Neglected Risks: The Psychology of Financial Crises

Abstract

We model a financial market in which investor beliefs are shaped by representativeness. Investors overreact to a series of good news, because such a series is representative of a good state. A few bad news do not change investor minds because the good state is still representative, but enough bad news leads to a radical change in beliefs and a financial crisis. The model generates debt over-issuance, “this time is different” beliefs, neglect of tail risks, under- and over-reaction to information, boom-bust cycles, and excess volatility of prices in a unified psychological model of expectations.