frictionless commerce a comparison of internet and conventional retailers there have been many claims that the internet represents a new nearly frictionless market our research empirically analyzes the characteristics of the internet as a channel for two categories of homogeneous products books and cds using a data set of over 8 500 price observations collected over a period of 15 months we compare pricing behavior at 41 internet and conventional retail outlets we find that prices on the internet are 9 16 lower than prices in conventional outlets depending on whether taxes shipping and shopping costs are included in the price additionally we find that internet retailers price adjustments over time are up to 100 times smaller than conventional retailers price adjustments presumably reflecting lower menu costs in internet channels we also find that levels of price dispersion depend importantly on the measures employed when we compare the prices posted by different internet retailers we find substantial dispersion internet retailer prices differ by an average of 33 for books and 25 for cds however when we weight these prices by proxies for market share we find dispersion is lower in internet channels than in conventional channels reflecting the dominance of certain heavily branded retailers we conclude that while there is lower friction in many dimensions of internet competition branding awareness and trust remain important sources of heterogeneity among internet retailers

s p 500 cash stock price volatilities s p 500 stock return volatilities are compared to the volatilities of a matched set of stocks after controlling for cross sectional differences in firm attributes known to affect volatility no significant difference in volatility is observed between 1975 and 1983before the start of trade in index futures and index options since then s p 500 stocks have been relatively more volatile the difference is statistically but not economically significant the relative increase occurs primarily in daily returns and only to a lesser extent in longer interval returns other factors besides the start of derivative trade could be responsible for the small increase in volatility stock price volatility has received much attention in the popular press over the last few years especially since the october 19 1987 stock market crash the rise in volatility has alarmed investors regulators and the public in general some suggest that the start of trade in stock index futures and index options increased speculative activity that in turn destabilized cash markets causing higher volatility large trading activity in the derivative contracts makes the suggestion plausible volume in index futures and index options increased dramatically since their introductions in 1982 and 1983 by 1987 the average daily dollar volume in the s p 500 futures contracts alone exceeded the dollar volume of cash s p 500 trade by a factor of about two while the dollar value of the daily net change in total open interest is about 8 of s p 500 stock dollar volume speculative trade in futures and options frequently is accused of destabilizing underlying cash markets the charge has been made for more than a century in the agricultural precious metal and currency markets recent evidence by french and roll 1986 showing stock variance to be strongly related to trading session hours heightens these concerns unfortunately theoretical analyses of whether speculative trade destabilizes cash markets lead to conflicting conclusions depending on what assumptions are made 1 school of business administration university of southern california and office of economic analysis u s securities and exchange commission i wish to thank mary denny mcsweeny and steve hornstein for their valuable research assistance and the referee and editor for their many suggestions and insights the opinions expressed in this paper do not necessarily reflect those of the u s securities and exchange commission or those of the author s colleagues on its staff an increase in well informed speculative trade has two opposite effects on measured volatility it decreases volatility due to order flow imbalances caused by uninformed traders because informed traders provide liquidity in such events and it increases volatility due to new fundamental information since the information which is assumed to be generated at discrete time intervals is impounded into

competition and the number of firms in a market are duopolies more competitive than atomistic markets this paper uses a variant of the standard search model to examine market equilibrium and the consequences for market equilibrium of an increase in the number of firms if marginal search costs increase with the number of searches then the demand curve facing any firm will be kinked with the elasticity of demand with respect to price decreases being less than with respect to price increases prices may not change in response to changes in marginal costs as the number of firms increases the maximum price that is consistent with equilibrium increases to the monopoly price but the minimum price decreases on the other hand if marginal search costs decrease with the number of searches equilibrium if it exists is characterized by a

price dispersion and seller heterogeneity in retail food markets price dispersion i e a homogeneous product being sold at different prices by different sellers is among the most replicated findings in empirical economics the paper assesses the extent and determinants of spatial price dispersion for 14 perfectly homogeneous food products in more than 400 retailers in a market characterized by the persistence of a large number of relatively small traditional food stores alongside large supermarkets the extent of observed price dispersion is quite high when prices in an urban area where the spatial concentration of sellers is higher are compared with those in smaller towns and rural areas differences in search costs and the potentially higher degree of competition do not yield lower prices other counteracting factors including differences in seller costs and consumer incomes make prices on average higher in the urban area for 11 of the 14 products considered for many but not all the products supermarkets proved to be less expensive than traditional retailers although average savings from food shopping at supermarkets were extremely low finally the results of the study provide evidence that retailers have different pricing strategies and these differences also emerge for supermarkets belonging to the same chain the results presented in the paper suggest that a variety of factors play a role in explaining price dispersion in addition to differences in seller costs the contemporaneous heterogeneity of retailers in terms of services provided and consumers in terms of search costs and preferences makes the emergence of monopolistic competition possible as well as allowing small traditional food retailers to remain in business

