Return Decomposition Over the Business Cycle

To analyze the determinants of the observed variation in stock prices, Campbell and Shiller (1988) have suggested decomposing unexpected stock returns into unexpected changes in investors' beliefs about future cash flows (cash flow news) and discount rates (discount rate news). Based on a generalization of this approach to a framework with regime-switching parameters and variances, we analyze the decomposition of the conditional variance of returns on the S&P 500 index over the business cycle. The cash flow news is relatively more important than discount rate news in determining the conditional variance of returns in expansions. The conditional variances of returns and its components increase in recessions. However, the conditional variance of discount rate news increases more than that of cash flow news and, thus, the discount rate news becomes relatively more important than cash flow news in determining the conditional variance of returns in recessions. In contrast to the standard Campbell and Shiller approach with constant parameters and variances, cash flow news becomes more important than discount rate news in determining the unconditional variance of returns when we allow parameters and variances to vary over the business cycle. We show that these results are broadly consistent with the implications of a stylized asset pricing model in which the growth rates of dividends and consumption take on different values depending on the underlying state of the economy