Mutual funds form the bedrock of retirement savings in the United States, and, considering their rapid growth, are sure to be more critical in the future. Because the size of fees paid by investors to mutual fund advisers can strongly affect the return on investment, these fees have become a contentious issue in Congress and the courts, with many arguing that investment advisers grow rich at the expense of investors.

This ground-breaking book not only conceptualizes a new economic model of the mutual fund industry, but also uses this model to test for price competition between investment...