Identifying skilled managers: Evidence from mutual fund short ...Document Transcript
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Identifying skilled managers: Evidence from mutual fund short sales
Department of Finance
College of Business Administration
University of Central Florida
Orlando, FL 32816
(407) 823 0895
Edwin L. Cox School of Business
Southern Methodist University
Dallas, TX 75275-0333
School of Management
SUNY – Binghamton University
Binghamton, NY 13902
(607) 777 6861
In this paper, we provide a first look at the short positions established by 75 mutual funds
that used short sales of US domestic stocks as an investment strategy. We document that mutual
funds tend to establish short positions in the larger and more liquid stocks, likely to minimize the
possibility of a short squeeze. We also find that the shorted stocks have low equity BM ratios,
higher total accruals, and higher prior sales growth, and that the shorted stocks earn an abnormal
return of between -3.3% and -9.1% on an annualized basis. This suggests that the fund managers
are able to use valuation and financial indicators and identify stocks that do poorly.
We use the portfolio holdings data and show that the mutual funds earn significant
abnormal returns on both the short and the long portfolios. The average alpha for the short
portfolio (using the Carhart (1997) four-factor model) ranges between 4.8% and 5.9% on an
annualized basis. The corresponding abnormal return on the long portfolio ranges between 1.9%
and 2.6%. Using a total net assets-matched control fund approach, the incremental alpha ranges
between 2.9% to 4.1% annually. Overall, the result that mutual fund managers using short sales
exhibit superior performance is consistent with the theoretical prediction (e.g., Diamond and
Verrecchia (1987)) that only informed investors will sell short.
In this paper, we extend the existing literature on mutual funds by conducting a detailed
analysis of the short positions held by mutual funds. To the best of our knowledge, no prior study
has analyzed the mutual funds’ short sales. Specifically, we investigate whether both the
characteristics and performance of the shorted stocks support the notion that skilled mutual fund
managers are more likely to use short selling as an investment strategy. Our approach is
motivated by the prior theoretical literature on short sales (e.g., Diamond and Verrecchia
(1987)), which posits that given the significant costs associated with shorting a stock, only
informed investors with negative information will engage in short selling.
Diamond and Verrecchia (1987) argue that liquidity investor who needs resources
quickly would prefer to liquidate other assets rather than short selling securities about which they
are uninformed since the restrictions associated with short selling prevent them from
immediately using the proceeds from short sales. Furthermore, if the costs of short selling are
sufficiently high, this would deter investors with marginally negative information from shorting.1
Since holding short positions is more restrictive than holding long positions, it is likely that
classifying managers based on whether or not they undertake short sales would separate skilled
managers from the population of all fund managers. Consequently, mutual fund shorting activity
may be a good alternative setting to evaluate the ability of mutual fund managers to generate
Earlier studies have examined the ability of mutual fund to earn an abnormal return on its
investments (long positions), with mixed results. In an early, influential paper, Jensen (1968)
concludes that mutual funds do not display evidence of superior performance. Consistent with
Jensen (1968), other studies (e.g., Malkiel (1995) and Carhart (1997)) find that superior
Several researchers (Asquith and Meulbroek (1995) and Desai et al (2002)) find that heavily shorted stocks
underperform, though Asquith, Pathak, and Ritter (2005) show that this relationship has weakened in recent times.
performance is not persistent, and conclude that mutual fund managers have little or no stock
picking skills. But, Grinblatt and Titman (1989, 1993), Chen, Jegadeesh, and Wermers (1999),
Wermers (1999), and Baker, Litov, Wachter, and Wurgler (2005), among others, examine the
performance of stocks that are actively purchased and sold by mutual funds and conclude that
fund managers have stock picking skill. Other recent studies (e.g., Brunnermeier and Nagel
(2004) and Griffin and Xu (2005)) investigate the performance of hedge funds using portfolio
data from 13F filings. But, their analysis is also restricted to the hedge funds’ long portfolio since
short positions are not reported in the 13F filings. Even though the evidence is mixed on whether
mutual fund managers exhibit stock picking skill or not, one salient feature that is common to
these studies is that they focus only on the long side of the mutual fund’s portfolio. In contrast to
these studies, we focus on the stocks shorted by mutual funds, a feature that has not been
explored in the extant literature.
