Price manipulation in an experimental asset market

We analyze in the laboratory whether an uninformed trader is able to manipulate the price of a financial asset by comparing the results of two experimental treatments. In the benchmark treatment, 12 subjects trade a common value asset that takes either a high or a low value. Only three subjects know the actual value of the asset while the market is open for trading. The manipulation treatment is identical to the benchmark treatment apart from the fact that we introduce a computer program as an additional uninformed trader. This robot buys a fixed number of shares in the beginning of a trading period and sells them again afterwards. Our main result shows that the last contract price is significantly higher in the manipulation treatment if the asset takes a low value and that private information is very well disseminated by both markets if the value of the asset is high. Finally, even though this simple manipulation program loses money on average, it is profitable in some instances.     

Endogenizing market institutions: An experimental approach

We study experimental two-sided markets in which the information structure is endogenous. When submitting an offer, a trader decides which other traders will be informed about the offer. This setup allows both a decentralized bargaining market (Chamberlin, J. Polit. Econ. 56 (1948) 95), and a double auction market (Smith J. Polit. Econ. 70 (1962) 111) as special cases. The results show that offers are typically directed to all traders of the other side of the market, but to none of the traders of the same side of the market. Even though traders receive much less information, the resulting market institution leads to the same outcomes in terms of prices and efficiency as a double auction market. In two additional treatments we examine the robustness of these results. First, it is found that the market institution adapts predictably, but not necessarily efficiently, to the imposition of transaction costs. Second, we find that the preference of sellers to conceal offers from competitors is strict. At the same time, sellers benefit collectively when they reveal offers to each other.     

The pre-marital investment game

Two sides of a finite marriage market engage in costly investment and are then matched assortatively. The purpose of the investment is solely to improve the quality of the match that the trader can attain in the second stage. The paper studies the limits of equilibrium of these finite matching games as the number of traders gets large. It is shown that mixed Nash equilibria in the finite games converge to degenerate pure strategy equilibria in the limit in which both sides of the market invest too much.     

Optimality versus practicality in market design: A comparison of two double auctions

We consider a market for indivisible items with m buyers and m sellers. Traders privately know their values/costs, which are statistically dependent. Two mechanisms are considered. The buyer's bid double auction collects bids and asks from traders and determines the allocation by selecting a market-clearing price. It fails to achieve all possible gains from trade because of strategic bidding. The designed mechanism is a revelation mechanism in which honest reporting of values/costs is incentive compatible and all gains from trade are achieved. This optimality, however, comes at the expense of plausibility: (i) the monetary transfers among the traders are defined in terms of the traders' beliefs about each other's value/cost; (ii) a trader may suffer a loss ex post; (iii) the mechanism may run a surplus/deficit ex post. We compare the virtues of the simple yet mildly inefficient buyer's bid double auction to the flawed yet perfectly efficient designed mechanism.     

Efficiency properties of strategies market games: An axiomatic approach

The paper investigates the conditions under which an abstractly given market game will have the property that if there is a continuum of traders then every noncooperative equilibrium is Walrasian. In orther words, we look for a general axiomatization of Cournot's well-known result. Besides some convexity, continuity, and nondegeneracy hypotheses, the crucial axioms are: anonymity (i.e., the names of traders are irrelevant to the market) and aggregation (i.e., the net trade received by a trader depends only on his own action and the mean action of all traders). It is also shown that the same axioms do not guarantee efficiency if there is only a finite number of traders. Some examples are discussed and a notion of strict noncooperative equilibrium for anonymous games is introduced.     

房地产市场噪声交易行为分析——基于进化博弈理论的视角

噪声交易是房地产市场长期存在的一种现象,理性交易者与噪声交易者也长期并存于房地产市场。本文运用进化博弈理论研究房地产市场噪声交易者行为,分析噪声交易行为的复制动态,得到了理性投资者不可能利用投机行为把噪声交易者逐出市场的结论,同时给出了当博弈达到稳定均衡时选择理性交易策略和噪声交易策略的比例。     

A comparison between the core and the monopoly solutions in a mixed exchange economy

Summary. Using a mixed market model for analyzing imperfectly competitive economies, we maximize the oligopolists' Welfare Function, given individual rationality and feasibility constraints. We prove that solutions belong to the core for a large class of economies. This class includes, in particular, every monopoly having a single type of small traders. Note that all such solutions yield the large trader, utility-wise, strictly more than at any monopoly solution, where the monopolist plays strategically, and the ocean of small traders act as being as price-takers. Received: March 4, 1996; revised version July 7, 1996     

The effect of sequential entry on choice of location

An important aspect of economics arises when entry into a market of differentiated products is sequential and essentially irrevocable. An approach to the investigation of this problem is offered by the theory of spatial competition. We consider a market consisting of a line segment or its equivalent and assume irrevocable location choices for all sellers, each of whom pursues a ‘maximin’ strategy in selecting a location, and negative elasticity of demand for all buyers. Results for small N are generalised to any finite N and the patterns are evaluated on a criterion of ‘Buyers' Welfare’.     