program trading and expiration day effects the arbitrage between index futures and the underlying cash index and the cash settlement feature of index futures contracts which requires arbitrageurs to unwind positions in the stock market are thought to be at the heart of the abnormal stock price movements during the triple witching hour the last hour of trading on days on which index futures index options and options on index futures expire simultaneously during 1984 and 1985 volume was substantially higher than normal in the last hour of trading on those quarterly fridays open interest in the expiring futures contracts on the expiration day amounted to about 40 per cent of the average month end open interest the incremental stock market volume however was approximately one third the volume that would be inmplied if the entire expiration day open interest were traded in the stock market analysis of stock market price changes in the last hour of expiration days and the first halfhour of the following day indicates that the volatility of price changes was significantly higher on expiration days with the stock market tending to fall stocks not in the sp index option expirations themselves did not lead to abnormal market movements when the magnitude of price effects was measured by the degree of reversal in prices on the morning after the expiration day the average magnitude of the price effect in the 10 most recent quarterly futures contract expirations examined was about 0 4 per cent of the closing index value at expiration the average expiration day price effect of 0 4 per cent is not large considering that a price impact of approximately 0 25 per cent of the value of the transaction can be expected on the basis of the bid ask spread once this market impact cost is drawn out the average expiration day price impact falls to about 0 15 per cent of the value of the transaction an amount representing the additional cost of liquidity furthermore price impacts in excess of those found on expiration days are frequently encountered in large block transactions where the cost of providing liquidity also increases on expiration days however transactions in many stocks occur simultaneously so the market as a whole is affected

search intensity in oligopoly a simultaneous price setting oligopoly game characterized by the existence of buyers with differing price information is presented the information structure of the game is more general than previously considered thereby permitting a richer analysis in addition to identifying the general conditions that lead to equilibrium with price dispersion the author provides a revealing reinterpretation of models characterized by simpler information structures an important finding of the paper is that additional price information in the market impacts prices differently only if the poorly informed buyers are reached can we expect average prices to decrease copyright 1996 by blackwell publishing ltd

strategic price complexity in retail financial markets abstract there is mounting empirical evidence to suggest that the law of one price is violated in retail financial markets there is significant price dispersion even when products are homogeneous also despite the large number of firms in the market prices remain above marginal cost and may even rise as more firms enter in a non cooperative oligopoly pricing model i show that these anomalies arise when firms add complexity to their price structures complexity increases the market power of the firms because it prevents some consumers from becoming knowledgeable about prices in the market in the model as competition increases firms tend to add more complexity to their prices as a best response rather than make their disclosures more transparent because this may substantially decrease consumer surplus in these markets such practices have important welfare implications

further implications of the reversion level in agenda setter models abstract the reversion level affects price and income elasticities of demand when expenditure levels are chosen by agenda setters this paper develops this relationship and shows how agenda setter produced elasticities differ from median voter elasticities

durable goods theory for real world markets the early 1970s witnessed three major advances in durable goods theory swan 1970 1971 and sieper and swan 1973 on optimal durability coase 1972 on time inconsistency and akerlof 1970 on adverse selection this paper surveys durable goods theory starting with these three contributions where much of the focus is on recent literature and on models that explain real world phenomena in addition to the ideas found in the contributions of swan coase and akerlof topics covered include why producers sometimes practice planned obsolescence the role of adverse selection in new car leasing and reasons for aftermarket monopolization

analyzing the impact of futures trading on spot price volatility evidence from the spot electricity market in france and germany abstract this paper examines the impact of the introduction of electricity futures on the spot price volatility of the french powernext and german eex electricity markets as well as the degree of their price correlation over the period 2002 2011 our working hypotheses were tested based on a bivariate vecm garch model the results indicate that the introduction of futures contracts in the french electricity market as well as the launch of the joint futures market in these countries in 2009 has decreased spot price volatility however this effect was not as explicit for the german market due to data specificities other interesting results are the german market dominates and leads the long run price relationship the impact of cooling needs on demand is greater than the impact of heating needs there is a substantial systematic pattern of electricity prices and their respective volatilities during weekdays and holidays overall results are supportive of policy making at the european commission regarding electricity market integration

how do banks respond to shocks a dynamic model of deposit taking institutions abstract this paper proposes a dynamic model of the optimal choices of a bank that benefits from market power and takes into account the impact of the deposit generation process interbank lending borrowing emerges as a buffer that assists the bank in smoothing intertemporal adjustments in interdependent loan and deposit choices the bank smooths the impact of interest rates shocks on its customers to minimize the adjustments over time of the stocks of deposits and loans it does not however provide insurance against negative shocks of real origin that increase its expected default costs the predictions of the model help to shed light on the available empirical evidence and to analyze some recent developments of the banking industry

