and energy management, line and surge protection products, HVAC installation, repair and maintenance, home protection products, carbon offsets, back-up power stations, portable power, portable solar, and portable lighting; retail services comprising demand response, commodity sales, energy efficiency, and energy management solutions; and system power, distributed generation, renewable and low-carbon products, carbon management and specialty services, backup generation, storage and distributed solar, and energy advisory services. In addition, the company trades in power, natural gas, and related commodities; environmental products; weather products; and financial products, including forwards, futures, options, and swaps. It offers its products and services under the NRG, Reliant, Direct Energy, Green Mountain Energy, and Vivint. It serves residential, commercial, government, industrial, and wholesale customers. NRG Energy, Inc. was founded in 1989 and is headquartered in Houston, Texas.

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.

ONE Gas, Inc., together with its subsidiaries, operates as a regulated natural gas distribution company in the United States. The company provides natural gas distribution services to approximately 2.3 million customers in Oklahoma, Kansas, and Texas. It serves residential, commercial, and transportation customers. The company was founded in 1906 and is headquartered in Tulsa, Oklahoma.

Black Hills Corporation, through its subsidiaries, operates as an electric and natural gas utility company in the United States. The company operates in two segments: Electric Utilities and Gas Utilities. The Electric Utilities segment generates, transmits, and distributes electricity to approximately 222,000 electric utility customers in Colorado, Montana, South Dakota, and Wyoming; and owns and operates 1,394 megawatts of generation capacity and 9,106 miles of electric transmission and distribution lines. The Gas Utilities segment distributes natural gas to approximately 1,116,000 natural gas utility customers in Arkansas, Colorado, Iowa, Kansas, Nebraska, and Wyoming; owns and operates 4,663 miles of intrastate gas transmission pipelines; 42,514 miles of gas distribution mains and service lines; seven natural gas storage sites; and approximately 50,000 horsepower of compression and 516 miles of gathering lines. It also constructs and maintains customer owned gas infrastructure facilities for gas transportation customers; and provides appliance repair services to residential utility customers, as well as electrical system construction services to large industrial customers. In addition, the company produces electric power through wind, natural gas, and coal-fired generating plants; and coal at its coal mine located near Gillette, Wyoming. Black Hills Corporation was incorporated in 1941 and is headquartered in Rapid City, South Dakota.

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.