Characterization of a class of moral-hazard, adverse selection games

Studying a principal-agent game in which the agent alone observes the state of the world and reports it, but the moral hazard is not reducible, shows that, if the principal uses all signals, then no solution exists, i.e. there is no contract that elicits truth-telling and motivates the agent to exert effort. When the principal does not use signals on the state of the world that seem irrelevant, a solution exists in which some of the ex post signals on outcome are not used, even though they obey the informativeness condition of Holmstrom (Bell Journal of Economics, 1979, 10, 74–91).     

Dynamic market for lemons with endogenous quality choice by the seller

We analyze a dynamic market for lemons in which the quality of the good is endogenously determined by the seller. Potential buyers sequentially submit offers to one seller. The seller can make an investment that determines the quality of the item at the beginning of the game, which is unobservable to buyers. At the interim stage of the game, the information and payoff structures are the same as in the market for lemons. Our main result is that the possibility of trade does not create any efficiency gain if (i) the common discounting is low, and (ii) the static incentive constraints preclude the mutually agreeable ex-ante contract under which the trade happens with probability one. Our result does not depend on whether the offers by buyers are private or public.     

Collusion and group lending with adverse selection

In an environment with correlated returns, this paper characterizes optimal lending contracts when the bank faces adverse selection and borrowers have limited liability. Group lending contracts are shown to be dominated by revelation mechanisms which do not use the ex post observability of the partners' performances. However, when collusion between borrowers under complete information is allowed, group lending contracts are optimal in the class of simple revelation mechanisms (which elicit only the borrower's own private information) and remain useful with extended revelation mechanisms.     

Screening risk-averse agents under moral hazard: single-crossing and the CARA case

Principal-agent models of moral hazard have been developed under the assumption that the principal knows the agent's risk-aversion. This paper extends the moral hazard model to the case when the agent's risk-aversion is his private information, so that the model also exhibits adverse selection. We characterize the optimal menu of contracts; while its detailed properties depend on the setting, we show that some of them must hold for all environments. In particular, the power of incentives always decreases with risk-aversion. We also characterize the relationship between the outside option and the optimal contracts. We then apply our results to testing for asymmetric information in insurance markets.The authors thank P.A. Chiappori, D. de Mezza, R. Myerson, C. Prendergast, the late S. Rosen, D. Webb and an anonymous referee for helpful discussions or comments, as well as seminar participants in Berkeley, Chicago, Montré al, Northwestern, Rome, Stanford and Wisconsin. Bruno Jullien gratefully acknowledges financial support from the Fédération Francaise des Sociétés d'Assurance; Bernard Salanié thanks the University of Chicago for its hospitality.     

Insurance contracts with imprecise probabilities and adverse selection

Summary. This article deals with optimal insurance contracts in the framework of imprecise probabilities and adverse selection. Agents differ not only in the objective risk they face but also in the perception of risk. In monopoly, a range of configurations that VNM preferences preclude appears: a pooling contract may be optimal, incomplete coverage may be offered to high risks, low risks may be better covered.Received: 1 November 2001, Revised: 15 April 2003, JEL Classification Numbers: D81, D82, G22.Useful suggestions by Emmanuelle Auriol, Bernard Bensaïd, Michéle Cohen, Isaac Meilijson and the anonymous referee are acknowledged. Correspondence to: M. Jeleva     

General equilibrium in economies with adverse selection

We model economies of adverse selection as Arrow–Debreu economies. In the spirit of Prescott and Townsend (Econometrica 52(1), 21–45, 1984a), we identify the consumption set of the individuals with the set of lotteries over net transfers. Thus, prices are linear in lotteries, but they may be non linear in commodity bundles. First, we study a weak equilibrium notion by viewing the economy of adverse selection as a pure exchange economy. The weak equilibrium set is non empty, but some of the allocations may be inefficient, and the equilibria indeterminate. Second, following Prescott and Townsend (Econometrica 52(1), 21–45, 1984a), we introduce an intermediary (firm) supplying feasible and incentive compatible measures. Equilibria are constrained efficient, but the equilibrium set is empty for an open set of economies containing the Rothschild and Stiglitz insurance economies. The research of A. Rustichini was supported by the NSF grant NSF/SES-0136556.     

Assortative matching, adverse selection, and group lending

This note reconsiders a theoretical result asserted to explain the success of group lending programs in LDCs. It has been claimed that if groups are allowed to form themselves, risky and safe borrowers will sort themselves into relatively homogenous groups. This “positive assortative matching” can be exploited by lenders to solve an adverse selection problem that would otherwise undermine the effectiveness of such lending programs. I show that the positive assortative matching result does not necessarily hold if earlier models are extended to incorporate dynamic incentives.     

