mean reversion in short horizon expected returns this article develops and estimates a simple model for monthly expected stock returns that relies on the rapidly decaying structure of shorter horizon weekly expected returns the most striking aspect of our findings is that the rapid mean reversion in short horizon expected returns implies much greater variation through time in monthly expected returns than has been documented in earlier studies for instance during the 1962 to 1985 period over 25 percent of the return variance of small firms can be explained by time variation in expected returns article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies

liquidity and autocorrelations in individual stock returns this paper documents a strong relationship between short run reversals and stock illiquidity even after controlling for trading volume the largest reversals and the potential contrarian trading strategy profits occur in high turnover low liquidity stocks as the price pressures caused by non informational demands for immediacy are accommodated however the contrarian trading strategy profits are smaller than the likely transactions costs this lack of profitability and the fact that the overall findings are consistent with rational equilibrium paradigms suggest that the violation of the efficient market hypothesis due to short term reversals is not so egregious after all asset prices should follow a martingale process over short horizons as systematic short run changes in fundamental values should be negligible in an efficient market with unpredictable information arrival however lehmann 1990 and jegadeesh 1990 show that contrarian strategies that exploit the short run return reversals in individual stocks generate abnormal returns of about 1 7 per week and 2 5 per month respectively subsequently ball kothari and wasley 1995 and conrad gultekin and kaul 1997 suggest that much of such reversal profitability is within the bid ask bounce theoretically the potential role of liquidity in explaining the high abnormal payoffs to short run contrarian strategies is implied by the rational equilibrium framework of campbell grossman and wang 1993 henceforth cgw in the cgw model non informational trading causes price movements that when absorbed by liquidity suppliers cause prices to revert such non informed trading is accompanied by high trading volume whereas informed trading is accompanied by little trading volume thus price changes accompanied by high low trading volume should should not revert empirically conrad hameed and niden 1994 henceforth chn find that reversal profitability increases with trading

biotechnology boosts to crop productivity in china trade and welfare implications genetically modified gm cotton is widely adopted and the list of gm technologies in trials is impressive in china at the same time there is an active debate on when china should commercialize its gm food crops this paper provides an economy wide assessment of some of the issues surrounding the adoption and commercialization of biotechnology based on unique data from empirical micro level study and field trials in china and a modified gtap model our results indicate that the development of biotechnology has an important impact on china s production trade and welfare welfare gains far outweigh the public biotechnology research expenditures most gains occur inside china and can be achieved independently from biotech unfriendly polices adopted in some industrialized countries

trading volume and cross autocorrelations in stock returns this paper finds that trading volume is a significant determinant of the lead lag patterns observed in stock returns daily and weekly returns on high volume portfolios lead returns on low volume portfolios controlling for firm size nonsynchronous trading or low volume portfolio autocorrelations cannot explain these findings these patterns arise because returns on low volume portfolios respond more slowly to information in market returns the speed of adjustment of individual stocks confirms these findings overall the results indicate that differential speed of adjustment to information is a significant source of the cross autocorrelation patterns in short horizon stock returns both academics and practitioners have long been interested in the role played by trading volume in predicting future stock returns 1 in this paper we examine the interaction between trading volume and the predictability of short horizon stock returns specifically that due to lead lag cross autocorrelations in stock returns our investigation indicates that trading volume is a significant determinant of the cross autocorrelation patterns in stock returns 2 we find that daily or weekly returns of stocks with high trading volume lead daily or weekly returns of stocks with low trading volume additional tests indicate that this effect is related to the tendency of high volume stocks to respond rapidly and low volume stocks to respond slowly to marketwide information

a further analysis of the lead lag relationship between the cash market and stock index futures market the intraday lead lag relation between returns of the major market cash index and returns of the major market index futures and s p 500 futures is investigated empirical results show strong evidence that the futures leads the cash index and weak evidence that the cash index leads the futures the asymmetric lead lag relation holds between the futures and all component stocks including those that trade in almost every five minute interval evidence indicates that when more stocks move together market wide information the futures leads the cash index to a greater degree this suggests that the futures market is the main source of market wide information article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies

balancing productivity and trade objectives in a competing environment should india commercialize gm rice with or without china india is considering approving genetically modified gm rice but it fears losing rice exports to sensitive countries with import regulations on gm food and may wait for china to lead the way using a multiregion computable general equilibrium cge model we simulate the economic effects of introducing gm rice in india with or without china in the presence of labeling and import approval regulations of gm food in gm sensitive importing countries we find that the welfare gains with gm rice in india would largely exceed any potential export loss and that the segregation of non gm rice could help reduce these minor losses we also find no significant first mover advantage for india or china on gm rice the opportunity cost of segregation of non gm rice is much larger for sensitive importers than for india which suggests that these importers would have the incentive to pay for the cost of segregation

investment analysis and the adjustment of stock prices to common information in this article we are concerned with the effect of the number of investment analysts following a firm on the speed of adjustment of the firm s stock price to new information that has common effects across firms it is found that returns on portfolios of firms that are followed by many analysts tend to lead those of firms that are followed by fewer analysts even when the firms are of approximately the same size many analyst firms also tend to respond more rapidly to market returns than do few analyst firms adjusting for firm size this relation however is nonlinear and the marginal effect of the number of analysts on the speed of price adjustment increases with the number of analysts article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies

nonsynchronous security trading and market index autocorrelation the theoretical portfolio autocorrelation due solely to nonsynchronous trading is estimated from a derived model this estimated level is found to be substantially less than that observed empirically the theoretical and empirical relationship between portfolio size and autocorrelation also is investigated the results of this study suggest that other price adjustment delay factors in addition to nonsynchronous trading cause the high autocorrelations present in daily returns on stock index portfolios

indexing and stock market serial dependence around the world abstract we show a striking change in index return serial dependence across 20 major market indexes covering 15 countries in north america europe and asia while many studies find serial dependence to be positive until the 1990s it switches to negative since the 2000s this change happens in most stock markets around the world and is both statistically significant and economically meaningful further tests reveal that the decline in serial dependence links to the increasing popularity of index products e g futures exchange traded funds and index mutual funds the link between serial dependence and indexing is not driven by a time trend holds up in the cross section of stock indexes is confirmed by tests exploiting nikkei 225 index weights and standard poor s 500 membership and in part reflects the arbitrage mechanism between index products and the underlying stocks

shadow pricing in a specific factors model rejoinder in their comment on my paper maneschi 1985 tower pursell and han henceforth tph correctly point out that in the specific factors model unlike the situation in a model where goods and factors are equal in number the withdrawal of a unit of a factor induces changes in the prices of all factors which may have repercussions on a policy maker s welfare function and occasion a drain on foreign exchange in addition to value of the production loss associated with the withdrawal of the factor itself they list a number of possible implicit assumptions that could dispense with the need to reckon with these repercussions and go on to set out a model that explicitly allows for them the model used by tph for this purpose is based on a welfare function for the policy maker given by the summation of changes in different individuals incomes yo i multiplied by distributional weights vi that this is a more general welfare function than one that weights every individual equally is of course incontrovertible however for better or worse most of the international trade theory literature is predicated upon the national welfare function s being a blown up version of that of a single representative individual this is also true of some papers of the trade theoretic shadow pricing literature which derive utility based shadow prices of factors such as bhagwati and srinivasan 1981 in which a social utility function is postulated containing the aggregate amounts of consumptions of commodities as arguments interestingly enough even in the monograph by tower and pursell 1986 referred to by tph most of the analysis is conducted in terms of aggregate consumer preferences and only one section of a chapter section 9 of chapter iii assumes heterogeneity of individual consuming units while in theory it is doubtless desirable to allow

where have the profits gone market efficiency and the disappearing equity anomalies in country and industry returns abstract we are the first to demonstrate the decline in the cross sectional predictability of country and industry returns in recent years we examine 53 anomalies in country and industry indices from 64 markets for the years 1973 2018 the profitability of the strategies has significantly decreased recently driven particularly by the disappearance of value and reversal effects the phenomenon is strongest in large developed markets neither changes in country and industry specific risks nor investor learning from the academic literature can explain the effect our findings support the view that the fall in return predictability is caused by the overall improvement in market efficiency

