Communication in financial markets with several informed traders

This paper investigates the incentives for informed traders in financial markets to reveal their information truthfully to the public. In the model, a subset of traders receive noisy signals about the value of a risky asset. The signals are composed of a directional component (“high” vs. “low”) as well as a precision component that represents the quality of the directional component. Between trading periods, the informed agents make public announcements to the uninformed traders. With a sufficiently large number of informed traders, an equilibrium exists in which the directional components are credibly revealed, but not the precision components. Even though the informed traders retain some of their rivate information, the post-communication estimate of the asset value converges in probability to the full-information estimate as the number of informed traders increases. The paper is based on a chapter of my Ph.D. thesis at the University of Western Ontario and was circulated previously under the title “Public Communication Devices in Financial Markets.” I thank my dissertation committee Arthur Robson, Hari Govindan, and Al Slivinski for their guidance and support. I also thank Murali Agastya, Roland Benabou, Philippe Grégoire, Rick Harbaugh, Mike Peters, an anonymous referee and an associate editor, and seminar participants at various universities and conferences at which this paper was presented.     

The bargaining set of a large economy with differential information

Summary. We study the Mas-Colell bargaining set of an exchange economy with differential information and a continuum of traders. We established the equivalence of the private bargaining set and the set of Radner competitive equilibrium allocations. As for the weak fine bargaining set, we show that it contains the set of competitive equilibrium allocations of an associated symmetric information economy in which each trader has the “joint information” of all the traders in the original economy, but unlike the weak fine core and the set of fine value allocations, it may also contain allocations which are not competitive in the associated economy. Received: February 15, 1999; revised version: August 9, 1999     

Comparing finite mechanisms

Summary. This paper obtains finite analogues to propositions that a previous literature obtained about the informational efficiency of mechanisms whose possible messages form a continuum. Upon reaching an equilibrium message, to which all persons “agree”, a mechanism obtains an action appropriate to the organization's environment. Each person's privately observed characteristic (a part of the organization's environment) enters her agreement rule. An example is the Walrasian mechanism in an exchange economy. There a message specifies a proposed trade vector for each trader as well as a price for each non-numeraire commodity. A trader agrees if the price of each non-numeraire commodity equals her marginal utility for that commodity (at the proposed trades) divided by her marginal utility for the numeraire. At an equilibrium message, the mechanism's action consists of the trades specified in that message, and (for classic economies) those trades are Pareto-optimal and individually rational. Even though the space of environments (characteristics) is a continuum, mechanisms with a continuum of possible messages are unrealistic, since transmitting every point of a continuum is impossible. In reality, messages have to be rounded off and the number of possible messages has to be finite. Moreover, reaching a continuum mechanism's equilibrium message typically requires infinite time and that difficulty is absent if the number of possible messages is finite. The question therefore arises whether results about continuum mechanisms have finite counterparts. If we measure a continuum mechanism's communication cost by its message-space dimension, then our corresponding cost measure for a finite mechanism is the (finite) number of possible equilibrium messages. We find that if two continuum mechanisms yield the same action but the first has higher message-space dimension, then a sufficiently fine finite approximation of the first has larger error than an approximation of the second if the cost of the first approximation is no higher than the cost of the second approximation. An approximation's “error” is the largest distance between the continuum mechanism's action and the approximation's action. We obtain bounds on error. We also study the performance of Direct Revelation (DR) mechanisms relative to “indirect” mechanisms, both yielding the same action, when the environment set grows. We find that as the environment-set dimension goes to infinity, so does the extra cost of the DR approximation, if the error of the DR approximation is at least as small as the error of the indirect approximation. While the paper deals with information-processing costs and not incentives, it is related to the incentive literature, since the Revelation Principle is central to much of that literature and one of our main results is the informational inefficiency of finite Direct Revelation mechanisms. Received: May 21, 2001; revised version: December 14, 2001 RID="*" ID="*" Earlier versions of this paper were presented at the Decentralization Conference, Washington University, St Louis, April 2000 and at the Eighth World Congress of the Econometric Society, August 2000. We are grateful for comments received on those occasions. The second author gratefully acknowledges support from National Science Foundation grant #IIS9712131. Correspondence to: T. Marschak     

Competitive and core allocations in large economies with differential information

Summary. We study the core and competitive allocations in exchange economies with a continuum of traders and differential information. We show that if the economy is “irreducible”, then a competitive equilibrium, in the sense of Radner (1968, 1982), exists. Moreover, the set of competitive equilibrium allocations coincides with the “private core” (Yannelis, 1991). We also show that the “weak fine core” of an economy coincides with the set of competitive allocations of an associated symmetric information economy in which the traders information is the joint information of all the traders in the original economy. Received March 22, 2000; revised version: May 1, 2000     

Rational panics and stock market crashes

This paper offers an explanation for stock market crashes which focuses on the role of rational but uninformed traders. We show that uninformed traders can precipitate a price crash because as prices decline, they surmise that informed traders received negative information, which leads them to reduce their demand for assets and drive the price of stocks even lower. The model yields several implications, such as that crashes can occur even when the fundamentals are strong, and that the magnitude of the crash depends on the fraction of uninformed investors and the amount of unsophisticated passive investing present in the market.     

