In recent years, index funds, a type of passively managed mutual fund, have soared among investors in popularity. These funds track larger market indices like the Nifty 50 and S&P BSE Sensex, or small indices like the Nifty midcap 50, and can be cheaper for investors because of less management expenses as a fund manager's service is minimal when tracking an index. However, despite their apparent advantages, there are several downsides investors should consider before diving in.