Some of the world's largest utility companies, by market capitalization, are Duke Energy (U.S.), GDF Suez (France) and the National Grid Company (UK).

Headquartered in Charlotte, North Carolina, Duke Energy (DUK) is the largest electric utility in the world, with a market capitalization of approximately $55 billion. Its service area in the United States stretches from the East Coast to the Midwest and encompasses over 100,000 square miles. Its subsidiary company, Duke Energy Renewable Services (DERS), specializes in developing renewable energy sources with a primary focus on wind power. The company has a significant emerging market presence in Brazil, where it operates several hydroelectric facilities.

GDF Suez (GSZ), renamed Engie, is a multinational utility company headquartered in La Defense, Courbevoie, France, with operations in electric energy, natural gas, renewable energy, water and waste treatment. It has a market capitalization, as of 2015, of almost $50 billion. The company was created in 2008 from a merger between Gaz de France and Suez. The French government owns a 37% stake in the company. A notable acquisition in 2010 was the UK company International Power.

National Grid (NGG) is a multinational electric and gas utility company headquartered in London. Its principal operations are in the United Kingdom, but it also has a significant presence in the Northeastern United States. National Grid was formed in the 1990s during the breakup of the Central Electricity Generating Board, or CEGB, which previously was responsible for all electrical power generation and transmission in the UK. The CEGB was broken up into four companies: PowerGen; National Power; Nuclear Electric, which eventually became EDF Energy; and National Grid. Since 2000, the company has acquired several power companies in the United States, including New England Electric System, Eastern Utilities Associates, Niagara Mohawk Holdings, KeySpan and the New England Gas Co. National Grid has a market capitalization of $49 billion.