decentralized trade mitigates the lemons problem in markets with adverse selection only low quality units trade in the competitive equilibrium when the average quality of the good held by sellers is low we show that under decentralized trade however both high and low quality units trade although with delay moreover when frictions are small the surplus realized is greater than the static competitive surplus thus decentralized trade mitigates the lemons problem remarkably payoffs are competitive as frictions vanish even though both high and low quality units continue to trade and there is trade at several prices markets differ in the degree to which trade is centralized call markets used to set opening prices on the nyse are highly centralized and all trade takes place at a single price the market clearing price in contrast in housing labor or used car markets trade is highly decentralized and prices are determined by bilateral bargaining between buyers and sellers and may differ between trades the competitive model abstracts away from these institutional aspects thus providing a model suitable in principle for the study of both centralized and decentralized markets our results suggest that decentralized markets with adverse selection may perform better than anticipated by the static competitive model and therefore that these institutional features cannot be ignored it is known that in markets for homogenous goods decentralized trade tends to yield competitive outcomes when trading frictions are small because competitive equilibrium is efficient in these markets this implies that decentralized trade generates nearly efficient outcomes in markets with adverse selection however competitive equilibria ce need not be efficient which raises the possibility that alternative market structures perform better in this article we study a version of akerlof s 1970 market for lemons in which trade is decentralized each period an equal measure of buyers and sellers enters the market every seller is endowed with a unit of either high or low quality at each period every agent in the market has a positive probability of meeting an agent of the opposite type once matched a buyer without observing the quality of the seller s unit makes a take it or leave it price offer if the seller accepts then they trade at the offered price and both agents exit the market if the seller rejects the offer then both agents remain in the market at the next period discounting of future gains and the possible delay in matching with a trading partner constitute trading frictions when the average quality of the good held by entering sellers is low the market has a unique competitive equilibrium ce in which the price equals the buyers value of a low quality unit

efficiency in decentralised markets with aggregate uncertainty we study efficiency in decentralized markets with aggregate uncertainty and one sided private information there is a continuum of mass one of uninformed buyers and a continuum of mass one of informed sellers buyers and sellers are randomly and anonymously matched in pairs over time and buyers make the offers we show that all equilibria become efficient as trading frictions vanish

information disclosure and asymmetric speed of learning in booms and busts we consider a model in which agents gradually learn about the aggregate market conditions boom or bust from the information disclosed after a trading round the disclosure rules can generate asymmetric learning and affect the degree of asymmetry in particular when only winning bids are publicly disclosed learning is more rapid in a bust

on the frequency of large stock returns putting booms and busts into perspective textabstractnumerous articles have investigated the distribution of share prices and find that the returns are fat tailed nevertheless there is still controversy about the amount of probability mass in the tails and hence about the most appropriate distribution to use in modeling returns this controversy has proven hard to resolve as the alternatives are non nested we employ extreme value theory focusing exclusively on the larger observations in order to assess the tail shape within a unified framework we find that at least the first two moments exist this enables one to generate robust probabilities on large returns which put the recent stock market swings into historical perspective

the asymptotic distribution of extreme stock market returns this article presents a study of extreme stock market price movements according to extreme value theory the form of the distribution of extreme returns is precisely known and independent of the process generating returns using data for an index of the most traded stocks on the new york stock exchange for the period 1885 1990 the author shows empirically that the extreme returns obey a frechet distribution copyright 1996 by university of chicago press

the relative contributions of private information sharing and public information releases to information aggregation we calculate learning rates when agents are informed through public and private observation of other agents actions we characterize the evolution of the distribution of posterior beliefs if the private learning channel is present convergence of the distribution of beliefs to the perfect information limit is exponential at a rate equal to the sum of the mean arrival rate of public information and the mean rate at which individual agents are randomly matched with other agents if however there is no private information sharing then convergence is exponential at a rate strictly lower than the mean arrival rate of public information c 2009 elsevier inc all rights reserved

learning from private and public observations of othersʼ actions we study how a continuum of agents learn about disseminated information by observing others actions every period each agent observes a public and private noisy signal centered around the aggregate action taken by the population the public signal represents an endogenous aggregate variable such as a price or a quantity the private signal represents the information gathered through private communication and local interactions we identify conditions such that the average learning curve is s shaped learning is slow initially intensifies rapidly and finally converges slowly to the truth we show that increasing public information always slows down learning in the long run and under some conditions reduces welfare lastly optimal diffusion of information requires that agents strive to be different agents need to be rewarded for choosing actions away from the population average