an empirical examination of information differences of opinion and trading activity abstract we investigate the relations between trading volumes and our proxies for information flows and divergences in opinions we view s p 500 index futures open interest as a useful proxy for divergences of traders opinions and find that volumes are higher on days when open interest increases than on days with declines volume in individual equities is more closely related to firm specific information flows while equity basket volume is more closely associated with market information this differential impact is greatest for small capitalization stocks where market wide news has no explanatory power

search unemployment in an overlapping generations setting this paper constructs an overlapping generations model in which the steady state equilibrium is characterized by the existence of search unemployment this dynamic general equilibrium model captures the possible existence of search unemployment in the long run despite the absence of exogenous shocks furthermore it allows for the wage offers distribution to be determined endogenously the effect of partial revelation of information on the existence of search unemployment in the long run is examined it is shown that search unemployment may be eliminated in the long run despite the persistence of the state of imperfect information this paper develops an overlapping generations model in which the steady state equilibrium is characterized by search unemployment 2 unemployment is created via a rational rejection of available wage offers in favor of further search for potentially more attractive offers the proposed dynamic general equilibrium model allows for the existence of long run search unemployment despite the absence of exogenous shocks and permits the presence of an endogenously determined nondegenerate wage offer distribution 3 the paper analyzes the trade off between revelation of information and the level of search unemployment in the long run in the absence of external disturbances the level of search unemployment would be expected to decrease as information becomes available in particular if information is fully revealed search unemployment is naturally eliminated exploring the likelihood of the existence of long run search unemployment in a deterministic world this study provides an example of partial revelation of information which eliminates search unemployment in the long run despite the persistence of the state of imperfect information 4 the proposed model presents a discrete infinite time horizon world where economic activity is conducted under imperfect information in every period a single homogeneous good is produced using two factors capital and labor in the production process the aggregate endowment of labor is exogenously given in

order consolidation price efficiency and extreme liquidity shocks we show that the consolidation of orders is important for producing efficient prices especially during times of high liquidity demand the nyse s centralized opening call market performs better than nasdaq s decentralized opening process on typical trading days the nyse is much better than nasdaq on witching days when index arbitrage activity subjects s p 500 stocks to large predictable and mostly informationless order flow around quarterly futures contract expirations nasdaq opening price efficiency improves to nyse levels once nasdaq initiates a consolidated opening call in november 2004 but prices on the decentralized nasdaq remain less efficient at other times of day

intertemporal pricing and consumer stockpiling we study a dynamic pricing problem for a class of products with stable consumption patterns e g household items staple foods consumers may stock up the product at current prices for future consumption but they incur inventory holding costs we model this situation as a dynamic game over an infinite time horizon in each period the seller sets a price and each consumer chooses how many units to buy we develop a solution methodology based on rational expectations by endowing each player with beliefs we decouple the dynamic game into individual dynamic programs for each player we solve for the rational expectations equilibrium where all players make optimal dynamic decisions given correct beliefs about others behavior in equilibrium the seller may either charge a constant fixed price or offer periodic price promotions at predictable time intervals we show that promotions are useful when frequent shoppers are willing to pay more for the product than are occasional shoppers we also develop several model extensions to study the impact of consumer stockpiling on the seller s inventory production and rationing strategies

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

economic incentives and political institutions spending and voting in school budget referenda abstract allocation of resources in the local public sector involves economic and political forces in many u s states the bulk of spending on public education is subject to referendum we link spending proposals to referendum outcomes our model makes use of voting data to shed light on the extent to which referenda constrain spending we use data from school budget referenda in 544 new york school districts for the 1975 1976 school year our econometric results and simulations based on them reveal considerable sensitivity of spending to the form of the state grants in aid structure as well as to the referendum requirement in addition large school districts appear to behave more like budget maximizers than do small districts where proposals appear more in line with median voter demands

measuring the effects of search costs on equilibrium prices and profits abstract this paper assesses the effects of search costs on equilibrium prices and profits using an estimated model of demand and costs in a laundry detergent market i find that some firms profits initially rise and then fall with search costs overall the magnitude and direction of the search costs effects on prices and profits are heterogeneous this is because search costs create conflicting incentives for a firm to reduce prices to attract the attention of searching consumers yet also raise prices to harvest profit from consumers who are unaware of competing products these effects can vary with the relationship between the firms actual prices and the consumers pre search beliefs about prices

a model of price promotions with consumer search this paper presents a price discrimination model of price promotions the distinguishing feature of our model is the explicit distinction between regular and promotional prices regular prices are chosen first then promotional prices further while regular prices are always available to everyone promotional prices are only available when offered and only to those who search for them we show that even a monopolist will offer random promotions under these circumstances furthermore as search costs increase the frequency and depth of promotions increase with competition for the promotion oriented consumers the seller becomes more aggressive in his promotional policies even more so as search costs increase the high reservation price consumers however end up worse off with competition