Our research is facilitated by the fact that in recent times, mutual funds have been
increasingly engaging in short sales. Prior to 1997, mutual funds were subject to the ‘short-short’
rule that limited gains from short-term positions to less than 30% of their total income. Since
gains from short sales were considered short-term irrespective of how long the position was held,
this rule limited the extent to which mutual funds were able to hold short positions. The
Taxpayer Relief Act of 1997 repealed this rule, and relaxed the constraints on the ability of
mutual funds to undertake short positions. Consequently, mutual funds started using short selling
as an active component of their investment strategy.2 Almazan, Brown, Carlson, and Chapman
(2004) provide evidence confirming this trend. About one-third of the domestic equity mutual
funds in their sample state that the fund’s investment policy guidelines allow short selling, and
this fraction has increased near-monotonically from 26.7% in 1994 to about 34% in 2000. More
“Funds that tame bull and bear”, January 26, 1998, BusinessWeek, pg. 98.
interestingly, 75 funds actually used short selling in our sample period of 2003-2005, which is
about 4% of the total number of actively managed domestic equity funds that existed in 2004.3
Since prior academic literature has not examined short selling by mutual funds, the first
part of this study is descriptive in nature. Our sample of 75 domestic (US) equity mutual funds
that established short positions in US stocks includes both large and small funds. For example,
the total net assets including all securities averages $461 million, but the median is much smaller
at $44 million. In the first period that the fund reports short positions, they short sell an average
of 38 stocks with a market value of $18 million. In the same period, the average long position is
$278 million invested in 81 stocks, indicating that the average size of the short position per stock
is smaller than that for long positions ($0.47 million versus $3.44 million). The mean expense
ratio is 2.17% of assets and the portfolio turnover is about 277% per year.
We also investigate whether mutual funds exhibit preferences for specific stock
characteristics in their short portfolios. This investigation is motivated by the evidence that
mutual funds prefer investing in stocks with particular characteristics and systematically avoid
other stocks (e.g., Falkenstein (1996)). Compared to stocks in their long portfolios, stocks in the
short portfolio are significantly different along several dimensions. Mutual funds prefer to
establish short positions in the larger, more liquid stocks, likely to minimize the possibility of a
short squeeze. Both the equity beta and the standard deviation of returns are higher for the
shorted stocks, indicating that they are subject to higher levels of information asymmetry.
Further, compared to stocks in the long portfolios, the shorted stocks have lower equity book to
market ratio and prior momentum and higher industry-adjusted total accruals and prior sales
growth. Overall, this evidence suggests that compared to long positions, mutual funds choose to
We identify sample funds from the CRSP mutual fund database, which begins reporting portfolio holdings on a
regular basis from 2003 onwards.
establish short positions in glamour stocks with greater degree of information asymmetry and
poor earnings quality. This is consistent with prior research which documents that such firms
underperform. However, to minimize the likelihood of a short squeeze that may force them to
close out short positions prematurely, the funds prefer to short larger and more liquid stocks.
The second part of the study examines the performance of mutual funds engaging in short
selling activities using three complementary approaches. First, if skilled mutual fund managers
are more likely to short stocks than other managers, then we expect the shorted stocks to
underperform on a risk-adjusted basis. Using calendar time regressions and the Carhart (1997)
four factor model, we find that on an annualized basis, portfolios of the shorted stocks
underperform by between 3.3% (equally-weighted) to 9.1% (weighted by the intensity of mutual
fund shorting activity). The statistically significant and large negative abnormal return confirms
that mutual fund managers are able to identify stocks that decline in value and establish short
positions in such firms. This result also corroborates the findings from earlier papers that
document the underperformance of highly shorted stocks.
The second series of tests extends this analysis and investigates whether the short
portfolio of these mutual funds also earns negative abnormal returns. Unlike prior literature on
short sales that commonly uses short interest data, the portfolio-level analysis directly tests the
assertion that sophisticated investors such as mutual fund managers are able to establish and
unwind short positions at a profit. The use of short interest data imposes two limitations that do
not permit reliable inferences about whether on average, informed short sellers earn abnormal
returns. First, the publicly available data consists of monthly short interest reported by the NYSE
and Nasdaq for each security. This data aggregates short interest that is due to either valuation
reasons or arbitrage reasons, making it difficult to separately identify valuation-based short
selling. Second, detailed portfolio holdings of informed arbitrageurs engaging in short sales are
not publicly available to researchers. Hence, it is difficult to establish when the short positions
are initiated and closed. The analysis in this study circumvents this limitation because individual
mutual funds periodically disclose their complete portfolio holdings, including short positions.
This allows us to estimate the gain or loss at the individual portfolio level for one group of
informed investors, i.e., mutual funds, that engages in short selling.4 Consistent with the stock
return evidence, the average abnormal return on the short portfolios of individual mutual funds is
also negative. The mean abnormal return ranges between -4.8% to -5.9% on an annualized basis,
and are statistically significant at conventional levels. This result further confirms that mutual
fund managers are able to establish and close their short positions profitably.
Finally, if mutual fund managers that use short selling as part of their investment strategy
are indeed more likely to be skilled managers, then we would expect their skill to be reflected in
their investments (long positions) also. The long portfolio of these mutual funds would also
generate positive abnormal returns. The estimates of abnormal returns earned on the long
portfolio further corroborate this line of reasoning. The mean abnormal return varies between
+0.16% and +0.21% per month, and is statistically significant at the five-percent level or better.
The results also hold up when we use the abnormal return earned by size-matched control funds
as the benchmark abnormal return. Thus, mutual fund managers who choose to undertake short
positions are able to earn significant abnormal returns on both their short and long portfolios.