long lived private information and imperfect competition we develop a multi period auction model in which multiple privately informed agents strategically exploit their long lived information we show that such traders compete aggressively and cause most of their common private information to be revealed very rapidly in the limit as the interval between auctions approaches zero market depth becomes infinite and all private information is revealed immediately these results are in contrast to those of kyle 1985 in which the monopolistic informed trader causes his information to be incorporated into prices gradually and when the interval between auctions is vanishingly small market depth is constant over time fama 1970 defines a strong form efficient market as one in which security prices fully reflect all available information including both publicly and privately held information in a pioneering and influential article kyle 1985 develops a model in which a single privately informed trader with long lived information optimally exploits his monopoly power over time kyle s 1985 main results are i the informed trader trades in a gradual manner so that his information is incorporated into prices at a slow almost linear rate and ii when auctions are held continuously the depth of the market is constant over time however kyle s 1985 assumption of a single informed trader is strong in the sense that in actual financial markets it is reasonable to expect that at least a few players will have access to private information and will trade in the knowledge that they will face competition with other informed agents in the market 1 we develop a multi period auction model in which multiple strategic informed traders optimally exploit their long lived informational advantage we thus explore the restrictiveness of kyle s assumption of a single informed trader and also examine

do etfs increase volatility due to their low trading costs exchange traded funds etfs are a potential catalyst for short horizon liquidity traders the liquidity shocks can propagate to the underlying securities through the arbitrage channel and etfs may increase the nonfundamental volatility of the securities in their baskets we exploit exogenous changes in index membership and find that stocks with higher etf ownership display significantly higher volatility etf ownership increases the negative autocorrelation in stock prices the increase in volatility appears to introduce undiversifiable risk in prices because stocks with high etf ownership earn a significant risk premium of up to 56 basis points monthly

the price response to s p 500 index additions and deletions evidence of asymmetry and a new explanation we study the price effects of changes to the s p 500 index and document an asymmetric price response there is a permanent increase in the price of added firms but no permanent decline for deleted firms these results are at odds with extant explanations of the effects of index changes that imply a symmetric price response to additions and deletions a possible explanation for asymmetric price effects arises from the changes in investor awareness results from our empirical tests support the thesis that changes in investor awareness contribute to the asymmetric price effects of s p 500 index additions and deletions the long held assumption that stocks have perfect substitutes and the perfect elasticity of demand that follows from it is central to modern finance theory if securities have almost perfectly elastic demand then any supply or demand shocks that are devoid of information should have no effect on the prevailing price early empirical research on whether price changes occur in the absence of new information focused on block trades equity issues and stock splits but was unable to exclude information effects around these events since there is no obvious reason to believe ex ante that index changes contain new information they constitute a natural framework for testing whether stocks have almost perfectly elastic or horizontal demand curves a stock s excess return around such changes could be consistent with a downward sloping demand curve with the advent of indexed mutual funds in 1976 and the public announcement of s p index changes in the same year there is much evidence that such announcements are accompanied by an increase in price for firms added to the index if stocks have a short term downward sloping demand curve the price should be momentarily affected by a demand shock due to indexing but that effect

hedging demand and market intraday momentum hedging short gamma exposure requires trading in the direction of price movements thereby creating price momentum using intraday returns on over 60 futures on equities bonds commodities and currencies between 1974 and 2020 we document strong market intraday momentum everywhere the return during the last 30 minutes before the market close is positively predicted by the return during the rest of the day from previous market close to the last 30 minutes the predictive power is economically and statistically highly significant and reverts over the next days we provide novel evidence that links market intraday momentum to the gamma hedging demand from market participants such as market makers of options and leveraged etfs

on the asynchronous approvals of gm crops potential market impacts of a trade disruption of eu soy imports due to their high protein content soybeans are important feedstuffs in the european union eu however the cultivation of soybeans using genetically modified gm varieties in non eu countries is increasing and the eu authorization of gm products takes longer than in other countries leading to an asynchronous approval between the eu and non eu countries that might induce soybean trade disruptions this paper uses an integrated modelling system to simulate argentina brazil and the united states ending soybean exports to the eu the impact on world trade and on the eu import prices of soy products is analysed with a computable general equilibrium model eu soy imports are shown to decline and the import price of soybeans in the eu increases the effects on eu agricultural markets are analysed based on a partial equilibrium model feed costs in the eu are found to increase with poultry and pork the most affected production and exports decline and imports increase however the effects of a trade ban are found to be less profound than in many other studies due to compensating substitution effects at various market levels increasing imports from third countries increasing domestic oilseed production and the use of other protein feeds

a unified approach to testing for serial correlation in stock returns this article provides a unified approach for testing serial correlation in stock returns the authors describe a general class of statistics that are linear combinations of consistent estimators of autocorrelations as special cases they show that this class captures many of the statistics studied in the recent finance and macroeconomics literature using this result the authors then provide a common perspective on the asymptotic distribution and power of these statistics copyright 1994 by university of chicago press

