bulls bears and market sheep abstract a deterministic excess demand model of stock market behavior is presented that generates stochastically fluctuating prices and randomly switching bear and bull markets

prizes and lemons procurement of innovation under imperfect commitment the literature on r d contests implicitly assumes that contestants submit their innovation regardless of its value this ignores a potential adverse selection problem the present paper analyzes the procurement of innovations when the procurer cannot commit to never bargain with innovators who bypass the contest we compare xed prize tournaments with and without entry fees and optimal scoring auctions with and without minimum score requirement our main result is that the optimal xed prize tournament is more pro table than the optimal auction since preventing bypass is more costly in the optimal auction

put call parity and expected returns this study examines the hypothesis that in the presence of market frictions relative put and call prices contain information concerning future returns of the underlying asset a measure of relative prices is derived from the put call parity relationship for index options and applied to a three year sample of oex option transactions the results show that the measure of relative index option prices leads the stock market by at least 15 minutes

using price distributions to estimate search costs we show how the equilibrium restrictions implied by standard search models can be used to estimate search cost distributions using price data alone we consider both sequential and nonsequential search strategies and develop estimation methodologies that exploit equilibrium restrictions to recover estimates of search cost heterogeneity that are theoretically consistent with the search models we illustrate the method using online prices for several economics and statistics textbooks

maximum likelihood estimation of search costs abstract in a recent paper hong and shum 2006 using price distributions to estimate search costs rand journal of economics 37 257 275 present a structural method to estimate search cost distributions we extend their approach to the case of oligopoly and present a new maximum likelihood method to estimate search costs we apply our method to a data set of online prices for different computer memory chips the estimates suggest that the consumer population can be roughly split into two groups which either have quite high or quite low search costs search frictions confer a significant amount of market power to the firms despite more than 20 firms operating in each of the markets we estimate price cost margins to be around 25 the paper also illustrates how the structural method can be employed to simulate the effects of the introduction of a sales tax

testing models of consumer search using data on web browsing and purchasing behavior using a large data set on web browsing and purchasing behavior we test to what extent consumers are searching in accordance to various classical search models we nd that the benchmark model of sequential search with a known distributions of prices can be rejected based on the recall patterns we observe in the data moreover we show that even if consumers are initially unaware of the price distribution and have to learn the price distribution observed search behavior for given consumers over time is more consistent with non sequential search than sequential search with learning our

nonparametric estimation of search costs for differentiated products evidence from medigap this article develops a method to estimate search frictions as well as preference parameters in differentiated product markets search costs are nonparametrically identified which means our method

advertising for attention in a consumer search model we model the idea that when consumers search for products they first visit the firm whose advertising is most salient the gains a firm derives from being visited early increase in search costs so equilibrium advertising increases as search costs rise as a result higher search costs may decrease both consumer welfare and firm profits we extend the basic model by allowing for firm heterogeneity in advertising costs firms that raise attention more easily advertise more but also charge lower prices and obtain higher profits as advertising cost asymmetries increase consumer surplus falls and aggregate profits rise

estimation of financial agent based models with simulated maximum likelihood abstract this paper proposes a general computational framework for empirical estimation of financial agent based models for which criterion functions have unknown analytical form for this purpose we adapt a recently developed nonparametric simulated maximum likelihood estimation based on kernel methods in combination with the model developed by brock and hommes 1998 which is one of the most widely analysed heterogeneous agent models in the literature we extensively test the properties and behaviour of the estimation framework as well as its ability to recover parameters consistently and efficiently using simulations key empirical findings indicate the statistical insignificance of the switching coefficient but markedly significant belief parameters that define heterogeneous trading regimes with a predominance of trend following over contrarian strategies in addition we document a slight proportional dominance of fundamentalists over trend following chartists in major world markets