information learning and the stability of fiat money abstract we analyze the stability of monetary regimes in an economy where fiat money is endogenously created by the government information about its value is imperfect and learning is decentralized we show that monetary stability depends crucially on the speed of information transmission in the economy our model generates a dynamic on the acceptability of fiat money that resembles historical accounts of the rise and eventual collapse of overissued paper money it also provides an explanation of the fact that despite its obvious advantages the widespread use of fiat money is only a recent development

screening in a matching market contract design under incomplete information is often analysed in a bilaterally monopolistic setting if the informed party s reservation value does not depend on its private information its type it is a standard result that the uninformed side offers low types distorted contracts to reduce the information rent left to high types we challenge this result by embedding contract design in a matching market environment we consider a market where players meet pairwise and where in each match either side may be chosen to make a take it or leave it offer as frictions become sufficiently low we find that the set of equilibria is independent of whether there is complete or incomplete information in particular all contracts are free of distortions

dynamic matching and bargaining games a general approach this paper presents a new characterization result for competitive allocations in quasilinear economies this result is informed by the analysis of non cooperative dynamic search and bargaining games such games provide models of decentralized markets with trading frictions a central objective of this literature is to investigate how equilibrium outcomes depend on the level of the frictions in particular does the trading outcome become walrasian when frictions become small existing specifications of such games provide divergent answers the characterization result is used to investigate what causes these differences and to generalize insights from the analysis of specific search and bargaining games

bargaining in a network of buyers and sellers abstract we analyze bargaining between buyers and sellers who are connected by an exogenously given network players can make repeated alternating public offers that may be accepted by any of the responders linked to each specific proposer our purpose is to find the conditions of the network which drive the price distribution in equilibrium this paper uses graph theory tools to provide necessary and sufficient conditions regarding the architecture of networks for the subgame perfect equilibrium of the bargaining game to coincide with the walrasian outcome

market power and information revelation in dynamic trading we study a strategic model of dynamic trading where agents are asymmetrically informed over common value sources of uncertainty there is a continuum of buyers and a finite number n of sellers all buyers are uninformed while at least one seller is privately informed about the true state of the world when n 1 full information revelation never occurs in equilibrium and the only information transmission happens in the first period with n 1 the outcome depends both on the structure of the sellers information and even more importantly on the intensity of competition allowed by the existing trading rules when there is intense competition absence of clienteles information is fully and immediately revealed to the buyers in every equilibrium for n large enough regardless of the number of informed sellers on the other hand for trading arrangements characterized by less intense forms of competition presence of clienteles for any n we always have equilibria where information is never fully revealed moreover in that case when only one seller is informed for many parameter configurations there are no equilibria with full information revelation even for large n jel c72 c78 d82 d83

the rate of convergence to perfect competition of matching and bargaining mechanisms abstract we study the steady state of a market with incoming cohorts of buyers and sellers who are matched pairwise and bargain under private information a friction parameter is the length of the time period until the next meeting we provide a necessary and sufficient condition for the convergence of mechanism outcomes to perfect competition at the linear rate in which is shown to be the fastest possible among all bargaining mechanisms the condition requires that buyers and sellers always retain some bargaining power the bargaining mechanisms that satisfy this condition are called nonvanishing bargaining power nbp mechanisms simple random proposer take it or leave it protocols are nbp while k double auctions k da are not we find that k das have equilibria that converge to perfect competition at a linear rate converge at a slower rate or even do not converge at all

price dispersion information and learning abstract we consider an economy where trade is decentralized and agents have incomplete information with respect to the value of money agents learning evolves from private experiences and we explore how the formation of prices interacts with learning we show that multiple equilibria arise and equilibria with price dispersion entail more learning than equilibria with one price price dispersion increases communication about private histories which in turn increases the overall amount of information in the economy we also compare ex ante welfare under price dispersion and one price our results show that despite the existence of some meetings where no trade takes place ex ante welfare under price dispersion may be higher than under one price

the dynamics of stock index and stock index futures returns in rational efficiently functioning markets the returns on stock index and stock index futures contracts should be perfectly contemporaneously correlated this study investigates the time series properties of 5 minute intraday returns of stock index and stock index futures contracts and finds that sp however the effect is not completely unidirectional with lagged stock index returns having a mild positive predictive impact on futures returns

