Natural Selection and Market Efficiency in a Futures Market with Random Shocks

Even when participants know very little about their environment, the market itself, by serving as a selection process of information, promotes an efficient aggregate outcome. To emphasize the role of the market and the importance of natural selection rather than the strategic actions of participants, an evolutionary model of a commodity futures market is presented, in which there is a continual inflow of unsophisticated traders with predetermined distributions of prediction errors with respect to the fundamental value of the spot price. The market acts as a selection process by constantly shifting wealth from traders with less accurate information to those with more accurate information. Consequently, with probability 1, if the volatility of the underlying spot market is sufficiently small, the proportion of time that the futures price is sufficiently close to the fundamental value converges to one. Furthermore, the width of the interval containing the fundamental value, where the futures price eventually lies, increases as the volatility of the underlying spot market increases. © 2001 John Wiley & Sons, Inc. Jrl Fut Mark 21:489–516, 2001