Collectively, the evidence from analyses of both short and long positions consistently
suggests that fund managers engaging in short sales are more likely to be better informed/skilled
managers. While the empirical evidence is robust, we urge care in interpreting the results since
Since the portfolio holdings are available at discrete points of time (usually every three months), we cannot
identify the exact dates within the quarter when the mutual funds sell short and when they buy back the stock to
cover their short positions.
the time period that we examine is relatively short. However, given that mutual funds are
increasingly utilizing short sales as part of their investment strategy, we expect this methodology
to be more applicable in the future. As more machine-readable data becomes available, future
research could also examine whether the persistence of performance is more prevalent for
managers that use short sales.
The rest of the paper is organized as follows. Section I describes the sample selection and
provides summary statistics. Section II compares the characteristics of stocks in the short
portfolio with both stocks in the long portfolio and other CRSP-listed stocks. Section III
examines the performance of the mutual funds’ short positions. Section IV investigates the
performance of the long positions of our sample funds and tests whether it is different from that
of the other mutual funds that do not undertake short positions. Section V concludes the paper.
I. Sample and Descriptive Statistics
From the Center for Research in Security Prices (CRSP) Mutual Fund database, we
identify all actively managed mutual funds that focus on domestic equity. We eliminate bond
funds, global and international equity funds, index funds, asset allocation funds and money
market funds. This database provides all the mutual fund data used in the study, including fund
objective, fees, loads, portfolio holdings and turnover. Since the availability of portfolio holdings
of individual mutual funds on the CRSP database is sparse prior to the second quarter of 2003,
we focus on portfolio holdings from April 2003 to December 2005. We aggregate different
classes of the same portfolio into one observation. If the portfolio holdings indicate that a fund
held short positions in publicly traded domestic (U.S.) stocks with a share code of 10 or 11, then
it is considered a sample mutual fund that engages in short sales.5 The final sample includes 75
mutual funds that had short positions in domestic US stocks.6 All other actively managed
domestic equity funds are considered as potential control funds, including funds that may have
shorted only international stocks, ADRs, or other non-common stock securities.
Some of our empirical tests use the performance of ‘control funds’ as the benchmark to
infer the abnormal performance of the sample funds. Berk and Green (2004) present a model
where investors assign high ability to a manager and invest in the fund after observing high
returns. If there are decreasing returns to scale in deploying the manager’s ability to generate
abnormal returns, then the fund (which is now larger, due to higher inflows) would earn only
normal returns. Consistent with this model, Chen, Hong, Huang, and Kubik (2004) find that
larger funds experience lower returns. Following this literature, we select five control funds that
are closest in total net assets to the sample fund and use the abnormal return on these control
funds as the benchmark to estimate the abnormal return of the long portfolio of the sample funds.
We note that this approach is feasible only for assessing the performance of the long portfolio of
the sample mutual funds. We cannot use this benchmark for estimating the performance of the
short portfolio since all funds that use short sales are part of the sample and none of the control
funds would have short positions.
The portfolio holdings data include the effective date of the portfolio holdings, number of
shares held in either the long or the short portfolio, the name of the firm, and the CRSP identifier
‘permno’. For a random sample, we manually verify the portfolio holdings data for shorted
We note that our sample includes only funds that had short positions outstanding at the portfolio report date. Funds
that initiated and covered all their short positions within two adjacent portfolio reporting dates are not considered
sample funds if they did not have outstanding short positions at the portfolio reporting dates. Thus, our sample
represents a lower bound on the prevalence of shorting among mutual funds.
We exclude one fund (Merger Fund) that engaged in short sales as part of merger arbitrage transactions, since
these are not considered valuation shorts.
stocks with the data from Form N-Q filed with the Securities and Exchange Commission (SEC).
In all instances that we checked, we found no discrepancies between the portfolio holdings
available from CRSP and those in the SEC filing. We link the portfolio holdings data to the
CRSP stock database using the permno as the link variable, and collect returns and shares
outstanding data from CRSP. We only retain portfolio holdings of domestic US stocks (CRSP
share code 10 or 11), and exclude all other securities. We use the merged CRSP-Compustat file
to link the portfolio holdings data with Compustat. All financial data are from Compustat.
B. Descriptive Statistics
The sample consists of both small and large funds since there is considerable variation in
the size of the mutual funds that use short sales. The average total net assets for the 75 sample
funds is $461 million, and the median is $44 million (not tabulated). This is comparable to the
values reported in the prior literature.7 Table I summarizes the characteristics of the sample
mutual funds in more detail. In the first reporting period during 2003-2005 when these mutual
funds reported short positions outstanding, they short sell an average of 38 stocks. The average
market value of the short positions, calculated using the stock price on the portfolio reporting
date, is $18 million. In the same quarter, the average market value of long positions is $278
million. However, the average number of stocks in the long portfolio is about twice as large (81
stocks versus 38 stocks), indicating that the average size of the short position per stock ($0.47
million) is smaller than that for long positions ($3.45 million). The mean long position for the
control funds in the same quarter is $402 million invested in 90 stocks.8
The mean total net assets in Chen et al. (2004) is $282 million, and in Kacperczyk, Sialm, and Zheng (2005) is
We note that the control funds are matched on total net assets at the start of the period when the abnormal return on
the long portfolio is computed, which is different from the first quarter when the fund first reported short positions.
