FTSE 100 Index

An index of the share prices of the 100 largest companies (by market capitalisation) in the UK which is updated throughout the trading day in real time. The index was started in 1984 with a base of 1,000. See also FTSE Actuaries All-Share Index.

Stock Exchange indices are designed to give investors an idea of the general movement of the stock markets and its overall value. By comparing the performance of their own portfolios with the performance of one of the Stock Exchange indices, investors can see how well they have done from a comparative point of view. In particular they can see whether they would have been better off putting their money in an index tracker fund.

The main sub-indices of the FTSE Actuaries All-Share are:

• FTSE 100: the 100 largest quoted companies in the UK
• FTSE MID 250: the next largest 250 companies
• FTSE A 350: combination of FTSE 100 and FTSE 250
• FTSE Smallcap: the remaining companies listed in the FTSE Actuaries All-Share index
• FTSE A Fledgling: companies too small to qualify for the FTSE All-Share
• FTSE AIM: companies trading on the Alternative Investment Market
• TechMark: index of companies primarily involved in technology

The companies in the FTSE Actuaries All-Share Index are also divided into 7 main industrial groupings:

• Mineral extraction
• General industrial
• Consumer goods
• Services
• Utilities
• Financials
• Investment trusts

These categories are divided further into 37 subcategories.