《金融投资学》教学资源（英文文献）can investors profit from the prophets.pdf

THE JOURNAL OF FINANCE.VOL.LVI.NO.2 APRIL 2001 Can Investors Profit from the Prophets? Security Analyst Recommendations and Stock Returns BRAD BARBER,REUVEN LEHAVY,MAUREEN McNICHOLS, and BRETT TRUEMAN* ABSTRACT We document that purchasing(selling short)stocks with the most(least)favorable consensus recommendations,in conjunction with daily portfolio rebalancing and a timely response to recommendation changes,yield annual abnormal gross returns greater than four percent.Less frequent portfolio rebalancing or a delay in react- ing to recommendation changes diminishes these returns;however,they remain significant for the least favorably rated stocks.We also show that high trading levels are required to capture the excess returns generated by the strategies ana- lyzed,entailing substantial transactions costs and leading to abnormal net returns for these strategies that are not reliably greater than zero. THIS STUDY EXAMINES WHETHER INVESTORS can profit from the publicly available recommendations of security analysts.Academic theory and Wall Street practice are clearly at odds regarding this issue.On the one hand,the semi- strong form of market efficiency posits that investors should not be able to trade profitably on the basis of publicly available information,such as ana- lyst recommendations.On the other hand,research departments of broker- age houses spend large sums of money on security analysis,presumably because these firms and their clients believe its use can generate superior returns. Barber is an associate professor at the Graduate School of Management,University of California,Davis;Lehavy is an assistant professor at the Haas School of Business,University of California,Berkeley;MeNichols is a professor at the Graduate School of Business,Stanford University;and Trueman is the Donald and Ruth Seiler Professor of Public Accounting at the Haas School of Business,University of California,Berkeley.We thank Jeff Abarbanell,Sudipto Basu,Bill Beaver,George Foster,Charles Lee,Terry Odean,Sheridan Titman,Russ Wermers, Kent Womack,the editor,Rene Stulz,and participants at the October 1998 NBER(Behavioral Finance)conference,the ninth annual Conference on Financial Economics and Accounting at NYU,the Berkeley Program in Finance(Behavioral Finance)conference,Barclay's Global In- vestors,Baruch College,Mellon Capital Management,Stanford University,Tel Aviv University, the Universities of British Columbia,Florida,and Houston,and UCLA,for their valuable com- ments,and Zacks Investment Research for providing the data used in this study.Lehavy and Trueman also thank the Center for Financial Reporting and Management at the Haas School of Business and McNichols thanks the Financial Research Initiative of the Stanford Graduate School of Business for providing research support.All remaining errors are our own. 531

Can Investors Profit from the Prophets? Security Analyst Recommendations and Stock Returns BRAD BARBER, REUVEN LEHAVY, MAUREEN McNICHOLS, and BRETT TRUEMAN* ABSTRACT We document that purchasing ~selling short! stocks with the most ~least! favorable consensus recommendations, in conjunction with daily portfolio rebalancing and a timely response to recommendation changes, yield annual abnormal gross returns greater than four percent. Less frequent portfolio rebalancing or a delay in reacting to recommendation changes diminishes these returns; however, they remain significant for the least favorably rated stocks. We also show that high trading levels are required to capture the excess returns generated by the strategies analyzed, entailing substantial transactions costs and leading to abnormal net returns for these strategies that are not reliably greater than zero. THIS STUDY EXAMINES WHETHER INVESTORS can profit from the publicly available recommendations of security analysts. Academic theory and Wall Street practice are clearly at odds regarding this issue. On the one hand, the semistrong form of market efficiency posits that investors should not be able to trade profitably on the basis of publicly available information, such as analyst recommendations. On the other hand, research departments of brokerage houses spend large sums of money on security analysis, presumably because these firms and their clients believe its use can generate superior returns. * Barber is an associate professor at the Graduate School of Management, University of California, Davis; Lehavy is an assistant professor at the Haas School of Business, University of California, Berkeley; McNichols is a professor at the Graduate School of Business, Stanford University; and Trueman is the Donald and Ruth Seiler Professor of Public Accounting at the Haas School of Business, University of California, Berkeley. We thank Jeff Abarbanell, Sudipto Basu, Bill Beaver, George Foster, Charles Lee, Terry Odean, Sheridan Titman, Russ Wermers, Kent Womack, the editor, Rene Stulz, and participants at the October 1998 NBER ~Behavioral Finance! conference, the ninth annual Conference on Financial Economics and Accounting at NYU, the Berkeley Program in Finance ~Behavioral Finance! conference, Barclay’s Global Investors, Baruch College, Mellon Capital Management, Stanford University, Tel Aviv University, the Universities of British Columbia, Florida, and Houston, and UCLA, for their valuable comments, and Zacks Investment Research for providing the data used in this study. Lehavy and Trueman also thank the Center for Financial Reporting and Management at the Haas School of Business and McNichols thanks the Financial Research Initiative of the Stanford Graduate School of Business for providing research support. All remaining errors are our own. THE JOURNAL OF FINANCE • VOL. LVI, NO. 2 • APRIL 2001 531

