Competitive equilibria with limited enforcement

We show how to decentralize constrained efficient allocations that arise from enforcement constraints between sovereign nations. In a pure exchange economy these allocations can be decentralized with private agents acting competitively and taking as given government default decisions on foreign debt. In an economy with capital these allocations can be decentralized if the government can tax capital income as well as default on foreign debt. The tax on capital income is needed to make private agents internalize a subtle externality. The decisions of the government can arise as an equilibrium of a dynamic game between governments.     

Jointly optimal monetary and fiscal policy rules under liquidity constraints

We study the welfare properties of an economy where both monetary and fiscal policies follow simple rules, and where a subset of agents is liquidity constrained. The welfare benefits of optimizing the fiscal rule are far larger than those of optimizing the monetary rule. The optimized fiscal rule implements strong automatic stabilizers that primarily stabilize the income of liquidity-constrained agents, rather than output. Transfers targeted to liquidity-constrained agents are the preferred fiscal instrument. The optimized monetary rule exhibits super-inertia and a weak inflation response. Optimized simple rules perform as well as the optimal policy under the timeless perspective.     

Robustness of sunspot equilibria

Summary. A sunspot equilibrium (SSE) is based on some extrinsic randomizing device (RD). We analyze the robustness of SSE. (1) We say that an SSE allocation is robust to refinements if it is also an SSE allocation based on any refinement of its RD. (2) We introduce two core concepts for analyzing the robustness of SSE in the face of cooperative-coalition formation. In the first, the blocking allocations are based on the RD that defines the SSE. In the second (stronger) core concept, coalitions select their own RDs. For the convex economy with restricted market participation, SSE allocations are robust under each of the definitions and the cores converge on replication of the economy to the set of SSE allocations. For the economy with an indivisible good, SSE allocations are not always robust. We provide examples of each of the following: (i) an SSE allocation that is not robust to refinement, (ii) an SSE allocation that is in neither core, (iii) an SSE allocation that is in the first core, but not in the second, and (iv) a core that does not converge upon replication to the set of SSE allocations. Received: July 31, 1995; revised version August 30, 1996     

A coalition proof equilibrium for a private information credit economy

Summary This paper examines an economy in which agents with private information about their own productive capabilities seek to raise capital to fund their investment projects. We employ an equilibrium concept which is closely related to Coalition Proof Nash Equilibrium. In equilibrium, all agents who succeed in raising capital (entrepreneurs) are pooled; they all receive the same contract or consumption schedule. Entrepreneurs, however, are separated from those who fail to raise capital. This separation results in productive efficiency for the economy. If the economy has no viable alternative investment opportunity (other than agents' projects) then equilibrium allocations can be supported by a (non-intermediated) securities market. If there is a viable alternative, the equilibrium allocations cannot be supported by a securities market equilibrium. We interpret this case as suggesting the emergence of financial intermedary coalitions.     

Collateral fluctuations in a monetary economy

This paper studies economy-wide fluctuations that occur endogenously in the presence of monetary and real assets. Using a standard monetary search model, we consider an economy in which agents can increase consumption, over and above what their liquid monetary asset holdings would allow, pledging real assets as collateral for monetary loans. It is shown that, if the liquidation value of real assets is below full market value, a stable cyclical equilibrium can emerge in consumption and capital around the unstable steady state. We also provide conditions for the existence of cycles of higher order, chaos and sunspot equilibria.     

Credit and inflation under borrower?s lack of commitment

In this paper we study the effects of monetary policy on privately supplied credit in model economies where money is needed for transaction purposes and agents who default on their loans cannot participate in the credit market but are allowed to accumulate money. In our deterministic benchmark economy where agents alternate in productivity, credit has the role of smoothing consumption. We show that deflation crowds out credit completely. The reason is that deflation increases the value of being excluded from the credit market and eliminates the incentive to repay loans. When inflation is positive but low, credit, consumption smoothing and welfare increase with inflation, until inflation reaches a threshold at which the allocation is efficient and money becomes superneutral.     

