This paper extends the benchmark New-Keynesian model with a representative agent and rational expectations by introducing two key frictions: (1) incomplete markets with uninsurable idiosyncratic risk and occasionally-binding borrowing constraints; and (2) bounded rationality in the form of level- k thinking. Compared to the benchmark model, we show that the interaction of these two frictions leads to a powerful mitigation of the effects of monetary policy, which is much more pronounced at long horizons. This offers a potential rationalization of the “forward guidance puzzle”. Each of these frictions, in isolation, would lead to no or much smaller departures from the benchmark model. We conclude that the interaction of bounded rationality and is important.

This paper develops a theory of optimal taxation with behavioral agents. We use a general behavioral framework that encompasses a wide range of behavioral biases such as misperceptions, internalities and mental accounting. We revisit the three pillars of optimal taxation: Ramsey (linear commodity taxation to raise revenues and redistribute), Pigou (linear commodity taxation to correct externalities) and Mirrlees (nonlinear income taxation). We show how the canonical optimal tax formulas are modified and lead to a rich set of novel economic insights. We also show how to incorporate nudges in the optimal taxation frameworks, and jointly characterize optimal taxes and nudges. We explore the Diamond-Mirrlees productive efficiency result and the Atkinson-Stiglitz uniform commodity taxation proposition, and find that they are more likely to fail with behavioral agents.

We provide a nonlinear characterization of the macroeconomic impact of microeconomic productivity shocks in terms of reduced-form non-parametric elasticities for efficient economies. We also show how structural microeconomic parameters are mapped to these reduced-form general equilibrium elasticities. In this sense, we extend the foundational theorem of Hulten (1978) beyond first-order terms to capture nonlinearities. Key features ignored by first-order approximations that play a crucial role are: structural elasticities of substitution, network linkages, structural returns to scale, and the extent of factor reallocation. In a business-cycle calibration with sectoral shocks, nonlinearities magnify negative shocks and attenuate positive shocks, resulting in an aggregate output distribution that is asymmetric (negative skewness), fat-tailed (excess kurtosis), and has a lower mean, even when shocks are symmetric and thin-tailed. Average output losses due to short-run sectoral shocks are an order of magnitude larger than the welfare cost of business cycles calculated by Lucas1(987). Nonlinearities can also cause shocks to critical sectors to have disproportionate macroeconomic effects, almost tripling the estimated impact of the 1970s oil shocks on world aggregate output. Finally, in a long-run growth context, nonlinearities, which underpin Baumol's cost disease, account for a 20 percentage point reduction in aggregate TFP growth over the period 1948-2017 in the US.

We propose a simple model of the international monetary system. We study the world supply and demand for reserve assets denominated in different currencies under a variety of scenarios: a Hegemon vs. a multipolar world; abundant vs. scarce reserve assets; a gold exchange standard vs. a floating rate system. We rationalize the Triffin dilemma, which posits the fundamental instability of the system, as well as the common prediction regarding the natural and beneficial emergence of a multipolar world, the Nurkse warning that a multipolar world is more unstable than a Hegemon world, and the Keynesian argument that a scarcity of reserve assets under a gold standard or at the zero lower bound is recessive. Our analysis is both positive and normative.

The recent unravelling of the Eurozone's financial integration raised concerns about feedback loops between sovereign and banking insolvency. This paper provides a theory of the feedback loop that allows for both domestic bailouts of the banking system and sovereign debt forgiveness by international creditors or solidarity by other countries. Our theory has important implications for the re-nationalization of sovereign debt and the rationale for banking unions.

The secular decline in safe interest rates since the early 1980s has been the subject of considerable attention. In this short paper, we argue that it is important to consider the evolution of safe real rates in conjunction with three other first-order macroeconomic stylized facts: the relative constancy of the real return to productive capital, the decline in the labor share, and the decline and subsequent stabilization of the earnings yield. Through the lens of a simple accounting framework, these four facts offer insights into the economic forces that might be at work.

