day of the week effects and asset returns the number of empirical studies using daily stock returns is rapidly increasing researchers generally assume that the distribution of stock returns is identical for all days of the week a convenient statistical assumption but not a necessary condition of market equilibrium nevertheless there are reasons to suspect that the distribution of returns may vary according to the day of the week the most obvious is the impact of weekends on monday s return since monday s return is calculated over three instead of one calender day the mean and variance may well be higher on monday compared with any other daily return perhaps three times as large previous research has examined the daily distribution of stock returns for a monday effect while fama 1965 does not compare daily mean returns he does report that monday s variance is about 20o greater than other daily returns with a traditional distributional assumption regarding the returns on a financial asset specifies that the expected returns are identical for all days of the week contrary to this plausible assumption this paper discovers that the expected returns on common stocks and treasury bills are not constant across days of the week the most notable evidence is for monday s returns where the mean is unusually low or even negative several explanations of the results are investigated but none proves satisfactory aside from documenting significant day of the week effects the implications of the results for tests of market efficiency are examined while market adjusted returns continue to exhibit day of the week effects these effects are no longer concentrated on monday during the last year we have had many conversations with our colleagues throughout the professions we are particularly thankful to the participants at sessions of the western and american finance associations where preliminary versions of this paper were presented special thanks are due to gene fama gailen hite jon ingersoll robert jarrow merton miller clifford smith and rex thompson the expert research assistance of frank rabinovitch and youngsup yun is gratefully acknowledged 1 the list of papers using daily stock returns is too long to name recent examples include charest 1978 dodd 1980 banz 1981 and reinganum 1981

the sensitivity of vpin to the choice of trade classification algorithm abstract the vpin metric easley et al 2012b aims to detect and predict the toxicity of order flow this paper examines the sensitivity and robustness of vpin to the choice of trade classification scheme which is the major input used to compute vpin we compare deterministic trade by trade classification approaches with results computed using a newly proposed heuristic approach bulk volume classification we find substantial differences for all levels of aggregation trade classification order imbalance vpin and identifying toxic periods we also find that the detection of toxic periods does not yield consistent results in more than 60 of cases but regression analysis can identify volume and return volatility as parameters that contribute to higher levels of sensitivity

a day end transaction price anomaly a large mean price change is observed on the last daily nyse transaction this suggests that closing prices may not consistently represent stock values transaction prices are studied to further characterize the day end price rise and to determine whether it is due to any limited subsample of stocks or dates the results indicate that the phenomenon is pervasive over most firms and days some evidence suggests that it is caused by a change in the frequency of ask prices at day end

stock price clustering and discreteness stock prices cluster on round fractions clustering increases with price level and volatility and decreases with capitalization and transaction frequency clustering is pervasive price clustering will occur if traders use discrete price sets to simplify their negotiations exchange regulations require that most stocks be traded on eighths clustering on larger fractions will occur if traders choose to use discrete price sets based on quarters halves or whole numbers an econometric model of clustering is derived and estimated projections from the results suggest that traders would frequently use odd sixteenths when trading low price stocks if exchange regulations permitted trading on sixteenths article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies

border adjustments supplementing nationally determined carbon pricing as agreed on in the paris agreement each country determines its own contribution to combat climate change on a voluntary basis there is no mechanism to force a country to comply with its own nationally determined contributions this bottom up approach builds on unilateral actions and yields a kind of carbon pricing which is not necessarily identical across countries as a consequence these nationally determined climate policies have drawbacks in terms of carbon leakage and loss of competitiveness for firms producing in high carbon price countries to reduce these negative effects border adjustments bas may be appropriate subsequent to more stringent environmental regulation we model a three stage game involving carbon price competition in the first stage the introduction of bas in the second stage and oligopolistic competition between firms in the third stage strategic trade theory suggests that the qualitative results about the optimal ba policy may vary with the underlying type of competition namely bertrand and cournot competition however our results are similar for both types of competition we conclude that bas are suitable for supporting a more stringent environmental policy moreover we find that anticipation of the implementation of bas in the second stage yields higher average carbon prices in the first stage since high carbon price countries increase their carbon prices whereas the other countries partially offset

