The AES Corporation is a Fortune 500 company that generates and distributes electrical power.[3] AES is headquartered in Arlington, Virginia, and is one of the world’s leading power companies, generating and distributing electric power in 15 countries[4] and employing 10,500 people worldwide.

American Electric Power (AEP) is a major investor-owned electric utility in the United States of America, delivering electricity to more than five million customers in 11 states. AEP ranks among the nation’s largest generators of electricity, owning nearly 38,000 megawatts of generating capacity in the U.S. AEP also owns the nation’s largest electricity transmission system, a nearly 39,000-mile (63,000 km) network that includes 765 kilovolt ultra-high voltage transmission lines, more than all other U.S. transmission systems combined.[4] AEP’s transmission system directly or indirectly serves about 10 percent of the electricity demand in the Eastern Interconnection, the interconnected transmission system that covers 38 eastern and central U.S. states and eastern Canada, and approximately 11 percent of the electricity demand in the Electric Reliability Council of Texas, the transmission system that covers much of Texas. AEP’s utility units operate as AEP Ohio, AEP Texas, Appalachian Power (in Virginia, West Virginia, and Tennessee), Indiana Michigan Power, Kentucky Power, Public Service Company of Oklahoma, and Southwestern Electric Power Company (in Arkansas, Louisiana and east Texas). AEP’s headquarters are in Columbus, Ohio. American Electric Power was the first utility to utilize 345 kV transmission lines which took place in 1953. The company ranked 185th on the 2018 Fortune 500 of the largest United States corporations by revenue.

CenterPoint Energy is a Fortune 500 electric and natural gas utility serving several markets in the U.S. states of Arkansas, Louisiana, Minnesota, Mississippi, Oklahoma, and Texas. It was formerly known as Reliant Energy (from which it is now separated), NorAm Energy, Houston Industries, and HL&P. The company is headquartered in the CenterPoint Energy Tower at 1111 Louisiana Street in Downtown Houston.[2][3] Some of its notable subscribers include Retail Electric Providers (REPs), such as NRG Energy, Champion Energy, Eligo Energy, Dynowatt, Ambit Energy, Texas Power, Bounce Energy, MXenergy, Direct Energy, Stream Energy, First Texas Energy Corporation, Gexa Energy, Cirro Energy, and Kona Energy.

Consolidated Edison, Inc., commonly known as Con Edison or Con Ed, is one of the largest investor-owned energy companies in the United States, with approximately $12 billion in annual revenues as of 2017, and over $48 billion in assets.[2] The company provides a wide range of energy-related products and services to its customers through its subsidiaries: Consolidated Edison Company of New York, Inc., (CECONY), a regulated utility providing electric and gas service in New York City and Westchester County, New York, and steam service in the borough of Manhattan; Orange and Rockland Utilities, Inc., a regulated utility serving customers in a 1,300-square-mile (3,400 km2) area in southeastern New York and northern New Jersey; Con Edison Solutions, an energy services company; Con Edison Energy, a wholesale energy services company; Con Edison Development, a company that owns and operates renewable and energy infrastructure projects, and, Con Edison Transmission, Inc., which invests in electric and natural gas transmission projects. In 2015, electric revenues accounted for 70.35% of consolidated sales (70.55% in 2014); gas revenues 13.61% (14.96% in 2014); steam revenues 5.01% (4.86% in 2014); and non-utility revenues of 11.02% (9.63 in 2014%).[3] Though the company provides an indispensable service to New York residents, a number of major incidents and service problems have negatively impacted its reputation with the public.

DTE Energy (formerly Detroit Edison until 1996, now DTE Electric Company) is a Detroit-based diversified energy company involved in the development and management of energy-related businesses and services nationwide. Its operating units include an electric utility serving 2.2 million customers in Southeastern Michigan and a natural gas utility serving 1.3 million customers in Michigan. The DTE Energy portfolio includes non-utility energy businesses focused on power and industrial projects, natural gas pipelines, gathering and storage, and energy marketing and trading. The name DTE is taken from the company’s stock ticker symbol.

