PORTFOLIO MANAGEMENT WITH TRANSACTION COSTS: AN ASYMPTOTIC ANALYSIS OF THE MORTON AND PLISKA MODEL

We examine the Morton and Pliska (1993) model for the optimal management of a portfolio when there are transaction costs proportional to a fixed fraction of the portfolio value. We analyze this model in the realistic case of small transaction costs by conducting a perturbation analysis about the no-transaction-cost solution. Although the full problem is a free-boundary diffusion problem in as many dimensions as there are assets in the portfolio, we find explicit solutions for the optimal trading policy in this limit. This makes the solution for a realistically large number of assets a practical possibility.     

Demography and welfare economics

The focusing on demographic issues as an important part of welfare-economic assessment shifts the evaluative space in the direction of public discussion and social concern. A commoditycentred view of individual success and social welfare is often used in economics. But the linkage between our economic wealth and our ability to live as we would like has strong limits. This is partly because of interpersonal variations between individuals, but also because of variations in public and social arrangements (for example, for public health care, education and social security). The use of demographic perspectives can enrich economic analysis in several ways. In particular a demographically oriented system of evaluation can not only focus on variables that we all value, but it also gives us the freedom to decide what weights would be most appropriate for the exercise in which we might be engaged. The problem of valuation in welfare economics is ultimately a social-choice issue, requiring the use of explicit judgments on which the society can achieve some consensus through political processes.Lecture presented to the annual meeting of the Austrian Economic Association in Vienna, 24 May 1994. The author is grateful for support from the National Science Foundation for the research on which this paper draws.     

A note on linear utility

Summary We show that any complete, lower-semicontinuous, and translation-invariant preorder defined on a topological vector space admits a linear and continuous utility representation.Thanks are given to an anonymous referee for his/her valuable suggestions and comments.     

Transaction cost economics in practice: Applications and evidence

Transaction cost economics (TCE) has been criticized for presenting an undersocialized view of human nature, for confusing cause and effect, and for being ad hoc. This article attempts to rebut the last charge by reviewing a large body of empirical evidence on contracting and economic organization. Specifically, we maintain that enough empirical work has been carried out to shift the burden of persuasion to TCE's skeptics. As we show, the empirical evidence lines up remarkably well with the logic of organization described by TCE. After a conceptual and methodological review, we survey a range of studies on vertical integration (including forward integration into marketing and distribution), complex contracts and hybrid modes of organization, transfer pricing, and multinational corporations. We conclude with a discussion of the implications of TCE for business organization.This paper draws on material in Shelanski and Klein, 1995.     

改革开放以来我国税制结构的演进特征及趋向

改革开放30年来,我国已逐渐形成以增值税为代表的流转税类为第一主体税种,以企业所得税为代表的所得税类为第二主体税种的"双主体"税制结构。从税收全球化的角度来看,我国税制结构的演化势必会遵循发达国家的演进路径,即,所得税取代流转税成为我国第一大税类,最终进入以所得税为主体的时代。     

基于信息修正的非期望效用模型

人们对事件发生的可能性存在着主观判断。在不同的概率区间,人们对概率变化的敏感度是不一样的。传统的期望效用理论忽视了决策者对概率的主观反应,无法准确描述风险决策行为。基于信息修正的非期望效用模型,将客观概率转换成主观决策权重,可以弥补期望效用模型在捕捉决策者对概率主观反应方面的缺陷;同时,利用基于信息修正的非期望效用模型,通过量化人们在购买保险或股票时对风险的主观概率判断,可以对人们的保险需求和证券投资行为作出更好的解释或预测。     

论交易效率对分工演进的影响

交易作为人类经济生活中最基本的活动之一,在国民经济中的影响日益增大,相应地带来了交易费用理论的蓬勃发展,但传统交易费用理论的许多不足严重制约了它在经济分析中的有效应用,其中主要的两点不足表现在:一是交易费用的概念过于庞杂、笼统;二是交易费用的概念更多地是被应用于企业理论的研究之中,应用于经济结构变迁、长期经济增长等宏观理论领域的研究较少.从分工演进的角度较为明确地提出了交易效率的概念,并在此基础上进一步探求交易效率影响分工演进所带来的经济结构变迁的内在机理.     

Jensen’s Inequality in Finance

The purpose of this paper is to measure the size and the statistical significance of three inequalities in the field of financial economics. The three are variants of Jensen’s inequality. The first inequality is a comparison of the expected value of a ratio to the ratio of the expected value, a problem that arises in pricing foreign exchange rates. The second is a comparison of the log of the expected value to the expected value of the log, a problem that arises in testing forward market efficiency, money demand, production functions, and trade gravity models. The third is a comparison of the expected utility to the utility of the expected value, and helps in determining the importance of the expected utility paradigm, and the magnitude of the equity risk premium. The methodology used is by simulation of random normal variables, thereby introducing sampling error. Despite this sampling error the conclusion is general: all three inequalities are economically material, and stand statistically as inequalities. The major conclusion is that Jensen’s inequality is not a theoretical and superfluous exercise in finance as some have advocated.

有关交易成本测度的评述

本文在回顾交易成本测度文献的基础上对直接交易成本研究方式提出了如下见解:交易的概念经Williamson的转换后,实际上不再要求交易主体与交易对象的产权关系以及产权关系的转移,也放弃了市场这个参照系.面对越来越复杂的研究对象,直接交易成本测度研究因跟从了交易概念转换而引致交易成本的概念扩展.在测度的实际研究中,交易成本面临主体的转换、内涵的变化和配置效果的明显差异,使得交易成本的比较意义不明晰.