ON THE LOWER ARBITRAGE BOUND OF AMERICAN CONTINGENT CLAIMS

We prove that in a discrete‐time market model the lower arbitrage bound of an American contingent claim is itself an arbitrage‐free price if and only if it corresponds to the price of the claim optimally exercised under some equivalent martingale measure.     

基于农产品“最后一公里”流通模式的思考

为加快农产品流通、减少流通环节,降低农产品终端零售价格,解决"卖难买贵"的难题,最近各地推出了"平价商店"和"平价市场"两种新的农产品流通模式。在客观分析"平价商店"对抑制农产品价格效果的基础上,指出其存在的不足,并提出建立公益性农产品直销"零收费平价市场"流通模式的设想以及配套措施的建议。     

On the Pricing of Contingent Claims with Frictions

This paper studies the problem of pricing contingent claims in a market which has frictions in the form of costs, such as penalty functions corresponding to constraints. An arbitrage-free interval is identified, and a fair price based upon utility functions is proposed. It provides a framework to study incomplete markets that is simplier than the one related to constraints on portfolios introduced by Karatzas and Kou.     

Portfolio Optimization and Martingale Measures

The paper studies connections between risk aversion and martingale measures in a discrete-time incomplete financial market. An investor is considered whose attitude toward risk is specified in terms of the index b of constant proportional risk aversion. Then dynamic portfolios are admissible if the terminal wealth is positive. It is assumed that the return (risk) processes are bounded. Sufficient (and nearly necessary) conditions are given for the existence of an optimal dynamic portfolio which chooses portfolios from the interior of the set of admissible portfolios. This property leads to an equivalent martingale measure defined through the optimal dynamic portfolio and the index 0 < b ≤ 1. Moreover, the option pricing formula of Davis is given by this martingale measure. In the case of b = 1; that is, in the case of the log-utility, the optimal dynamic portfolio defines the numéraire portfolio.     

公充价值计量的估值方法和影响因素分析

建立公开的市场价格体系,优化市场资产的估价系统,使各种资产的市价很好地反映其真实价值。同时,充分发挥资产评估中中介、物价等机构应有的监管作用,建立起完善的监督、制约、平衡机制,防止利用公允价值进行造假;提高公允价值的可操作性,为公允价值全面应用提供保障。同时,加强计量理论研究,有利于公允价值在操作层面上的推广,从公充价值计量的估值方法和应用进行探讨,从而改善企业业绩,设计最优的路径。     

European‐Type Contingent Claims in an Incomplete Market with Constrained Wealth and Portfolio

This paper considers the problem of hedgeability and replicability of European‐type contingent claims in an incomplete market with the wealth and the portfolio possibly being constrained. For the case of no constraint, using the idea of a Four Step Scheme (Ma, Protter, and Yong 1994), we prove the replicability of a class of contingent claims (including European call and put options) without assuming ad hoc technical conditions. For the case with the wealth and portfolio being constrained, several positive and negative results concerning hedgeability and replicability are presented.     

Hedging under Transaction Costs in Currency Markets: a Continuous‐Time Model

We consider a general semimartingale model of a currency market with transaction costs. Assuming that the price process is continuous and the solvency cone is proper we prove a hedging theorem describing the set of initial endowments that allows the investor to hedge a contingent claim in various currencies by a self‐financing portfolio.     

Multidimensional Variance‐Optimal Hedging in Discrete‐Time Model—A General Approach

One of the well‐known approaches to the problem of option pricing is a minimization of the global risk, considered as the expected quadratic net loss. In the paper, a multidimensional variant of the problem is studied. To obtain the existence of the variance‐optimal hedging strategy in a model without transaction costs, we can apply the result of Monat and Stricker. Another possibility is a generalization of the nondegeneracy condition that appeared in a paper of Schweizer, in which a one‐dimensional problem is solved. The relationship between the two approaches is shown. A more difficult problem is the existence of an optimal solution in the model with transaction costs. A sufficient condition in a multidimensional case is formulated.     

A Simple Counterexample to Several Problems in the Theory of Asset Pricing

We give an easy example of two strictly positive local martingales that fail to be uniformly integrable, but such that their product is a uniformly integrable martingale. The example simplifies an earlier example given by the second author. We give applications in mathematical finance and we show that the phenomenon is present in many incomplete markets.     

