Portfolio Insurance and Other Investor Fashions as Factors in the 1987 Stock Market Crash

Robert Shiller asserts that investors already had a "crash mentality" before October 19, associated with views about borrowing, government debt, and the perception that portfolio insurance was affecting markets. The proximate cause of the crash, he believes, was a response to price declines: the assumption by investors that the crash had arrived. In Shiller's opinion, the crash was as much a sociological or psychological phenomenon as an economic one.