search adverse selection and market clearing we examine a dynamic decentralized trading model with infinitesimal sellers and buyers to investigate whether or not the market fails to clear in the limit of search friction vanishing a seller who has private information about product quality and a buyer are matched to bargain over price they form a long term relationship if they reach agreement they return to the matching pool if they fail to agree or the existing relationship is dissolved the market fails to clear if and only if the ratio of agents patience over the dissolution rate exceeds a threshold

from value at risk to stress testing the extreme value approach this article presents an application of extreme value theory to compute the value at risk of a market position in statistics extremes of a random process refer to the lowest observation the minimum and to the highest observation the maximum over a given time period extreme value theory gives some interesting results about the distribution of extreme returns in particular the limiting distribution of extreme returns observed over a long time period is largely independent of the distribution of returns itself in financial markets extreme price movements correspond to market corrections during ordinary periods and also to stock market crashes bond market collapses or foreign exchange crises during extraordinary periods an approach based on extreme values to compute the var thus covers market conditions ranging from the usual environment considered by the existing var methods to the financial crises which are the focus of stress testing univariate extreme value theory is used to compute the var of a fully aggregated position while multivariate extreme value theory is used to compute the var of a position decomposed on risk factors 2000 elsevier science b v all rights reserved

the threshold effect in expected volatility a model based on asymmetric information this article develops theoretical insight into the threshold effect in expected volatility which means that large shocks are less persistent in volatility than small shocks the model uses the kyle admati pfleiderer setup with liquidity traders informed traders and a market maker information is modeled as a garch process it is shown that the garch process for information is transformed into a tarch process for threshold garch for the market price changes working with information flows allows one to derive implications for trading volume and market liquidity which provide the basis for a more complete test of the model article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies

correlated demand shocks and price wars during booms the supergame theoretic model of price competition rotemberg and saloner 1986 is re examined in the case of serially correlated demand shocks the equilibrium price is shown to exhibit the same counter cyclical movement as in the i i d case if the discount factor and the number of firms satisfy certain relationship

reprint of information percolation in segmented markets we study equilibria of dynamic over the counter markets in which agents are distinguished by their preferences and information over time agents are privately informed by bids and offers investors differ with respect to information quality including initial information precision and also in terms of market connectivity the expected frequency of their bilateral trading opportunities we characterize endogenous information acquisition and show how learning externalities affect information gathering incentives more liquid markets lead to higher equilibrium information acquisition when the gains from trade and market duration are sufficiently large on the other hand for a small market duration the opposite may occur if agents vary sufficiently in terms of their market connectivity c 2014 published by elsevier inc

price discovery in a matching and bargaining market with aggregate uncertainty abstract we introduce aggregate uncertainty into a rubinstein and wolinsky 1985 type dynamic matching and bilateral bargaining model the market can be either in a high state where there are more buyers than sellers or in a low state where there are more sellers than buyers traders do not know the state they randomly meet each other and bargain by making take it or leave it offers the only information transmitted in a meeting is the time a trader spent on the market there are two kinds of search frictions time discounting and exogenous exit we find that as the search frictions vanish the market discovers the competitive price quickly the prices offered in equilibrium converge in expectation to the true state walrasian price at the rate linear in the total search friction this rate is the same as it would be if the state were commonly known

screening peers softly inferring the quality of small borrowers this paper examines the performance of new online lending markets that rely on nonexpert individuals to screen their peers creditworthiness we find that these peer lenders predict an individual s likelihood of defaulting on a loan with 45 greater accuracy than the borrower s exact credit score unobserved by the lenders who only see a credit category moreover peer lenders achieve 87 of the predictive power of an econometrician who observes all standard financial information about borrowers screening through soft or nonstandard information is relatively more important when evaluating lower quality borrowers our results highlight how aggregating over the views of peers and leveraging nonstandard information can enhance lending efficiency this paper was accepted by amit seru finance

var seductive but dangerous value at risk var has gained rapid acceptance as a valuable approach to risk management not all vars are equal however a study of var techniques used by dealers and end users reveals that var calculations differ significantly for the same portfolio vars are extremely dependent on parameters data assumptions and methodology calculation of eight common vars for three hypothetical portfolios demonstrates the potentially seductive but dangerous nature of any single approach to risk management in sum although var and other quantitative techniques are necessary aspects of an effective risk management program they are not sufficient to control risk

