FTSE 100

The FTSE 100 Index (or just the FTSE, pronounced footsie) is a share index of the 100 most highly capitalised companies listed on the London Stock Exchange. The index began on 3 January 1984 with a base level of 1000; the highest value reached to date is 6950.6, on 30 December 1999.
FTSE 100 companies represent about 80% of the market capitalization of the whole London Stock Exchange. Even though the FTSE All-Share Index is more comprehensive, the FTSE 100 is by far the most widely used UK stock market indicator. Other related indices are the FTSE 250 Index (which lists the next largest 250 companies after the FTSE 100), the FTSE 350 Index (which is the aggregation of the FTSE 100 and 250), FTSE SmallCap Index and FTSE Fledgling. The FTSE All-Share aggregates the FTSE 100, FTSE 250 and FTSE SmallCap.