Stock market overreactions to bad news in good times: a rational expectations equilibrium model

This article presents a dynamic, rational expectations equilibriummodel of asset prices where the drift of fundamentals (dividends)shifts between two unobservable states at random times. I showthat in equilibrium, investors' willingness to hedge againstchanges in their own 'uncertainty' on the true state makes stockprices overreact to bad news in good times and underreact togood news in bad times. I then show that this model is betterable than conventional models with no regime shifts to explainfeatures of stock returns, including volatility clustering,'leverage effects,' excess volatility, and time-varying expectedreturns.