While the base date for the new index has been fixed as February 1, 1999, the base value will be 1000 points. As on March 31, 1999, BSE-500 index had a market capitalisation of Rs 4,25,779.08 crore or 82.17 per cent of the total BSE market capitalisation of that day. According to BSE officials, the changing pattern of the economy and that of the market have been considered while constructing the new index. The BSE index and S&P CNX 500 have 385 common scrips while 115 scrips are different.

The BSE index represents all the 23 major industries and 102 sub-sectors in the economy. The scrips in BSE-200 are part of BSE-500. According to BSE officials, the scrip chosen for the index should have been traded on at least 70 per cent of the trading days for the last six months and accounted for at leastfive trades on an average per day for the last six months.

Information technology has been accorded the highest weightage of 13.76 per cent in the index with 32 companies. Close on the heels is consumer non-durables with a weight of 13.55 per cent and 18 companies.