penny wise dollar foolish buy sell imbalances on and around round numbers this paper provides evidence that stock traders focus on round numbers as cognitive reference points for value using a random sample of more than 100 million stock transactions we find excess buying selling by liquidity demanders at all price points one penny below above round numbers further the size of the buy sell imbalance is monotonic in the roundness of the adjacent round number i e largest adjacent to integers second largest adjacent to half dollars etc conditioning on the price path we find much stronger excess buying selling by liquidity demanders when the ask falls bid rises to reach the integer than when it crosses the integer we discuss and test three explanations for these results finally 24 hour returns also vary by price point and buy sell imbalances are a major determinant of that variation across price points buying selling by liquidity demanders below above round numbers yield losses approaching 1 billion per year this paper was accepted by brad barber teck ho and terrance odean special issue editors

information disclosure and price manipulation during the pre closing session evidence from an order driven market on 20 february 2012 the taiwan stock exchange corporation launched an order matching simulation mechanism for five minutes during the start of the pre closing session in order to increase information disclosure during this period 13 25 13 30 pre closing information disclosure significantly reduces both trading costs and closing price volatility as well as price manipulation the decrease in price manipulation found in this work is due to pre closing information disclosure not the behaviour of investors shifting to an earlier time further if a stock price rises or falls by more than 3 5 in the simulation in the last minute during the closing session trading of the stock will be suspended for two minutes from 13 31 to reduce volatility however this trading mechanism suspended closing does not seem to have achieved the intended goals of the authorities as it has not been able to significantly reduce closing price volatility and price manipulation

large block transactions the speed of response and temporary and permanent stock price effects abstract the paper investigates how quickly prices attain new equilibrium levels after large block transactions and measures the associated temporary and permanent price effects we find that prices adjust within at most three trades with most of the adjustment occurring in the first trade the temporary price effect for seller initiated transactions is related to block size but the temporary price effect observed for buyer initiated transactions is no larger than that observed in 100 share trades most of the price effect associated with block trades is permanent and is related to block size regardless of the initiating party

cooperation among strangers under the shadow of the future we study the emergence of norms of cooperation in experimental economies populated by strangers interacting indefinitely can these economies achieve full efficiency even without formal enforcement institutions which institutions for monitoring and enforcement facilitate cooperation finally what classes of strategies do subjects employ we find that first cooperation can be sustained even in anonymous settings second some type of monitoring and punishment institutions significantly promote cooperation and third subjects mostly employ strategies that are selective in punishment

regulatory and legal pressures and the costs of nasdaq trading the nasdaq market came under intense pressure from regulators and class action lawsuits following allegations of tacit collusion by christie and schultz 1994 this article examines the changes in transaction costs on the nasdaq from january 1993 through june 1996 using 16 million trades in 30 stocks effective spreads cannot be matched however the autocovariance spread estimator of roll 1984 works well with intraday data over this period this spread estimator reveals that trading costs declined significantly for 29 of the 30 stocks over 1993 96 article published by oxford university press on behalf of the society for financial studies in its journal the review of financial studies

an investigation of transactions data for nyse stocks using transactions data the behavior of returns and characteristics of trades at the micro level is examined a minute by minute market return series is formed and tested for normality and autocorrelation evidence of differences in return distributions is found among overnight trades trades during the first 30 minutes following the market opening trades at the close and trades during the remainder of the day the latter distribution is found to be normal unusually high returns and standard deviations of returns are found at the beginning and the end of the trading day when the beginningand end of the day effects are omitted autocorrelation in the market return series is reduced substantially a number of patterns in trading are reported this paper empirically investigates the nature of the return generating process and the characteristics of trade size price changes trading frequency and trading interval at the level of individual trades for a large sample of nyse stocks previous studies of market indices have used daily weekly or monthly

efficiency of experimental security markets with insider information an application of rational expectations models the study reports on the ability of competing models of market information integration and dissemination to explain the behavior of simple laboratory markets for a one priced security returns to the security depended upon a randomly drawn state of nature some agents insiders whose identity was unknown to other agents knew the state before the markets opened with replication of market conditions the predictions of a fully revealing rational expectations model are relatively accurate prices adjusted immediately to near rational expectations prices profits of insiders were virtually indistinguishable from non insiders and efficiency levels converged to near 100 percent

autocorrelation of daily index returns intraday to intraday versus close to close intervals abstract first order autocorrelation coefficients of 1 daily equally weighted open to open returns 2 daily equally weighted intraday to intraday returns terminating at each of 23 successive 15 minute intervals of the trading day beginning at 10 15 a m and 3 daily equally weighted and value weighted close to close returns interval 24 are examined a number of findings concerning the behavior of these autocorrelations are reported first order autocorrelation is shown to follow a crude u shaped pattern when plotted against the time of the trading day but there is no significant difference in the behavior of autocorrelations based on open to open returns and 24 hour returns terminating at 10 15 a m evidence that intraday patterns in autocorrelation cannot be explained fully by trading delays also is presented

