According to an analysis last year by David Brown, an assistant professor of finance at the University of Arizona's Eller College of Management, and University of Colorado professor Shaun Davis, Americans could be paying in excess of $2 billion a year more than they would if they managed their own savings with a portfolio of low-fee exchange traded funds. One reason for inflated fees, the professors say: Many fund managers stock their target-date-fund portfolios with their own actively managed products, which tend to have much higher fees.