Liquidity supply and adverse selection in a pure limit order book market

This paper analyzes adverse selection costs and liquidity supply in a pure open limit order book market. We relax assumptions of the Glosten/Såndas modeling framework regarding marginal zero profit order book equilibrium and the parametric market order size distribution. We show that using average zero profit conditions considerably increases the empirical performance while a nonparametric specification for market order size combined with marginal zero profit conditions does not. A cross sectional analysis corroborates the finding that adverse selection costs are more severe for smaller capitalized stocks. We also find additional support for one of the central hypothesis put forth by the theory of limit order book markets, which states that liquidity supply and adverse selection costs are inversely related. Furthermore, adverse selection cost estimates based on our structural model and those obtained using popular model-free methods are strongly correlated. This indicates the robustness of the theory-based approach.     

Equilibrium in a decentralized market with adverse selection

Summary. This paper deals with trade volume and distribution of surplus in markets subject to adverse selection. In a model where two qualities of a good exist, I show that if trade is decentralized (i.e. conducted via random pairwise meetings of agents), then all units of the good are traded, and all agents have positive ex-ante expected payoffs. This feature is present regardless of the quality distribution, and persists in the limit as discounting is made negligible. This offers a sharp contrast to models of centralized trade with adverse selection (Akerlof, Wilson). Received: April 2, 2001; revised version: March 29, 2002 RID="*" ID="*" This research was funded by a grant from UQAM. I wish to thank Roberto Serrano and seminar participants at UQAM, Queen's University at Kingston, the 2001 CEME General Equilibrium Conference (Brown University), and the 2001 North American Summer Meeting of the Econometric Society (University of Maryland) for comments.     

二级供应链中代理人的甄别与激励研究

文章分析了由一个制造商与一个分销商所组成的二级供应链中,既存在契约签订之前的逆向选择问题又存在契约签订之后的道德风险问题这一情况下,制造商对分销商的类型甄别及努力激励的机制设计问题。主要得到以下结论：①制造商可以通过努力收益分享的方式激励销售商投入最优的努力水平,进而规避道德风险行为。②制造商通过设计一组激励相容机制可以达到甄别分销商类型的目的,但必须支付给高销售能力分销商一定的租金。③高销售能力分销商的销量水平不存在扭曲,而低销售能力分销商的销量水平向下扭曲,其原因在于制造商降低给低销售能力分销商规定的销量就能够降低支付给高销售能力分销商的信息租金。文章从供应链中逆向选择与道德风险共存的角度对供应链委托代理关系进行研究,得出结论为供应链中的委托代理双方提供了一定的决策依据。     

Exporting to bypass weak institutions

Institutions have been shown to be important for trade and growth. In particular, weak institutions may reduce the returns to product quality, harming domestic welfare and making it attractive to export to countries with strong institutions where quality is better rewarded. We model this alternative story as to why the “good apples are shipped out” and explore whether exporting ameliorates the problems created by weak institutions. We find that, instead, because home prices do not reflect the marginal value of quality, access to developed markets can be welfare reducing. Specifically, there are always export prices such that total welfare (and not just consumer welfare) is harmed by exporting. Furthermore, if the domestic price equilibrates to the export price, then the marginal unit exported reduces total welfare. Exporting can even reduce producer surplus, leading to a contraction of the export industry; although, welfare can decrease even if production of the exported good increases. Thus, our results reinforce the importance of strengthening institutions to help the development of economies.     

存款保险制度的实施是否促进金融秩序的稳定--一个实证分析

本文采用Logit回归方法对61个国家1980～2002年间存款保险制度对金融稳定的影响关系进行了实证分析.实证结果说明在较完善的制度监管环境下存款保险制度的实施有利于金融稳定,并且设置合理的组成内容也可促进存款保险制度发挥对金融稳定的积极作用.     

成交风险、交易成本、逆向选择风险与投资者订单选择

本文利用多元对教条件自田归计数模型讨论了交易概率、交易成本以及选择成本等市场微观结构因素对中国证券市场投资者订单选择的影响.实证研究发现:(1)交易成本的增加会削弱投贵者递交指令的积极性,当成交风险较大时,投资者更偏好市价订单;(2)由于中国证券市场订单类型较为单一,逆向选择风险对投资者订单选择行为并无显著性的影响;(3)在同质信息的驱动下不同类型订单之间具有显著的持续和交叉相关性.     

