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 £31.4 billion on 4 August 2014, the 20th-largest of any company with a primary listing on the London Stock Exchange.