逆向选择条件下带奖惩金的两期保险契约模型及其Pareto改进性研究

为了更有效的规避影响保险市场交易效率的逆向选择问题,本文分投保人风险类型为两种和多种情形建立了带奖惩金的两期保险契约模型,首次提出可以用奖励金和惩罚金有效甄别投保人的风险类型。该模型根据投保人第一个保险期内的索赔情况在第二个保险期对其进行奖励或惩罚,高风险类型的投保人如果选择为低风险类型投保人设计的保险契约,则其在第二阶段受到惩罚的概率要远远大于得到奖励的概率,即风险越高的投保人越害怕惩罚金,因此所建模型满足斯彭斯-莫里斯分离条件。带奖惩金的两期保险契约模型中保险公司的期望利润仍然为0,并不会给投保人带来额外的经济负担,却能够实现对传统部分保险契约简单重复两次的严格帕累托改进。最后采用一个算例说明了该模型的有效性。     

机构投资者信息搜寻、公开信息透明度与私有信息套利

本文利用特有的机构投资者私有信息搜寻数据,研究了机构投资者的信息搜寻、透明度与私有信息套利的关系。本文的研究发现,机构投资者的信息搜寻和信息披露的透明度降低了私有信息套利,而且机构投资者信息搜寻、信息披露透明度在私有信息套利严重的公司对降低私有信息套利的作用更加明显。同时,本文的研究结果也表明,机构投资者信息搜寻与信息披露透明度对私有信息套利存在交互效应,随着信息披露透明度的提高,机构投资者信息搜寻对私有信息套利的边际效应下降。     

Strategic Supply Function Competition With Private Information

A finite number of sellers (n) compete in schedules to supply an elastic demand. The cost of each seller is random, with common and private value components, and the seller receives a private signal about it. A Bayesian supply function equilibrium is characterized: The equilibrium is privately revealing and the incentives to rely on private signals are preserved. Supply functions are steeper with higher correlation among the cost parameters. For high (positive) correlation, supply functions are downward sloping, price is above the Cournot level, and as we approach the common value case, price tends to the collusive level. As correlation becomes maximally negative, we approach the competitive outcome. With positive correlation, private information coupled with strategic behavior induces additional distortionary market power above full information levels. Efficiency can be restored with appropriate subsidy schemes or with a precise enough public signal about the common value component. As the market grows large with the number of sellers, the equilibrium becomes price‐taking, bid shading is on the order of 1/n, and the order of magnitude of welfare losses is 1/n². The results extend to inelastic demand, demand uncertainty, and demand schedule competition. A range of applications in product and financial markets is presented.     

Moral Hazard Contracting and Private Credit Markets

This paper studies the impact of credit markets on optimal contracting, when the agent's “interim preference” over upcoming contracts is private information because personal financial decisions affect it via the wealth effect. The main result is a severe loss of incentive provision: equilibrium contracts invariably cause the agent to shirk (i.e., exert minimal effort) if the agent's private financial decision precedes moral hazard contracting. The basic intuition is that committing on another private variable, other than the effort level, exposes the parties to further exploitation of efficient risk‐sharing by relaxing the incentive constraint that was binding ex ante, unless the risk‐sharing was fully efficient to begin with.     

强制性约束下企业信息安全投资与网络保险的最优决策分析

研究了强制性约束下企业信息安全投资和网络保险的最优决策问题,对比了可观测企业损失和不可观测企业损失两种情形下基于破产概率约束的最优安全投资和网络保险保费厘定。研究结果表明：在可观测损失和公平保费情况下,当最大化单个企业的期望效用时,存在最优安全投资额,并且政府补贴和强制性约束都可以激励企业增加安全投资;但是当最大化所有企业效用时,只有强制性约束才能增加企业安全投资使得总效用最大化,并且企业的最优安全投资与损失的可观测程度无关。在不可观测损失情况下,当最大化单个企业期望效用时,企业的安全投资增大,而最大化所有企业效用时,存在正网络外部性,即任何企业均不敢轻易的减少安全投资,即使同在一个网络中的其他企业减少了安全投资。此外,在破产概率约束下,随着保费的增加,当损失可观测时,企业的安全投资也增加,但期望效用减少了;而当损失不可观测时,企业的安全投资和期望效用均减少。本文所得结论对政府设定强制性标准,以及企业利用安全投资和网络保险进行信息安全风险控制具有较好的参考价值。     

代理人信息租金抽取的贝叶斯优化与配置效率均衡分析

研究逆向选择下,委托人通过信号辅助改善信息结构后所面临的代理人信息租金抽取与配置效率的均衡决策问题。首先,分析讨论了完全信息下的最优契约和逆向选择下先验分布基础上的次优契约;之后,基于贝叶斯规则,将与代理人相关的外部信号及信号搜集成本纳入委托人的最优规划问题,对后验分布下的均衡变动进行了分析,给出了信号搜集成本可行预算集。研究表明,贝叶斯方法有利于委托人在信息租金与效率扭曲冲突中优化决策,为复杂环境下的实务契约设计逼近激励相容契约提供了量化参考依据。     