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

convergence to perfect competition of a dynamic matching and bargaining market with two sided incomplete information and exogenous exit rate abstract consider a decentralized dynamic market with an infinite horizon and incomplete information in which buyers and sellers values for the traded good are private and independently drawn time is discrete each period has length and each unit of time a large number of new buyers and sellers enter the market within a period each buyer is matched with a seller and each seller is matched with zero one or more buyers every seller runs a first price auction with a reservation price and if trade occurs the seller and winning buyer exit with their realized utility traders who fail to trade either continue in the market to be rematched or exit at an exogenous rate we show that in all steady state perfect bayesian equilibria as approaches zero equilibrium prices converge to the walrasian price and realized allocations converge to the competitive allocation

bargaining and reputation in search markets in a two sided search market agents are paired to bargain over a unit surplus the matching market serves as an endogenous outside option for a bargaining agent behavioral agents are commitment types that demand a constant portion of the surplus the frequency of behavioral types is determined in equilibrium even if the frequency of behavioral types is negligible they aect the terms of trade and eciency in an unbalanced market where the entering

information percolation in segmented markets we study equilibria of dynamic over the counter markets in which agents are distinguished by their preferences and information over time agents are privately informed by bids and offers investors differ with respect to information quality including initial information precision and also in terms of market connectivity the expected frequency of their bilateral trading opportunities we characterize endogenous information acquisition and show how learning externalities affect information gathering incentives more liquid markets lead to higher equilibrium information acquisition when the gains from trade and market duration are sufficiently large on the other hand for a small market duration the opposite may occur if agents vary sufficiently in terms of their market connectivity c 2014 published by elsevier inc

learning and price discovery in a search market we introduce learning into an otherwise standard two sided search and bargaining market there is uncertainty about the price distribution due to uncertainty about an underlying exogenous state of relative demand in the high state buyers are on the long side otherwise they are on the short side in equilibrium prices are on average higher in the high state individual agents learn about the distribution while searching agents typically start out by experimenting with a tough bargaining position buyers may initially insist on a low price and sellers on a high price after successive failures to trade agents become increasingly pessimistic about the market conditions and soften their bargaining stance when frictions are small equilibrium transaction prices are approximately market clearing despite aggregate demand being unknown thus the search and bargaining procedure enables price discovery in a decentralized market

risk2 measuring the risk in value at risk the recent derivatives disasters have focused the attention of the finance industry on the need to control financial risks better this search has led to a uniform measure of risk called value at risk var which is the expected worst loss over a given horizon at a given confidence level var numbers however are themselves affected by sampling variation or estimation risk thus the risk in value at risk itself nevertheless given these limitations var is an indispensable tool to control financial risks this article lays out the statistical methodology for analyzing estimation error in var and shows how to improve the accuracy of var estimates

search with adverse selection this paper analyzes a sequential search model with adverse selection we study information aggregation by the price how close the equilibrium prices are to the full information prices when search frictions are small we identify circumstances under which prices fail to aggregate information well even when search frictions are small we trace this to a strong form of the winner s curse that is present in the sequential search model the failure of information aggregation may result in inefficient allocations

should buyers or sellers organize trade in a frictional market to answer the question in the title this article characterizes the socially efficient organization of the market with search frictions the efficient organization depends on the relative elasticity in the supply between the two sides of the market the costs of participating in the market and organizing trade and the a symmetry in matching we also show that the social optimum can be implemented by a realistic market equilibrium where the organizers set up trading sites to direct the other side s search the results provide a unified explanation for why trade has often been organized by sellers in the goods market by buyers firms in the labor market and by both sides in the asset market the analysis also sheds light on how the efficient market organization can change with innovations such as e commerce and just in time production

on the informational content of wage offers this article investigates signaling and screening roles of wage offers in a single play matching model with two sided unobservable characteristics it generates the following predictions as matching equilibrium outcomes i good jobs offer premia if high quality worker population is large ii bad jobs pay compensating differentials if the proportion of good jobs to low quality workers is large iii all firms may offer a pooling wage in markets dominated by high quality workers and firms or iv gresham s law prevails good types withdraw if bad types dominate the population the screening signaling motive thus has the potential of explaining a variety of wage patterns

decentralized markets and endogenous institutions this paper is concerned with decentralized models of market equilibrium in which the primary interest lies in the nature of the institutions that govern trade there are two separate branches in this literature in the first the institutions that govern trade are taken to be given exogenously the primary motivation for models in this class is essentially the study of comparative institutions in particular the papers are interested in whether there are specific institutions that will generate walrasian prices and allocations approximately when transactions costs are small in the second branch of the literature the institutions that govern trade themselves are made endogenous these models characterize the nature of these endogenously generated institutions and examine their efficiency in environments where transactions costs are small

