Efficient markets and Bayes’ rule

Summary. A series of financial anomalies motivated the development of new theories that modify the rational expectations ideal. Two possibilities have been systematically explored. The literature on behavioral finance relaxes the assumption that agents form beliefs according to the laws of probability and assume, instead, that simpler heuristic rules are used. Another stream of the literature assumes that agents process information according to Bayes rule, but do not posses sufficient information to know the true data generating process. In this paper, Bayesian and Behavioral agents coexist and trade in a standard dynamic asset pricing model. A long-standing conjecture is demonstrated. It is shown that, under suitable assumptions, Bayesian agents drive Behavioral, non-Bayesian agents out of the market. Hence, asset prices are eventually determined under the Bayesian paradigm.Received: 3 June 2004, Revised: 17 September 2004, JEL Classification Numbers: D83.Preliminary versions have circulated under the titles Markets Favor Bayesian Models and Market Selection of Empirical Models under Limited Information. I thank Larry Blume, David Easley, Larry Epstein, Armando Gomes, Bruce Hansen, Lars Hansen, Richard Kihlstrom, Grace Koo, George Mailath, Werner Ploberger, Andrew Postlewaite and Shakeeb Khan for useful comments. I also thank participants at the NBER GE meetings, Evolutionary Finance conference in Zurich, Latin American Meetings of the Econometric Society, Stanford Institute for Theoretical Economics, the Instituto de Matematica Pura e Aplicada, the theory seminar at Brown, Chicago, Harvard-MIT, Minnesota, Penn and Wisconsin. I gratefully acknowledge the financial support from the National Science Foundation Grant SES 0109650.     

Perpetual youth and endogenous labor supply: A problem and a possible solution

In the “perpetual youth” overlapping-generations model of Blanchard and Yaari, if leisure is a “normal” good then some agents will have negative labor supply. We suggest a solution to this problem by using a modified version of Greenwood, Hercowitz and Huffman’s utility function. The modification incorporates real money balances, so that the model may be used to analyze monetary as well as fiscal policy. In a Walrasian version of the economy, we show that increased government debt and increased government spending raise the interest rate and lower output, while an open-market operation to increase the money supply lowers the interest rate and raises output.     

Wealth and sustainable development: the role of David Pearce

Green net national product was thought to be one way of measuring sustainable income. However, David Pearce understood that a better measure of sustainable development was to look at what a generation is leaving in form of capital assets to later generations. In this article, his arguments and insights are highlighted against recent theoretical advances.     

上市公司控制权转移的财富效应分析

上市公司控制权的转移会改变投资者对目标公司的预期,从而引起目标公司股价的变化,进而使得目标公司股东的财富发生变化。本文采用事件研究法,分行业对2002年我国资本市场上第一大股东发生变更的目标方公司股东财富进行了实证研究。结果表明:对于整个资本市场而言,控制权转移能为目标公司带来显著的财富增加;而对于不同行业控制权转移的财富效应存在着较大的差别,只有原材料企业在公告日前可以获得显著的正财富效应,而工业企业和消费企业的财富效应并不明显。     

持续发展中代际财富转移简单模型

代际均衡发展是持续发展论的主要内容之一，其中代际财富转移和贴现率应用是其核心内容。本文探讨了一个代际财富转移的简单模型，并采用人们熟悉的柯布──道格拉斯函数形式表达。模型的敏感因素为利息率、工资和自然资源价格，并且是由代际间的跨代收入分配决定的。贴现率等于同期利息率，其水平是变动的。     

城镇居民金融资产与不动产财富效应的比较分析

城镇居民两种资产的财富效应呈现三个特点:一是住房资产的财富效应大于金融资产的财富效应;二是两种资产的财富效应差别不大;三是两种资产的财富效应较微弱。这表明:第一,住房对消费具有一定的支撑作用;第二,金融资产增值性不强和股市的波动限制财富效应的发挥;第三,较强的流动性约束制约住房资产的财富效应;第四,消费的过度敏感性使资产财富效应微弱。为了通过财富效应来促进消费,必须维持股市和房地产市场稳定的预期,大力发展金融市场,抑制住房价格的过快增长并促进住房市场平稳发展。     

社会保障制度对财富分配的影响以及在避免贫富差距进一步加大的作用

伴随着经济的增长,贪富差距逐渐加大和财富朝少数人集中是当今社会中出现的一个现象。在本文中,我们基于财富分布是随机性的这个一般性假设,探讨了在经济增长过程中财富分布的最可几状态。通过对财富在随机状态下的分布函数的建立,证明了如果只考虑人均收入时,财富会以负指数函数的方式作为财富分布的最可几态。并且,随着人均财富的增加,贪富差距不仅不能减小,反而还有扩大的趋势,财富会朝着少数人更集中。如果不仅考虑人均收入（算术平均）,还同时考虑几何平均的话。随着经济增长的同时,由于几何平均是不能容许零或负的财富值存在,这正是社会保障系统所起到一个作用。在这种情况下,财富的分布会呈Gamma分布。在Gamma分布中,财富将集中在大多数人中,财富多或财富少的人数在社会总人数中所占的密度较小。     

我国居民消费财富效应的实证研究

基于1998年1月至2007年10月的我国居民消费、股票市场和房地产市场有关数据,运用协整方程、误差修正模型和Granger因果检验方法,对我国居民消费的财富效应进行了实证研究.实证分析表明,我国不存在股票市场的财富效应,通过股票市场刺激消费的政策无效;我国存在房地产市场的财富效应,长期房地产市场发展与居民消费有协同趋势,短期内房地产市场发展抑制居民消费支出.     

我国资产价格与通货膨胀的关系研究——基于ARDL的技术分析

随着资产市场投资品种日益丰富,居民参与资产投资的程度不断深入,资产通过财富效应和投资效应对经济的影响越来越大,资产价格对一般物价水平的影响不断增强,因此资产价格波动是否会影响通货膨胀率就成为当前理论和实务界关注的焦点。为了检验我国资产价格与通货膨胀的关系,本文选择股票、汇率、房地产价格以及其他影响通货膨胀的因素,运用ARDL模型对我国资产价格和通货膨胀的关系进行经验分析。经验分析结果表明:资产价格波动影响通货膨胀,但各因素对通货膨胀的影响差异较大,即房地产价格和汇率两个指标作用显著,股票作用较弱。     

Wealth effects and agency costs

We analyze how the agent's initial wealth affects the principal's expected profits in the standard principal–agent model with moral hazard.We show that if the principal prefers a poorer agent for all specifications of action sets, probability distributions, and disutility of effort, then the agent's utility of income must exhibit a coefficient of absolute prudence less than three times the coefficient of absolute risk aversion for all levels of income, thus strengthening the sufficiency result of Thiele and Wambach (1999). Also, we prove that there is no condition on the agent's utility of income alone that will make the principal prefer richer agents. Moreover, we show that, for an interesting class of problems, the principal prefers a relatively poorer agent if agent's wealth is sufficiently large. Finally, we discuss how alternative ways of modeling the agent's outside option affects the principal's preferences for agent's wealth.