The Role of Insurance in Managing Natural Hazard Risks: Private Versus Social Decisions

We explore the interaction between individual and collective decisions concerning natural hazards. Collective actions such as building a dam change the risks faced by private individuals. We show that, with proper incentives, individual reactions to such changes in risk can serve to enhance risk management by utilizing individual's decisions to take account of their specialized knowledge about their risk preferences and losses. We demonstrate that the efficient response to construction of a dam may be private actions that lead to a fully anticipated increase in flood damage. In such instances, zoning that focuses on reducing flood damage may lead to less efficient use of the flood plain. More generally, even where incentives for underinvestment in market insurance and self-insurance are present, constraining use of the flood plain by zoning will not generally lead to efficient outcomes. The model identifying conditions under which informed individuals have the incentives to make efficient decisions is powerful and directs attention toward more fruitful approaches.     

不对称信息下创新产品研发外包的甄别契约设计

在创新产品研发过程中,许多企业会将部分研发模块外包,而接包方能力水平和成本信息的不对称,会给发包方带来收益风险。对此采用委托代理理论中的信息甄别模型,将研发的接包方分为高成本系数和低成本系数两类,由创新企业设计包含固定支付和收益共享系数两个参数的外包甄别契约,来推断其真实能力。通过考虑创新研发成功的概率因素和技术成果转化后的市场收益分成,以激励接包方做出最优的努力。研究结果表明：高成本系数接包方的收益共享系数将被向下扭曲,低成本系数接包方既获得了保留效用,还会得到额外的信息租金;契约中两类参数的取值受到不同类型接包方所占比例的影响,随着市场中高成本系数企业数量的增加,发包方的期望收益降低。     

信号成本与服务外包供应商信号传递关系的博弈模型

由于服务外包市场的信息不对称性和不完美性,外包商难以清楚了解供应商的能力,使得服务外包供应商选择市场出现逆向选择。为解决非对称信息条件下服务外包供应商选择市场运行的低效问题,本文利用信号博弈建立了信号成本与外包供应商信号传递关系的数学模型,并通过案例分析说明了该模型对管理的指导意义。     

羊群效应与内幕信息的揭示分析

本文用金融市场微观结构模型的序贯交易框架分析了证券市场上的多维不确定性怎样引起投资者的羊群交易行为。结论表明当市场上存在事件不确定和信息精度不确定时,投资者之间可能发生羊群行为,这种行为会导致内幕信息在一段时间内得不到有效揭示。做市商在发生羊群效应期间虽然只能判断出事件的存在性,而无法学习到内幕信息的好坏和精度,但他仍会继续调整资产的价格并最终结束羊群效应。     

需求信息不对称下基于战略库存的信息披露与契约选择

在考虑市场需求信息为零售商私有信息的基础上,研究了制造商和零售商之间的两阶段动态博弈问题,其中零售商进行信息披露和战略库存决策,而制造商则决定合适的批发价格承诺契约或动态契约。通过对比分析信息披露与不披露两种情形下不同定价契约的博弈均衡决策及供应链各方利润,发现：零售商在实际市场规模小于其均值时披露需求信息、大于其均值时不披露需求信息;无论零售商是否披露信息,制造商通过使期望利润最大化,始终会选择动态定价契约;信息不披露条件下,若单位库存持有成本大于某一阈值或实际市场规模小于某一阈值,零售商则不会持有战略库存。最终通过数值分析,发现零售商的披露决策总能使供应链的总体利润增加;且信息不披露条件下零售商第一阶段的订货量以及战略库存持有量都要高于信息披露情形,而制造商两阶段的定价始终小于信息披露情形。     

基本医疗保险中共谋问题的研究与防范

本文首先讨论了在我国当前实行的基本医疗保险体系中患者和医疗机构为了共同的利益,利用信息优势,形成共谋来欺骗医疗保险机构的可能性。然后在建立基本医疗保险体系的简单模型的基础上,分析了医患共谋产生的情况,详细讨论了有效防止医患共谋的保险合同的设计问题,并且得出了此类保险合同所具有的一系列基本特性。     

Waiting for News in the Market for Lemons

We study a dynamic setting in which stochastic information (news) about the value of a privately informed seller's asset is gradually revealed to a market of buyers. We construct an equilibrium that involves periods of no trade or market failure. The no‐trade period ends in one of two ways: either enough good news arrives, restoring confidence and markets reopen, or bad news arrives, making buyers more pessimistic and forcing capitulation that is, a partial sell‐off of low‐value assets. Conditions under which the equilibrium is unique are provided. We analyze welfare and efficiency as they depend on the quality of the news. Higher quality news can lead to more inefficient outcomes. Our model encompasses settings with or without a standard static adverse selection problem—in a dynamic setting with sufficiently informative news, reservation values arise endogenously from the option to sell in the future and the two environments have the same equilibrium structure.     