The evolution of portfolio rules and the capital asset pricing model

The aim of this paper is to test the performance of capital asset pricing model (CAPM) in an evolutionary framework. We model an economy where a heterogeneous population of long-lived agents invest their wealth according to different portfolio rules, and prove that traders who either “believe” in CAPM and use it as a rule of thumb, or are endowed with genuine mean-variance preferences, under some very weak conditions, vanish in the long run.We show that a sufficient condition to drive CAPM or mean-variance traders’ wealth shares to zero is that an investor endowed with a logarithmic utility function enters the market.     

Pareto and contemporary economic theory

This paper provides explanations for Pareto’s apparently contradictory approach to demand theory in simultaneously insisting that measurability of utility is not needed to explain the equilibrium of consumers in competitive markets, and embracing concavifiability and thus measurability of utility when this implies restrictions on consumers’ behavior such as the law of demand. It also treats his method of calibrating an aggregate demand function by employing his law of income distribution, so as to reproduce “Gregory King’s law”. Finally, some disputed issues are dealt with concerning the nature of Pareto’s contributions to welfare economics. (JEL: B13, D11, D60).     

Experienced Utility as a Standard of Policy Evaluation

This paper explores the possibility of basing economic appraisal on the measurement of experienced utility (utility as hedonic experience) rather than decision utility (utility as a representation of preference). Because of underestimation of the extent of hedonic adaptation to changed circumstances and because of the “focusing illusion” (exaggerating the importance of the current focus of one’s attention), individuals’ forecasts of experienced utility are subject to systematic error. Such errors induce preference anomalies which the experienced utility approach might circumvent. The “day reconstruction method” of measuring experienced utility is considered as a possible alternative to stated preference methods. JEL classifications: D63, Q51     

Information aggregation in experimental asset markets in the presence of a manipulator

We study with the help of a laboratory experiment the conditions under which an uninformed manipulator—a robot trader that unconditionally buys several shares of a common value asset in the beginning of a trading period and unwinds this position later on—is able to induce higher asset prices. We find that the average price is significantly higher in the presence of the manipulator if and only if the asset takes the lowest possible value and insiders receive perfect information about the true value of the asset. It is also evidenced that the robot trader makes trading gains. Finally, both uninformed and partially informed traders may suffer from the presence of the robot.     

Commitment to a strategy of uniform pricing in a two-period duopoly with switching costs

This paper studies decisions by firms of whether to attempt “behavior-based” price discrimination in markets with switching costs by using a two-period duopoly model. When both firms commit themselves to a pricing policy and consumers are “sophisticated” and have rational expectations, there is a dominant strategy equilibrium with both firms engaging in uniform pricing. Both firms are better off in the uniform pricing equilibrium, compared with the discriminatory equilibrium.      

Cheap home goods and persistent inequality

There exists a large literature which shows that public education is favorable for growth because it increases the level of human capital and at the same time it tends to produce a more even income distribution. More egalitarian societies are also associated with less social conflicts, and individuals have a lower tendency to report themselves happy when inequality is high. Therefore, it is important to study the reasons why the elite opposes the development of a strong public education system. It might be that education is related to social status and a strong public education system might threaten the elite’s political power. We show that one aspect of social status is the specialization of skilled workers in high-paid jobs and the abundance of unskilled workers in the production of cheap “home goods” in the market, such as painting and cleaning a house, babysitting, and/or cooking. We emphasize the role of general equilibrium price adjustments to show that depending on the level of inequality, the elite might prefer an economy with a positive and “high” cost of education than an economy where skills are freely provided. We show that this result goes through even if the skilled wage is not directly affected by the ratio of skilled to unskilled workers. We also provide empirical evidence consistent with our theory.     

Strategic noise traders and liquidity pressure with a physically deliverable futures contract

Do physically deliverable futures contracts induce liquidity pressure in the underlying spot market? The answer is believed to be no since the asset is delivered sometimes after the expiration of the contract so that the futures trader's payoff does not clearly depend on the price of the underlying stock at expiration. We construct a rational expectations equilibrium model in which a strategic uninformed trader induces liquidity pressure in the underlying spot market at the expiration of a physically deliverable futures contract. Liquidity pressure is the result of a pure informational advantage: if it is known that futures traders hedge their position in the spot market then a strategic trader with no information about the fundamental value of the underlying has an incentive to create noise in the futures market in order to gain information on the composition of the spot order flow at future auctions. We show that informed traders benefit from this form of strategic noise and that the efficiency of the prices remains unaffected.     

