The notion that business cycles are driven by demand shocks is subtle. I first review some of the conceptual and empirical challenges faced when trying to accommodate this notion in micro-founded, general-equilibrium models. I next review my own research, which sheds new light on the observed...

This paper shows how rational investors can have different degrees of optimism regarding the prospects of the economy, even if they share exactly the same information regarding all economic fundamentals. The key is that heterogeneity in expectations regarding endogenous outcomes can emerge as a...

This paper augments the neoclassical growth model to study the macroeconomic effects of idiosyncratic investment risk. The general equilibrium is solved in closed form under standard assumptions for preferences and technologies. A simple condition is identified for incomplete markets to result...