A number of studies have identifed patterns of positive correlation of returns, or comovement, among different traded securities. We distinguish three views of such comovement. The traditional 'fundamentals' view explains the comovement of securities through positive correlations in the rational...

This paper examines the economic environments in which past U.S. stock market booms occurred as a first step toward understanding how asset price booms come about and whether monetary policy should be used to defuse booms. We identify several episodes of sustained rapid rise in equity prices in...