shadow pricing in a specific factors model comment recently in this journal maneschi 1985 calculated shadow prices of factors for a small country that produces and consumes many goods all of which are traded at fixed world prices and are produced using intersectorally mobile labour and a sector specific capital stock all factors are fixed in supply and the distortions considered consist of fixed import tariffs and or export subsidies sector specific wage differentials and minimum wages the work is closely related to that of srinivasan and bhagwati 1978 henceforth sb who calculate shadow prices of factors for a country which produces two goods using two intersectorally mobile factors of production the analysis is similar in that both papers calculate the shadow price of a factor of production as the fall in the value of the country s output measured at world prices resulting from governmental withdrawal of a unit of the factor from the private sector for use in a hypothetical project this is always legitimate in the sb model because fixed import tariffs fixed export subsidies and fixed world prices serve to freeze all product and factor prices in the domestic economy in the face of altered factor supplies to the private sector this means that when the government withdraws a unit of a factor from the private sector to use in a project each individual s utility and consumption bundle will be left unchanged and the only cost to the government will be the increase in the rate at which its foreign exchange reserves are used up which will just equal the change in the value of domestic output at world prices thus in this case the social cost or shadow price of a unit of the factor in foreign exchange numeraire is just the change in domestic output valued at world prices

a tale of three schools insights on autocorrelations of short horizon stock returns this article reexamines the autocorrelation patterns of short horizon stock returns we document empirical results which imply that these autocorrelations have been overstated in the existing literature based on several new insights we provide support for a market efficiency based explanation of the evidence our analysis suggests that institutional factors are the most likely source of the autocorrelation patterns

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

partial adjustment or stale prices implications from stock index and futures return autocorrelations we investigate the relation between returns on stock indices and their corresponding futures contracts to evaluate potential explanations for the pervasive yet anomalous evidence of positive short horizon portfolio autocorrelations using a simple theoretical framework we generate empirical implications for both microstructure and partial adjustment models the major findings are i return autocorrelations of indices are generally positive even though futures contracts have autocorrelations close to zero and ii these autocorrelation differences are maintained under conditions favorable for spot futures arbitrage and are most prevalent during low volume periods these results point toward microstructure based explanations and away from explanations based on behavioral models

components of short horizon individual security returns abstract in this paper we present a simple model which relates security returns to three components an expected return a bid ask error and white noise the relative importance of the various components is empirically assessed and the model s ability to explain the various time series properties of individual security and portfolio returns is tested time varying expected returns and bid ask errors are found to explain substantial proportions up to 24 of the variance of security returns we also reconcile the typically negative autocorrelation in security returns with the strong positive autocorrelation in portfolio returns

industry information diffusion and the lead lag effect in stock returns i argue that the slow diffusion of industry information is a leading cause of the lead lag effect in stock returns i find that the lead lag effect between big firms and small firms is predominantly an intra industry phenomenon moreover this effect is driven by sluggish adjustment to negative information and is robust to alternative determinants of the lead lag effect small less competitive and neglected industries experience a more pronounced lead lag effect the lead lag effect is related to the post announcement drift of small firms following the earnings releases of big firms within the industry

trading volume and serial correlation in stock returns this paper investigates the relationship between aggregate stock market trading volume and the serial correlation of daily stock returns for both stock indexes and individual large stocks the first order daily return autocorrelation tends to decline with volume the paper explains this phenomenon using a model in which risk averse market makers accommodate buying or selling pressure from liquidity or noninformational traders changing expected stock returns reward market makers for playing this role the model implies that a stock price decline on a high volume day is more likely than a stock price decline on a low volume day to be associated with an increase in the expected stock return

estimating the impact of transgenic bt cotton on west and central africa a general equilibrium approach summary west and central africa wca s cotton sector is experiencing rising production costs and lower yields reversing decades of growth declining input use soil fertility and inefficient chemical pest controls are contributing factors we evaluate the potential impact of bt cotton on wca using a multiregion general equilibrium model and multicountry estimates of bt induced productivity we find that bt cotton raises growers returns land value and welfare released labor from cotton is shifted to food crops hence reducing labor shortage constraints overall results indicate that potential gross benefits from bt cotton are substantial for wca cotton sector and that the economic costs of nonadoption are equally significant published by elsevier ltd