The FTSE 250 Index ( ) is a capitalisation-weighted index consisting of the 101st to the 350th largest companies listed on the London Stock Exchange. Promotions and demotions to and from this index take place quarterly in March, June, September and December. This Index is calculated in real-time and published every minute. Related indices are the FTSE 100 Index (which lists the largest 100 companies), the FTSE 350 Index (which combines the FTSE 100 and 250), the FTSE SmallCap Index and the FTSE All-Share Index (which is the aggregation of the FTSE 100 Index, FTSE 250 Index and FTSE SmallCap Index). Quite a number of companies within this index are investment trusts. As of 30 September 2008, the net market capitalisation of FTSE 250 Index was £161 billion (or 13 per cent of FTSE 100 Index).