Non-myopic learning in differential information economies: the core

Summary. We study the process of learning in a differential information economy, with a continuum of states of nature that follow a Markov process. The economy extends over an infinite number of periods and we assume that the agents behave non-myopically, i.e., they discount the future. We adopt a new equilibrium concept, the non-myopic core. A realized agreement in each period generates information that changes the underlying structure in the economy. The results we obtain serve as an extension to the results in Koutsougeras and Yannelis (1999) in a setting where agents behave non-myopically. In particular, we examine the following two questions: 1) If we have a sequence of allocations that are in an approximate non-myopic core (we allow for bounded rationality), is it possible to find a subsequence that converges to a non-myopic core allocation in a limit full information economy? 2) Given a non-myopic core allocation in a limit full information economy can we find a sequence of approximate non-myopic core allocations that converges to that allocation? Received: May 25, 1999; revised version: August 9, 1999     

Existence and fairness of value allocation without convex preferences

Shafer (Econometrica, 48 (1980), 467–476) proved that in a finite exchange economy value allocations exist, provided that each agent has convex, complete, transitive, compact and monotone preferences. However, if preferences are not convex, then value allocations may not exist. To remedy this difficulty we enlarge the set of value allocations by introducing the concept of approximate value allocations, and show that in a finite exchange economy approximate value allocations exist, even if preferences are not convex, or compact, or monotone. This value existence result can be used to provide a very general value existence theorem for a sequence of finite economies. Further, we show that value allocations may discriminate in favor of or against a coalition of agents.     

On spatial equilibria in a social interaction model

Social interactions are at the essence of societies and explain the gathering of individuals in villages, agglomerations, or cities. We study the emergence of multiple agglomerations as resulting from the interplay between spatial interaction externalities and competition in the land market. We show that the geography of the spatial economy affects significantly the properties of spatial equilibria. In particular, when agents locate on an open land strip (line segment), a single city emerges in equilibrium. In contrast, when the spatial economy extends along a closed land strip (circumference), multiple equilibria with odd numbers of cities arise. Spatial equilibrium configurations involve a high degree of spatial symmetry in terms of city size and location, and can be Pareto-ranked.     

Financial market imperfections and monetary policy strategy

In a model with imperfect money, credit and reserve markets, we examine if an inflation-targeting central bank applying the funds rate operating procedure to indirectly control market interest rates also needs a monetary aggregate as policy instrument. We show that if private agents use information extracted from money and financial markets to form inflation expectations and if interest rate pass-through is incomplete, the central bank can use a narrow monetary aggregate and the discount interest rate as independent and complementary policy instruments to reinforce the credibility of its announcements and the role of inflation target as a nominal anchor for inflation expectations. This study shows how a monetary policy strategy combining inflation targeting and monetary targeting can be conceived to guarantee macroeconomic stability and the credibility of monetary policy. Friedman's k-percent money growth rule, which can generate dynamic instability, and two alternative stabilizing feedback monetary targeting rules are examined.     

A simple dynamic general equilibrium model

We analyse a single sector economy with H > 1 infinitely-lived agents that operate in a continuous-time framework. Utility functions are recursive but not additive. Both efficient and perfect foresight competitive equilibrium allocations are considered. The existence and stability of such allocations are investigated locally, i.e., in a neighbourhood of steady-state allocations. The model is shown to be useful for explaining the distribution of wealth and consumption across agents, and for analysing the way in which wealth redistribution can affect the dynamics of aggregate economic variables.     

Sovereign default: Which shocks matter?

This paper analyses a small open economy that wants to borrow from abroad, cannot commit to repay debt but faces costs if it decides to default. The model generates analytical expressions for the impact of shocks on the incentive compatible level of debt. Debt reduction generated by severe output shocks is no more than a couple of percentage points. In contrast, shocks to world interest rates can substantially affect the incentive compatible level of debt.     

Public versus private risk sharing

Can public income insurance through progressive income taxation improve the allocation of risk in an economy where private risk sharing is incomplete? The answer depends crucially on the fundamental friction that limits private risk sharing in the first place. If risk sharing is limited because insurance markets are missing for model-exogenous reasons (as in Bewley (1986) [8]) publicly provided risk sharing improves on the allocation of risk. If instead private insurance markets exist but their use is limited by limited enforcement (as in Kehoe and Levine (1993) [23]) then the provision of public insurance interacts with equilibrium private insurance, as, by providing risk sharing, the government affects the value of exclusion from private insurance markets and thus the enforcement mechanism of these contracts. We characterize consumption allocations in an economy with limited enforcement and a continuum of agents facing plausible income risk and tax systems with various degrees of progressivity (public risk sharing). We provide conditions under which more publicly provided insurance actually reduces total insurance for agents (excess crowding-out), or under which more public insurance increases total insurance (partial crowding-out).     

