Dynamic versus one-period completeness in event-tree security markets

We show that in event-tree security markets dynamic completeness does not coincide with one-period completeness unless the law of one price is explicitely assumed. We do so by means of a simple example of a dynamically complete market with an incomplete one-period sub-market.     

Arbitrage opportunities in frictionless markets with sophisticated investors

An example shows that when preferences change over time and consumers are sophisticated, it is possible that arbitrage opportunities exist in frictionless markets, even in equilibrium. The author would like to thank Han Bleichrodt, P. Jean-Jacques Herings, and Peter P. Wakker for helpful suggestions.     

Uncertainty and insurance in strategic market games

Summary. For perfectly competitive economies under uncertainty, there is a well-known equivalence between a formulation with contingent goods and one with state-specific securities followed by spot markets for goods. In this paper, I examine whether this equivalence carries over to a particular form of imperfect competition. Specifically, I look at three Shapley-Shubik strategic market games: one with contingent commodities, one with Arrow securities traded under imperfect competition and one with Arrow securities traded under perfect competition. First I compare the feasibility constraints of these three games. Then I compare their equilibrium sets. As in Peck and Shell (1989), the only common equilibria between the first and the second game are those which involve no transfer of income across states. However, if the securities markets are competitive, then the set of equilibria of the contingent commodities game and the securities game coincide. Received: June 16, 1997; revised version: April 30, 1998     

Computable general equilibrium with financial markets

Summary. There are a wide variety of theoretical general equilibrium models with incomplete security markets. In this paper we give a general recipe for using homotopy algorithm to compute equilibria in these models. In many models, taxes, transaction-costs or other market frictions introduce the additional difficulty that equilibrium prices or choices (but not equilibrium allocations) may be undetermined. In order to demonstrate how these difficulties can be dealt with, we develop a globally convergent algorithm to compute equilibria in a model with cash-in-advance constraints, several goods and incomplete financial markets. Furthermore we describe how to implement the algorithm using a publicly available suite of subroutines for homotopy-pathfollowing. Received: October 1, 1999; revised version: December 16, 2000     

Unemployment equilibrium and economic policy in mixed markets

This paper features a simple static Cournot-Nash model of an exchange economy with two productive sectors at flexible prices and wages. The traders in the atomless sector are price-takers, while the atoms behave strategically. We focus on the consequences of strategic interactions on the market outcome. Firstly, strategic interactions create underemployment on the labor market. Secondly, when the number of atoms increases without limit, the CWE coincides with the competitive equilibrium. Thirdly, we compare the welfare reached by traders at both equilibria. Fourthly, we consider the implementation of a tax levied on strategic supplies. Finally, we compare the approach retained with the monopolistic competition framework.     

Strategic market games with a finite horizon and incomplete markets

Summary. We study a strategic market game associated to an intertemporal economy with a finite horizon and incomplete markets. We demonstrate that generically, for any finite number of players, every sequentially strictly individually rational and default-free stream of allocations can be approximated by a full subgame-perfect equilibrium. As a consequence, imperfect competition may Pareto-dominate perfect competition when markets are incomplete. Moreover - and this contrasts with the main message conveyed by the market games literature - there exists a large open set of initial endowments for which full subgame-perfect equilibria do not converge to -efficient allocations when the number of players tends to infinity. Finally, strategic speculative bubbles may survive at full subgame-perfect equilibria.Received: 24 January 2002, Revised: 21 February 2003, JEL Classification Numbers: C72, D43, D52. Correspondence to: Gaël GiraudWe thank Tim Van Zandt for his comments.     

On the completeness of complete markets

We reconsider the allocational invariance of equilibria to different formulations of market completeness. We identify the so-far neglected assumption of sophisticated behavior as being crucial. First, the Arrow–Debreu setting is considered, where markets do not reopen in the future. Second, sequentially complete markets are analyzed, where goods on the spot markets and all contingent one-period ahead commodities can be traded in every state. Finally, complete markets are analyzed, where all possible contingent commodities can be traded at every state. Preferences may be time-consistent or time-inconsistent. A distinction is made between naïve and sophisticated behavior.     

Recursive equilibrium in endogenous growth models with incomplete markets

This paper analyzes the existence of recursive equilibria in a class of convex growth models with incomplete markets. Households have identical CRRA-preferences, production displays constant returns to scale with respect to physical and human capital, and all markets are competitive. There are aggregate productivity shocks that affect aggregate returns to physical and human capital investment (stock returns and wages), and there are idiosyncratic shocks to human capital (idiosyncratic depreciation shocks) that only affect individual human capital returns. Aggregate and idiosyncratic shocks follow a joint Markov process. Conditional on the aggregate state, idiosyncratic shocks are independently distributed over time and identically distributed across households. Finally, households have the opportunity to trade assets in zero net supply with payoffs that depend on the aggregate shock, but markets are incomplete in the sense that there are no assets with payoffs depending on idiosyncratic shocks. It is shown that there exists a recursive equilibrium for which equilibrium prices (returns) only depend on the exogenous aggregate shock variable (the wealth distribution is not a relevant state variable). Moreover, the allocation associated with this recursive equilibrium is identical to the equilibrium allocation of an economy in which households live in autarky and face both aggregate and idiosyncratic risk.I would like to thank for helpful comments Peter Howitt, Bob Lucas, Michael Magill, Tomo Nakajima, Herakles Polemarchakis, Martine Quinzii, Kevin Reffett, an anonymous referee, and seminar participants at various universities and conferences.     