Adverse Selection in Competitive Search Equilibrium

We study economies with adverse selection, plus the frictions in competitive search theory. With competitive search, principals post terms of trade (contracts), then agents choose where to apply, and they match bilaterally. Search allows us to analyze the effects of private information on both the intensive and extensive margins (the terms and probability of trade). There always exists a separating equilibrium where each type applies to a different contract. The equilibrium is unique in terms of payoffs. It is not generally efficient. We provide an algorithm for constructing equilibrium. Three applications illustrate the usefulness of the approach, and contrast our results with those in standard contract and search theory.     

The Effects of Health Insurance and Self‐Insurance on Retirement Behavior

This paper provides an empirical analysis of the effects of employer‐provided health insurance, Medicare, and Social Security on retirement behavior. Using data from the Health and Retirement Study, we estimate a dynamic programming model of retirement that accounts for both saving and uncertain medical expenses. Our results suggest that Medicare is important for understanding retirement behavior, and that uncertainty and saving are both important for understanding the labor supply responses to Medicare. Half the value placed by a typical worker on his employer‐provided health insurance is the value of reduced medical expense risk. Raising the Medicare eligibility age from 65 to 67 leads individuals to work an additional 0.074 years over ages 60–69. In comparison, eliminating 2 years worth of Social Security benefits increases years of work by 0.076 years.     

Optimal Mandates and the Welfare Cost of Asymmetric Information: Evidence From the U.K. Annuity Market

Much of the extensive empirical literature on insurance markets has focused on whether adverse selection can be detected. Once detected, however, there has been little attempt to quantify its welfare cost or to assess whether and what potential government interventions may reduce these costs. To do so, we develop a model of annuity contract choice and estimate it using data from the U.K. annuity market. The model allows for private information about mortality risk as well as heterogeneity in preferences over different contract options. We focus on the choice of length of guarantee among individuals who are required to buy annuities. The results suggest that asymmetric information along the guarantee margin reduces welfare relative to a first‐best symmetric information benchmark by about £127 million per year or about 2 percent of annuitized wealth. We also find that by requiring that individuals choose the longest guarantee period allowed, mandates could achieve the first‐best allocation. However, we estimate that other mandated guarantee lengths would have detrimental effects on welfare. Since determining the optimal mandate is empirically difficult, our findings suggest that achieving welfare gains through mandatory social insurance may be harder in practice than simple theory may suggest.     

筛选不同竞争类型零售商的贸易信用合同设计研究

考虑了信息不对称环境下资金约束供应链中贸易信用合同的设计问题。其中,零售商面临资金短缺困境,对自身的竞争类型具有信息优势;供应商愿意为资金短缺的零售商提供贸易信用。本文基于高低不同类型零售商的保留收益信息,将零售商的竞争环境分为三种类型,即高度竞争、适度竞争和低度竞争。据此,供应商应用筛选方法设计合同甄别不同竞争环境的零售商类型,提高自身和供应链的整体收益。研究还表明,在信息不对称的情况下,适度竞争环境中,贸易信用合同能实现供应链整体收益最大化。     

机构投资者私人信息、散户投资者情绪与IPO首日回报率

针对影响IPO首日回报率的一级市场与二级市场因素,本文将机构投资者的私人信息和散户投资者的情绪结合起来,以我国新股发行市场为背景建立模型,对IPO破发或抑价产生的微观机制给出一种理论上的解释。模型结论表明:IPO是否破发主要取决于散户投资者的情绪,而不是机构投资者的私人信息,并且散户投资者情绪越乐观,IPO破发的可能性就越小;同时发现IPO首日回报率与散户投资者情绪正相关,与机构投资者的私人信息负相关。以2010年11月至2013年12月在沪深交易所上市且披露网下具体报价情况的477家IPO公司为样本对模型进行实证检验,实证结果支持了模型结论。研究结果对于如何提高IPO发行效率提供了一些启示。     

Contracting and Coordination under Asymmetric Production Cost Information

We analyze a supply chain consisting of a supplier and a retailer. The supplier's unit production cost, which characterizes his type, is only privately known to him. When trading with the retailer, the supplier demands a reservation profit that depends on his unit production cost. We model this problem as a game of adverse selection. In this model, the retailer offers a menu of contracts, each of which consists of two parameters: the ordering quantity and the supplier's share of the channel profit. We show that the optimal contract depends critically on a surrogate measure—the ratio of the types’ reservation profit differential to their production cost differential. An important implication from our analysis is that information asymmetry alone does not necessarily induce loss in channel efficiency. The optimal contract can coordinate the supply chain as long as the low‐cost supplier's cost efficiency is neither much overvalued nor much undervalued in the outside market. We further discuss the retailer's preference of the supplier's type under different market conditions, as well as evaluate the effects of the supplier's reservation profit, the retail price, and the demand uncertainty on the optimal contract.