FTSE 100

The FTSE 100 Index (pronounced "Footsie 100") is a stock market index comprising the 100 companies with the highest free-float market capitalization listed on the London Stock Exchange (LSE). Launched on 3 January 1984 with a base value of 1,000 points, the index is maintained by FTSE Russell, a subsidiary of the London Stock Exchange Group (LSEG). The FTSE 100 is widely regarded as the principal benchmark of the United Kingdom equity market and serves as an indicator of the performance of the country's largest publicly traded companies.

The index is weighted by free-float market capitalization, with constituent companies selected based on their publicly tradable market value rather than total shares outstanding. It includes corporations from a broad range of industries, including finance, energy, mining, pharmaceuticals, consumer goods, telecommunications, and industrial manufacturing. Membership is reviewed quarterly to ensure that the index reflects changes in market capitalization and liquidity. Because many FTSE 100 constituents generate a substantial proportion of their revenues outside the United Kingdom, the index is often viewed as a measure of the performance of multinational corporations rather than solely the domestic British economy.

The FTSE 100 is extensively used as a benchmark for institutional and retail investment portfolios and underlies numerous financial products, including index funds, exchange-traded funds (ETFs), futures, and options. It is one of the world's most closely followed equity indices alongside the S&P 500, Dow Jones Industrial Average, NASDAQ-100, DAX, CAC 40, and Nikkei 225. The index plays a significant role in global financial markets by providing a widely recognized measure of the performance of large-cap companies listed in the United Kingdom.