Sampling equilibrium, with an application to strategic voting

We suggest an equilibrium concept for a strategic model with a large number of players in which each player observes the actions of only a small number of the other players. The concept fits well situations in which each player treats his sample as a prediction of the distribution of actions in the entire population, and responds optimally to this prediction. We apply the concept to a strategic voting model and investigate the conditions under which a centrist candidate can win the popular vote although his strength in the population is smaller than the strengths of the right and left candidates.     

Generic inefficiency of equilibria in the general equilibrium model with incomplete asset markets and infinite time

Summary. We consider a Lucas asset-pricing model with heterogeneous agents, exogenous labor income, and a finite number of exogenous shocks. Although agents are infinitely lived, endowments and dividends are time-invariant functions of the exogenous shock alone and are thus restricted to lie in a finite-dimensional space; genericity analysis can be conducted on sets of zero Lebesgue measure. When financial markets are incomplete, that is, there are fewer financial securities than shocks, we show that generically in individual endowments all competitive equilibria are Pareto inefficient. Received: November 22, 1999; revised version: March 4, 2002 RID="*" ID="*" We are grateful to an anonymous referee for very insightful comments on earlier drafts.     

A model for international capital markets closure in an economy with incomplete markets and short sales

Using a two-country dynamic optimization model, we investigate the impact of exchange risk, incomplete information and short sales constraints on international portfolio decisions around market closure. Using optimal control theory, we provide solutions and simulation results. Our model can be applied to solve several problems in financial economics in the presence of market closure, information asymmetry and short sales constraints.     

Complete and incomplete markets with short-sale constraints

Summary. This paper argues that the introduction of a short-sale constraint in the Arrow-Radner framework invalidates standard definitions of complete and incomplete markets. Two threshold values with familiar properties arise in this constrained set-up. If short sales are not allowed on some security, then financial markets will be incomplete in the standard sense. Beyond a particular level of the short-sale bound, financial markets are “complete”, since the short-sale constraint is not effective. For intermediate bounds the distinction between complete and incomplete financial markets is blurred. Although some technical definitions hold, agents can not fully transfer wealth among states. These intermediate cases, called “technically incomplete markets”, exhibit interesting welfare properties. For instance, the resulting equilibrium allocations may not be Pareto-dominated by those of the non-restricted complete markets equilibrium. Received: November 28, 2000; / revised version: November 9, 2001     

基于三期模型框架的噪音交易和有限套利条件下的基金经理投资行为研究

笔者利用三期模型框架,考虑噪音交易和有限套利两个约束条件,构建噪音交易者、基金投资者和长短期套利基金的投资行为模型,分析长、短期套利基金的投资业绩及其差异。研究发现:无论第2期后市场悲观情绪更加恶化或得到改善,短期套利基金的投资行为对基金投资者都是有害的;长期套利基金由于追求长期收益最大化,对基金投资者是有益的;基金投资者可以根据基金经理在第1期的投资行为及其仓位,识别是短期套利基金还是长期套利基金。     

Water markets design and evidence from experimental economics

Market mechanisms are gaining increasing acceptance all over the world as a way of making more efficient use of scarce water resources. Designing regulatory frameworks that ensure both inter- and intra-temporal efficient allocations is a daunting task, especially if supply is stochastic and there is ample storage capacity. In addition to defining tradable rights, specific provisions must regulate the use of reservoirs. Commonly, water statutes include provisions that establish asymmetries regarding the allocation of water, and market restrictions that ban water trading across different users. In this article, we use data collected in a laboratory to test two specific market regulations included in the 1999 Water reform in Spain. First, junior right holders are not allowed to buy water from senior users. Second, the law does not explicitly define water rights over units left in reservoirs for the following season. Results suggest that trading restrictions among water right holders lead to welfare losses for senior users. It is shown that removing this restriction would increase senior right holders’ benefits, without reducing those of junior users. Results show that defining water rights over saved units across periods would increase the average stock levels of reservoirs, and reduce market price instability. The lessons learned from the Spanish experience are applicable to settings characterized by unstable natural water supply and the availability of large storage facilities.      