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

search prominence and return costs abstract it is widely held that sellers prefer to appear early in a consumer s search but evidence suggests this need not be the case we develop a model which incorporates costly search and costly return and demonstrate that appearing later may be better when return is free prominence is desirable by standard logic however costly return induces a tradeoff it benefits an earlier seller by reducing the initial search but also benefits a later seller by preventing return conditional on search we show that for small search costs later is better whenever high outcomes have a low likelihood or whenever two independent match value draws are likely to be near one another later can still be better if sellers compete in prices prior to search finally with many sellers the optimal position may be first last or in between but earlier positions are favored as the number of sellers grows

equilibrium with product differentiation tive consumer formulations is used to examine the properties of single and multiple price equilibria conditions under which decreases in the intensity of consumer preferences reduce price are given it is shown that with certain types of demand curves entry can eliminate price cost markups even given product differentiation if competition is localized it is demonstrated that entry does not affect the markup finally the effect of spurious product differentiation on price is examined

can a stochastic cusp catastrophe model explain stock market crashes this paper is the first attempt to fit a stochastic cusp catastrophe model to stock market data we show that the cusp catastrophe model explains the crash of stock exchanges much better than other models using the data of u s stock markets we demonstrate that the crash of october 19 1987 may be better explained by cusp catastrophe theory which is not true for the crash of september 11 2001 with the help of sentiment measures such as the index put call options ratio and trading volume the former models the chartists the latter the fundamentalists we have found that the 1987 returns are bimodal and the cusp catastrophe model fits these data better than alternative models therefore we may say that the crash has been led by internal forces however the causes for the crash of 2001 are external which is also evident in much weaker presence of bifurcations in the data in this case alternative models explain the crash of stock exchanges better than the cusp catastrophe model

an analysis of the effect of noise in a heterogeneous agent financial market model abstract heterogeneous agent models hams in finance and economics are often characterised by high dimensional nonlinear stochastic differential or difference systems because of the complexity of the interaction between the nonlinearities and noise a commonly used often called indirect approach to the study of hams combines theoretical analysis of the underlying deterministic skeleton with numerical analysis of the stochastic model however it is well known that this indirect approach may not properly characterise the nature of the stochastic model this paper aims to tackle this issue by developing a direct and analytical approach to the analysis of a stochastic model of speculative price dynamics involving two types of agents fundamentalists and chartists and the market price equilibria of which can be characterised by the stationary measures of a stochastic dynamical system using the stochastic method of averaging and stochastic bifurcation theory we show that the stochastic model displays behaviour consistent with that of the underlying deterministic model when the time lag in the formation of price trends used by the chartists is far away from zero however when this lag approaches zero such consistency breaks down

true monopolistic competition as a result of imperfect information the paper restates hart s 1985a 1985b definition of large group monopolistic competition distinguishes it from oligopolistic competition and raises the question of whether there are reasonable circumstances that give rise to true monopolistic competition as defined the purpose is to show that consumers imperfect information may create conditions that will turn an otherwise oligopolistic market into a truly monopolistically competitive one

oligopolistic pricing with heterogeneous consumer search abstract a finite number of identical stores sell a homogeneous good to consumers with heterogeneous search costs who search sequentially with perfect recall and without replacement consumers search rules are optimal with respect to the stores pricing strategies and consumers must visit a store to obtain information about its actual price a symmetric nash equilibrium sne always exists the model exhibits a variety of equilibrium behaviors between monopoly pricing and marginal cost pricing the competitiveness of a market depends crucially on the shape of the search cost distribution moreso than on the number of competing firms

nonsequential search equilibrium with search cost heterogeneity we generalize the model of burdett and judd 1983 to the case where an arbitrary finite number of firms sells a homogeneous good to buyers who have heterogeneous search costs we show that a price dispersed symmetric nash equilibrium always exists numerical results show that the behavior of prices and consumer surplus with respect to the number of firms hinges upon the nature of search cost dispersion when search costs are relatively concentrated entry of firms leads to lower average prices and greater consumer surplus however for relatively dispersed search costs the mean price goes up and consumer surplus may decrease with the number of firms

oligopolistic pricing with sequential consumer search n identical stores compete by choosing prices for a homogeneous good with constant marginal costs consumers search sequentially with perfect recall for the lowest price one class of consumers called shoppers have zero search costs while all other consumers have a positive search cost c there is a unique symmetric nash equilibrium price distribution with the property that it changes smoothly from marginal cost pricing when all consumers are shoppers and or c 0 and monopoly pricing when no consumers are shoppers remarkably as the number of stores increases the nash equilibrium becomes more monopolistic copyright 1989 by american economic association

