The FTSE 250 Index is a capitalisation-weighted index consisting of the 101st to the 350th largest companies listed on the London Stock Exchange, mostly covering the mid cap sector between large and small companies. The index contains a higher proportion of companies whose primary business is conducted in the UK, compared to the FTSE 100. Due to this, the FTSE 250 tends to be more representative of the strength of the UK economy than the FTSE 100. Promotions and demotions to and from the index occur quarterly in March, June, September, and December. The index consists of 38 sectors, four of which have a market cap exceeding £25 billion as at 3 May 2024. These are collective investments, investment banking & investment services, hotels and entertainment services and residential and commercial REIT, which together account for approximately 51% of the index's market cap. Given that 25% of the index is made up of investment trusts a separate index is sometimes quoted excluding them. At the same date there were two companies with a market cap exceeding £5 billion: Carnival and Endeavour Mining, which together account for approximately 6% of the market cap. Wikipedia