基于R~2的中国股市私有信息套利分析

R2在统计学中是模型对实证数据拟合优度的度量指标,自Roll(1988)"R2"开创性研究后,R2在金融学研究中得以更为广泛地度量应用。遗憾的是,在对Roll(1988)进一步研究中所进行的大胆理论延伸,造成了R2在金融领域度量标准在经济意义上的混乱。本文通过对现有文献的梳理、解读和评价,采用逻辑演绎的方法推导出R2可作为私有信息套利的度量指标。本文对2005—2007年上证180中的140只股票进行实证研究表明:(1)几乎所有股票都存在着私有信息套利,且60%的股票私有信息套利程度较深。(2)通过面板模型进一步分析了影响私有信息套利的主要变量,发现上市公司第一大股东持股比例、限售股比例与R2存在显著的负相关关系,机构投资者持股比例、股权分置改革完成时间、公司规模与R2存在正相关关系。     

Price clustering in Australian water markets

The finding of clustering in financial prices on particular digits is common across a broad range of financial markets. This article explores whether price clustering is also present in the case of the weekly market for seasonal water in rural Victoria, Australia. We find a similar degree of clustering in the seasonal water market. This suggests that the trading activities of the market produce characteristics that are similar to more sophisticated and deeper financial markets.     

Evolutionary stable stock markets

Summary. This paper shows that a stock market is evolutionary stable if and only if stocks are evaluated by expected relative dividends. Any other market can be invaded in the sense that there is a portfolio rule that, when introduced on the market with arbitrarily small initial wealth, increases its market share at the incumbents expense. This mutant portfolio rule changes the asset valuation in the course of time. The stochastic wealth dynamics in our evolutionary stock market model is formulated as a random dynamical system. Applying this theory, necessary and sufficient conditions are derived for the evolutionary stability of portfolio rules when relative dividend payoffs follow a stationary Markov process. These local stability conditions lead to a unique evolutionary stable portfolio rule according to which assets are evaluated by expected relative dividends (with respect to the objective probabilities).Received: 7 October 2003, Revised: 18 January 2005, JEL Classification Numbers: G11, D52, D81. Correspondence to: Klaus Reiner Schenk-HoppéWe are grateful to Jarrod Wilcox and William Ziemba for valuable comments. Financial support by the national center of competence in research Financial Valuation and Risk Management is gratefully acknowledged. The national centers in research are managed by the Swiss National Science Foundation on behalf of the federal authorities.     

"四重套利"模型与短期国际资本流动

本文从人民币升值预期、资产溢价、中美利差和中美税差等方面探讨短期国际资本流动的影响因素,并构建了基于套汇、套价、套利和套税的四重套利模型,利用中美之间2002—2009年的月度数据进行实证研究。研究表明:套汇和套价是短期国际资本持续流入的主要动机,而套利和套税又在一定程度上加快其流入。因此,弱化人民币升值预期、遏制资产价格膨胀和利用税收手段将有助于解决套利资本过剩问题。     

New financial markets: who gains and who loses

Summary. We evaluate the effects of new financial markets in a two-period incomplete markets model with heterogenous agents. For analytical tractability, we focus on the special case where utility is exponential and risks are normally distributed. We provide a complete characterization of life-cycle consumption and portfolio choice. The effect of new financial markets on individual welfare equals the sum of what we call the portfolio effect and the price effect. The portfolio effect is proportional to the square of the difference between the average exposure to the new asset in the economy and an individual investors exposure adjusted for risk aversion. The portfolio effect is always positive and measures the improved ability of investors to transfer consumption across states. The price effect captures the effect on individual welfare of changes in asset prices. We show that new financial markets drive down the prices of all assets which raises the interest rate and thus affects the ability of investors to transfer consumption across time. The price effect is positive for net savers but can be negative for net borrowers. For net borrower households, the price effect can wipe out the portfolio effect and lead to welfare reductions.Received: 24 July 2003, Revised: 22 March 2004, JEL Classification Numbers: D31, D52, G11, G12.Paul Willen: Thanks to Viral Acharaya, Alberto Bisin, Steve Davis, John Geanakoplos and a thoughtful anonymous referee for helpful comments and suggestions. Thanks also to seminar audiences at Stanford, Berkeley and at the 2001 Stony Brook workshop on incomplete markets for comments and suggestions. I gratefully acknowledge research support from the Graduate School of Business at the University of Chicago.     

The effects of information on strategic investment and welfare

Summary. The paper analyses the influence of uncertainty and competition on the strategic considerations of a firm’s investment decision, where the firm receives imperfect signals about the profitability of an investment project. We find a preemptive or an attrition equilibrium depending on a trade-off between first and second mover advantages. We show that welfare can be negatively affected by decreasing uncertainty, i.e. more and/or better information. Furthermore, simulations indicate that duopoly leads to higher welfare than monopoly if there are few and relatively non-informative signals, whereas the opposite holds if there are many and relatively informative signals.Received: 13 May 2004, Revised: 22 March 2005, JEL Classification Numbers: C61, D43, D81.Jacco J. J. Thijssen: Correspondence toDolf Talman is acknowledged for many inspiring discussions and meticulous proof-reading. Jan Boone, Thomas Sparla, participants in the workshop on “Recent Topics in Real Options Valuation”, July 2002, Krems, Austria, and an anonymous referee are thanked for helpful comments. The usual disclaimer applies.