price wars triggered by entry abstract to attract customers who incur set up or switching costs new firms offer below market prices when entering a market the incumbent responds with discounts resulting in a price war once new entrants have locked in their customers the price warfare stops and all firms raise their prices during the price war the incumbent s price is not as low as the entrants after the price war the market price is lower and output is greater than the pre entry price and output entrants attract new buyers to the market and depending on the size distribution of set up costs we show that some of the incumbent s customers switch to entrants the model is shown to square with the price and output sequences observed in a price war that was the subject of a recent and prominent antitrust case in the cigarette market

price dispersion in an automobile insurance market from automobile insurance data for alberta over the period 1974 81 we find thatpremiums are highly correlated across driver classes in a given year but that premiums for a given driver class are not correlated over a period of more than 5 years firms relative market shares among drivers over age 25 and married males under 25 are inversely related to their deviations from the mean premiums in these driver classes the variance of real premiums decreases with the numberof firms in the market and increases with the real loss cost per car insured and the number of cars insured from these results we conclude that the price dispersion in automobile insurance in alberta is based on costly consumer search

peak load pricing in competitive markets the paper offers an explanation for temporal price dispersion temporal price dispersion in the model is due neither to exogenous shifts in demand nor to price discrimination motives as shown in other papers in this paper the explanation relies on peak load pricing in the model presented consumers decide to purchase a given product in a certain time period according to the satisfaction they derive from the product at that time and to the prices and number of customers they expect at each firm and period the demand in each period is controlled by sellers through prices by offering different prices in different periods sellers motivate consumers to spread themselves across periods in a profitable way therefore the demand and price in each time period is determined endogeneously

a theory of clearance sales clearance sales are widely used by firms as an intertemporal selling policy in particular in markets where firms face demand uncertainty and need to choose capacity in advance clearance sales consist in charging a high price initially but then lowering the price in the sales period high valuation consumers purchase the good at the high initial price so as to avoid rationing at the low price while low valuation consumers wait for the price to drop we develop a simple model of intertemporal monopoly pricing under demand uncertainty and show that clearance sales may be the optimal intertemporal selling policy

running against the status quo institutions for direct democracy referenda and allocations over time stylized institutions for direct democracy referenda are examined in a dynamic full information environment with myopic voters competitive agenda median voter processes are contrasted with monopolistic controlled agenda processes by extending existing static analyses to a class of dynamic institutions not previously characterized the status quo reversion rule this highlights the dependence of the progression of real equilibrium allocations over time on institutional structure by delineating the restrictions implied by each institutional form the model explains some persistent empirical regularities in particular a strict ceteris paribus ordering of the magnitudes of budgets by institutional form is derived for a wide portion of the parameter space

program trading and intraday volatility program trading and intraday changes in the s p 500 index are correlated future prices and to a lesser extent cash prices lead program trades index arbitrage trades are followed by an immediate change in the cash index which ultimately reverses slightly no reversal follows nonarbitrage trades the cumulative index changes associated with buy and sell trades and with arbitrage and nonarbitrage trades all are similar price decompositions suggest that the results are not due to microstructure effects program trades in this 1989 1990 sample do not seem to have created major short term liquidity problems the results are stable within the sample many practitioners regulators and public commentators have expressed concerns about potential destabilizing effects of program trading they argue that program trades especially index arbitrage programs increase intraday volatility and decrease

the impact of public information on the stock market we study the relation between the number of news announcements reported daily by dow jones company and aggregate measures of securities market activity including trading volume and market returns we find that the number of dow jones announcements and market activity are directly related and that the results are robust to the addition of factors previously found to influence financial markets such as day of the week dummy variables news importance as proxied by large new york times headlines and major macroeconomic announcements and non information sources of market activity as measured by dividend capture and triple witching trading however the observed relation between news and market activity is not particularly strong and the patterns in news announcements do not explain the day of the week seasonalities in market activity our analysis of the dow jones database confirms the difficulty of linking volume and volatility to observed measures of information

the contributions of the economics of information to twentieth century economics in the e eld of economics perhaps the most important break with the past one that leaves open huge areas for future work lies in the economics of information it is now recognized that information is imperfect obtaining information can be costly there are important asymmetries of information and the extent of information asymmetries is affected by actions of e rms and individuals this recognition deeply affects the understanding of wisdom inherited from the past such as the fundamental welfare theorem and some of the basic characterization of a market economy and provides explanations of economic and social phenomena that otherwise would be hard to understand i introduction the century coming to a close has seen vast changes in economics in both ideas and methodology upon ree ection it is remarkable however how many of the seeds of advances in this century were sowed in the previous i would argue that perhaps the most important break with the past one that leaves open huge areas for future work lies in the economics of information the recognition that information is imperfect that obtaining information can be costly that there are important asymmetries of information and that the extent of information asymmetries is affected by actions of e rms and individuals has had profound implications for the wisdom inherited from the past and has provided explanations of economic and social phenomena that otherwise would be hard to understand in this essay i wish to argue that information economics has had directly and indirectly a profound effect on how we think about economics today eighteenth and nineteenth century antecedents to be sure marshall and other nineteenth century economists talked about problems of imperfect information but with one exception discussions of information were obiter dicta caveats at the end of the analysis they were never at the center

