Sunspot Equilibria in a Production Economy: Do Rational Animal Spirits Cause Overproduction?

We study a standard two period economy with one nominal bond and one firm. The input of the firm is done in the first period and financed with the nominal bond, and its profits are distributed to the shareholders in the second period. We show that a sunspot equilibrium exists around each efficient equilibrium. The interest rate is lower than optimal and there is over production in sunspot equilibria, under some conditions. But a sunspot equilibrium does not exist if the profit share can be traded as well as the bond.

Welfare Gains and Losses in Sunspot Equilibria

We study a standard two period exchange economy with one nominal asset. As is well known there is a continuum of sunspot equilibria around each efficient equilibrium. A sunspot equilibrium is inefficient but some household may gain in sunspot equilibria relative to the efficient equilibrium. We show that a household's equilibrium utility level is either locally maximized or locally minimized at the efficient equilibrium, and derive a condition which identifies whether or not a household's utility is locally minimized or maximized.

Incomplete Information Games with Multiple Priors

We present a model of incomplete information games with sets of priors. Upon arrival of private information, each player "updates" by the Bayes rule each of priors in this set to construct the set of posteriors consistent with the arrived piece of information. Then the player uses a possibly proper subset of this set of posteriors to form beliefs about the opponents' strategic choices. And finally the player evaluates his actions by the most pessimistic posterior beliefs `a la Gilboa and Schmeidler (1989). So each player's preferences may exhibit non-linearity in probabilities which can be interpreted as the player's aversion to ambiguity or uncertainty. In this setup, we define a couple of equilibrium concepts, establish existence results for them, and demonstrate by examples how players' views on uncertainty about the environment affect the strategic outcomes.incomplete information games; multiple priors; ambiguity aversion; uncertainty aversion

Interim Efficient Allocations under Uncertainty

This paper considers an exchange economy under uncertainty with asymmetric information. Uncertainty is represented by multiple priors and posteriors of agents who have either Bewley's incomplete preferences or Gilboa-Schmeidler's maximin expected utility preferences. The main results characterize interim efficient allocations under uncertainty; that is, they provide conditions on the sets of posteriors, thus implicitly on the way how agents update the sets of priors, for non-existence of a trade which makes all agents better off at any realization of private information. For agents with the incomplete preferences, the condition is necessary and sufficient, but for agents with the maximin expected utility preferences, the condition is sufficient only. A couple of necessary conditions for the latter case are provided.multiple priors; interim efficiency; no trade; dynamic consistency; rectangular prior set

Risk-Free Bond Prices in Incomplete Markets with Recursive Utility Functions and Multiple Beliefs

We consider an exchange economy under uncertainty, in which agents' utility functions exhibit constant absolute risk aversion, but they may be recursive and the expected utility calculation may be based on multiple subjective beliefs. The risk aversion coefficients, subjective beliefs, subjective time discount factors, initial endowments, and tradeable assets may differ across agents. We prove that the risk-free bond price goes down (and the interest rate goes up) monotonically as the markets become more complete. We find the range of equilibrium bond prices that depends on the primitives of the economy but not on the structures of financial markets.multiple priors; no trade; dynamic consistency; interim efficiency; rectangularityi

Probabilistically Sophisticated Multiple Priors.

We characterize the intersection of the probabilistically sophisticated and multiple prior models. We show this class is strictly larger than the subjective expected utility model and that its elements can be generated from a generalized class of the -contaminated priors, which we dub the - contaminated/ -truncated prior.subjective probability, maximin expected utility, epsilon-contamined priors.

Agreeable Bets with Multiple Priors

This paper considers a two agent model of trade with multiple priors. First, we characterize the existence of an agreeable bet on some event in terms of the set of priors. It is then shown that the existence of an agreeable bet on some event is a strictly stronger condition than the existence of an agreeable trade, whereas the two conditions are equivalent in the standard Bayesian framework. Secondly, we show that the two conditions are equivalent when the set of priors is the core of a convex capacity.multiple priors, convex capacity, agreeing and disagreeing, Choquet integralm