Understanding the effects of technology shocks

The research led by Gali (AER 1999) and Basu et al. (AER 2006) raises two important questions regarding the validity of the RBC theory: (i) How important are technology shocks in explaining the business cycle? (ii) Do impulse responses to technology shocks found in the data reject the assumption of flexible prices? Using an RBC model, this paper argues that the conditional impulse responses of the U.S. economy to technology shocks are not grounds to reject the notion that technology shocks are the main driving force of the business cycle and the assumption of flexible prices, in contrast with the conclusions reached by the literature.     

Assessing the effects of financial heterogeneity in a monetary union a DSGE approach

The aim of this article is to analyze how financial heterogeneity can accentuate the cyclical divergences inside a monetary union that faces technological, monetary, budgetary and financial shocks. To this purpose, this study relies on a two-country Dynamic Stochastic General Equilibrium model, where the two countries are supposed to be differently sensitive to the bank capital channel. The model allows us to demonstrate how a given symmetric shock causes cyclical divergences inside a heterogeneous monetary union. On this point, it allows reproducing some stylized facts recently observed in the Euro Area. Moreover, it appears that the more heterogeneous the union, the larger the effects of financial asymmetries on the transmission of shocks. Finally, we show that a common monetary policy contributes to worsen cyclical divergences, in comparison with monetary policies that would be nationally conducted.     

Cyclical wage movements in emerging markets compared to developed economies: The role of interest rates

This paper documents that, at the aggregate level, (i) real wages are positively correlated with output and, on average, lag output by about one quarter in emerging markets, while there are no systematic patterns in developed economies, and (ii) real wage volatility (relative to output volatility) is about twice as high in emerging markets compared with developed economies. We then present a small open economy model with productivity shocks and countercyclical interest rates. The model incorporates a working capital requirement and the Jaimovich and Rebelo (2009) preference that allows for flexible parameterization of the strength of income effects on labor supply. The model can account for the high volatility of wage and consumption relative to output and countercyclical trade balances that characterize emerging-market economies. During economic downturns, rising interest rates in emerging markets induce relatively large income effects on labor supply, so households would not reduce their labor input as much even though wages drop significantly.     

Credibility and endogenous societal discounting

We consider a dynamic moral hazard economy inhabited by a planner and a population of privately informed agents. We assume that the planner and the agents share the same discount factor, but that the planner cannot commit. We show that optimal allocations in such settings solve the problems of committed planners who discount the future less heavily than agents. Thus, we provide micro-foundations for dynamic moral hazard models that assume a societal discount factor in excess of the private one. We extend the analysis to allocations that are reconsideration-proof in the sense of Kocherlakota [Kocherlakota, N., 1996. Reconsideration-proofness: A refinement for infinite horizon time inconsistency. Games and Economic Behavior 15, 33–54]. We show that these allocations solve the choice problem of a committed planner with a unit discount factor.     

Private Value Allocations in Large Economies with Differential Information

We consider a Radner-type (e.g., Radner, 1968, Econometrica36, 31–58) pure exchange economy with differential information and a continuum of agents. We show that under appropriate assumptions the set of Aumann–Shapley private value allocations in such an economy coincides with the set of Radner competitive equilibrium allocations. Journal of Economic Literature Classification Numbers: C71, D51, D82.     

The implications for an open economy of partisan political business cycles: Theory and evidence

This paper develops and tests the predictions of two open economy models in which partisan effects are present, a small-country-one-good model of exchange rate determination and a model that assumes the two countries each specialize in the production of one good. From these models, we can obtain predictions for the behaviour of the terms of trade, the current account, and real and nominal exchange rates. The predictions are tested empirically using panel data from 14 OECD countries and the results provide support for the theoretical predictions that systematic partisan effects are present in current accounts, real exchange rates, and the terms of trade.     

Retrading in market games

When agents are not price takers, they typically cannot obtain an efficient real location of resources in one round of trade. This paper presents a non-cooperative model of imperfect competition where agents can retrade allocations, consistent with Edgeworth's idea of recontracting. We show (a) there are Pareto optimal allocations, including competitive equilibrium allocations, that can be approximated arbitrarily closely when trade is myopic, i.e., when agents play a static Nash equilibrium at every round of retrading; (b) any converging sequence of allocations generated by myopic retrading can be supported along some retrade-proof subgame perfect equilibrium path when traders anticipate future rounds of trading.