stock and option markets the swiss evidence abstract the interactions between the markets for options and underlying shares are examined for switzerland three topics are investigated first the introduction of traded options in the spring of 1988 lead to a permanent and significant increase in the prices of the underlying shares and a reduction in the volatility of returns second price changes on the stock and options markets are positively related during trading on the exchanges the evidence suggests that the stock leads the options market by about ten minutes some feedback is also present third the stochastic characteristics of stock returns are not affected by the expiration of options

the behavior of the volatility implicit in the prices of stock index options abstract we examine stock market volatility around the quarterly expirations of stock index futures contracts and nonquarterly expirations of stock index options using estimates of the volatility implicit in the option prices the option prices reflect increases in the volatility of the underlying stock indexes around both quarterly and nonquarterly expiration dates analysis of the residual returns on index options provides evidence consistent with an unexpected increase in market volatility around expiration dates

stock market structure and volatility the procedure for opening stocks on the nyse appears to affect price volatility an analytical framework for assessing the magnitude of the structurally induced volatility is presented the ratio of variance of open to open returns to closeto close returns is shown to be consistently greater than one for nyse common stocks during the period 1982 through 1986 tbe greater volatility at the open is not attributable to the way in which public information is released since both the opento open return and the close to close return span the same period of time instead the greater volatility appears to be attributable to private information revealed in trading and to temporaryprice deviations induced by specialist and other traders the implied cost of immediacy at the open is significantly higher than at the close other empirical evidence in this article documents the volume of trading at the open the time delays between the exchange opening and the first transaction in a stock the difference in daytime volatility versus overnight volatility and the extent to which volatility is related to trading volume

coupons and everyday low prices price competition with multiple instruments abstract a simple two stage game is examined where firms compete in prices by chosen pricing instruments those considered include a simple uniform pricing technology and a promotional pricing technology like an advertised discount coupon consumers are separated by types informed and uninformed therefore a motive for price competition exists for the purpose of separating the two types of consumers it is shown that the sustainability of an asymmetric choice of pricing instrument between the two firms will prevail in a duopoly market in equilibrium consequently the coexistence of two different pricing schemes is viable even when firms are otherwise symmetric jel classification l1 l13 coupons et bas prix tous les jours concurrence par les prix a l aide de multiples instruments ce memoire examine un simple jeu a deux etapes dans lequel des entreprises se concurrencent par les prix a l aide d un instrument particulier les instruments consideres incluent une simple technologie de prix uniforme et une technologie de prix de promotion sous la forme de l annonce d un coupon d escompte on divise les consommateurs en deux groupes ceux qui sont informes et ceux qui ne le sont pas un des motifs pour ce genre de concurrence est de separer les deux types de consommateurs on montre qu on peut soutenir un choix asymetrique d instrument de tarification entre les deux entreprises dans un marche de duopole en equilibre en consequence la coexistence de deux strategies de prix differentes est viable quand les entreprises sont symetriques sous tous les autres rapports

stock index futures mispricing profit opportunities or risk premia this paper reports empirical evidence on stock index futures pricing based on about four years of synchronous hourly data from the uk reported index values are based on firm quotes identified arbitrage opportunities are therefore actually exploitable and economically significant the analysis controls for cash market settlement procedures the results show that ex ante trading rules would have generated attractive profits after transaction costs and after the risks of dividend uncertainties marking to market and possible delays in execution are considered the far contract and the near contract tend to be mispriced in the same direction the mild tendency of futures to be overpriced in rising markets and underpriced in falling markets appears to be unimportant finally significant positive relationships are observed between the absolute magnitude of mispricing and time to maturity and between mispricing and index option implied volatility

arbitrage in stock index futures the textbook description of arbitrage suggests that it is a straightforward matter of taking offsetting positions in different securities and realizing the arbitrage profit such descriptions however typically ignore the transaction costs that give rise to the arbitrage opportunity in the first place taking proper account of these transactions costs may considerably complicate the problem particularly when as is usually the case the arbitrage potential is restricted this article is concerned withoptimal arbitrage strategies with transaction costs when the arbitrage potential is restricted by position limits the particular case we shall analyze is the standard and poor s sp the corresponding figure for the s p 500 portfolio for the same period was