An admissible set occurring in various bargaining situations

Given a set of alternatives S and a binary relation M on S the admissible set of the pair (S, M) is defined to be the set of maximal elements with respect to the transitive closure of M. It is shown that existing solutions in game theory and mathematical economics are special cases of this concept (they are admissible sets of a natural S and M). These include the core of an n-person cooperative game, Nash equilibria of a noncooperative game, and the max-min solution of a two-person zero sum game. The competitive equilibrium prices of a finite exchange economy are always contained in its admissible set. Special general properties of the admissible set are discussed. These include existence, stability, and a stochastic dynamic process which leads to outcomes in the admissible set with high probability.     

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.     

The extended linear expenditure system

The purpose of this paper is to derive the aggregate consumption function associated with the linear expenditure system (LES) from simple utility maximization procedures. The parameter set (β, γ) of LES plus an added parameter (μ: the ratio of the subjective rate of discount to the market rate of interest) characterize the consumption-savings and the expenditure allocation decisions under the Klein-Rubin utility function. The term p′y appears in the aggregate consumption function.The distinction between subjective, planning time and historical time (a continuum of initial points of optimal plans) is basic here: thus the focus on solutions at t = 0.     

Strategic Bargaining and Competitive Bidding in a Dynamic Market Equilibrium

This paper extends the bargaining and matching literature, such as Rubinstein and Wolinsky (1985), by considering a new matching process. We assume that a central information agency exists, such as real estate agencies in the housing market and employment agencies (or newspapers) in the labour market, which puts traders into direct contact with each other. With heterogeneity of trader preferences, equilibrium trade is characterized by existing traders on each side of the market trying to match with the flow of new traders on the other side (since existing traders have already sampled and rejected each other). Two procedures of trade co-exist, namely a strategic bilateral bargaining process and a competitive bidding process, depending on the number of potential matches a new trader obtains. We characterize the unique symmetric Markov perfect equilibrium to this stochastic trading game.     

An Elementary Approach to Approximate Equilibria with Infinitely Many Commodities

We prove the existence of approximate equilibria in a finite exchange economy with a countably infinite number of commodities and nonconvex preferences, when every trader has an excess demand set that is finitely spannable, i.e., that could be covered by a union of its convex subsets in finitely many steps. We show that the bound on the norm of the per capita aggregate excess demand is reciprocally related to the square root of the population. Extensions are also made to the case where countably many commodities are indivisible. The proofs are elementary. Journal of Economic Literature Classification Numbers: D50, C62, D52.     

The behavior of the exchange rate in the genetic algorithm with agents having long memory

This paper studies the behavior of the exchange rate in Kareken and Wallace (1981)'s model under the genetic algorithm adaptation with agents having long memory. The simulation results show that, if agents have full memory, the average portfolio fraction will converge, and the initial equilibrium that it converges to is history dependent. Under the lasting evolutionary pressure of the noise trader, the market will eventually drift from one equilibrium to another, and asymptotically will converge to the neighborhood of an equilibrium with agents putting their savings equally into two currencies. If the agents do not have full memory, the foreign exchange market will show periodic crisis. Before and after a market crises, the average portfolio fraction will converge to different stationary equilibria. A mean difference equation of the average portfolio fraction is also given to describe the dynamics of the model.

Manipulation and the Allocational Role of Prices

It is commonly believed that prices in secondary financial markets play an important allocational role because they contain information that facilitates the efficient allocation of resources. This paper identifies a limitation inherent in this role of prices. It shows that the presence of a feedback effect from the financial market to the real value of a firm creates an incentive for an uninformed trader to sell the firm's stock. When this happens the informativeness of the stock price decreases, and the beneficial allocational role of the financial market weakens. The trader profits from this trading strategy, partly because his trading distorts the firm's investment. We therefore refer to this strategy as manipulation . We show that trading without information is profitable only with sell orders, driving a wedge between the allocational implications of buyer and seller initiated speculation, and providing justification for restrictions on short sales.     

The nonatomic assignment model

Summary We formulate a model with a continuum of individuals to be assigned to a continuum of different positions which is an extension of the finite housing market version due to Shapley and Shubik. We show that optimal solutions to such a model exist and have properties similar to those established for finite models, namely, an equivalence among the following: (i) optimal solutions to the linear programming problem (and its dual) associated with the assignment model; (ii) the core of the associated market game; (iii) the Walrasian equilibria of the associated market economy.     

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。     

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     

Noise trading, transaction costs, and the relationship of stock returns and trading volume

This article constructs an economic model of a rational trader who operates in a market with transaction costs and noise trading. The level of trading affects the rational trader's marginal cost of transacting; as a result, trading volume (through its effect on marginal cost) is a source of risk. This engenders an equilibrium relationship between returns and volume. The model also provides a simple way to scrutinize this relationship empirically. Empirical evidence supports the implications of the model.     

The number of commodities required to represent a market game

An n-person game with side payments that can arise from an economic market is called a market game. It is proved here that any n-person market game can be obtained from a market with at most n ? 1 commodities. Moreover, no smaller number will suffice in some cases (e.g., the unanimity game). This result is then applied to settle a question regarding market games with a continuum of traders.