In this paper we provide a model of the macroeconomic implications of safe
asset shortages. In particular, we discuss the emergence of a deflationary 
safety trap equilibrium with endogenous risk premia. It is an acute
form of a liquidity trap, in which the shortage of a specific form of
assets, safe assets, as opposed to a general shortage of assets, is the
fundamental driving force. At the ZLB, our model has a Keynesian cross
representation, in which net safe asset supply plays the role of an
aggregate demand shifter. Essentially, safety traps correspond to liquidity
traps in which the emergence of an endogenous risk premium significantly
alters the connection between macroeconomic policy and economic activity.
``Helicopter drops'' of money, safe public debt issuances, swaps of private
risky assets for safe public debt, or increases in the inflation target,
stimulate aggregate demand and output, while forward guidance is less
effective. The safety trap can be arbitrarily persistent, as in the secular
stagnation hypothesis, despite the existence of infinitely lived assets. 

We study cross-country risk sharing as a second-best problem for members of a currency union using an open economy model with nominal rigidities and provide two key results. First, we show that, if financial markets are incomplete, the value of gaining access to any given level of aggregate risk sharing is greater for countries that are members of a currency union. Second, we show that, even if financial markets are complete, privately optimal risk sharing is constrained inefficient. A role emerges for government intervention in risk sharing to both guarantee its existence and to influence its operation. The constrained efficient risk sharing arrangement can be implemented by contingent transfers within a fiscal union. The benefits of such a fiscal union are larger, the bigger the asymmetric shocks affecting the members of the currency union, the more persistent these shocks, and the less open the member economies.

We provide explicit solutions for government spending multipliers during a liquidity trap and within a fixed exchange regime using standard closed and open-economy New Keynesian models. We confirm the potential for large multipliers during liquidity traps. For a currency union, we show that self-financed multipliers are small, always below unity, unless the accompanying tax adjustments involve substantial static redistribution from low to high marginal propensity to consume agents, or dynamic redistribu- tion from future to present non-Ricardian agents. But outside-financed multipliers which require no domestic tax adjustment can be large, especially when the average marginal propensity to consume on domestic goods is high or when government spending shocks are very persistent. Our solutions are relevant for local and national multipliers, providing insight into the economic mechanisms at work as well as the testable implications of these models.

We study fiscal and monetary policy in a monetary union with the potential for rollover crises in sovereign debt markets. Member-country fiscal authorities lack commitment to repay their debt and choose fiscal policy independently. A common monetary authority chooses inflation for the union, also without commitment.  We first describe the existence of a fiscal externality that arises in the presence of limited commitment and leads countries to over borrow; this externality rationalizes the imposition of debt ceilings in a monetary union. We then investigate the impact of the composition of debt in a monetary union, that is the fraction of high-debt versus low-debt members, on the occurrence of self-fulfilling debt crises. We demonstrate that a high-debt country may be less vulnerable to crises and have higher welfare when it belongs to a union with an intermediate mix of high- and low-debt members, than one where all other members are low-debt. This contrasts with the conventional wisdom that all countries should prefer a union with low-debt members, as such a union can credibly deliver low inflation. These findings shed new light on the criteria for an optimal currency area in the presence of rollover crises.
 

Parties in financial markets, industries, compensation design or politics may negotiate on either a piecemeal or a bundled basis. Little is known about the desirability of bundling when values are common and/or information endogenous. The paper shows that bundling encourages information-equalizing investments, thereby facilitating trade. It accordingly revisits and qualifies existing knowledge on security design.

Though risk aversion and the elasticity of intertemporal substitution have been the subjects of careful scrutiny when calibrating preferences, the long-run risks literature as well as the broader literature using recursive utility to address asset pricing puzzles have ignored the full implications of their parameter specifications. Recursive utility implies that the temporal resolution of risk matters and a quantitative assessment of how much it matters should be part of the calibration process. This paper gives a sense of the magnitudes of implied timing premia. Its objective is to inject temporal resolution of risk into the discussion of the quantitative properties of long-run risks and related models.