decentralized dispersed exchange without an auctioneer abstract we stimulate exchange among geographically dispersed agents who face real costs of communication along with bounds to rationality and calculation exchange is entirely decentralized it is initiated by individual agents who broadcast costly messages indicating their interest in trade it is accomplished by bilateral bargaining between pairs of agents agents use the information gained from previous attempts at local trade to calculate their search strategies for succeeding rounds this decentralized mechanism can achieve a substantial improvement in the allocation of resources and the average welfare of agents in comparison with a randomized initial endowment but in comparison with walrasian equilibrium agents who begin with endowments of equal value end up with substantially unequal wealth although the initial inequality of utility is reduced

information and economic analysis a perspective ten years ago i delivered a paper before this group with the title information and economic analysis i chose the title deliberately i did not call the subject on which i was speaking the economics of information because to do so would have been to suggest that my topic like the economics of agriculture or the economics of industry or the economics of labour represented another branch of specialisation within economics i wanted to suggest that informational considerations were in fact central to the analysis of a wide variety of phenomena that they constituted a central part of the foundations of economic analysis at the time though economists had long paid lip service to the importance of information there was little formal literature the last decade has seen a burgeoning of the literature it has become to the late 7o s and early 8o s what growth theory was to the early 6o s and it has been greeted with some of the same scepticism there seems to be a myriad ofspecial cases and few general principles the little examples are often contrasted unfavourably with the generality of general equilibrium theory what have we learned have diminishing returns set in are there fruitful directions for future research and if so what are they these are the questions which i wish to address here the work of the past decade has made i think a fundamental and lasting contribution to economic analysis the contributions have been both negative and positive we have learned that much of what we believed before is of only limited validity that the traditional competitive equilibrium analysis though having the superficial appearance of generality in terms of superscripts and subscripts is indeed not very general the theory is not robust to slight alterations in the informational assumptions it is but a special and not very plausible example among the possible set of informational assumptions which can be employed to characterise an economy at the same time the theory has been able to provide insights into phenomena about which the traditional model had nothing to say or which seemed inconsistent or inexplicable within the competitive paradigm it has provided some of the micro foundations for macro economics it has provided the basis of a new theory of the firm of a new new welfare economics and of a theory of economic organisation including a comparison of economic

a simple model of price dispersion abstract this article considers a simple stock flow matching model with fully informed market participants unlike the standard matching literature prices are assumed to be set ex ante when sellers pre commit themselves to sell their products at an advertised price the unique equilibrium is characterized by price dispersion due to the idiosyncratic match payoffs in a marketplace with full information this provides new insights into the price dispersion literature which instead commonly assumes that buyers are not perfectly informed and engage in a costly search

word of mouth model of sales in this paper i develop a model of the dynamic pricing of a monopolist while information about its product is diffusing through word of mouth individuals who purchase the product engage in word of mouth with their friends the main result establishes that prices optimally fluctuate over time a monopolist sets prices over time to balance extracting profits in the short term with increasing information diffusion through word of mouth and thereby the population of potential consumers in the future the key state variable for determining this tradeoff is the distribution of valuations of the individuals on the edge of the diffusion this distribution of valuations is determined by the history of prices and changes over time our analysis reveals that prices must move up and down infinitely often

program trading and individual stock returns ingredients of the triple witching brew the price and trading volume behaviors of individual stocks in the standard and poor s 500 stock index s p 500 are analyzed on stock index futures expiration days a time when the market is known to be subject to heavy program trading the price behavior of stocks that are subject to program trading is shown to be very similar to stocks that are not stocks that decline in price in the last half hour friday tend to increase in price at the opening on monday and vice versa the monday reversal as a fraction of the friday price change is only slightly higher for the s p 500 stocks than for non s p 500 stocks indicating that the price reversals reflect for the most part the bid ask spreads of the individual stocks trading volume in the last half hour of expiration days is shown to be substantially higher than normal copyright 1990 by the university of chicago

equilibrium price dispersion in retail markets for prescription drugs this study seeks to establish the empirical importance of price dispersion due to costly consumer search by examining retail prices for prescription drugs posted prices in two geographically distinct markets are shown to vary considerably across pharmacies within the same market even after one controls for variation due to pharmacy differences pharmacy heterogeneity accounts for at most one third of the observed price dispersion the empirical analysis hinges on the observation that consumers incentives to price shop depend on characteristics of the drug therapy cross sectional patterns in price distributions across drugs are consistent with the predictions of a search model prices for repeatedly purchased prescriptions for which the expected benefits of search are highest exhibit significant reductions in both dispersion and price cost margins

