Those who felt that passive investing is for sissies need to sit up and look around. In the past one year, the asset base of equity ETFs has shot up from Rs 15,066 crore as on March 31, 2016 to Rs 43,234 crore as of March 31, 2017, according to the AMFI data. An exchange traded fund (ETF) is similar to an index fund, which invests in a basket of securities, which are part of a pre-decided index, in the same proportion as that of the index. For instance, the Reliance ETF Sensex will invest in exactly the same proportion as the constituents of the S&P BSE Sensex.