MARIOTTI Thomas

We study competing-mechanism games under exclusive competition: principals first simultaneously post mechanisms, after which agents simultaneously choose to participate and communicate with at most one principal. In this setting, which is common to competing-auction and competitive-search applications, we develop two complete-information examples that question the relevance of the folk theorems for competing-mechanism games documented in the literature. The first example shows that there can exist pure-strategy equilibria in which some principal obtains a payoff below her min-max payoff, computed over all principals' decisions. Thus folk-theoremlike results may have to involve a bound on principals' payoffs that depends on the spaces of messages available to the agents, and not only on the players' actions. The second example shows that even this nonintrinsic approach is misleading when agents' participation decisions are strategic: there can exist incentive-feasible allocations in which principals obtain payoffs above their min-max payoffs, computed over arbitrary spaces of mechanisms, but which cannot be supported in equilibrium.

This paper studies competitive allocations under adverse selection. We rst provide a general necessary and sucient condition for entry on an inactive market to be unprotable. We then use this result to characterize, for an active market, a unique budget-balanced allocation implemented by a market tari making additional trades with an entrant unprotable. Motivated by the recursive structure of this allocation, we nally show that it emerges as the essentially unique equilibrium outcome of a discriminatory ascending auction. These results yield sharp predictions for competitive nonexclusive markets.

We study games in which several principals contract with several privately-informed agents. We show that enabling the principals to engage in contractible private disclosures – by sending private signals to the agents about how the mechanisms will respond to the agents’ messages – can significantly affect the predictions of such games. Our first result shows that private disclosures may generate equilibrium outcomes that cannot be supported in any game without private disclosures, no matter the richness of the message spaces and the availability of public randomizing devices. The result thus challenges the canonicity of the universal mechanisms of Epstein and Peters (1999). Our second result shows that equilibrium outcomes of games without private disclosures need not be sustainable when private disclosures are allowed. The result thus challenges the robustness of the “folk theorems” of Yamashita (2010) and Peters and Troncoso-Valverde (2013). These findings call for a novel approach to the analysis of competing-mechanism games.

We study competing-mechanism games under exclusive competition: principals first simultaneously post mechanisms, after which agents simultaneously choose to participate and communicate with at most one principal. In this setting, which is common to competing-auction and competitive-search applications, we develop two complete-information examples that question the relevance of the folk theorems for competing-mechanism games documented in the literature. The first example shows that there can exist pure-strategy equilibria in which some principal obtains a payoff below her min-max payoff, computed over all principals' decisions. Thus folk-theoremlike results may have to involve a bound on principals' payoffs that depends on the spaces of messages available to the agents, and not only on the players' actions. The second example shows that even this nonintrinsic approach is misleading when agents' participation decisions are strategic: there can exist incentive-feasible allocations in which principals obtain payoffs above their min-max payoffs, computed over arbitrary spaces of mechanisms, but which cannot be supported in equilibrium.

We study the optimal investment policy of a firm facing both technological and cash-flow uncertainty. At any point in time, the firm can decide to invest in a standalone technology or to wait for a technological breakthrough. Breakthroughs occur when market conditions become favorable enough, exceeding a certain threshold value that is ex-ante unknown to the firm. A microfoundation for this assumption is that a breakthrough occurs when the share of the surplus from the new technology accruing to its developer is high enough to cover her privately observed cost. We show that the relevant Markov state variables for the firm's optimal investment policy are the current market conditions and their current historic maximum, and that the firm optimally invests in the stand-alone technology only when market conditions deteriorate enough after reaching a maximum. Empirically, investments in new technologies requiring the active cooperation of developers should thus take place in booms, whereas investments in state-of-the-art technologies should take place in busts. Moreover, the required return for investing in the stand-alone technology is always higher than if this were the only available technology and can take arbitrarily large values following certain histories. Finally, a decrease in development costs, or an increase in the value of the new technology, makes the firm more prone to bear downside risk and to delay investment in the stand-alone technology.

