The Asymmetric Effect of the Business Cycle on the Relation between Stock Market Returns and Their Volatility

We examine the relation between US stock market returns and the US business cycle for the period 1960 - 2003 using a new methodology that allows us to estimate a time-varying equity premium. We identify two channels in the transmission mechanism. One is through the mean of stock returns via the equity risk premium, and the other is through the volatility of returns. We confirm previous findings based on simple correlation analysis that the relation is asymmetric with downturns in the business cycle having a greater negative impact on stock returns than the positive effect of upturns. We also obtain a new result, that demand and supply shocks affect stock returns differently. Our model of the relation between returns and their volatility is derived from the stochastic discount factor model of asset pricing which encompasses CAPM, consumption CAPM and Merton's (1973) inter-temporal CAPM. It is implemented using a multi-variate GARCH-in-mean model with a time-varying conditional heteroskedasticity and correlation structure