In the FTSE 100 index, the F stands for “Financial.”
FTSE is an acronym for Financial Times Stock Exchange, the name associated with the index’s original ownership and administration. The FTSE 100 tracks 100 of the largest companies listed on the London Stock Exchange by market capitalization, subject to the index’s eligibility rules.
The index was launched on 3 January 1984 with a base level of 1,000. It is commonly nicknamed the “Footsie” and is one of the best-known indicators of the performance of large publicly traded companies in the United Kingdom, although many constituents earn substantial revenues internationally.
The FTSE 100 is weighted by market capitalization, so larger companies have a greater influence on its movements. It should not be confused with the FTSE 250, which covers the next tier of large listed companies, or with the London Stock Exchange itself, which is the marketplace where shares are listed and traded.