532 The Journal of Finance These observations provide a compelling empirical motivation for our in- quiry and distinguish our analysis from many recent studies of stock return anomalies.1 In contrast to many of these studies,which focus on corporate events,such as stock splits,or firm characteristics,such as recent return performance,that are not directly tied to how people invest their money,we analyze an activity-security analysis-that is undertaken by investment professionals at hundreds of major brokerage houses with the express pur- pose of improving the return performance of their clients. The possibility that there could exist profitable investment strategies based on the publicly available recommendations of security analysts is suggested by the findings of Stickel (1995)and Womack (1996),who show that favor- able (unfavorable)changes in individual analyst recommendations are ac- companied by positive(negative)returns at the time of their announcement.2 Additionally,they document a post-recommendation stock price drift,which Womack finds to last up to one month for upgrades and six months for downgrades. Our paper's perspective,however,is different from that of Stickel and Womack.Their primary goal is to measure the average price reaction to changes in individual analysts'recommendations;therefore,they take an analyst and event-time perspective.This approach can only provide evidence as to whether,absent transactions costs,profitable investment strategies could potentially be designed around those recommendations.In contrast, we take a more investor-oriented,calendar-time perspective.This permits us to directly measure the abnormal gross returns to a number of invest- ment strategies and to estimate portfolio turnover and the associated trans- actions costs incurred in implementing them.Consequently,we are able to determine whether investors can earn positive abnormal profits on these strategies after accounting for transactions costs. By measuring turnover and assessing whether investors can generate ab- normal returns net of trading costs on the various stock market investment strategies we examine,our analysis contributes to the market efficiency debate. Our methodology could easily be extended to the study of other strategies, such as those based on price momentum or the post-earnings announcement drift. We focus on the profitability of investment strategies involving consensus (average)analyst recommendations.The consensus is a natural choice,as it takes into account the information implicit in the recommendations of all the analysts following a particular stock.It is arguably the analyst statistic that is most easily accessed by investors,as it appears on many Internet 1 See Fama(1998)for a review and critique of this body of work. 2Other papers examining the investment performance of security analysts'stock recommen- dations are Diefenbach(1972),Bidwell(1977),Groth et al.(1979),Dimson and Marsh(1984), and Barber and Loeffler(1993).Copeland and Mayers(1982)study the investment performance of the Value Line Investment Survey and Desai and Jain(1995)analyze the return from fol- lowing Barron's annual roundtable recommendations

These observations provide a compelling empirical motivation for our inquiry and distinguish our analysis from many recent studies of stock return anomalies.1 In contrast to many of these studies, which focus on corporate events, such as stock splits, or firm characteristics, such as recent return performance, that are not directly tied to how people invest their money, we analyze an activity—security analysis—that is undertaken by investment professionals at hundreds of major brokerage houses with the express purpose of improving the return performance of their clients. The possibility that there could exist profitable investment strategies based on the publicly available recommendations of security analysts is suggested by the findings of Stickel ~1995! and Womack ~1996!, who show that favorable ~unfavorable! changes in individual analyst recommendations are accompanied by positive ~negative! returns at the time of their announcement.2 Additionally, they document a post-recommendation stock price drift, which Womack finds to last up to one month for upgrades and six months for downgrades. Our paper’s perspective, however, is different from that of Stickel and Womack. Their primary goal is to measure the average price reaction to changes in individual analysts’ recommendations; therefore, they