François Salanié

Should More Risk-Averse Agents Exert More Effort?

Consider an agent facing a risky distribution of losses who can change this distribution by exerting some effort. Should he exert more effort when he becomes more risk-averse? For instance, should we expect more risk-averse drivers to drive more cautiously? In this article, we give sufficient conditions under which the answer is positive, using results presented in Jewitt (1989). We first extend the standard models of self-insurance and self-protection and show that the comparative statics depends only on the effect of effort on the net loss. We then present conditions for the continuous case with applications.

Softening competition through forward trading

Abstract In the history of alleged manipulations on forward markets, it has been observed that high prices resulted from a cartels long positions. The present paper addresses this issue in a simple model of price setting duopolists. We show that forward trading results in producers buying forward their own production, so that equilibrium prices are increased compared to the case without forward trading. This result contrasts with the social desirability of forward markets emphasized by the academic literature.

Lobbying under political uncertainty

Abstract This paper considers a model of lobbying described as a common agency game; it departs from the current literature by assuming that the special interest groups are not a priori organized or unorganized and that the type of the politician is not common knowledge. We characterize equilibria when the choice set of the politician consists of two policies; we discuss the conditions leading to efficiency and the characteristics of the groups explaining their relative success in the process of influence. We also offer some results for the general case, including disjoint necessary and sufficient conditions for the equilibria to be efficient.

Floors, dealer markets and limit order markets

In dealer markets, liquidity suppliers have entire flexibility to bargain on the price with their customers. In limit order markets, they are restricted to convex schedules: they cannot sell the first share at a higher price than the second. Floor traders simply respond to the liquidity demand conveyed by brokers by crying out one price. In floor markets risk-sharing is inefficient and spreads are large. In dealer markets, risk-sharing can be efficient, but spreads tend to be large. In limit order markets, the unique equilibrium entails efficient risk-sharing and competitive spreads. Hence there is a non-monotonic relation between the efficiency of the market and the extent to which the offers of the liquidity suppliers are restricted.

Nonexclusive Competition in the Market for Lemons

We consider an exchange economy in which a seller can trade an endowment of a divisible good whose quality she privately knows. Buyers compete in menus of non-exclusive contracts, so that the seller may choose to trade with several buyers. In this context, we show that an equilibrium always exists and that aggregate equilibrium allocations are generically unique. Although the good offered by the seller is divisible, aggregate equilibrium allocations exhibit no fractional trades. In equilibrium, goods of relatively low quality are traded at the same price, while goods of higher quality may end up not being traded at all if the adverse selection problem is severe. This provides a novel strategic foundation for Akerlof’s (1970) results, which contrasts with standard competitive screening models postulating enforceability of exclusive contracts. Latent contracts that are issued but not traded in equilibrium turn out to be an essential feature of our construction.(This abstract was borrowed from another version of this item.)

A Theory of Fraud and Overtreatment in Experts Markets

Consumers often rely on an expert’s diagnosis to assess their needs. If the expert is also the seller of services, he may use his informational advantage to induce overtreatment, which is a pervasive phenomenon in experts markets. We offer and discuss conditions leading to equilibrium overtreatment in an otherwise purely competitive model. This market failure results from consumers’ ability to turn down an expert’s recommendation: experts defraud consumers to keep them uninformed, as this deters them from seeking a better price elsewhere.

Non-Exclusive Competition in the Market for Lemons

We consider an exchange economy in which a seller can trade an endowment of a divisible good whose quality she privately knows. Buyers compete in menus of non-exclusive contracts, so that the seller may choose to trade with several buyers. In this context, we show that an equilibrium always exists and that aggregate equilibrium allocations are generically unique. Although the good offered by the seller is divisible, aggregate equilibrium allocations exhibit no fractional trades. In equilibrium, goods of relatively low quality are traded at the same price, while goods of higher quality may end up not being traded at all if the adverse selection problem is severe. This provides a novel strategic foundation for Akerlofs (1970) results, which contrasts with standard competitive screening models postulating enforceability of exclusive contracts. Latent contracts that are issued but not traded in equilibrium turn out to be an essential feature of our construction.

Non-Exclusive Competition Under Adverse Selection

A seller of a divisible good faces several identical buyers. The quality of the good may be low or high, and is the sellers 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.

On Competitive Nonlinear Pricing

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.

A Theory of Fraud and Over-Consumption in Experts Markets

Consumers often have to rely on an experts diagnosis to assess their needs. If the expert is also the seller of services, he may use his informational advantage to induce over-consumption. Empirical evidence suggests that over-consumption is a pervasive phenomenon in experts markets. We prove the existence of equilibrium over-consumption in an otherwise purely competitive model. This market failure results from the freedom of consumers to turn down an experts recommendation: experts defraud consumers in order to keep them uninformed, as this deters them from seeking a better price elsewhere. Our model also yields predictions on the diagnosis price that are in line with stylized facts, and provides a theory for why risk-neutral consumers would demand extended warranties on durables.