National Grid plc (LSE: NG., NYSE: NGG) is a British multinational electricity and gas utility company headquartered in London, United Kingdom. Its principal activities are in the United Kingdom and northeastern United States. National Grid has a primary listing on the London Stock Exchange and is a constituent of the FTSE 100 Index. It had a market capitalisation of approximately £22 billion as of 23 December 2011, the 22nd-largest of any company with a primary listing on the London Stock Exchange.[3] It has a secondary listing on the New York Stock Exchange.