take an analyst and event-time perspective. This approach can only provide evidence as to whether, absent transactions costs, profitable investment strategies could potentially be designed around those recommendations. In contrast, we take a more investor-oriented, calendar-time perspective. This permits us to directly measure the abnormal gross returns to a number of investment strategies and to estimate portfolio turnover and the associated transactions costs incurred in implementing them. Consequently, we are able to determine whether investors can earn positive abnormal profits on these strategies after accounting for transactions costs. By measuring turnover and assessing whether investors can generate abnormal returns net of trading costs on the various stock market investment strategies we examine, our analysis contributes to the market efficiency debate. Our methodology could easily be extended to the study of other strategies, such as those based on price momentum or the post-earnings announcement drift. We focus on the profitability of investment strategies involving consensus ~average! analyst recommendations. The consensus is a natural choice, as it takes into account the information implicit in the recommendations of all the analysts following a particular stock. It is arguably the analyst statistic that is most easily accessed by investors, as it appears on many Internet 1 See Fama ~1998! for a review and critique of this body of work. 2 Other papers examining the investment performance of security analysts’ stock recommendations are Diefenbach ~1972!, Bidwell ~1977!, Groth et al. ~1979!, Dimson and Marsh ~1984!, and Barber and Loeffler ~1993!. Copeland and Mayers ~1982! study the investment performance of the Value Line Investment Survey and Desai and Jain ~1995! analyze the return from following Barron’s annual roundtable recommendations. 532 The Journal of Finance

Security Analyst Recommendations and Stock Returns 533 financial Web sites (such as CBS.MarketWatch.com and Yahoo!Finance)and is incorporated into the databases of several financial information providers (such as Dow Jones Interactive). The data used in this paper come from the Zacks database for the period 1985 to 1996,which includes over 360,000 recommendations from 269 bro- kerage houses and 4,340 analysts.As such,our study uses a much larger sample of analyst recommendations than has been employed in past re- search.Stickel,by comparison,studies the price impact of 16,957 changes in analyst recommendations over the 1988 to 1991 period,and Womack ana- lyzes the impact of 1,573 changes in analyst recommendations for the top 14 U.S.brokerage research departments during the 1989 to 1991 period. With the Zacks database,we track in calendar time the investment per- formance of firms grouped into portfolios according to their consensus ana- lyst recommendations.Every time an analyst is reported as initiating coverage, changing his or her rating of a firm,or dropping coverage,the consensus recommendation of the firm is recalculated and the firm moves between portfolios,if necessary.Any required portfolio rebalancing occurs at the end of the trading day.This means that investors are assumed to react to a change in consensus recommendation at the close of trading on the day that the change took place.Consequently,any return that investors might have earned from advance knowledge of the recommendations(or from trading in the recommended stocks at the start of the trading day)is excluded from the return calculations. For our sample period we find that buying the stocks with the most favor- able consensus recommendations earns an annualized geometric mean re- turn of 18.8 percent,whereas buying those with the least favorable consensus recommendations earns only 5.78 percent (see Figure 1).As a benchmark, during the same period an investment in a value-weighted market portfolio earns an annualized geometric mean return of 14.5 percent.Alternatively stated,the most highly recommended stocks outperform the least favorably recommended ones by 102 basis points per month. After controlling for market risk,size,book-to-market,and price momen- tum effects,a portfolio comprised of the most highly recommended stocks provides an average annual abnormal gross return of 4.13 percent whereas a portfolio of the least favorably recommended ones yields an average an- nual abnormal gross return of-4.91 percent.Consequently,purchasing the securities in the top portfolio and selling short those in the lowest portfolio yields an average abnormal gross return of 75 basis points per month.3 By comparison,over the same period,high book-to-market stocks outperform low book-to-market stocks by a mere 17 basis points,and large firms out- 3 If large institutional clients were to gain access to,and trade on,analysts'recommenda- tions before they were made public,their investment value would be even greater.This is due to the strong market reaction that immediately follows the announcement of a recommenda- tion.(The magnitude of this reaction for our sample of analyst recommendations is documented in Table III.)

