For Leland, then, the key factor in the 1987 crash was not portfolio insurance per se but lack of awareness of the true extent of portfolio insurance's "mechanical" sales. "If everybody knows that we're uninformed traders, then people don't revise their expectations downward when the price falls. They just say things are on sale. Then they will take the other side [i.e. buy] more willingly. If everyone thinks the price is falling because somebody has information, then they won't take the other side." (Leland interview) The price fall will then be much larger.

Donald MacKenzie, An Engine, Not a Camera, loc. 871