Heterogeneous Beliefs, Monetary Policy, and Stock Price Volatility

Abstract

This paper investigates how the stance of monetary policy affects stock price volatilities in an economy where two types of households with subjective and objective beliefs about expected capital gains from stock prices exist. I assume that investors construct subjective beliefs about expected capital gains by Bayesian learning from observed growth rates of stock prices. In a model with only homogenous subjective beliefs, the effect of the interest rate on stock prices tends to be unrealistically strong. In contrast, assuming heterogeneity by including investors with both subjective and objective beliefs improves the t of theoretical moments to the data and especially helps to explain stock price volatility under interest rate shocks with conventional sizes. This quantitative improvement in stock price reactions to interest rate shocks allows me to conduct realistic analysis about how the stance of monetary policy affects stock price volatilities. Strong inertia of monetary policy rule does not necessarily reduce asset price volatilities. This depends on what kind of shock the economy is experiencing. When the monetary policy is persistent, stock price volatilities magnify under an unexpected monetary policy shock.