We study the role of heterogeneity in the transmission of foreign shocks. We build a Heterogeneous-Agent New-Keynesian Small Open Model Economy (HANKSOME) that experiences a current account reversal. Households' portfolio composition and the extent of foreign currency borrowing are key determinants of the magnitude of the contraction in consumption associated with a sudden stop in capital inflows. The contraction is more severe when households are leveraged and owe debt in foreign currency. In this setting, the revaluation of foreign debt causes a larger contraction in aggregate consumption when debt and leverage are concentrated among poorer households. Closing the output gap via an exchange-rate devaluation may therefore be detrimental to household welfare due to the heterogeneous impact of the foreign debt revaluation. Our HANKSOME framework can rationalize the observed "fear of floating" in emerging market economies, even in the absence of contractionary devaluations.

We assess the power of forward guidance-promises about future interest rates-as a monetary tool in a liquidity trap using a quantitative incomplete-markets model. Our results suggest the effects of forward guidance are negligible. A commitment to keep future nominal interest rates low for a few quarters---although macro indicators suggest otherwise---has only trivial effects on current output and employment. We explain theoretically why in complete markets models forward guidance is powerful---generating a ``forward guidance puzzle"---and why this puzzle disappears in our model. We also clarify theoretically ambiguous conclusions from previous research about the effectiveness of forward guidance in incomplete and complete markets models.

We propose a new method for computing equilibria in heterogeneous-agent models with aggregate uncertainty. The idea relies on an assumption that linearization offers a good approximation; we share this assumption with existing linearization methods. However, unlike those methods, the approach here does not rely on direct derivation of first-order Taylor terms. It also does not use recursive methods, whereby aggregates and prices would be expressed as linear functions of the state, usually a very high-dimensional object (such as the wealth distribution). Rather, we rely merely on solving nonlinearly for a deterministic transition path: we study the equilibrium response to a single, small "MIT shock" carefully. We then regard this impulse response path as a numerical derivative in sequence space and hence provide our linearized solution directly using this path. The method can easily be extended to the case of many shocks and computation time rises linearly in the number of shocks. We also propose a set of checks on whether linearization is a good approximation. We assert that our method is the simplest and most transparent linearization technique among currently known methods. The key numerical tool required to implement it is value-function iteration, using a very limited set of state variables.

I study the implications of two major debt-relief policies in the US: the Bankruptcy Abuse and Consumer Protection Act (BAPCPA) and the Home Affordable Refinance Program (HARP). To do so, I develop a model of housing and default that includes relevant dimensions of credit-market policy and captures rich heterogeneity in household balance sheets. The model also explains the observed cross-state variation in consumer default rates. I find that BAPCPA significantly reduced bankruptcy rates, but increased foreclosure rates when house prices fell. HARP reduced foreclosures by one percentage point and provided substantial welfare gains to households with high loan-to-value mortgages.

The goal of this chapter is study how, and by how much household income, wealth and preference heterogeneity amplifies and propagates a macroeconomic shock. We focus on the U.S. Great Recession of 2007-2009 and proceed in two steps. First, using data from the Panel Study of Income Dynamics, we document the patterns of household income, consumption and wealth inequality before and during the Great Recession. We then investigate how households in different segments of the wealth distribution were affected by income declines, and how they changed their expenditures differentially during the aggregate downturn. Motivated by this evidence we study several variants of a standard heterogeneous household model with aggregate shocks and an endogenous cross-sectional wealth distribution. Our key model finding is that wealth inequality can significantly amplify the impact of an aggregate shock, but it does so if (and only if) the distribution features a sufficiently large fraction of households with very little net worth, as is empirically observed in the PSID. We also investigate the role social insurance policies, such as unemployment insurance, play for shaping the cross-sectional income and wealth distribution, and through it, the dynamics of business cycles.

How big are the welfare losses from severe economic downturns, such as the Great Recession the U.S. experienced in recent years? How are those losses distributed across the population? In this paper we answer these questions using a canonical business-cycle model featuring household income and wealth heterogeneity that matches micro data from the Panel Study of Income Dynamics (PSID). We document how these losses are distributed across households and how they are affected by social insurance policies. We find the welfare cost of losing one's job in a Great Recession ranges from 2% of lifetime consumption for the wealthiest households to 5% for low wealth households. The cost increases to approximately 8% for low wealth households if unemployment insurance benefits are cut from 50% to 10%. The fact that welfare losses fall with wealth, and that in our model (as in the data) a large fraction of households has very low wealth, implies that the impact of a severe recession, once aggregated across all households, is very significant (2.2% of lifetime consumption). We finally show that a more generous unemployment insurance system unequivocally helps low-wealth job losers, but that it hurts households who keep their job, even in a version of the model in which output is partly demand determined and therefore unemployment insurance stabilizes aggregate demand and output.

The optimal cyclical behavior of unemployment insurance is characterized in an equilibrium search model with risk-averse workers. Contrary to the current US policy, the path of optimal unemployment benefits is pro-cyclical - positively correlated with productivity and employment. Furthermore, optimal unemployment benefits react non-monotonically to a productivity shock: in response to a fall in productivity, they rise on impact but then fall significantly below their pre-recession level during the recovery. As compared to the current US unemployment insurance policy, the optimal state-contingent unemployment benefits smooth cyclical fluctuations in unemployment and deliver substantial welfare gains.

What are the macroeconomic and distributional effects of government bailout guarantees for Government Sponsored Enterprises (e.g., Fannie Mae)? A model with heterogeneous, infinitely lived households and competitive housing and mortgage markets is constructed to evaluate this question. Households can default on their mortgages via foreclosure. The bailout guarantee is a tax-financed mortgage interest rate subsidy. Eliminating this subsidy leads to a large decline in mortgage origination and increases aggregate welfare by 0.5% in consumption equivalent variation, but has little effect on foreclosure rates and housing investment. The interest rate subsidy is a regressive policy: it hurts low-income and low-asset households.