The London Stock Exchange (LSE) is a stock exchange in London, England. It is the biggest stock exchange in the Europe and third largest in the world. It is the home of the FTSE 100 Index, as well as others. The Exchange was opened in 1801 by Queen Elizabeth I. There are currently 2,938 companies from over 60 countries listed on the London Stock Exchange. The total value of these companies is £3.9 trillion.