The mean total load is 2.54% for the sample funds and is 1.93% for control funds, but the
difference is not statistically significant. However, both the average 12b1 fees attributed to
marketing and distribution costs and the overall operating expenses (including the 12b1 fees) are
significantly higher for the sample funds than for control funds (0.30% and 2.17% versus 0.2%
and 1.49%, respectively). The average turnover of the fund assets is 277% for the sample funds
and 193% for the control funds. These values are also higher than the values for actively
managed equity funds reported in prior literature. For example, Kacperczyk, Sialm, and Zheng
(2005) report that for their sample of 1,771 funds during 1984 to 1999, the average expense ratio
was 1.26% and the mean turnover was 88.3%.
II. Stock Characteristics
In this section, we provide a detailed characterization of the stocks that the mutual funds choose
to short. Every year (July t to June t+1), we identify all domestic common stocks that were shorted
at least once by any domestic equity mutual fund from the portfolio holdings data reported
during this time period. We construct two comparison samples and compare the characteristics of
the shorted stocks to the characteristics of stocks in the two comparison samples. The first
includes all stocks held in the long portfolio by these same mutual funds that had reported, at
least once, a short position in US domestic stocks. The second includes all CRSP-listed stocks,
excluding the stocks in the mutual funds’ short portfolios. For ease of exposition, we term these
samples the ‘shorted stocks’, ‘long stocks’, and ‘CRSP stocks’, respectively.
This analysis is motivated by the evidence in Falkenstein (1996), that mutual funds avoid
investing in small, low-priced stocks, and in illiquid stocks with little information. On the other
hand, Dechow, Hutton, Meulbroek, and Sloan (2001) find that stocks with high short interest are
more likely to have low fundamentals (e.g., cash flow, book value, earnings) to price ratios, and
conclude that short sellers take positions in such stocks. D’Avolio (2002) examines stock loan
data and concludes that small, illiquid firms are difficult to short. Our results are consistent with
mutual funds using valuation and fundamental indicators to establish short positions that are
significantly different from long positions.
We match the stocks with characteristics measured at the end of June in year‘t’, and
present the results in Table II. The results suggest that mutual fund managers take the possibility
of a short squeeze into account when they select which stocks to short. Specifically, the shorted
stocks are larger and more liquid than the long stocks. The average equity market value,
measured as the product of the number of shares outstanding and share price at the end of June,
from CRSP), is $6,104 million, and the median is $1,016 million. This is significantly higher
than the mean (median) size of $4,497 million ($696 million) for the long stocks at the one-
percent significance level. The mean (median) size decile for the shorted stocks is 4.86 (4.00),
and is significantly higher than that for the long stocks (4.18 and 3.00, respectively).9 We define
the annual turnover as the sum (over the prior twelve months) of the share volume in each month
divided by the total number of shares outstanding at the end of the month. The mean annual
turnover for the shorted stocks is larger than that for the long stocks (2.43 versus 1.98). A similar
pattern obtains when we use the other CRSP-listed stocks as the benchmark – the shorted stocks
are significantly larger and more liquid than a typical CRSP-listed stock.
Since institutional investors prefer investing in large, liquid stocks (e.g., Falkenstein
(1996)), these results have a straightforward interpretation. Given that institutions are responsible
The decile breakpoints are based on NYSE stocks and are downloaded from Ken French’s website.
for the bulk of the stock lending, ceteris paribus, the shorted stocks are more likely to be those
where institutional investments are anticipated. Mutual funds prefer to establish short positions
in stocks where locating a lender is easier, to minimize the likelihood of a short squeeze.
B. Performance Indicators
The mean prior momentum (buy and hold raw return over the eleven months ending in
May of year ‘t’) for the short stocks is 17%, and is significantly smaller than both the average
momentum of stocks in their long portfolios (23%) and that of the other CRSP stocks (20%).
Consistently, both the mean and median momentum decile for the shorted stocks (5.25, 5.00) are
smaller than for the long stocks (5.77, 6.00) and the other CRSP stocks (5.56, 6.00).
