As of 2015, the top index funds include Vanguard index fund, Charles Schwab index funds and ishares exchange traded index funds, according to About.com. Index funds own stocks they track so that investors don't have to control funds.
Vanguard centers on low-cost investments, explains About.com. As of 2015, Vanguard offers investors over 100 different mutual funds to choose from.
Charles Schwab index funds have a fund expense ratio of less than 0.9, which is below the industry's level. Additionally, Charles Schwab charges no transaction fees, as noted by About.com.
ishares offers exchange traded funds, which are similar to mutual funds but are traded throughout the day in the same manner as stocks, states About.com.