financial Web sites ~such as CBS.MarketWatch.com and Yahoo!Finance! and is incorporated into the databases of several financial information providers ~such as Dow Jones Interactive!. The data used in this paper come from the Zacks database for the period 1985 to 1996, which includes over 360,000 recommendations from 269 brokerage houses and 4,340 analysts. As such, our study uses a much larger sample of analyst recommendations than has been employed in past research. Stickel, by comparison, studies the price impact of 16,957 changes in analyst recommendations over the 1988 to 1991 period, and Womack analyzes the impact of 1,573 changes in analyst recommendations for the top 14 U.S. brokerage research departments during the 1989 to 1991 period. With the Zacks database, we track in calendar time the investment performance of firms grouped into portfolios according to their consensus analyst recommendations. Every time an analyst is reported as initiating coverage, changing his or her rating of a firm, or dropping coverage, the consensus recommendation of the firm is recalculated and the firm moves between portfolios, if necessary. Any required portfolio rebalancing occurs at the end of the trading day. This means that investors are assumed to react to a change in consensus recommendation at the close of trading on the day that the change took place. Consequently, any return that investors might have earned from advance knowledge of the recommendations ~or from trading in the recommended stocks at the start of the trading day! is excluded from the return calculations. For our sample period we find that buying the stocks with the most favorable consensus recommendations earns an annualized geometric mean return of 18.8 percent, whereas buying those with the least favorable consensus recommendations earns only 5.78 percent ~see Figure 1!. As a benchmark, during the same period an investment in a value-weighted market portfolio earns an annualized geometric mean return of 14.5 percent. Alternatively stated, the most highly recommended stocks outperform the least favorably recommended ones by 102 basis points per month. After controlling for market risk, size, book-to-market, and price momentum effects, a portfolio comprised of the most highly recommended stocks provides an average annual abnormal gross return of 4.13 percent whereas a portfolio of the least favorably recommended ones yields an average annual abnormal gross return of 24.91 percent. Consequently, purchasing the securities in the top portfolio and selling short those in the lowest portfolio yields an average abnormal gross return of 75 basis points per month.3 By comparison, over the same period, high book-to-market stocks outperform low book-to-market stocks by a mere 17 basis points, and large firms out- 3 If large institutional clients were to gain access to, and trade on, analysts’ recommendations before they were made public, their investment value would be even greater. This is due to the strong market reaction that immediately follows the announcement of a recommendation. ~The magnitude of this reaction for our sample of analyst recommendations is documented in Table III.! Security Analyst Recommendations and Stock Returns 533

Security Analyst Recommendations and Stock Returns 535 The second set of alternative strategies retains daily portfolio rebalancing but assumes a delayed reaction by investors to all changes in analysts'con- sensus recommendations-of either one week,a half-month,or a full month. We show that a delay of either one week or a half month decreases the average annual abnormal gross return on the portfolio of the most highly recommended stocks to around two percent,whereas a month's delay re- duced it to less than one percent.None of these returns is reliably greater than zero.In contrast,the average annual abnormal gross return on the portfolio of the least favorably rated stocks remains significantly negative for all delay periods examined,standing at over -4 percent for a one-week delay and about -2 percent for either a half month's or a full month's delay.These results highlight the importance to investors of acting quickly to capture the gross returns on the highest rated stocks. None of the returns documented thus far take into account transactions costs,such as the bid-ask spread,brokerage commissions,and the market impact of trading.As we show,under the assumption of daily rebalancing, purchasing the most highly recommended securities or shorting the least favorably recommended ones requires a great deal of trading,with turnover rates at times in excess of 400 percent annually.After accounting for trans- actions costs,these active trading strategies do not reliably beat a market index.Restricting these trading strategies to the smallest firms (whose ab- normal gross returns are shown to be the highest)does not alter this con- clusion;transactions costs remain very large,and abnormal net returns are not