Compensation schemes,liquidity provision,and asset prices: an experimental analysis

In an experimental setting in which investors can entrust their money to traders, we investigate how compensation schemes affect liquidity provision and asset prices, two outcomes that are important for financial stability. Compensation schemes can drive a wedge between how investors and traders value the asset. Limited liability makes traders value the asset more than investors. To limit losses, investors should thus restrict liquidity provision to force traders to trade at a lower price. By contrast, bonus caps make traders value the asset less than investors. This should encourage liquidity provision and increase prices. In contrast to these predictions, we find that under limited liability investors increase liquidity provision and asset price bubbles are larger. Bonus caps have no clear effect on liquidity provision and they fail to tame bubbles. Overall, giving traders skin in the game fosters financial stability.     

Rationally mispriced assets in equilibrium

We present a simple model of trading in a financial market where agents are asymmetrically informed and information is transmitted through the price system. We characterize the equilibrium for this economy and show that ‘rational mispricing’ of assets occurs if the price system fails to reveal the insider information accurately. It is argued that the communication of wrong information through equilibrium prices is compatible with full rationality on the part of the investors and may explain deviations from the efficient markets hypothesis.     

Dynamic price formation in a futures market via double auctions

Summary We report an exploratory study of the process of price formation in a speculative market in the absence of liquidity traders. Traders exchange a futures contract because they interpret information differently. We formulate trading as a sequence of anonymous double auctions and introduce a notion of bounded rationality in which traders use approximate models of market response in forming their bids. We prove existence of a perfect equilibrium in the sequential anonymous auctions game, and show that the equilibrium has a no-regret property. After learning the market price, a trader regrets neither the bid that he made nor the position that he holds. We show that trading volume is related to changes in the distribution of information in the economy. We also show that volume and expected change in price are related to two different attributes of the pattern of private information flow. Fundamentally, no particular relationship between the time series of these variables is always valid for all futures contracts. This point is emphasized by an example.I am thankful for useful comments made by Avraham Beja, James Gammil, Chi-fu Huang, David Scharfstein and three anonymous referees. Financial support from Stanford Graduate School Faculty Fellowship is gratefully acknowledged.     

Asymmetric information in a competitive market game: Reexamining the implications of rational expectations

Summary. We examine price formation in a simple static model with asymmetric information, an infinite number of risk neutral traders and no noise traders. Here we re-examine four results associated with rational expectations models relating to the existence of fully revealing equilibrium prices, the advantage of becoming informed, the costly acquisition of information, and the impossibility of having equilibrium prices with higher volatility than the underlying fundamentals. Received: August 27, 1997; revised version: February 11, 1998     

日内效应、知情交易与市场微观结构——招商银行的例证

本文通过对Engle和Russell模型的扩展,使用我国沪市A股的高频数据,分析了我国股票的市场微观结构。在我国的股票市场中,股票交易存在明显的日内效应,日内效应的产生主要是因为知情交易者的存在,知情交易者通过影响交易量从而加剧了价格的波动。     

Standards and the regulation of environmental risk

We study regulatory design for a pollution-generating firm who is better informed than the regulator regarding pollution mitigation possibilities, and who chooses an unobservable action when employing a particular mitigation plan. We distinguish among performance, process, and design standards, and study the relative merit of each type of regulatory instrument. Relative to previous work on standards design, we emphasize technology and process verification. An optimal performance standard is relatively strict when regulator and firm preferences are congruent, but the regulator may prefer no performance standard at all if verification costs are sufficiently high. A process standard unambiguously increases expected surplus (relative to no regulation) in some environments, and otherwise improves welfare only when it is unlikely to generate a “bad” technology choice by the firm. A design standard can improve welfare if the regulator is sufficiently well informed about the technological possibilities for pollution control, but only when the firm’s private benefits from technology choice are sufficiently small.     

The option of joint purchase in vertically differentiated markets

Summary. Within the framework proposed by Mussa and Rosen (1978) for modelling quality differentiation, consumers are assumed to make mutually exclusive purchases. A unique pure strategy equilibrium exists in this case. In this note, we allow consumers to buy simultaneously different variants of the differentiated good. We call this the “joint purchase option”. The paper proposes a detailed analysis of price competition when this option is opened: first, we show that either uniqueness, or multiplicity, or absence of price equilibrium arise, depending on the utility derived from joint purchase relative to exclusive purchase. Second, we characterize these equilibria, whenever they exist. Received: July 25, 2001; revised version: October 21, 2002 RID="*" ID="*" The second author gratefully acknowledges the financial support from Interuniversity Attraction Pole Program- Belgian State- Federal Office for Scientific, Technical and Cultural Affairs under contract PAI 5/26. Correspondence to: X.Y. Wauthy     

Reputation, control rights and game equilibrium

Using the reputation model of Kreps (1982), Vickers (1986) and Barro(1986), we develop a dynamic game model with incomplete information to examine the relations between the managers of state-owned enterprises(SOEs) in China and the government as the enterprise’s owner. Employing the model, we show that even a noncoopertive manager will not intrude the owner’s interests until the last period of his term in order to maximize his long term utility. The paper also discusses some phenomenona in state-owned enterprises in China, such as “insiders’ control”, “59 phenomenon” and excess on-the-job consumption.