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Financial support from National Science Foundation Grant No. SES-1559209 is gratefully acknowledged. We introduce a new class of solutions to nonlinear forward-looking models called near-rational sunspot equilibria (NRSE). NRSE are natural nonlinear extensions of the usual sunspot equilibria associated with the linearized version of the economy, and are near-rational in that agents use the optimal linear forecasting model when forming expectations. Generic results for existence and stability under learning are established. NRSE in indeterminate nonlinear models are found to be stable under learning provided that the corresponding linearized model's minimal state variable solution is E-stable. NRSE are readily computable, and our results make it possible to use the standard linear tools to search for stable NRSE. We illustrate our results using a canonical nonlinear New Keynesian model. Postprint

International audience; In this paper we investigate if government balanced-budget rules together with endogenous taxation may lead to aggregate instability in an endogenous growth framework. After highlighting the differences with the exogenous growth framework, we prove that under counter-cyclical consumption taxes, while there exists a unique balanced growth path, sunspot equilibria based on self-fulfilling expectations occur through a form of global indeterminacy. In addition, we argue that this result is empirically plausible for a large set of OECD countries and that it may also emerge with endogenous income taxes.

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We study optimal monetary and fiscal policy in a New Keynesian model where occasional declines in agents' confidence can give rise to persistent liquidity trap episodes. Unlike in the case of fundamental-driven liquidity traps, there is no straightforward recipe for mitigating the welfare costs and the systematic in ation shortfall associated with expectations-driven liquidity traps. Raising the in ation target or appointing an in ation-conservative central banker improves in ation outcomes away from the lower bound but exacerbates the shortfall at the lower bound. Using government spending as an additional policy tool worsens stabilization outcomes both at and away from the lower bound. However, appointing a policymaker who is sufficiently less concerned with government spending stabilization than society can eliminate expectations-driven liquidity traps altogether.

Summary.: We show that for international economies with two countries, in which agents have additively separable utility functions, the existence of sunspot equilibria is equivalent to the occurrence of the transfer paradox. This equivalence enables us to provide some new insights on the relation of the existence of sunspot equilibria and the multiplicity of spot market equilibria

We consider a two-sector economy with money-in-the-utility-function and sector-specific externalities. We provide conditions on technologies leading to the existence of local indeterminacy for any value of the interest rate elasticity of money demand, provided the elasticity of intertemporal substitution in consumption is large enough. Moreover, we show that the occurrence of multiple equilibria is intimately linked with the existence of a flip bifurcation and period-two cycles.

In this paper, we study the occurrence of local indeterminacy in two-sector monetary economies. In order to capture the credit market imperfections and the liquidity services of money, we consider a general MIUF model with two alternative timings in monetary payments: the Cash-In-Advance timing, in which the cash available to buy goods is money in the consumers' hands after they leave the bond market but before they enter the goods market, and the Cash-After-the-Market timing, in which agents hold money for transactions after leaving the goods market. We consider three standard specifications of preferences: the additively separable formulation, the Greenwood-Hercovitz-Huffman (GHH) [18] formulation and the King-Plosser-Rebelo (KPR) [21] formulation. First, we show that for all the three types of preferences, local indeterminacy easily arises under the CIA timing with a low enough interest rate elasticity of money demand. Second, we show that with the CAM timing, determinacy always holds under separable preferences, but local indeterminacy can arise in the case of GHH and KPR preferences. We thus prove that compared to aggregate models, two-sector models provide new rooms for local indeterminacy when non-separable standard preferences are considered.

We introduce a solution technique for the study of discrete time stochastic models populated by long-lived agents. We introduce aggregate uncertainty and complete markets into a 'perpetual-youth' model of a kind first studied by Olivier Blanchard and we show that the pure-trade version of the model behaves much like the two-period overlapping generations model. Our methods are easily generalized to economies with production and they should prove useful to researchers who seek a tractable stochastic model in which fiscal policy has real effects on aggregate allocations.

In this paper, is show how procyclical capital flows originate boom-bust and sunspot episodes in a neoclassical growth model of a small, open economy. All markets are perfect, with the exception of the fact that some upper, endogenous limit is imposed on how much the economy can borrow from foreign creditors, due to potential debtor default. It is shown that the steady state is locally indeterminate when the credit multiplier is larger than some threshold level, whereas saddle-point stability prevails when the credit multiplier is low enough. As a consequence, high levels of the credit multiplier lead to both booms followed by busts and sunspot-driven volatility near the steady state, while, in contrast, low levels ensure monotonic convergence. Compared with saddle-path equilibria, boom-bust and sunspot equilibria are associated with both lower welfare and debt overhang, that is, a crowding-out effect of credit : when the economy is highly leveraged, it uses savings to cut down foreign debt, at the expense of both human and physical investment. Numerical examples show that volatility arises at rather low values of financial development and for debt-to-GDP ratios that fall within the range of available estimates. Finally, the effects of shocks to the world interest rate on output and consumption are amplified and persistent in the debt overhang regime.

We consider a two‐sector infinite horizon economy with a fractional cash‐in‐advance constraint on consumption expenditures. This formulation allows us to consider a steady‐state velocity of money that is strictly greater than one and, therefore, provides a more plausible framework than the standard formulation in which all the consumption purchases are paid cash. We prove that the steady state is bound to be indeterminate and multiple equilibria occur when the share of the liquidity constraint is low enough and that a capital‐intensive investment good or a strongly capital‐intensive consumption good improve considerably the scope for indeterminacy. As a consequence, we show that without any restriction on the elasticity of intertemporal substitution in consumption, multiple equilibria might occur if the velocity of money is greater than a critical bound that is compatible with empirical estimates.

We consider economies with additively separable utility functions and give conditions for the two-agents case under which the existence of sunspot equilibria is equivalent to the occurrence of the transfer paradox. This equivalence enables us to show that sunspots cannot matter if the initial economy has a unique spot market equilibrium and there are only two commodities or if the economy has a unique equilibrium for all distributions of endowments induced by asset trade. For more than two agents the equivalence breaks and we give an example for sunspot equilibria even though the economy has a unique equilibrium for all distributions of endowments induced by asset trade.

International audience; It is well known from the literature that the introduction of liquidity constraints in infinite-horizon economies may be responsible for the occurrence of local indeterminacy and sunspot fluctuations. Yet, the question of the robustness of such phenomena when the constraints are progressively relaxed, and the possibility of intertemporal arbitrage on the part of the agents increases, remains open. In this paper we study such an issue by departing from the Cazzavillan et al. (J. Economic Theory 80 (1998) 60-107) framework with heterogeneous agents, financial constraint on wage income, and positive externalities in aggregate capital and labor. We observe that local indeterminacy and sunspot fluctuations persist for a wide range of amplitudes of the liquidity constraint, although they finally disappear when the 'degree' of liquidity of the economy is made arbitrarily large. © 2002 Elsevier Science B.V. All rights reserved.