In the first chapter of the thesis, I study the impact of rebuttal incentives on publication quality. One lesson to be learned from the analysis conducted is that the impact of the rebuttal reward on publication quality depends on the difference in speed between pioneering research and rebuttal activities. If the former is greater than the latter, publication quality decreases with the reward for rebuttal. Otherwise, the opposite is true. Compared to this basic model, publication quality is always lower when publication quality is uncertain. This last result suggests that transparency improves research quality. In the remaining two chapters of the thesis, I examine the trade-offs of scientists accessing citizen science (CS) or traditional science (TS) to conduct their research. By using CS, scientists involve the help of citizens, which is expensive and makes the research process faster. However, the quality of the results obtained is diminished. The analysis in the second chapter shows that if a scientific project is socially desirable, a scientist without a competitor chooses CS. Otherwise, he chooses ST. If the latter has a rival, the two scientists compete only if they both choose the SC. An interesting result emerges if scientific projects are moderately socially desirable: scientists randomly choose either SC or ST. The public policy implications depend on the scientists' choice. If one chooses CS and the other ST, there is no loss of efficiency. This result suggests a laissez-faire policy. If both choose ST, the research process is slowed down compared to the case where the scientist has no competitor. Therefore, the government should encourage CS through grants. In the third chapter, the scientists fight to establish publication priority for an innovative idea. Unlike the second chapter, the two scientists compete if they both choose ST. CS is an option they can exercise at the time they discover the idea. One lesson to be learned from the analysis conducted is that the scientists' choice between CS and ST does not depend on when they discover the idea. If SC has a low cost, they both choose SC. If not, they both choose ST. Compared to a research environment where it is not possible to choose CS, these results have two implications. First, scientists do not have time to adapt to this new research opportunity. Second, it increases the fear of being pre-empted. Therefore, in terms of public policy, the government must encourage the use of CS if it wishes to increase the speed of publication.

We study resource allocation under private information when the planner cannot prevent bilateral side trading between consumers and firms. Adverse selection and side trading severely restrict feasible trades: each marginal quantity must be fairly priced given the consumer types who purchase it. The resulting social costs are twofold. First, second-best efficiency and robustness to side trading are in general irreconcilable requirements. Second, there actually exists a unique budget-feasible allocation robust to side trading, which deprives the planner from any capacity to redistribute resources between different types of consumers. We discuss the relevance of our results for insurance and financial markets.

We study resource allocation under private information when the planner cannot prevent bilateral side trading between consumers and firms. Adverse selection and side trading severely restrict feasible trades: each marginal quantity must be fairly priced given the consumer types who purchase it. The resulting social costs are twofold. First, second-best efficiency and robustness to side trading are in general irreconcilable requirements. Second, there actually exists a unique budget-feasible allocation robust to side trading, which deprives the planner from any capacity to redistribute resources between different types of consumers. We discuss the relevance of our results for insurance and financial markets.

We study resource allocation under private information when the planner cannot prevent bilateral side trading between consumers and firms. Adverse selection and side trading severely restrict feasible trades: each marginal quantity must be fairly priced given the consumer types who purchase it. The resulting social costs are twofold. First, second-best efficiency and robustness to side trading are in general irreconcilable requirements. Second, there actually exists a unique budget-feasible allocation robust to side trading, which deprives the planner from any capacity to redistribute resources between different types of consumers. We discuss the relevance of our results for insurance and financial markets.

We study capital markets in which investors compete by designing financial contracts to control an entrepreneur’s ability to side trade and default on multiple loans. We show that covenants may have anticompetitive effects: in particular, they prevent investors from providing additional funds and reduce the entrepreneur’s investment capacity. As a result, a large number of inefficient allocations is supported at equilibrium. We propose a subsidy mechanism similar to guarantee funds in financial markets that efficiently controls the entrepreneur’s side trading and sustains the competitive allocation as the unique equilibrium one.

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We study resource allocation under private information when the planner cannot prevent bilateral side trading between consumers and firms. Adverse selection and side trading severely restrict feasible trades: each marginal quantity must be fairly priced given the consumer types who purchase it. The resulting social costs are twofold. First, second-best efficiency and robustness to side trading are in general irreconcilable requirements. Second, there actually exists a unique budget-feasible allocation robust to side trading, which deprives the planner from any capacity to redistribute resources between different types of consumers. We discuss the relevance of our results for insurance and financial markets.

