Academic research has amply demonstrated that actively managed funds as a group badly trail their benchmark indices. So, why are actively managed funds so popular with trillions of dollars invested in them?

My guess is that the vast majority of the investing public just buys a fund in the hottest sector sporting blockbuster recent performance numbers. They don’t pay attention to the costs but are sold on the recent performance numbers. The thinking goes something like: “Wow. This fund returned 89% last year. I got to get in on that!”

A fascinating article on Knowledge@Wharton describes a study in which test subjects (MBA students and undergraduates) were asked to choose between different index funds that tracked the S&P 500 but had different fee structures based on the information given to them. The results show that even if the fee structure is clearly explained, over 80% of the subjects do not invest in the fund with the lowest fees. The investors who were given a detailed prospectus or a “returns sheet” that highlighted the fund’s returns since inception fared even worse. The depressing conclusion is that investors underestimate the impact of fees even when it is clearly spelled out.