a decentralized market with common values uncertainty non steady states we analyse a market where i trade proceeds by random and anonymous pairwise meetings with bargaining ii agents are asymmetrically informed about the value of the traded good and iii no new entrants are allowed once the market is open we show that information revelation and efficiency never obtain in equilibrium even as discounting is removed this holds whether the asymmetry is two sided or one sided in some cases there exist equilibria where a substantial amount goes untraded this contrasts with the earlier literature which was based on the steadystate equilibria of a model where agents enter the market every period

a battle of informed traders and the market game foundations for rational expectations equilibrium abstract potential manipulation of prices and convergence to rational expectations equilibrium is studied in a game without noise traders informed players with initially long and short positions bulls and bears seek to manipulate consumer expectations in opposite directions in equilibrium period 1 prices reveal the state so manipulation is unsuccessful bears and uninformed consumers sell up to their short sale limits in period 1 bulls buy in period 1 but receive arbitrage losses when the number of bulls and bears approaches infinity the equilibrium converges to the ree without short sale constraints there is a non revealing equilibrium but no revealing equilibrium

strategic firms and endogenous consumer emulation better informed consumers may be treated preferentially by firms since their consumption serves as a quality signal for other customers for normal goods this results in wealthy individuals being treated better than poor individuals we investigate this phenomenon in an equilibrium model of social learning with heterogeneous consumers and firms that act strategically consumers search for high quality firms and condition their choices on observed actions of other consumers when they observe consumers who are more likely to have identified a high quality firm uninformed individuals will optimally emulate those consumers one group of consumers arises endogenously as leaders whose consumption behavior is emulated follow on sales induce firms to give preferential treatment to these lead consumers which reinforces their learning

information revelation in a market with pairwise meetings the paper presents a simple pairwise meetings model of trade the new feature is that agents have asymmetric information about the true state of the world the focus is on the transmission of the information through the process of trade the qualitative question is to what extent is the information revealed to uninformed agents through the trading process when the market is in some sense frictionless in particular does the decentralized process give rise to full revelation results as derived by the literature on rational expectations for centralized and competitive environments in the context of the model of this paper it turns out that the information is not fully revealed to uninformed agents even when the market is in some sense approximately frictionless

presidential address asset price dynamics with slow moving capital i describe asset price dynamics caused by the slow movement of investment capital to trading opportunities the pattern of price responses to supply or demand shocks typically involves a sharp reaction to the shock and a subsequent and more extended reversal the amplitude of the immediate price impact and the pattern of the subsequent recovery can reflect institutional impediments to immediate trade such as search costs for trading counterparties or time to raise capital by intermediaries i discuss special impediments to capital formation during the recent financial crisis that caused asset price distortions which subsided afterward after presenting examples of price reactions to supply shocks in normal market settings i offer a simple illustrative model of price dynamics associated with slow moving capital due to the presence of inattentive investors i address the implications for asset price dynamics of the apparent slow movement of investment capital to trading opportunities the arrival of new capital to an investment opportunity can be delayed by fractions of a second in some markets for example an electronic limit order book market for equities or by months in other markets such as that for catastrophe risk insurance accordingly prices respond to supply or demand shocks with a sharp reaction because of the relatively small subset of capital and thus risk bearing capacity that is immediately available to absorb a shock on short notice such a price impact is substantially reversed over time as additional capital becomes available the amplitude of the immediate price impact and the pattern of the subsequent recovery can reflect many sorts of attention costs to trade as well as institutional impediments to capital movement such as search costs for trading

decentralized trading with private information the paper studies how asset prices are determined in a decentralized market with asymmetric information about asset values we consider an economy in which a large number of agents trade two assets in bilateral meetings a fraction of the agents has private information about the asset values we show that over time uninformed agents can elicit information from their trading partners by making small offers this form of experimentation allows the uninformed agents to acquire information as long as there are potential gains from trade in the economy as a consequence the economy converges to a pareto efficient allocation

follies subdued informational efficiency under adaptive expectations and confirmatory bias abstract we study the informational efficiency of a market with a single traded asset the price initially differs from the fundamental value about which the agents have noisy private information which is on average correct a fraction of traders revise their price expectations in each period the price at which the asset is traded is public information the agents expectations have an adaptive component and a social interactions component with confirmatory bias we show that taken separately each of the deviations from rationality worsens the informational efficiency of the market however when the two biases are combined the degree of informational inefficiency of the market measured as the deviation of the long run market price from the fundamental value of the asset can be non monotonic both in the weight of the adaptive component and in the degree of confirmatory bias for some ranges of parameters two biases tend to mitigate each other s effect thus increasing informational efficiency

