As I talk about index funds to buy, investors need to understand the difference between active and passive investing. Active investing involves using the top-down or bottom-up approach to finding quality stocks. Passive investing is to invest in the index. Why does it make sense to invest in the index? John Bogle, founder and retired chairman and CEO of The Vanguard Group, has the answer. Bogle has advocated index investing and points to a study that “showed that 35% of managers beat the market in any single year.