In this paper we develop a general framework to analyze state space models with time-varying system matrices where time variation is driven by the score of the conditional likelihood. We derive a new filter that allows for the simultaneous estimation of the state vector and of the time-varying...

This paper attempts to assemble evidence for the relationship between the product and the financial market. Drawing back on work in industrial organization, we analyze the relationship between profit persistence and expected stock returns. We show that long-run profit persistence together with...