We dissect the comovement patterns of the macroeconomic data, identify a single shock that accounts for the bulk of the business-cycle volatility in the key quantities, and use its empirical properties to appraise parsimonious models of the business cycle. Through this lens, the data appears to...

We develop a tractable method for augmenting macroeconomic models with autonomous variation in higher-order beliefs. We use this to accommodate a certain type of waves of optimism and pessimism that can be interpreted as the product of frictional coordination and, unlike the one featured in the...

We study the Ramsey policy problem in an economy in which firms face a collateral constraint. Issuing more public debt alleviates this friction by increasing the aggregate quantity of collateral. In so doing, however, the issuance of more debt also raises interest rates, which in turn increases...

We study the Ramsey policy problem in an economy in which public debt contributes to the supply of assets that private agents can use as buffer stock and collateral, or as a vehicle of liquidity. Issuing more debt eases the underlying financial friction. This raises welfare by improving the...

We show that international trade in goods is the main determinant of international equity portfolios and offers a compelling -- theoretically and empirically -- resolution of the portfolio home bias puzzle. The model implies that investors can achieve full international risk diversification if...

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...

We study whether a central bank should deviate from its objective of price stability to promote financial stability. We tackle this question within a textbook New Keynesian model augmented with capital accumulation and microfounded endogenous financial crises. We compare several interest rate...

Gold rushes are periods of economic boom, generally associated with large increases in expenditures aimed at securing claims near new found veins of gold. An interesting aspect of gold rushes is that, from a social point of view, much of the increased activity is wasteful since it contributes...