the crash of ʼ87 was it expected the evidence from options markets transactions prices of s p 500 futures options over 1985 1987 are examined for evidence of expectations prior to october 1987 of an impending stock market crash first it is shown that out of the money puts became unusually expensive during the year preceding the crash second a model is derived for pricing american options on jump diffusion processes with systematic jump risk the jump diffusion parameters implicit in options prices indicate that a crash was expected and that implicit distributions were negatively skewed during october 1986 to august 1987 both approaches indicate no strong crash fears during the 2 months immediately preceding the crash attempts to explain what caused the stock market crashes around the world in october 1987 have suffered from the paucity of major economic developments occurring around that time that could have triggered the crashes shifting expectations regarding monetary policy foreign investors fears of a dollar decline increasing riskiness of assets none of these appeared major enough if present at all to explain the magnitude of the crashes and although portfolio insurance strategies could conceivably magnify the effects of a jump in fundamentals the initiating jump in fundamentals appears to be lacking

prices and heterogeneous search costs we study price formation in a model of consumer search for differentiated products in which consumers have heterogeneous search costs we provide conditions under which a pure strategy symmetric nash equilibrium exists and is unique search costs affect two margins the intensive search margin or search intensity and the extensive search margin or the decision to search rather than to not search at all these two margins affect the elasticity of demand in opposite directions and whether lower search costs result in higher or lower prices depends on the properties of the search cost density

semi nonparametric estimation of consumer search costs this paper studies the estimation of the distribution of non sequential search costs we show that the search cost distribution is identified by combining data from multiple markets with common search technology but varying consumer valuations firms costs and numbers of competitors to exploit such data optimally we provide a new method based on semi nonparametric estimation we apply our method to a dataset of online prices for memory chips and find that the search cost density is essentially bimodal such that a large fraction of consumers searches very little whereas a smaller fraction searches a relatively large number of stores copyright c 2012 john wiley sons ltd

an empirical model of search with vertically differentiated products this paper presents a nonsequential search model that allows for vertical product dierentiation in the unique symmetric equilibrium firms with dierent characteristics draw utilities from a common utility distribution because the firms dier in their characteristics this leads to dierent price distributions the model therefore provides a theoretical rationale for explaining price dispersion as a result of quality dierences and search behavior of consumers together using the equilibrium conditions derived from the model it is shown how to estimate search costs by maximum likelihood using only price data a data set on prices from dutch supermarkets reveals that the amount of search has decreased over the sampling period moreover ignoring vertical product dierentiation results in an overestimation of search costs

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

paying for prominence we investigate three ways in which firms can become prominent and thereby influence the order in which consumers consider options first firms can affect an intermediary s sales efforts by means of commission payments when firms pay commission to a salesman the salesman promotes the product with the highest commission and steers ignorant consumers towards the more expensive product second sellers can advertise prices on a price comparison website so that consumers investigate the suitability of products in order of increasing price in such a market equilibrium prices are lower when search costs are higher since a firm s benefit from being investigated first increases with search costs finally consumers might first consider their existing supplier when they purchase a new product which suggests a relatively benign rationale for the prevalence of cross selling in markets such as retail banking

pricing product diversity and search costs a bertrand chamberlin diamond model we study price competition in the presence of search costs and product differentiation the limit cases of the model are the bertrand paradox the diamond paradox and chamberlinian monopolistic competition market prices rise with search costs and decrease with the number of firms prices may initially fall with the degree of product differentiation because more diversity leads to more search and more competition equilibrium diversity rises with search costs while the optimum level falls so entry is excessive the market failure is most pronounced for low preference for variety and high search costs

