A Note on Walrasian Equilibria with Moral Hazard and Aggregate Uncertainty

In a fundamental contribution, Prescott and Townsend (1984) [PT] have shown that the existence and efficiency properties of Walrasian equilibria extend to economies with moral hazard, when agents' trades are observable (exclusive contracts can be implemented). More recently, Bennardo and Chiappori (2003) [BC] have argued that Walrasian equilibria may (robustly) fail to exist when the class of moral hazard economies considered by Prescott and Townsend is generalized to allow for the presence of aggregate, in addition to idiosyncratic, uncertainty and for preferences which are nonseparable in consumption and effort. We re-examine here the existence and efficiency properties of Walrasian equilibria in the moral hazard economy considered by Bennardo and Chiappori. We show that Walrasian equilibria always exist in such economy and are incentive efficient, so the results of Prescott and Townsend continue to hold in the more general set-up considered by Bennardo and Chiappori

Markets for information : of inefficient firewalls and efficient monopolies

In this paper we build a formal model to study market environments where information is costly to acquire and is of use also to potential competitors. In such situations a market for information may form, where reports - of unverifiable quality - over the information acquired are sold. A complete characterization of the equilibria of the game is provided. We find that information is acquired when its costs are not too high and in that case it is also sold, though reports are typically noisy. Also, the market for information tends to be a monopoly, and there is typically inefficiency given by underinvestment in information acquisition. Regulatory interventions in the form of firewalls, limiting the access to the sale of information to third parties, uninterested in trading the underlying object, only make the inefficiency worse. On the other hand, efficiency can be attained with a monopolist selling differentiated information, provided entry is blocked. The above findings hold when information has a prevalent horizontal differentiation component. When that is not the case, and the vertical differentiation element is more important, firewalls can in fact be beneficial

Value of Information in Competitive Economies with Incomplete Markets

A substantial literature addresses the negative effect on welfare of the release of information in a competitive market economy. We show that the value of information in this setting is typically positive if asset markets are sufficiently incomplete. More specifically, for any competitive equilibrium of a generic economy, we can find a finer information structure such that an allocation that is resource feasible and measurable with respect to this information ex-post Pareto dominates the given equilibrium allocation.Competitive Equilibrium, Incomplete Markets, Value of Information.

Decentralizing Incentive Efficient Allocations of Economies with Adverse Selection

We study competitive economies with adverse selection and fully exclusive contractual relationships. We consider economies where agents are privately informed over the probability distribution of their endowments, and trade to insure against this uncertainty. As in Prescott-Townsend (1984), we model exclusivity by imposing the incentive compatibility constraints directly on the agents' consumption possibility set. In this set-up, we identify the externality associated with the presence of adverse selection as a special form of consumption externality. We consider a structure of markets which allows to internalize such externality, for which we show that competitive equilibria exist and are incentive efficient. On the other hand, when this 'expanded' set of markets required to internalize such externality does not exist, competitive equilibria are shown to be, typically, not incentive efficient, but to satisfy an appropriately defined notion of third best efficiency. Appropriate versions of the second welfare theorem for these two market structures are also established.

Efficient Competitive Equilibria with Adverse Selection

Do Walrasian markets function orderly in the presence of adverse selection? In particular, is their outcome efficient? This paper addresses these questions in the context of a Rothschild and Stiglitz insurance economy. We identify an externality associated with the presence of adverse selection as a special form of consumption externality. Consequently, we show that while competitive equilibria always exist, they are not typically incentive efficient. However, as markets for pollution rights can internalize environmental externalities, markets for consumption rights can be designed so as to internalize the consumption externality due to adverse selection. With such markets competitive equilibria exist and are always incentive efficient. Moreover, any incentive efficient allocation can be decentralized as a competitive equilibrium.

A Note on Walrasian Equilibria with Moral Hazard and Aggregate Uncertainty

In a fundamental contribution, Prescott and Townsend (1984) [PT] have shown that the existence and efficiency properties of Walrasian equilibria extend to economies with moral hazard, when agents' trades are observable (exclusive contracts can be implemented). More recently, Bennardo and Chiappori (2003) [BC] have argued that Walrasian equilibria may (robustly) fail to exist when the class of moral hazard economies considered by Prescott and Townsend is generalized to allow for the presence of aggregate, in addition to idiosyncratic, uncertainty and for preferences which are nonseparable in consumption and effort. We re-examine here the existence and efficiency properties of Walrasian equilibria in the moral hazard economy considered by Bennardo and Chiappori. We show that Walrasian equilibria always exist in such economy and are incentive efficient, so the results of Prescott and Townsend continue to hold in the more general set-up considered by Bennardo and Chiappori.Moral Hazard, Aggregate Risk, Incentive Efficiency, Walrasian Markets

Illiquidity and Under-Valuation of Firms

We study a competitive model in which market incompleteness implies that debt-financed firms may default in some states of nature and default may lead to the sale of the firms’ assets at fire sale prices when markets are illiquid. This incompleteness is the only friction in the model and the only cost of default. The anticipation of such losses alone may distort .rms.investment decisions. We characterize the conditions under which fire sales occur in equilibrium and their consequences on firms' investment decisions. We also show that endogenous financial crises may arise in this environment, with asset prices collapsing as a result of pure self-fulfilling beliefs. Finally, we examine alternative interventions to restore the efficiency of equilibria.illiquid markets, default, incomplete markets, price distortions, inefficient investment

Market Power and Information Revelation in Dynamic Trading

We study a strategic model of dynamic trading where agents are asymmetrically informed over common value sources of uncertainty. There is a continuum of uninformed buyers and a finite number of sellers, some of them informed. When there is only one seller, full information revelation never occurs in equilibrium and the only information transmission happens in the first period. The outcome with n sellers depends both on the structure of sellers' information and, more importantly, on the intensity of competition among them allowed by the trading rules. With intense competition (absence of clienteles), information is fully and immediately revealed to the buyers in every equilibrium for n large enough, both when all sellers are informed and when only one seller is informed. On the other hand, with a less intense form of competition (presence of clienteles), we always have equilibria where information is never fully revealed, whatever the number of sellers. Moreover in this case, when only one seller is informed, for many parameter configurations there are no equilibria with full information revelation, for any n.asymmetric information, information revelation, dynamic trading, oligopolistic competition, clienteles