Firm-level return dispersion and the future volatility of aggregate stock market returns

We find a sizeable positive relation between firm return dispersion and future market-level volatility in U.S. monthly equity returns from 1927 to 1995. This intertemporal relation remains strong when controlling for return shocks in the aggregate stock market, widely-used factor-mimicking portfolios, and government bonds. In contrast, the well-known positive relation between market-return shocks and future market-level volatility largely disappears when controlling for firm return dispersion. We also document how firm return dispersion moves with the contemporaneous market return and with economic conditions. Collectively, our evidence suggests that the time variation in firm return dispersion has important marketwide implications. (C) 2002 Elsevier Science B.V. All rights reserved.