can a stochastic cusp catastrophe model explain housing market crashes abstract like stock market prices housing prices often exhibit temporary booms and busts a possible explanation for the observed abrupt changes is offered by the stochastic catastrophe model this paper addresses the question whether the catastrophe model can describe and predict the dynamics of housing markets we fit a stochastic cusp catastrophe model to empirical housing market data for six oecd countries us jp uk nl se and be two different estimation approaches are considered cobb s method and euler discretization the analysis shows that while cobb s approach describes the long run stationary density better euler discretization is more tailored for time series as it provides better one step ahead predictions proceeding using the euler discretization method we discuss the dynamics of housing markets in terms of the multiple equilibria cusp catastrophe model by considering the long term interest rate as an exogenous variable we obtain new insights into the policy implications of interest rate levels in particular concerning the stability of housing markets

prominence and consumer search this article examines the implications of prominence in search markets we model prominence by supposing that the prominent firm will be sampled first by all consumers if there are no systematic quality differences among firms we find that the prominent firm will charge a lower price than its less prominent rivals making a firm prominent will typically lead to higher industry profit but lower consumer surplus and welfare the model is extended by introducing heterogeneous product qualities in which case the firm with the highest quality product has the greatest incentive to become prominent and making it prominent will boost industry profit consumer surplus and welfare

dynamic interaction models of economic equilibrium abstract the paper develops a stochastic dynamic model of economic equilibrium with locally interacting agents the main focus of the study is on the modeling of market interactions those arising in connection with commodity exchange and regulated by price mechanisms the mathematical framework is a control theory for random vector fields on directed graphs the graphs involved serve to describe the spatio temporal structure of commodity flows in the system the main results are concerned with the existence uniqueness and stability of stochastic dynamic equilibria

product differentiation search costs and competition in the mutual fund industry a case study of s p 500 index funds we investigate the role that non portfolio fund differentiation and information search frictions play in creating two salient features of the mutual fund industry the large number of funds and the sizeable dispersion in fund fees in a case study we find that despite the financial homogeneity of s p 500 index funds this sector exhibits the fund proliferation and fee dispersion observed in the broader industry we show how extra portfolio mechanisms explain these features these mechanisms also suggest an explanation for the puzzling late 1990s shift in sector assets to more expensive and often newly entered funds an influx of highinformation cost novice investors

market liquidity hedging and crashes in the absence of significant news hedging strategies were blamed for the stock market crash of october 1987 but traditional models cannot explain how a relatively small amount of selling could cause so large a price drop the authors develop a rational expectations model in which prices play an important role in shaping expectations markets are much less liquid in their model than in traditional models discontinuities or crashes can occur even with relatively little hedging the model is consistent with theories as disparate as keynes beauty contest insights and thom s catastrophe analysis and suggests means to reduce volatility copyright 1990 by american economic association

budget deficits short term real interest rates and the specification of expected inflation an empirical investigation the purpose of this paper is to illustrate whether empirical estimates of the effects of budget deficits on short term real interest rates are sensitive to the choice of the expected inflation variable survey data on expected inflation and the rational expectations method described by mishkin 1981 are used to construct two measures of the short term real interest rate results for two previous studies on this deficit interest rate relationship are re estimated using these measures of expected inflation and the interest rate variables additional results reported in this paper further indicate that empirical estimates of the interest rate effects of budget deficits are sensitive to the choice of the expected inflation variable in addition to the choice of the inflation variable a number of other robustness tests are included we are able to conclude that 1 increases in budget deficits do not generally raise short term real interest rates and 2 short term real interest rates are not independent of

can prominence matter even in an almost frictionless market consumer search on the internet is rarely random sponsored links appear higher up a webpage and consumers often click them firms also bid aggressively for these prominent positions at the top of the page but why should prominence matter when visiting an additional website is almost costless i present a model in which consumers know their valuations for the products offered in the market but do not know which retailer sells which product i show that a prominent retailer earns significantly more profit than other firms even when the cost of searching websites and comparing products is essentially zero

staggered updating in an artificial financial market abstract we consider an environment in which traders search for trading opportunities and update their forecast rules at random intervals by ols the staggering of this updating process across traders allows differences in opinion to persist over time generating nontrivial price dynamics the nature of these dynamics is sensitive to the degree of overparameterization of forecast rules relative to market fundamentals