information percolation in large markets we introduce a simple model of the percolation of information of common interest through a large market as agents encounter each other over time and reveal information to each other some of which they may have received earlier from other agents we are particularly interested in the evolution over time of the cross sectional distribution in the population of the posterior probability assignments of the various agents we provide a market example based on privately held auctions and obtain a relatively explicit solution for the cross sectional distribution of posterior beliefs at each time our results contribute to the literature on information transmission in markets hayek 1945 argues that markets allow information that is dispersed in a population to be revealed through prices grossman s 1981 notion of a rational expectations equilibrium formalizes this idea in a setting with price taking agents milgrom 1981 pesendorfer and swinkels 1997 and reny and perry 2006 provide strategic foundations for the rational expectations equilibrium concept in centralized markets a number of important markets however are decentralized these include over the counter markets and private auction markets wolinsky 1990 and blouin and serrano 2002 study information transmission in decentralized markets in contrast to these two papers equilibrium behavior in our market example leads to full revelation of information we happily acknowledge conversations with manuel amador frank kelly jeremy stein and pierre olivier weill and research assistance from sergey lobanov rubinstein and wolinsky 1985 and gale 1986a 1986b study decentralized markets without asymmetric information satterthwaite and shneyerov 2003 study decentralized market with private value asymmetric information amador and weill 2006 study a more abstract setting regarding transmission of common and private i nformation

liquidity misallocation in an over the counter market abstract to understand the illiquidity of the over the counter market when dealers and traders are in long term relationships i develop a framework to study the endogenous liquidity distortions resulting from the profit maximizing screening behavior of dealers the dealer offers the trading mechanism contingent on the aggregate history of his customers summarized by the asset allocation the equilibrium distortion is type dependent trade with small surplus breaks down trade with intermediate surplus may be delayed trade with large surplus is carried out with a large bid ask spread but without delay because of dealers limited commitment the distortions become more severe when the valuation shock is frequent the valuation dispersion is large or the matching friction to form new relationships is large calibrating the model and running a horse race between matching efficiency trading speed and relationship stability i found that the liquidity disruption in the market during the recent financial crisis is more consistent with declining matching efficiency of forming trading relationships the optimal mechanism can be implemented by random quote posting

disagreement in markets with matching and bargaining this paper develops an explanation of why bargainers often terminate negotiations in disagreement in spite of positive expected gains from continued negotiation the key to the analysis is a model which embeds bargaining activity within a market agents are continually faced with the choice between continuing to bargain with an existing partner or searching for a new partner bargainers may then terminate negotiations without an agreement in spite of positive expected gains from continued bargaining because seeking a new bargaining partner promises a higher return

experiments on percolation of information in dark markets in dark markets order submissions are bilateral and transaction prices are known only to the trading counterparties here we study to what extent the information aggregation theory proposed by duffie and collaborators predicts outcomes in a laboratory version of such markets we find that prices aggregate the available information but not in the strict sense of the theory where prices converge exponentially fast to average private signals prices instead fluctuate within bands around this average the band widths reflect in the best case the precision of the average signal and otherwise the precision of a single private signal

information percolation with equilibrium search dynamics we solve for the equilibrium dynamics of information sharing in a large population each agent is endowed with signals regarding the likely outcome of a random variable of common concern individuals choose the effort with which they search for others from whom they can gather additional information when two agents meet they share their information the information gathered is further shared at subsequent meetings and so on equilibria exist in which agents search maximally until they acquire sufficient information precision and then search minimally a tax whose proceeds are used to subsidize the costs of search improves information sharing and can in some cases increase welfare on the other hand endowing agents with public signals reduces information sharing and can in some cases decrease welfare

learning from trades i study stationary cut off strategy equilibria of a dynamic market model where buyers sample sellers sequentially from an unknown distribution buyers learn about the distribution from the sampled sellers and a trade signal the trade signal reveals whether a randomly chosen seller traded yesterday observing a trade as opposed to no trade is good news about the distribution buyers who observe a trade use a higher cut off than buyers who observe no trade despite buyers learning from sampled sellers that puts a countervailing pressure on the cut offs the trade signal may reduce market efficiency while an appropriate exogenous signal increases efficiency