Measuring product market efficiency: A new methodology

This paper proposes a new methodology to measure product market efficiency. Our approach is based on the economic theory of product market equilibrium where consumers have incomplete information, and it allows quality to be multidimensional. We illustrate the methodology and compare it with other methodologies including the data envelopment analysis (DEA)-based procedure of Kamakura, Ratchford, and Agrawal (1988). The empirical results show that our model is robust to the precise distributional form of the disturbance term. In addition, our efficiency estimates are always equal to or lower than the DEA estimates of efficiency.     

中国可转债发行的股权价值效应

本文运用Merton(1990)的或有索取权分析方法,对中国上市公司发行可转债行为对非流通股东和流通股东股权价值的不同影响作了深入的分析,得出如下结论:(1)在中国目前股权分割的情况下,无论可转债是否按照合理价格发行,原有流通股的价值都会减少;(2)在非流通股东占控股地位的情况下,它会选择折价发行并向全体股东配售这一对其最为有利而对流通股东最为不利的可转债发行方案。并在此基础上提出政策建议:修改可转债发行法规,规定可转债只能向原有流通股股东配售,不能向社会公众和非流通股股东配售。     

CONSUMPTION AND PORTFOLIO POLICIES WITH INCOMPLETE MARKETS AND SHORT-SALE CONSTRAINTS IN THE FINITE-DIMENSIONAL CASE: SOME REMARKS

This paper extends He and Pearson's (1991) martingale approach to the study of optimal intertemporal consumption and portfolio policies with incomplete markets and short-sale constraints to a framework in which no assumptions are made on the price process for the securities. We show how both their characterization of the budget-feasible set and duality result can be extended to account for an unbounded set II of Arrow-Debreu state prices compatible with the arbitrage-free assumption. We also supply a (fairly general) sufficient condition for II to be bounded, as required in their setting.     

Consumption and Portfolio Policies With Incomplete Markets and Short-Sale Constraints: the Finite-Dimensional Case1

We use a martingale approach to study optimal intertemporal consumption and portfolio policies in a general discrete-time, discrete-state-space securities market with dynamically incomplete markets and short-sale constraints. We characterize the set of feasible consumption bundles as the budget-feasible set defined by constraints formed using the extreme points of the closure of the set of Arrow-Debreu state prices consistent with no arbitrage, and then establish a relationship between the original problem and a dual minimization problem.     

MARKOWITZ'S PORTFOLIO OPTIMIZATION IN AN INCOMPLETE MARKET

In this paper, for a process S , we establish a duality relation between K_p , the     - closure of the space of claims in     , which are attainable by "simple" strategies, and     , all signed martingale measures     with     , where   p ≥ 1, q ≥ 1  and     . If there exists a     with     a.s., then K_p consists precisely of the random variables     such that ϑ is predictable S -integrable and     for all     . The duality relation corresponding to the case   p = q = 2  is used to investigate the Markowitz's problem of mean–variance portfolio optimization in an incomplete market of semimartingale model via martingale/convex duality method. The duality relationship between the mean–variance efficient portfolios and the variance-optimal signed martingale measure (VSMM) is established. It turns out that the so-called market price of risk is just the standard deviation of the VSMM. An illustrative example of application to a geometric Lévy processes model is also given.     

基于契约理论的企业利益相关者命题探析

现代企业契约理论对企业所有权分配的研究令人关注,并引起越来越多的争论。以前人的研究为基础,将剩余控制权进行了分割,提出企业所有权是剩余索取权与终极剩余控制权的融合体,并对所有权最优安排进行了讨论,认为股东拥有企业所有权是现实与理论逻辑的统一,利益相关者财富最大化目标理论基础并不可靠,实际操作更不现实。     

Value Preserving Strategies and a General Framework for Local Approaches to Optimal Portfolios

We present some new general results on the existence and form of value preserving portfolio strategies in a general semimartingale setting. The concept of value preservation is derived via a mean-variance argument. It is also embedded into a framework for local approaches to the problem of portfolio optimization.