Edison International is a public utility holding company based in Rosemead, California. Its subsidiaries include Southern California Edison, and unregulated non-utility business assets Edison Energy. Edison’s roots trace back to Holt & Knupps, a company founded in 1886 as a provider of street lights in Visalia, California.

Eversource Energy (formerly known as Northeast Utilities) is a publicly traded, Fortune 500 energy company headquartered in Hartford, Connecticut and Boston, Massachusetts, with several regulated subsidiaries offering retail electricity, natural gas service and water service to approximately 4 million [6] customers in Connecticut, Massachusetts and New Hampshire. Following its 2012 merger with Boston-based NSTAR, Northeast Utilities had more than 4,270 circuit miles of electric transmission lines, 72,000 pole miles of distribution lines, and 6,459 miles of natural gas pipeline in New England.[7] On February 2, 2015, the company and all its subsidiaries rebranded themselves as “Eversource Energy”.[8] The stock symbol changed on February 19, 2015 from “NU” to “ES”.

FirstEnergy Corp is an electric utility headquartered in Akron, Ohio. Its subsidiaries and affiliates are involved in the distribution, transmission, and generation of electricity, as well as energy management and other energy-related services. Its ten electric utility operating companies comprise one of the United States’ largest investor-owned utilities, based on serving 6 million customers within a 65,000-square-mile (170,000 km2) area of Ohio, Pennsylvania, West Virginia, Virginia, Maryland, New Jersey and New York.[4] Its generation subsidiaries control more than 16,000 megawatts of capacity, and its distribution lines span over 194,000 miles. In 2018, FirstEnergy ranked 219 on the Fortune 500 list of the largest public corporations in the United States by revenue.[5] In November 2016, FirstEnergy made the decision to exit the competitive power business, and become a fully regulated company.

NextEra Energy, Inc. is a Fortune 200 energy company with about 45,900 megawatts of generating capacity,[3] revenues of over $17 billion in 2017, and about 14,000 employees[1] throughout the United States and Canada. It is the largest electric utility holding company by market capitalization. Its subsidiaries include Florida Power & Light, NextEra Energy Resources, NextEra Energy Partners, Gulf Power Company, and NextEra Energy Services. FPL, the largest of the subsidiaries, delivers rate-regulated electricity to approximately 5 million customer accounts, or an estimated 10 million people, across nearly half of Florida and is the third largest electric utility company in the United States.[2] NEER, together with its affiliated entities, is the world’s largest generator of renewable energy from the wind and sun.[4] In addition to wind and solar, NextEra Energy Resources owns and operates generating plants powered by natural gas, nuclear energy, and oil.[2] The company ranked 167th on the 2018 Fortune 500 of the largest United States corporations by revenue. [5] Nextera Energy is incorporated in Florida.

NRG Energy, Inc. is a large American energy company, dual-headquartered in Princeton, New Jersey[4][5] and Houston, Texas.[3][6][7] It was formerly the wholesale arm of Northern States Power Company (NSP), which became Xcel Energy, but became independent in 2000. NRG Energy is involved in energy generation and retail electricity.[8] Their portfolio includes nuclear generation, coal generation, wind generation, utility scale generation, distributed solar generation, and oil generation.[9] NRG serves 2.9 million retail customers in Texas, Connecticut, Delaware, Illinois, Maryland, Massachusetts, New Jersey, New York, Pennsylvania, Ohio, and the District of Columbia.[4] NRG Energy has acquired eleven other energy companies, both generation and retail, that include Reliant Energy,[10] XOOM Energy,[11] Green Mountain Energy,[8] Stream Energy[12] and Cirro Energy.[13] As of 2018, they generate 23,000 MW of energy from 40 power plants across the country.[10] They incorporate a range of sales channels for retail customers, including call centers, direct sales, websites, brokers, and brick-and-mortar stores. Their wholesale generation services include plant operations, commercial operations, energy services, distributed generation services, and energy, procurement, and construction (EPC) services.