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 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.

The Postprandial Appearance of Features of Cardiometabolic Risk: Acute Induction and Prevention by Nutrients and Other Dietary Substances

International audienceThe purpose of this review is to provide an overview of diets, food, and food components that affect postprandial inflammation, endothelial function, and oxidative stress, which are related to cardiometabolic risk. A high-energy meal, rich in saturated fat and sugars, induces the transient appearance of a series of metabolic, signaling and physiological dysregulations or dysfunctions, including oxidative stress, low-grade inflammation, and endothelial dysfunction, which are directly related to the amplitude of postprandial plasma triglycerides and glucose. Low-grade inflammation and endothelial dysfunction are also known to cluster together with insulin resistance, a third risk factor for cardiovascular diseases (CVD) and type-II diabetes, thus making a considerable contribution to cardiometabolic risk. Because of the marked relevance of the postprandial model to nutritional pathophysiology, many studies have investigated whether adding various nutrients and other substances to such a challenge meal might mitigate the onset of these adverse effects. Some foods (e.g., nuts, berries, and citrus), nutrients (e.g., l-arginine), and other substances (various polyphenols) have been widely studied. Reports of favorable effects in the postprandial state have concerned plasma markers for systemic or vascular pro-inflammatory conditions, the activation of inflammatory pathways in plasma monocytes, vascular endothelial function (mostly assessed using physiological criteria), and postprandial oxidative stress. Although the literature is fragmented, this topic warrants further study using multiple endpoints and markers to investigate whether the interesting candidates identified might prevent or limit the postprandial appearance of critical features of cardiometabolic risk

Cenon-sur-Vienne – Rivière Clain

Date de l'opération : 2003 - 2008 (PI) En 2007, un ensemble de blocs et trois chapiteaux antiques ont été mis au jour dans la rivière Clain au sud de Châtellerault (Fig. n°1 : Chapiteau antique mis au jour à la confluence du Clain et de la Vienne) . Situé au nord de la commune de Cenon-sur-Vienne, au lieu-dit Bretaigne, Fort-Clan, le site immergé dans le Clain est à 200 m en amont de la confluence avec la Vienne. Au cours de prospections aériennes menées en 1989 sur la confluence de la Vi..

Multiple Contracting in Insurance Markets

We study insurance markets in which privately informed consumers can purchase coverage from several insurers. Under adverse selection, multiple contracting severely restricts feasible trades. Indeed, only one budget-balanced allocation is implementable by an entry-proof tariff, and each layer of coverage must be fairly priced given the consumer types who purchase it. This allocation is the unique equilibrium outcome of a game in which cross-subsidies between contracts are prohibited. Equilibrium contracts exhibit quantity discounts and negative correlation between risk and coverage. Public intervention should target insurers’ strategic behavior, while consumers can be left free to choose their preferred amount of coverage

The social costs of side trading

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

Regulating insurance markets: multiple contracting and adverse selection

We study insurance markets in which privately informed consumers can purchase coverage from several firms whose pricing strategies are subject to an anti-dumping regulation. The resulting regulated game supports a single allocation in which each layer of coverage is fairly priced given the consumer types who purchase it. This competitive allocation cannot be Pareto-improved by a social planner who can neither observe consumer types nor monitor their trades with firms. Accordingly, we argue that public intervention under multiple contracting and adverse selection should penalize firms that cross-subsidize between contracts, while leaving consumers free to choose their preferred amount of coverage

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 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

Entry-proofness and discriminatory pricing under adverse selection

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 market

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 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

The social costs of side trading

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