Prices, Delay, and the Dynamics of Trade

We characterize the dynamics of trading patterns and market composition when trade is bilateral, finding a trading partner is costly, prices are determined by bargaining, and preferences are private information. We show that equilibrium is inefficient and exhibits delay as sellers price discriminate between buyers with different values. As frictions vanish, transaction prices are asymptotically competitive and the welfare loss of inefficient trading approaches zero, even though the trading patterns continue to be inefficient and delay persists. Journal of Economic Literature Classification Numbers: D40, D50.     

Liquidity and asset prices in rational expectations equilibrium with ambiguous information

The quality of information in financial asset markets is often hard to estimate. Reminiscent of the famous Ellsberg paradox, investors may be unable to form a single probability belief about asset returns conditional on information signals and may act on the basis of ambiguous (or multiple) probability beliefs. This paper analyzes information transmission in asset markets when agents?? information is ambiguous. We consider a market with risk-averse informed investors, risk-neutral competitive arbitrageurs, and noisy supply of the risky asset, first studied by Vives (Rev Financ Stud 8:3?C40, 1995a, J Econ Theory 67:178?C204, 1995b) with unambiguous information. Ambiguous information gives rise to the possibility of illiquid market where arbitrageurs choose not to trade in a rational expectations equilibrium. When market is illiquid, small informational or supply shocks have relatively large effects on asset prices.     

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 behaviour of Hong Kong stock prices

The primary function of a stock market is to allocate resources to the most profitable investment opportunities. If stock prices provide accurate signals for resource allocation, firms are able to make correct production–investment decisions, and investors are able to choose the most suitable stocks for investment. These choices are only possible if the market is efficient, that is, if stock prices ‘fully reflect’ all available information.

Hong Kong is now an international financial centre. Although Hong Kong's stock market is ranked as one of the five largest in the world in terms of turnover, little research has been devoted to the behaviour of its stock prices. This is a study of the efficiency of Hong Kong's stock market. It is based upon two widely accepted statistical tests, namely, serial correlation analysis and runs tests. Data used cover the daily prices of 28 major Hong Kong stocks over a period of four years from 1977 to 1980. The evidence is mixed; it does not provide clear support for the efficient market hypothesis.     

On persistent disequilibrium

Consider a standard model of a Walrasian economy where the time derivative of price change is a sign preserving function of excess demand. The only steady states of such a system are the Walrasian equilibria. For if the system is not at a Walrasian equilibrium then there must be excess demands or supplies in some market and thus those prices must be changing. Walras' law implies that all prices cannot change in the same direction, and thus relative prices must change.However, it seems that in real world economies there have been states of persistent disequilibrium. How can this be? How can there be stationary states of an economy that are not Walrasian equilibria?The answer presented in this paper goes something like this: the demands actually presented to the market, i.e., the demands that affect price movements, are not the Walrasian demands. Rather, these demands, the effective demands, are a function of both price and quantity signals. There is no reason why there cannot be equilibria of the effective demand system that are not equilibria of the Walrasian demand system.In this paper, I present a simple abstract model of effective demand systems and given a condition for this system to have non-Walrasian equilibria. I also present a simple example of this phenomena. Finally I discuss the real world implications of this model. Related concepts of effective demand are discussed in [A1H], [2], [3], [L5], and [L6].     

Learning from private and public observations of othersʼ actions

We study the diffusion of dispersed private information in a large economy, where agents learn from the actions of others through two channels: a public channel, such as equilibrium market prices, and a private channel, for example local interactions. We show that, when agents learn only from the public channel, an initial release of public information increases agents? total knowledge at all times and increases welfare. When a private learning channel is present, this result is reversed: more initial public information reduces agents asymptotic knowledge by an amount in order of $\log (t)$ units of precision. When agents are sufficiently patient, this reduces welfare.     

A monopolistic market for information

We analyze a model where traders buy information from a monopolistic seller, which is subsequently used in a speculative market. In order to overcome the dilution in the value of information due to its leakage through informative prices, the seller of information may prefer to sell noisier versions of the information he actually has. Moreover, to obtain higher profits, it is desirable for the seller to sell different signals to different traders, so that the added noise realizations do not affect equilibrium prices. One way of doing so, which does not require discrimination, is to sell identically distributed personalized signals to each of a large number of traders.     

Repeated price competition between individuals and between teams

We conducted an experimental study of price competition in a duopolistic market. The market was operationalized as a repeated game between two “teams” with one, two, or three players in each team. We found that asking (and winning) prices were significantly higher in competition between individuals than in competition between two- or three-person teams. There were no general effects of team size, but prices increased with time when each team member was paid his or her own asking price and decreased when the team's profits were divided equally. This result is consistent with a simple model of individual learning.     

Local coordination and market equilibria

We reformulate the local stability analysis of market equilibria in a competitive market as a local coordination problem in a market game, where the map associating market prices to best-responses of all traders is common knowledge and well-defined both in and out of equilibrium. Initial expectations over market variables differ from their equilibrium values and are not common knowledge. This results in a coordination problem as traders use the structure of the market game to converge back to equilibrium. We analyse a simultaneous move and a sequential move version of the market game and explore the link with local rationalizability.     

The Emergence of the Law of Value in a Dynamic Simple Commodity Economy

Abstract

A dynamic computational model of a simple commodity economy is examined and a theory of the relationship between commodity values, market prices and the efficient division of social labour is developed. The main conclusions are: (i) the labour value of a commodity is an attractor for its market price; (ii) market prices are error signals that function to allocate the available social labour between sectors of production; and (iii) the tendency of prices to approach labour values is the monetary expression of the tendency of a simple commodity economy to allocate social labour efficiently. The model demonstrates that, in the special case of simple commodity production, Marx's law of value can naturally emerge from multiple local exchanges and operate ‘behind the backs’ of actors solely via money flows that place budget constraints on their local evaluations of commodity prices, which are otherwise subjective and unconstrained.     