We study a discriminatory limit-order book in which market makers compete in nonlinear tariffs to serve a privately informed insider. Our model allows for general nonparametric specifications of preferences and arbitrary discrete distributions for the insider's private information. Adverse selection severely restricts equilibrium outcomes: in any pure-strategy equilibrium with convex tariffs, pricing must be linear and at most one type can trade, leading to an extreme form of market breakdown. As a result, such equilibria exist only under exceptional circumstances that we fully characterize. These results are strikingly different from those of existing analyses that postulate a continuum of types. The two approaches can be reconciled when we consider epsilon-equilibria of games with a large number of market makers or a large number of types.

We construct a complete space of smooth strictly convex preferences defined over commodities and monetary transfers. Our model extends the classical one in that preferences are strictly monotone in monetary transfers, but need not be monotone in all commodities. We thereby provide a natural framework for performing genericity analyses in situations involving inventory costs or decisions under risk. The constructed space of preferences is contractible, which allows for a natural aggregation procedure in collective decision situations.

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We provide in this article a survey of recent work on competition under adverse selection and nonexclusivity, that is, when an informed buyer can simultaneously trade with several sellers. We discuss the equilibrium outcomes of different trading games, depending on whether sellers can only post linear prices, limit-orders, or convex or arbitrary tariffs. We emphasize that the existence of an equilibrium is problematic and characterize the unique entry-proof tariff.

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A seller of a divisible good faces several identical buyers. The quality of the good may be low or high, and is the seller's private information. The seller has strictly convex preferences that satisfy a single-crossing property. Buyers compete by posting menus of nonexclusive contracts, so that the seller can simultaneously and privately trade with several buyers. We provide a necessary and sufficient condition for the existence of a pure-strategy equilibrium. Aggregate equilibrium trades are unique. Any traded contract must yield zero profit. If a quality is actually traded, then it is efficiently traded. Depending on parameters, both qualities may be traded, or only one of them, or the market may break down to a no-trade equilibrium.

Many financial markets rely on a discriminatory limit-order book to balance supply and demand. We study these markets in a static model in which uninformed market makers compete in nonlinear tariffs to trade with an informed insider, as in Glosten (1994), Biais, Martimort, and Rochet (2000), and Back and Baruch (2013). We analyze the case where tariffs are unconstrained and the case where tariffs are restricted to be convex. In both cases, we show that pure-strategy equilibrium tariffs must be linear and, moreover, that such equilibria only exist under exceptional circumstances. These results cast doubt on the stability of even well-organized financial markets.

The purpose of this thesis is to study the coherence of dynamic choices in various contexts of strategic interaction. Three themes are more particularly addressed: the coordination of decisions, the irreversibility of choices and the value of information. The first part of the thesis is devoted to the coordination of agents' strategies in continuous games with almost perfect information. Our goal is to show how the introduction of public signals is necessary to guarantee the existence of perfect equilibria in this class of games. To do so, we develop an original analysis method, based on the notion of continuation correspondence. The second part of the thesis deals with information acquisition in the context of dynamically inconsistent preferences. We show that, in the absence of commitment on future decisions, an agent with such preferences can be led to voluntarily restrict the information at his disposal, in order to optimally constrain his present and future choices. This strategic ignorance behavior is more efficient than exhaustive information acquisition. The last part of the thesis is devoted to the option value of information in the presence of irreversible choices. Two models are studied for this purpose. In the first one, we analyze the dynamics of investment in a market where demand fluctuates stochastically. We show that in a monopoly, investments are systematically postponed with respect to the social optimum. In duopoly, we determine the impact of the threat of preemption on the option value of waiting. In a second model, we examine how opportunistic political parties choose their candidates based on the information available about them. We characterize the type of inefficiencies to which the parties' strategic behavior gives rise. Finally, we show that a dynamic perspective modifies the candidate selection strategy within a party by increasing the incentives to replace a candidate if he or she fails to perform.