The spurt of initial public offerings (IPOs) on Dalal Street and the outperformance of indices such as the BSE mid-cap and BSE small-cap seem to have stemmed the dominance of heavy-weighted benchmark Sensex in relation to the total market capitalisation of stocks listed on the BSE in 2017. At the end of 2017, the market cap of top 30 companies accounted for only 39.8% of the total BSE market capitalisation, a sharp decline from 43.2% in 2016, data compiled from Capitaline showed. While the share of Sensex in the total market capitalisation has been on a gradual decline since 2013, the drop was sharp this year. Between 2015 and 2016, for instance, the share decline was just 1.3% against the 3.4% decline in 2017. Interestingly, the Sensex boasted of more than half the total exchange\u2019s market capitalisation in 2013 and an average of 45.7% in nine years through 2016. The sharp decline comes in a year when the Sensex yielded a return of 28%. Public listings by a few large companies in 2017 and an extraordinary performance by mid and small-cap stocks resulted in the reduction in the benchmark\u2019s overall market weight. The BSE small-cap surged 59.6% in 2017 and the BSE mid-cap rallied 48.1%. Both these indices together have a market cap of Rs 49.5 lakh crore, which is 82% of the Sensex market cap of Rs 60.4 lakh crore. The BSE small-cap and BSE-midcap account for 18.7% and 13.9% of the total exchange market cap. The aggregate market cap of 35 companies which went public last year stood at Rs 5.2 lakh crore, with HDFC Standard Life Insurance topping the list with Rs 77,566 crore. Avenue Supermarts ranked second in the market cap table with Rs 73,642 crore. In fact \u2014 the market cap of four Sensex constituents \u2014 Hero MotoCorp, Yes Bank, Tata Steel and Dr Reddy\u2019s Laboratories \u2014 was less than the market value of HDFC Standard Life Insurance at the end of 2017. At the end of last year, the combined market capitalisation of all listed companies on BSE stood at Rs 151.8 lakh crore. In absolute terms, the Sensex market capitalisation increased by 14.6 lakh crore in 2017 with Reliance Industries (RIL) and HDFC Bank contributing nearly a third of the index\u2019s market cap gain. The market cap of these two companies increased by 71% and 58%, respectively.