The Financial Times Stock Exchange 100 Index, also called the FTSE 100 Index, FTSE 100, FTSE, or, informally, the "Footsie" /ˈfʊtsi/, is a share index of the 100 companies listed on the London Stock Exchange with (in principle) the highest market capitalisation. The index is maintained by the FTSE Group, a subsidiary of the London Stock Exchange Group.