However, the shorted stocks tend to be glamour stocks with high total accruals and high
prior sales growth. The equity book to market ratio (BE/ME) is calculated as the equity book
value from the fiscal year ending in calendar year ‘t-1’, divided by equity market value
calculated from CRSP at the end of December t-1. The average BE/ME for the shorted stocks is
0.50, and is significantly smaller than that of 0.61 for the long stocks. The mean and median
BE/ME decile for the shorted stocks is also smaller than for the long stocks (3.97 and 3.00 versus
4.81 and 5.00, respectively). The differences are magnified when compared to a typical CRSP
firm. The mean and median BE/ME (BE/ME decile) for the other CRSP firms are 0.76 and 0.57
(5.60 and 6.00), and are significantly different from the values for the shorted stocks at less than
the one-percent significance level. For the shorted stocks, the mean industry-adjusted total
accruals is 3.5% and mean industry-adjusted sales growth is 11.6%.10 These are larger than the
We calculate the industry-adjusted values by subtracting the median for all the firms in the same two-digit SIC
industry from the value for individual firms.
corresponding values for the long stocks (2.4% and 8.4%, respectively) and the other CRSP
stocks (-0.3% and 6.4%, respectively) at the one-percent significance level.
These results are consistent with mutual fund managers using the information in
valuation and earnings quality indicators to identify appropriate stocks to short. For example,
Sloan (1996) and Fama and French (2006) find that firms reporting high accruals experience low
future returns. Consistently, Richardson, Sloan, Soliman, and Tuna (2006) conclude that extreme
accruals are likely due to temporary accounting distortions such as earnings manipulation. Given
that glamour (low BE/ME) firms with high prior sales growth are more likely to manage their
financial results and experience poor subsequent performance, our findings suggest that mutual
fund managers are sensitive to the information contained in such indicators of performance.
We find some differences in the risk characteristics of the shorted stocks compared to the
other stocks. The average equity beta for the shorted stocks (estimated using upto 60 monthly
returns and using both the current and lagged value-weighted market return as explanatory
variables) is 1.43, and the median is 1.18, suggesting that the shorted stocks have above-market
risk. The return standard deviation (estimated using monthly returns over the prior 60 months)
averages 0.17. These values are significantly higher than for the long stocks (mean beta 1.33,
median beta 1.05, and mean standard deviation 0.16) at the one-percent level. While the average
beta for the shorted stocks is similar when compared to the other CRSP stocks, the median beta
remains significantly higher for the shorted stocks. This suggests that mutual funds select more
risky and volatile stocks in which to establish short positions. It is likely that their informational
advantage would be higher in these stocks, rather than in the less risky, informationally
To summarize, the stocks in the short portfolio differ predictably from the long stocks
and the other CRSP stocks along several dimensions. The shorted stocks (a) are larger and more
liquid, (b) have low BE/ME, and whose current performance seems to be unsustainable, and (c)
are more risky and volatile.
III. Performance of Mutual Funds’ Short Positions
This section analyzes the profitability of the mutual fund’s shorting decisions. Following
Carhart (1997), several studies estimate abnormal returns as the intercept in calendar time
regressions of monthly portfolio returns on selected risk factors. We also adopt this framework to
estimate abnormal performance. The first set of tests examines whether mutual funds are
successful in selecting appropriate stocks to short. The second group of tests analyzes whether
the individual fund manager’s short portfolio as a whole is profitable. The results indicate that
fund managers are able to identify stocks that do poorly, and profit from their shorting decisions.
A. Stock Return Analysis
If fund managers are able to accurately identify overpriced stocks to include in their short
portfolio, then a portfolio of stocks shorted by mutual funds will earn negative abnormal returns.
Empirically, we proceed as follows. We aggregate the shorted stocks into portfolios using
several combinations of weighting schemes and assumed holding periods and calculate the
monthly raw return on this portfolio using the individual stock returns from CRSP. The resultant
monthly portfolio return (in excess of the risk free rate) is regressed on the four Carhart (1997)
factors – RmRf, SMB, HML, and MOM.11 The intercept from calendar time regressions of the
monthly portfolio return on the four Carhart (1997) factors is an estimate of the monthly
abnormal return for the shorted stocks.
In the baseline analysis, we assume a holding period of six months and construct equally
weighted portfolios. Every calendar month, all the stocks that are shorted by at least one mutual
fund in the relevant holding period (the prior six months) are aggregated into an equally-
weighted portfolio. The following example illustrates the procedure. For a given month (say
August 2004), we first identify all portfolio holdings that are reported in the preceding six
months (February to July 2004). All US common stocks that are shorted in these reported
portfolio holdings are included in the portfolio. The equally weighted portfolio return for the
month is then obtained. The time series of these monthly returns is then used as the dependent
variable in the calendar time regressions. The results are reported in Table III. The shorted stocks
load positively on the market factor RmRf with a coefficient of 1.21, suggesting that the shorted
stocks have slightly greater risk than the aggregate market. The coefficient on SMB is also
positive and significant, but the coefficients on both HML and MOM are not significantly
different from zero. Importantly, the intercept is -0.30%, and is significantly different from zero
at the five-percent level (t-value of -2.14). This annualizes to an abnormal return of -3.6%. The
results are similar when we assume a holding period of twelve months instead of six months. The
loadings on the four factors are similar to those obtained earlier assuming a six month holding
period. The magnitude of the abnormal return now is -0.28% per month or -3.3% on an
annualized basis. This abnormal return is significant at the five-percent level (t-value of -2.12).