strategic pricing consumer search and the number of firms discover prices there are three distinct price dispersed equilibria characterized by low moderate and high search intensity the effects of an increase in the number of firms on search behaviour expected prices price dispersion and welfare are sensitive i to the equilibrium consumers search intensity and ii to the status quo number of firms for instance when consumers search with low intensity an increase in the number of firms reduces search does not affect expected price leads to greater price dispersion and reduces welfare in contrast when consumers search with high intensity increased competition results in more search and lower prices when the number of competitors in the market is low to begin with but in less search and higher prices when the number of competitors is large duopoly yields identical expected price and price dispersion but higher welfare than an infinite number of firms a question that has received much attention in economic theory is how the number of competitors and market outcomes are related despite the existence of work showing the contrary see e g satterthwaite 1979 rosenthal 1980 the prediction that emerges from a market where firms interact in a cournot fashion has come to dominate economic thought namely that an increase in the number of competitors leads to larger aggregate production lower market price and improved market performance measured in terms of some social welfare criterion ruffin 1971 this paper challenges the generality of this belief by presenting an oligopoly model with consumer search where the equilibrium expected price may be constant increasing or nonmonotonic in the number of firms we present an economy with two types of consumers consumers who search for prices at no cost fully informed and consumers who must pay a fixed search cost for each price quotation they observe less informed 1 all buyers have the same willingness to pay for the good and buy either a single unit or nothing at all on the supply side of the market there are n firms producing a homogeneous good at constant marginal cost we analyse a one shot simultaneous move game firms set prices and consumers decide how many prices to search for at the same moment in time our model is essentially an oligopolistic version of burdett and judd 1983 where some consumers search costlessly in this model consumers search using a fixed sample size search strategy i e they choose the number of prices to observe before receiving any offer nonsequential search is appealing when consumers find it more advantageous to gather price information quickly morgan and manning 1985 this occurs when the search outcome is observed with delay and delay is costly for instance an mba graduate looking for a job 1 the presence in the model of consumers who search costlessly captures the fact that some people have a

collusion with intertemporal price dispersion we develop a theory of optimal collusive intertemporal price dispersion dispersion clouds consumer price awareness encouraging firms to coordinate on dispersed prices our theory generates a collusive rationale for price cycles and sales patient firms can support optimal collusion at the monopoly price for less patient firms monopoly prices must be punctuated with fleeting sales the most robust structure involves price cycles that resemble edgeworth cycles low consumer attentiveness enhances the effectiveness of price dispersion by reducing the payoff to deviations involving price reductions however for sufficiently low attentiveness price rises are also a concern

intertemporal substitution and storable products storable products allow consumers to time their purchases to exploit price fluctuations it has been documented that during promotions consumers buy more the additional purchases are potentially intended not only for current use but to be stockpiled for future consumption this paper discusses the predictions of a consumer inventory model and reviews the available evidence we then discuss the implications for demand estimation and present estimates of jel lo l4 dl d4 the economic magnitude of the dynamic effect of storability jel lo l4 dl d4 jel lo l4 dl d4

the impact of collusion on price behavior empirical results from two recent cases abstract we use extended arch and garch models to examine the differences in the behavior of the first two moments of the price distribution during collusive and competitive phases of two recently discovered conspiracies citric acid and lysine according to our results the conspirators managed to raise prices by 9 and 25 cents per pound in the short run relative to non collusive periods also the variance of prices during the lysine conspiracy was lower and the variance of prices during the citric acid conspiracy was higher than during more competitive periods the proposed methodology may be used for antitrust screening and prosecution purposes

futures trading activity and stock price volatility we examine whether greater futures trading activity volume and open interest is associated with greater equity volatility we partition each trading activity series into expected and unexpected components and document that while equity volatility covaries positively with unexpected futures trading volume it is negatively related to forecastable futures trading activity further though futures trading activity is systematically related to the futures contract life cycle we find no evidence of a relation between the futures life cycle and spot equity volatility these findings are consistent with theories predicting that active futures markets enhance the liquidity and depth of the equity markets

the impact of stock index futures trading on daily returns seasonality a multicountry study in this article we investigate the impact of the introduction of stock index futures trading on the daily returns seasonality of the underlying index for seven national markets it has been previously argued that the introduction of futures trading should lead to reduced seasonality of mean returns and generally our results support this conclusion the impact of index futures introduction on return autocorrelations and volatility is also tested and the evidence presented suggests that futures trading has no impact on the former although a change in the seasonal for the latter was detected

the timing of sales this paper presents a model of intertemporal price discrimination a fixed number of sellers produce a homogeneous good consumers with different preferences enter the market in each period and leave when they make a purchase the sellers typically vary their prices over time charging a high price in most periods but occasionally cutting the price to sell to a large group of customers with a low reservation price in some equilibria all stores lower their price at the same time and to the same level

