In later years, part of mutual fund underperformance seems to have resulted from arbitrageurs exploiting the fact that the prices of mutual fund shares were fixed once a day at a set time while the prices of the underlying portfolio fluctuated continuously. A study by Eric Zitzewitz of Stanford University estimated that in 2001 "stale-price arbitrage" cost the average shareholder in an internationally diversified mutual fund 1.1 percent of the value of his/her holding (Plender 2003). That this "stale-price arbitrage" was practiced in the 1960s is, however, doubtful. The much higher transaction costs of stock trading in the 1960s would probably have made it unattractive.

Donald MacKenzie, An Engine, Not a Camera, loc. 1474