Truthful Revelation Mechanisms for Simultaneous Common Agency Games

In games in which multiple principals contract simultaneously and non-cooperatively with the same agent, standard direct revelation mechanisms in which the agent reports his type(i.e. his exogenous private information) have been proven inadequate to characterize the entire set of equilibrium outcomes. This paper introduces a more general class of revelation mechanisms in which the agent reports also the contractual decisions he is inducing with the principals. We …rst show that such a class has the same nice properties as the class of all unrestricted menus: (i) for any equilibrium of any indirect game with arbitrary communication space for the principals, there exists a truthful equilibrium in the game in which the principals are restricted to o¤er revelation mechanisms that sustains the same outcomes; (ii) any truthful equilibrium is robust in the sense that it remains an equilibrium in any game in which the principalsstrategy space is enlarged. We next show how revelation mechanisms can be put to work in applications such as menu auctions, moral hazard settings, and competition in non-linear tariffs to identify necessary and sufficient conditions for the sustainability of outcomes as common agency equilibria.mechanism design, contracts, Revelation Principle.

Truthful Revelation Mechanisms for Simultaneous Common Agency Games

This paper considers games in which multiple principals contract simultaneously with the same agent. We introduce a new class of revelation mechanisms that, although it does not always permit a complete equilibrium characterization, it facilitates the characterization of the equilibrium outcomes that are typically of interest in applications (those sustained by pure-strategy profiles in which the agent's behavior in each relationship is Markov, i.e., it depends only on payoff-relevant information such as the agent's type and the decisions he is inducing with the other principals). We then illustrate how these mechanisms can be put to work in environments such as menu auctions, competition in nonlinear tariffs, and moral hazard settings. Lastly, we show how one can enrich the revelation mechanisms, albeit at a cost of an increase in complexity, to characterize also equilibrium outcomes sustained by non-Markov strategies and/or mixed-strategy profiles.Mechanism design, contracts, revelation principle, menus, endogenous payoff-relevant information

Robust Predictions in Global Games with Multiple Equilibria: Defense Policies Against Currency Attacks

This paper studies defense policies in a global-game model of speculative currency attacks. Although the signaling role of policy interventions sustains multiple equilibria, a number of novel predictions emerge which are robust across all equilibria. (i) The central bank intervenes by raising domestic interest rates, or otherwise raising the cost of speculation, only when the value it assigns to defending the peg—its “type”—is intermediate. (ii) Devaluation occurs only for low types. (iii) The set of types who intervene shrinks with the precision of market information. (iv) A unique equilibrium policy survives in the limit as the noise in market information vanishes, whereas the devaluation outcome remains indeterminate. (v) The payoff of the central bank is monotonic in its type. (vi) The option to intervene can be harmful only for sufficiently strong types; and when this happens, weak types are necessarily better off. While these predictions seem reasonable, none of them would have been possible in the common-knowledge version of the model. Combined, these results illustrate the broader methodological point of the paper: global games can retain significant selection power and deliver useful predictions even when the endogeneity of information sustains multiple equilibria.

Common Agency with Informed Principals: Menus and Signals

In this paper I consider games in which multiple informed principals simultaneously compete to influence the decisions of a common agent. I focus on the problem of characterizing the equilibrium outcomes of such games. I first show that, to solve this problem, one can invoke neither Myerson’s Inscrutability Principle, which holds in agency games with one informed principal, nor the Extended Taxation Principle, which holds in common-agency games with uninformed principals. I then provide two characterizations of the equilibrium outcomes: one for games in which the principals delegate the final decisions to the agent, and one for games in which they participate with the agent in making such decisions. JEL Classification Numbers: C72, D82, D83, D86Common agency, informed principals, Inscrutability Principals, Extended Taxation Principle, menus, signals, direct mechanisms Principle, menus, signals, direct revelation mechanisms.

Implicit Collusion in Non-Exclusive Contracting under Adverse Selection

This paper studies how implicit collusion may take place through simple non-exclusive contracting under adverse selection when multiple buyers (e.g., entrepreneurs with risky projects) non-exclusively contract with multiple firms (e.g., banks). It shows that any price schedule can be supported as equilibrium terms of trade in the market if each firm's expected profit is no less than its reservation profit. Firms sustain collusive outcomes through the triggering trading mechanism in which they change their terms of trade contingent only on buyers' reports on the lowest average price that the deviating firm's trading mechanism would induce. It suggests that a good can be overpriced in a competitive market even with fully rational traders and without firms' explicit collusive agreement.collusion, non-exclusive contracting, competing mechanisms

Game theory

game theory

On the Optimality of Privacy in Sequential Contracting

This paper studies the exchange of information between two principals who contract sequentially with the same agent, as in the case of a buyer who purchases from multiple sellers. We show that when (a) the upstream principal is not personally interested in the downstream level of trade, (b) the agent’s valuations are positively correlated, and (c) preferences in the downstream relationship are separable, then it is optimal for the upstream principal to offer the agent full privacy. On the contrary, when any of these conditions is violated, there exist preferences for which disclosure is strictly optimal, even if the downstream principal does not pay for the information. We also examine the effects of disclosure on welfare and show that it does not necessarily reduce the agent’s surplus in the two relationships and in some cases may even yield a Pareto improvement. The paper describes this condition and its implications.contractual and informational externalities, mechanism design, optimal disclosure policies, sequential common agency games, exogenous and endogenous private information.

On the Revelation Principle and Reciprocal Mechanisms in Competing Mechanism Games

This paper provides a set of mechanisms that we refer to as emph{reciprocal mechanisms. }These mechanisms have the property that every outcome that can be supported as a Bayesian equilibrium in a competing mechanism game can be supported as an equilibrium in reciprocal mechanisms. In this sense, reciprocal mechanisms play the same role as direct mechanisms do in single principal problems. The advantage of these mechanisms over alternatives like the universal set of mechanisms is that they are conceptually straightforward and no more difficult to deal with than the simple direct mechanisms used in single principal mechanism design.competing mechanisms, revelation principle

Tax Interactions with Asymmetric Information and Nonlinear Instruments

Tax Interactions with Asymmetric Information and Nonlinear Instruments

On Take It or Leave It Offers in Common Agency

If the agent's preference relation satisfies a strict monotonicity condition in common agency under the asymmetric information, the set of all equilibrium allocations in the menu game where menus of contracts are allowed coincides with the set of all equilibrium allocations in the single contract game where only single contracts are allowed.take it or leave it offers, menus, common agency, robust equilibrium allocations, mixed-strategy equilibrium