significantly greater than zero.Rebalancing less frequently does reduce turnover significantly (falling below 300 percent for monthly rebalancing). But,because the abnormal gross returns fall as well,abnormal net returns are still not reliably greater than zero,in general.Despite the lack of posi- tive net returns to the strategies we examine,analyst recommendations do remain valuable to investors who are otherwise considering buying or sell- ing.Ceteris paribus,an investor would be better off purchasing shares in firms with more favorable consensus recommendations and selling shares in those with less favorable consensus ratings. Although a large number of trading strategies are investigated and none are found to yield positive abnormal net returns,our analysis by no means rules out the possibility that profitable trading strategies exist.It remains an open question whether other strategies based on analysts'recommenda- tions (or based on a subset of analysts'recommendations,such as those of the top-ranked analysts or the largest brokerage houses),or even whether the strategies studied here,but applied to different time periods or different stock recommendation data,will be able to generate positive abnormal net returns. The plan of this paper is as follows.In Section I,we describe the data and our sample selection criteria.A discussion of our research design follows in Section II.In Section III,we form portfolios according to consensus analyst recommendations and analyze their returns.The impact of investment de- lays on the returns available to investors is considered in Section IV.In

The second set of alternative strategies retains daily portfolio rebalancing but assumes a delayed reaction by investors to all changes in analysts’ consensus recommendations—of either one week, a half-month, or a full month. We show that a delay of either one week or a half month decreases the average annual abnormal gross return on the portfolio of the most highly recommended stocks to around two percent, whereas a month’s delay reduced it to less than one percent. None of these returns is reliably greater than zero. In contrast, the average annual abnormal gross return on the portfolio of the least favorably rated stocks remains significantly negative for all delay periods examined, standing at over 24 percent for a one-week delay and about 22 1 2 _ percent for either a half month’s or a full month’s delay. These results highlight the importance to investors of acting quickly to capture the gross returns on the highest rated stocks. None of the returns documented thus far take into account transactions costs, such as the bid-ask spread, brokerage commissions, and the market impact of trading. As we show, under the assumption of daily rebalancing, purchasing the most highly recommended securities or shorting the least favorably recommended ones requires a great deal of trading, with turnover rates at times in excess of 400 percent annually. After accounting for transactions costs, these active trading strategies do not reliably beat a market index. Restricting these trading strategies to the smallest firms ~whose abnormal gross returns are shown to be the highest! does not alter this conclusion; transactions costs remain very large, and abnormal net returns are not significantly greater than zero. Rebalancing less frequently does reduce turnover significantly ~falling below 300 percent for monthly rebalancing!. But, because the abnormal gross returns fall as well, abnormal net returns are still not reliably greater than zero, in general. Despite the lack of positive net returns to the strategies we examine, analyst recommendations do remain valuable to investors who are otherwise considering buying or selling. Ceteris paribus, an investor would be better off purchasing shares in firms with more favorable consensus recommendations and selling shares in those with less favorable consensus ratings. Although a large number of trading strategies are investigated and none are found to yield positive abnormal net returns, our analysis by no means rules out the possibility that profitable trading strategies exist. It remains an open question whether other strategies based on analysts’ recommendations ~or based on a subset of analysts’ recommendations, such as those of the top-ranked analysts or the largest brokerage houses!, or even whether the strategies studied here, but applied to different time periods or different stock recommendation data, will be able to generate positive abnormal net returns. The plan of this paper is as follows. In Section I, we describe the data and our sample selection criteria. A discussion of our research design follows in Section II. In Section III, we form portfolios according to consensus analyst recommendations and analyze their returns. The impact of investment delays on the returns available to investors is considered in Section IV. In Security Analyst Recommendations and Stock Returns 535