Rubinstein's concerns were, however, brought into focus by a sharp market decline on September 11 and 12, 1986. On September 11, the Dow Jones industrial average fell 4.6 percent, its largest one-day fall for nearly 25 years (SEC 1987, p. 1). The Securities and Exchange Commission (SEC) investigated, and "concluded that the magnitude of the September decline was a result of changes in investors' perception of fundamental economic conditions, rather than artificial forces arising from index-related trading strategies."

Donald MacKenzie, An Engine, Not a Camera, loc. 814