The equal weighting scheme does not reflect the intensity of shorting activity by mutual
funds. Presumably, stocks that attract higher levels of relative short interest from fund managers
We downloaded the factor returns from Ken French’s website.
should be more likely to be overpriced. Ceteris paribus, if a particular stock is significantly
overvalued, many fund managers would consider the stock an attractive short candidate, and
their collective shorting would result in higher relative short interest. In contrast, stocks that
attract low levels of relative short interest from managers are not likely to be overvalued by
much. We use an alternative weighting scheme that incorporates this notion. Assuming a six
month holding period (or twelve months), we calculate the relative short interest for each stock
as follows. For a given month (say August 2004), we identify all short positions that are reported
in the preceding six months (February to July 2004). For every fund-stock pair, we calculate the
relative short interest ratio (RSI) as the sum of the ratio of the number of shares shorted by the
fund during the holding period divided by the total number of shares outstanding. The individual
RSIs for a given stock are then summed across all mutual funds. We use this summed RSI as the
weight in calculating the monthly portfolio return.
As expected, the magnitude of the abnormal return is much larger when the intensity of
shorting activity is taken into account. The abnormal return is -0.76% per month or -9.1% on an
annualized basis, and is statistically significant at the one-percent level (t-value of -3.61). The
abnormal return is similarly large and significant (-0.65% per month with a t-value of -3.48)
when the holding period is extended to twelve months instead of six months. Similar to the
equally weighted case, the coefficients of the four risk factors do not change by much.
Collectively, this evidence strongly supports the view that fund managers carefully select
the stocks to short. This may be due to the potentially large penalty associated with shorting a
stock that increases in value instead of declining. In such instances, fund managers would be
forced to cover their positions at a significant loss. Further, the high cost of shorting a stock may
prevent uninformed managers from using short sales, leaving only the more informed / skilled
managers to undertake short positions. The magnitude of this abnormal return is also
economically significant when compared to the results in prior short sales literature. For
example, Asquith, Pathak, and Ritter (2005) show that during 1988-2002, highly shorted stocks
(short interest greater than 10% of shares outstanding) underperform by -0.78% per month on an
equally weighted basis and an insignificant -0.27% per month on a value-weighted basis.
B. Portfolio Analysis
The results presented in Table III, while suggestive, do not provide direct evidence on
whether the individual mutual fund’s short portfolios generate abnormal returns. This is because
the stock return analysis does not consider the timing of the individual fund manager’s trading
decisions. It is possible that while the shorted stocks may experience negative abnormal returns
over the subsequent six or twelve months, the fund manager may either unwind their short
positions before the negative performance begins, or hold on to their short positions long after
the negative returns have materialized. Hence, even though the shorted stocks earn negative
abnormal returns, poor timing of the shorting and/or subsequent buying trades could result in a
fund manager not benefiting from this underperformance. We estimate calendar time regressions
at the individual mutual fund portfolio level to address this question.
For every sample mutual fund that reported short positions, we use the portfolio holdings
of short positions and calculate the monthly return. In order to allow sufficient degrees of
freedom and to enable accurate estimation of the coefficients, we require at least twenty-four
months (two years) of non-missing returns. The baseline estimation assumes a maximum holding
period of six months. In other words, we hold the portfolio composition constant for six months,
unless the fund reports updated portfolio holdings. For example, suppose that a fund reports
portfolio holdings with short positions in February 2004. If the next portfolio holdings report is
on August 2004, then the February 2004 short positions would be held until August 2004 (six
months holding period) , and the new portfolio holdings would be used starting in September
2004. But, if the next holdings report is on May 2004, then the portfolio composition would be
updated in June 2004, before the six months holding period expires. The portfolio return is set to
missing in the months after the assumed holding period if no short positions are reported, and
these months are not included in the calendar time regressions. Calendar time regressions are
estimated for individual funds, and the cross-sectional means of the coefficients are reported in
Table IV. The results show that the average fund earns an abnormal return of -0.45% per month,
and is statistically significant at the five-percent level (t-value of -2.12). We re-estimate the
model by increasing the holding period to twelve months rather than six months, and find similar
results. The intercept is a significant -0.40% per month (t-value of -2.11).
As an alternative specification, we re-estimate the abnormal returns, but only include
funds that shorted five or more stocks at least once. This restriction on the number of shorted
stocks eliminates funds that use short sales infrequently and never shorted five or more stocks in
any reporting period. We find that the results are unchanged. The intercept remains negative (-
0.49% and -0.42% per month for the six and twelve month holding period), and significant at the
five-percent level. Further, the coefficients on the four risk factors are similar in magnitude
across all four models. The coefficient on the market factor RmRf and the size factor (SMB) are
always positive and significant, and that on momentum (MOM) is never statistically significant.
The equity book to market ratio factor (HML) is negative but is significant only in two models.
