National Grid plc is a multinational electricity and gas utility company headquartered in London, England. Its principal activities are in the United Kingdom (where it owns and operates electricity and natural gas transmission networks) and in the Northeastern United States (where as well as operating transmission networks, the company is a producer and supplier of electricity and gas). National Grid has a primary listing on the London Stock Exchange, and is a constituent of the FTSE 100 Index. It has a secondary listing on the New York Stock Exchange.