Minimum standards, insurance regulation and adverse selection: evidence from the Medigap market

This paper examines the implications of minimum standards for insurance markets. I study the imposition of binding minimum standards on the market for voluntary private health insurance for the elderly. The central estimates suggest that the introduction of the standards was associated with an 8 percentage point (25%) decrease in the proportion of the population with coverage in the affected market, with no evidence of substitution toward other, unregulated sources of insurance coverage. To explore possible factors contributing to the impact of the minimum standards, I develop comparative static predictions of the impact of imposing minimum standards in an insurance market with adverse selection. The observed changes in market equilibrium associated with the minimum standards are broadly consistent with these predictions, providing evidence of the existence of adverse selection in this insurance market. More importantly, they suggest that the presence of adverse selection—which in principle may provide an economic rationale for minimum standards—in practice may have exacerbated the declines in insurance coverage associated with the minimum standards.     

Modelling countervailing incentives in adverse selection models: A synthesis

This paper is concerned with countervailing incentives in the adverse selection problems that typically arise in principal-agent relationships when the agent has private information. These incentives are present when the agent is tempted to either overstate or understate his private information depending upon the specific realization of his type. These problems were first analyzed by Lewis and Sappington (1989) and have been characterized and extended by Maggi and Rodríguez-Clare (1995a) and Jullien (2000). In this paper we propose a simple method of characterizing countervailing incentives in which the key element is the analysis of the properties of the full information problem. Our method for solving the principal problem, once identified the presence of countervailing incentives, follows closely the Baron’s (1989) approach, which does not require using optimal control theory. The methodology we present can be easily applied to many different economic settings. For example, in health economics, an insurer (or a hospital manager) might act as a principal and a physician as an agent. In labor settings, an employer may play the role of principal and a worker may act as the agent. In regulated industries, the regulatory agency might act as a principal designing incentive schemes for firms (the agents). In environmental regulation or resource exploitation, the principal might be an international agency dealing with national governments or firms.     

An evolutionary analysis of insurance markets with adverse selection

The equilibrium nonexistence problem in Rothschild and Stiglitz's insurance market is reexamined in a dynamic setting. Insurance firms are boundedly rational and offer menus of insurance contracts which are periodically revised: profitable competitors' contracts are imitated and loss-making contracts are withdrawn. Occasionally, a firm experiments by withdrawing or innovating a random set of contracts. We show that Rothschild and Stiglitz's candidate competitive equilibrium contracts constitute the unique long-run market outcome if innovation experiments are restricted to contracts which are sufficiently “similar” to those currently on the market.     

Contests to become CEO: incentives, selection and handicaps

Should a firm favor insiders (handicap outsiders) when selecting a CEO? One reason to do so is to take advantage of the contest to become CEO as a device for providing current incentives to employees. An important reason not to do so is that this can reduce the ability of future CEOs and, hence, future profits. The trade-off between providing current incentives and selecting the most able individual to become CEO is the focus of this paper. If insiders are good enough (better or nearly as good as outsiders), incentive provision to insiders typically dominates and it is optimal to handicap outsiders, sometimes so severely that they have no chance to win the contest. However, if outsiders are sufficiently better than insiders, selection dominates and it is the insiders who are severely handicapped. This finding is in sharp contrast to the existing literature which has so far ignored this trade-off. In all, our model provides useful insight into contests to become CEO and rationalizes empirical regularities in the source of CEOs chosen by firms. In particular, our analysis helps to explain the lower tendency of firms in more heterogeneous industries and firms with a product or line of business organizational structure to select an outsider as CEO.     

Ex post participation constraint in a principal–agent model with adverse selection and moral hazard

This paper analyzes optimal contracting when an agent has private information before contracting and exerts hidden effort that stochastically affects the output. Additionally, the contract is constrained to satisfy the agentʼs ex post participation. We highlight three features of this model. First, the agent faces countervailing incentives. Second, the separation of types is never optimal. Third, the optimal constant bonus rewarding success is distorted downward below its efficient level.     

Signaling in markets with two-sided adverse selection

Summary. The paper analyzes an economy with two-sided adverse selection, focusing on equilibria that satisfy a refinement based on the notion of strategic stability. In the familiar case of one-sided adverse selection, agents reveal all of their private information as long as the contract space is rich enough. However, with two-sided adverse selection, the sufficient conditions for separation are much stronger. Received: September 3, 1999; revised version: December 3, 1999     

Capacity constrained firms in (labor) markets with adverse selection

Summary. We discuss a competitive (labor) market where firms face capacity constraints and individuals differ according to their productivity. Firms offer two-dimensional contracts like wage and task level. Then workers choose firms and contracts. Workers might be rationed if the number of applicants exceeds the capacity of the firm. We show that under reasonable assumptions on the distribution of capacity an equilibrium in pure strategies (by the firms) exists. This result stands in contrast to the case of unlimited capacity. The utility level is uniquely determined in equilibrium. No rationing occurs in equilibrium, but it does off the equilibrium path. Received: December 29, 1999; revised version: November 30, 2000