These results provide confirmatory evidence that fund managers are able to initiate short
positions and unwind them profitably. Taken together with the stock return results discussed in
section III.A, the evidence supports the theoretical prediction that informed / skilled fund
managers are more likely to engage in short sales. We conduct an additional test to verify this
result. If these are indeed skilled managers, evidence of their stock picking skill should be
apparent in their long positions also. In other words, they should be able to earn positive
abnormal returns on their long portfolios, and the magnitude of abnormal return should be larger
than that earned by other fund managers that manage similar sized funds. In the next section, we
provide further evidence to test this claim.
IV. Performance of Mutual Funds’ Long Positions
The analysis presented in this section further examines whether mutual funds that include
short selling as a component of their investment strategy are indeed the better managed funds.
Similar to the analysis in section III.B, we test whether the portfolio of long stocks of the sample
funds earns a positive abnormal return. We also test whether the abnormal return is higher than
that earned by other funds with comparable total net assets (TNA). We select control funds based
on TNA since prior literature (e.g., Chen, Hong, Huang, and Kubik (2004)) finds evidence that
fund size erodes fund performance. The results corroborate the findings in Section III.B that fund
managers that engage in short sales are skilled and are able to earn significantly positive
As in Table IV, the baseline model estimates the four-factor calendar time regression for
individual funds that have at least twenty-four monthly returns available, assuming a six month
holding period. Panel A in Table V reports the cross-sectional mean of the regression
coefficients. The intercept averages 0.20% per month or 2.4% on an annualized basis, and is
statistically significant at the one-percent level (t-value of 2.77). The results are similar when we
use a twelve month holding period instead of six months, or when we exclude funds that use
short sales infrequently and never shorted five or more stocks in any reporting period. In all three
cases, the abnormal return averages between 0.16% per month to 0.21% per month, and all are
significant at the five-percent level or better. In all four models, the coefficient on the market risk
factor, SMB and MOM are significantly positive. In contrast, the coefficient on the HML factor
is statistically significant (positive) in only one of the four models.
While the results presented above are consistent with skilled fund managers using short
sales as an investment strategy, they may be an artifact of fund TNA. Chen et al. (2004) find
evidence that an increase in an individual fund’s TNA reduces subsequent performance. They
conduct additional tests to show that this relation is stronger for funds that invest in small stocks,
likely due to the larger funds incurring higher trading costs arising from liquidity and price
impact. Since Table II documents that the median size of an individual stock in the long portfolio
of our sample funds is $696 million (NYSE size decile 3), it is possible that the estimated
abnormal returns may be inflated. In other words, the superior performance of our sample funds
may be similar to that of other funds that have similar total net assets. In Panel B, we refine the
results in panel A by comparing the performance of our sample funds with that of actively
managed funds of similar size that invest in domestic equity, but do not engage in short sales.
We generate a time series of monthly control fund returns using the first control fund, replacing
it with the second best match if it ceases to exist, and so on. For both the sample and control
funds, we only use returns when the sample fund returns are available.
In the baseline case reported in panel B of Table VI, we require the funds to have at least
twenty-four monthly returns and assume a six month holding period, as before. The average
abnormal return earned by the control funds is -0.08% per month, and the mean difference in
abnormal return (sample – control) is 0.28% per month, which is statistically significant at the
one-percent level (t = 2.97). As in panel A, the results are unchanged when we use a twelve
month holding period instead of six months, or when we exclude funds that use short sales
infrequently and never shorted five or more stocks in any reporting period. In all three cases, the
difference in abnormal return (sample – control) averages between 0.24% per month to 0.34%
per month, and all are significant at the one-percent level.12 Further, in all instances, the mean
difference in fund size is around $1 million and the difference is never statistically significant,
confirming that the matching process works well.
The results in Table V provide strong confirmatory support for the theoretical prediction
that skilled fund managers are more likely to undertake short positions. Stated differently, sorting
fund managers on the basis of whether or nor they use short selling as a component of their
investment strategy helps identify skilled managers. The magnitude of abnormal returns (before
expenses) ranges between 1.9% and 2.6% on an annualized basis, which is comparable to that
documented in other settings. For example, Kacperczyk et al. (2005) find that mutual funds with
above average industry concentration earn an average abnormal return of 1.6% per year, before
In contrast to prior research that focuses on the long positions held by mutual funds, this
paper extends the mutual fund performance evaluation literature by providing a first look at the
performance of mutual funds that use short selling as an investment strategy. The rationale for
In unreported tests, we replicate the analysis using the monthly return reported by the CRSP mutual fund
database, rather than using the portfolio holdings data to calculate the returns. The former includes the effect of
expenses and other investments also, not just US common stocks. However, the mean difference in performance
(sample – control) remains positive and is statistically significant at the five-percent level or better.
using short selling as the criteria for identifying skilled managers is that only informed investors
are likely to use short sales. This follows from the theoretical model in Diamond and Verrecchia
(1987), which suggests that the costs associated with shorting would drive out the uninformed
investors, leaving only investors with bad news to sell short. Our approach complements those in
other recent studies that use geographic proximity (e.g., Coval and Moskowitz (2001)),
correlation of investments with other successful managers (e.g., Cohen, Coval, and Pastor
(2005)), degree of industry concentration (Kacperczyk, Sialm, and Zheng (2005)), and the extent
to which the fund portfolio deviates from its benchmark index (Cremers and Petajisto (2006)) as
ex-ante measures to identify stock picking skill among mutual fund managers.