volatility risk and the value premium evidence from the french stock market this paper documents that systematic volatility risk is an important factor that drives the value premium observed in the french stock market using returns on at the money straddles written on the cac 40 index as a proxy for systematic volatility risk i document significant differences between volatility factor loadings of value and growth stocks furthermore when markets are classified into expected booms and recessions volatility factor loadings are also time varying when expected market risk premium is above its average i e during expected recessions value stocks are seen riskier than their growth counterparts this implies in bad times investors shift their preferences away from value firms instead they use growth stocks as hedges against deteriorations in their wealth during those times the findings are in line with the predictions of rational asset pricing theory and support a flight to quality explanation

wine retail price dispersion in the united states searching for expensive wines similar to other markets in which deviations from jevons law of one price is the norm rather than the exception the retail wine market in the united states is characterized by large price dispersions drawing on a large sample of retail prices from wine searcher com we find an average per wine coefficient of variation of 23 percent some of this is due to differential market conditions especially state regulations our evidence suggests that dispersion also depends positively on price levels after controlling for consumer market and state heterogeneity

stock price clustering on option expiration dates abstract this paper presents striking evidence that option trading changes the prices of underlying stocks in particular we show that on expiration dates the closing prices of stocks with listed options cluster at option strike prices on each expiration date the returns of optionable stocks are altered by an average of at least 16 5 basis points which translates into aggregate market capitalization shifts on the order of 9 billion we provide evidence that hedge rebalancing by option market makers and stock price manipulation by firm proprietary traders contribute to the clustering

consumer stockpiling and competitive promotional strategies an examination of brand prices in several categories reveals that the distribution of prices is multimodal with firms offering shallow and deep discounts another interesting feature of these distributions is that they may have holes in the interior of the support these pricing distributions do not occur in extant theoretical models of price promotions we develop a dynamic model of competition in which some price sensitive consumers stockpile during periods of deep discounts a game theoretic analysis of our model generates a multimodal pricing distribution with a hole in the interior of the support consumer stockpiling in our model also gives rise to negative serial correlation in prices this is consistent with our empirical observation of the pricing distribution of several brands across multiple categories in the iri marketing data set we generate several interesting insights into firms optimal promotional strategies and their interplay with the clientele mix market structure and other market factors we find that in equilibrium stockpiling by price sensitive consumers neither harms nor benefits firms when they adopt equilibrium strategies interestingly when price sensitive consumers stockpile even increased consumption as a result of stockpiling does not lead to higher profits for firms

expiration and maturity effect empirical evidence from the spanish spot and futures stock index the paper studies how the time remaining to the expiration date of derivative markets affects the volatility of the ibex 35 index expiration effect and its futures market maturity effect the innovation of the study lies in both effects being studied together for the spanish stock market using bivariate ecm garch including dummy variables that express the time left to expiration day the results obtained show that during the week of the expiration day the conditional variance of both markets increases without presenting any significant behaviour in the correlation level during the second week however the conditional variance diminishes and the degree of correlation between both markets increases

a transaction data study of weekly and intradaily patterns in stock returns abstract weekly and intradaily patterns in common stock prices are examined using transaction data for large firms negative monday close to close returns accrue between the friday close and the monday open for smaller firms they accrue primarily during the monday trading day for all firms significant weekday differences in intraday returns accrue during the first 45 minutes after the market opens on monday mornings prices drop while on the other weekday mornings they rise otherwise the pattern of intraday returns is similar on all weekdays most notable is an increase in prices on the last trade of the day

the saga of the first stock index futures contract benchmarks models and learning in the presence of imperfect or perturbed benchmarks pricing based on relative valuation or arbitrage can be affected adversely this study highlights persistent pricing irregularities in the kansas city value line kcvl stock index futures market this contract is especially interesting because the underlying benchmark underwent a midstream change in definition from a complex equally weighted geometric index to an equally weighted arithmetic index empirical analysis reveals that during a four year period the market displayed herd like behavior and priced the kcvl geometric contract using the simple but wrong cost of carry benchmark model a dramatic change occurs around the publication of the eytan harpaz 1986 model when the market turns efficient from the perspective of this new model the market appears to have succumbed initially to a bad information cascade primarily because arbitrage was difficult to understand and carry out under complex benchmarking the evidence provides empirical extension to the observational social learning paradigms of simon 1955 banerjee 1992 and bikhchandani hirshleifer and welch 1992 that lead to behavioral herding and information cascades

storable good monopoly the role of commitment we study dynamic monopoly pricing of storable goods in an environment where demand changes over time the literature on durables has focused on incentives to delay purchases our analysis focuses on a different intertemporal demand incentive for consumers the key force on the consumer side is advance purchases or stockpiling this stockpiling motive can be present in the case of standard durables as well in environments unmodeled in the prior literature we show that if the monopolist cannot commit then prices are higher in all periods and social welfare is lower than in the case in which the monopolist can commit this is in contrast with the durable goods analysis in the literature on the coase conjecture