A class of monotone economies in which rational expectations equilibria exist but prices do not reveal all information

Some economies having excess demands which depend monotonically on agents' information signals are examined. If there are no multiple market clearing prices, then these economies have strict rational expectations equilibria in which equilibrium prices alone do not transmit all information.     

Entry and Vertical Differentiation

This paper analyzes the entry of new products into vertically differentiated markets where an entrant and an incumbent compete in quantities. The value of the new product is initially uncertain and new information is generated through purchases in the market. We derive the (unique) Markov perfect equilibrium of the infinite horizon game under the strong long run average payoff criterion. The qualitative features of the optimal entry strategy are shown to depend exclusively on the relative ranking of established and new products based on current beliefs. Superior products are launched relatively slowly and at high initial prices whereas substitutes for existing products are launched aggressively at low initial prices. The robustness of these results with respect to different model specifications is discussed. Journal of Economic Literature Classification Numbers: C72, C73, D43, D83.     

ON THE IMPACT OF FUNDAMENTALS,LIQUIDITY, AND COORDINATION ON MARKET STABILITY*

We develop a coordination game to model interactions between fundamentals and liquidity during unstable periods in financial markets. We then propose a flexible econometric framework for estimation of the model and analysis of its quantitative implications. The specific empirical application is carry trades in the yen–dollar market, including the turmoil of 1998. We find a generally very deep market, with low information disparities among agents. We observe occasional episodes of market fragility or turmoil with up by the escalator, down by the elevator patterns in prices. The key role of strategic behavior in the econometric model is also confirmed.     

Shopping hours and price competition

This paper develops an argument why retail prices may rise in response to the deregulation of opening hours. We make this point in a model of imperfect duopolistic competition. In a deregulated market retailers view the choice of opening hours as a means to increase the degree of perceived product differentiation thus relaxing price competition. If the consumers’ preference intensity for time is sufficiently high the equilibrium configuration has asymmetric shopping hours where one retailer stays open for longer than the other. Both retailers charge higher prices than under regulation, and both are strictly better off.     

Optimality and Natural Selection in Markets

We ask if natural selection in markets favors profit-maximizing firms and, if so, is there a difference between the predictions of models which assume all firms are profit maximizers and the predictions of models which explicitly take account of population dynamics in the market. We show that market selection favors profit maximizing firms, but we also show that the long-run behavior of evolutionary market models is nonetheless not consistent with equilibrium models based on the profit-maximization hypothesis. Dynamic equilibrium paths with market selection are not Pareto optimal, nor even asymptotically optimal. The discrepancy arises because the dynamics created by firm evolution causes prices to vary over time and the resulting dynamical system need not have stable steady states.     

Nodal pricing of electricity: how much does it cost to get it wrong?

Economists know how to calculate optimal prices for electricity transmission. These are rarely applied in practice. This paper develops a 13-node model of the transmission system in England and Wales, incorporating losses and transmission constraints. It is solved with optimal prices, and with uniform prices for demand and for generation, re-dispatching when needed to take account of transmission constraints. Moving from uniform prices to optimal nodal prices could raise welfare by 1.3% of the generators’ revenues, and would be less vulnerable to market power. It would also send better investment signals, but create politically sensitive regional gains and losses.      

Mergers in the food retailing sector: An empirical investigation

We address the problem of merger evaluation, for competition policy purposes, in the retailing sector. The likely effects of a possible merger are analysed ex ante. The novelty of the paper lies in the inclusion of downstream and upstream market power effects on the retailers. Also, it provides an empirical application to the Portuguese food retailing market. The effects of additional concentration on prices are estimated, as well as the price reduction insiders are likely to obtain via an improved bargaining position. The final effect on prices depends on how these cost reductions are reflected in insiders’ prices, i.e., on the pass-through rate. For realistic values of this rate we find that the merger in question will most likely increase consumer prices and, therefore, should not be allowed on an antitrust legislation basis.     

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.     

Garbling of signals and outcome equivalence

In a game with incomplete information players receive stochastic signals about the state of nature. The distribution of the signals given the state of nature is determined by the information structure. Different information structures may induce different equilibria.Two information structures are equivalent from the perspective of a modeler, if they induce the same equilibrium outcomes. We characterize the situations in which two information structures are equivalent in terms of natural transformations, called garblings, from one structure to another. We study the notion of ‘being equivalent to’ in relation with three equilibrium concepts: Nash equilibrium, agent normal-form correlated equilibrium and the belief invariant Bayesian solution.     

Price signaling and the strategic benefits of price rigidities

We analyze trade between a perfectly informed price setting party (seller) and an imperfectly informed price taker (buyer). Differently from most of the literature, we focus on the case in which, under full information, it would be inefficient to trade goods of sufficiently poor quality. We show that the unique equilibrium surviving D1 is characterized by market breakdown, although trade would be mutually beneficial in some state of nature. This occurs independently of the precision of the information available to the buyer. The model thus implies that signaling through prices may exacerbate the effect of adverse selection rather than mitigate it. Under D1, the seller would always benefit from committing to prices that do not reveal her information. We develop this intuition by analyzing the strategic advantages of price rigidities. We show that price rigidities help restore trade and could even enhance effectiveness of prices as signals of quality.