The Financial Times Stock Exchange 100 Index, also called the FTSE 100 Index, FTSE 100, FTSE, or, informally, the "Footsie", is a stock market index of 100 of the most highly capitalised blue chip companies listed on the London Stock Exchange. The index consists of 32 sectors, four of which have a market cap exceeding £200 billion as at 3 May 2024. These are pharmaceuticals, oil & gas, metals and mining and banking services, which together account for approximately 47% of the index's market cap. At the same date there were four companies with a market cap exceeding £100 billion: Shell, AstraZeneca, HSBC and Unilever, which together account for approximately 28% of the market cap. Each calendar quarter, the FTSE's constituents are reviewed and some companies will either exit or enter the index, resulting in irregular trading volume and price changes as market participants rebalance their portfolios. Wikipedia