New York Timesより：
Professor French’s study can also be used to show just how different the investment arena is from a so-called zero-sum game. In such a game, of course, any one individual’s gains must be matched by equal losses by other players, and vice versa. Investing would be a zero-sum game if no costs were associated with trying to beat the market. But with the costs of that effort totaling around $100 billion a year, active investing is a significantly negative-sum game. The very act of playing reduces the size of the pie that is divided among the various players.