trading and returns under periodic market closures this paper studies how market closures affect investors trading policies and the resulting return generating process it shows that closures generate rich patterns of time variation in trading and returns including those consistent with empirical findings 1 u shaped patterns in the mean and volatility of returns over trading periods 2 higher trading activity around the close and open 3 more volatile open to open returns than close to close returns 4 higher returns over trading periods than over nontrading periods 5 more volatile returns over trading periods than over nontrading periods it also shows that closures can make prices more informative about future payoffs we model a competitive stock market with periodic closures in which investors trade for both allocational and informational reasons we use the model to study how market closures intrinsically affect investors trading behavior and the return generating process the purpose of this analysis is to increase our understanding of the time variation in security trading and returns that are associated with regular market closures such as the intraday and intraweek patterns in stock returns volatility and trading volume we consider a stock market in which the exogenous information flow is homogeneous over time and the market closes periodically when the market is open investors trade the stock either to rebalance their overall portfolio of assets which also includes other illiquid assets or to speculate on future stock payoffs using their private information in particular investors adjust their asset portfolio by trading the stock in order to hedge the risk of illiquid assets we refer to these trades as hedging trades and those motivated by private information as speculative trades when the market is closed hong is from the graduate school of business stanford university and wang is from the sloan school of management massachusetts institute of technology and nber the authors thank jennifer huang for programming assistance and an anonymous referee for many valuable suggestions they also thank glenn ellison john heaton craig holden andrew lo steve slezak jeremy stein rene stulz the editor the nber asset pricing lunch group and par

otc trades and liquidity in the european carbon market more than meets the eye this study investigates whether the previously reported price impact of otc trades in the eu ets can be attributed to their distinctively larger size liquidity related or to their discretionary f

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

calendar anomalies abnormal returns at calendar turning points 1988 calendar anomalies abnormal returns at calendar turning points financial analysts journal vol 44 no 6 pp 28 39

standard poor s 500 index futures volatility and price changes around the new york stock exchange close we examine the effects of the closing of the new york stock exchange nyse on volatility and price changes in the standard poor s s p futures market which trades for 15 more minutes each day when the nyse closes volatility in the futures market drops significantly only to increase at the close of the futures market thus exhibiting a u shaped pattern after the nyse closes we also find that friday s close is the period of highest volatility in the futures market also in the final minutes on friday the s p futures price anticipates the well known weekend effect found in equities copyright 1995 by university of chicago press

the italian stock market efficiency and calendar anomalies abstract after describing the various concepts of efficiency information valuation full insurance and functional with special reference to the italian stock market the paper analyzes the impact of particular dates and periods of the civil year and stock exchange calendars on stock price changes to test the existence of information inefficiencies the analysis is based on the milan stock exchange s mib storico stock index with reference to the period 2 january 1975 22 august 1989 the events tested for systematic anomalies include weekend and public holidays the end of the calendar and stock exchange months and the end of the year the results obtained are in line with those found for the u s market with evidence of anomalous changes though not all are stable over time

trading behavior and the unbiasedness of the market reaction to dividend announcements this article examines the price formation process during dividend announcement day using daily closing prices and transactions data we find that the unconditional positive excess returns first documented by kalay and loewenstein 1985 are higher for small firm and low priced stocks price volatility and trading volume also increase during this period examination of trade prices relative to the bid ask spread and volume of trades at bid and asked prices shows that the excess returns cannot be attributed to measurement errors or to spillover effects of tax related ex day trading rather the price behavior is related to the absorption of dividend information

institutional trades and intraday stock price behavior abstract this paper examines the price effect of institutional stock trading using a unique data set that reports the transactions large and small of 37 large institutional money management firms the direction of each trade and the identity of the management firm behind each trade are known although institutional trades are associated with some price pressure we find that the average effect is small there is also a marked asymmetry between the price impact of buys versus sells we relate our findings to various hypotheses on the elasticity of demand for stocks the cost of executing transactions and the determinants of market impact although market capitalization and relative trade size influence the market impact of a trade the dominant influence is the identity of the money manager behind the trade