We find that the mutual funds prefer to establish short positions in the larger and more
liquid stocks, where the likelihood of a short squeeze is smaller. However, the shorted stocks are
glamour stocks with poor earnings quality, and exhibit poor subsequent performance. The mutual
funds are able to earn statistically significant and economically large average abnormal returns
on both their short and long portfolios. Overall, the evidence is consistent with the theoretical
prediction that it is possible to identify skilled fund managers based on whether or not they use
short sales as a component of their investment strategy.
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Table I. Summary characteristics of the funds that use short sales
This table reports the characteristics for the domestic equity funds that short. Fund characteristics are obtained when a fund first reported a short position in some
CRSP common stocks during our sample period. We obtain both the total dollar amount short and number of short positions for the funds with short positions in
CRSP stocks, as well as the total dollar amount of and number of long positions. Other fund characteristics such as expenses, fees, and loads are also obtained
for the fund. If there are several funds associated with one portfolio, the total net asset value (TNA) weighted average is used for the portfolio. We also compare
our sample fund characteristics with the average characteristics for a group of five matching funds that are closest in TNA to our sample funds. In addition, we
compare our sample fund characteristics with those of other non-index domestic equity funds in June 2004. The differences in mean and median are tested using
t-tests and Wilcoxon signed rank tests, respectively.
Positions Positions Expenses Front Rear 12b1 Mgmt
Funds Statistics Short Long Turnover
Short Long (%) Load (%) Load (%) Fees (%) Fees (%)
Mean 17.72 38 278.06 80.7 2.17 1.61 0.93 0.30 2.77 1.21
Funds Median 3.23 5 40.04 49.5 1.94 0.18 0.91 0.25 1.73 1.03
N 75 75 72 72 74 75 75 75 70 75
Mean 401.65a 89.62 1.49a 1.19 0.74 0.20a 1.93 0.77a
Median 46.05a 77.25a 1.47a 1.12 0.68 0.19a 1.16 0.78a
N 72 72 74 75 75 75 70 75
Mean 796.94 102.4b 1.50b 1.37 0.87 0.23c 1.27a 0.78a
Median 120.43a 66.0a 1.40a 0.02 0.39 0.15 0.71a 0.75a
N 2,187 2,187 2,134 2,142 2,178 2,187 2,128 2,187
a, b, and c denote significant difference from the characteristics of the sample funds at 1, 5, and 10 percent levels, respectively.
Table II. Characteristics of shorted, long, and other CRSP stocks
This table reports the characteristics for stocks shorted or longed by the domestic equity funds that short.
We look at the market characteristics as of June of each year for all the positions held by any sample fund
from the end of June through end of May of the next year. Each stock is included only once for either the
short or long side, regardless how many funds have the same position and how many times a position is
held. Size is measured as the end of June market capitalization. BE/ME at year t is the ratio of book equity
for the fiscal year ending in the previous year to the market equity at the end of year t-1. Momentum is
cumulative returns over the previous 11 months ending in May. The decile breakpoints for size, BE/ME,
and momentum are based on NYSE stocks, and downloaded from French’s website. Standard deviation
and beta are obtained from preceding 60 months of returns, and at least 24 months of returns are required
for the estimates to be included in the analysis. Beta is obtained from a regression on the con current and
one lagged value weighted market return. The differences in mean and median sample characteristics
between our sample funds and other funds are tested using t-tests and Wilcoxon signed rank tests,
Shorted Long Test Test
stocks stocks statistics statistics
(1) (2) (1)-(2) (1)-(3)
Size 6,104.45 4,496.94 910.29 4.64 22.65
1,016.11 696.29 115.99 14.22 63.00
Size Decile 4.86 4.18 2.08 12.65 66.89
4.00 3.00 1.00 13.57 61.24
Turnover 2.43 1.98 1.24 9.34 26.39
1.74 1.38 0.68 15.48 49.63
Momentum 0.17 0.23 0.20 -4.97 -2.24
0.06 0.12 0.11 -9.15 -4.90
Momentum Decile 5.25 5.77 5.56 -9.10 -5.40
5.00 6.00 6.00 -9.03 -5.11
BE/ME 0.50 0.61 0.76 -10.94 -19.86
0.40 0.49 0.57 -14.72 -28.12
BE/ME Decile 3.97 4.81 5.60 -16.45 -31.93
3.00 5.00 6.00 -16.23 -30.93
Total Accruals 0.023 0.014 0.003 2.735 5.685
Raw 0.012 0.006 0.006 3.190 4.922
Total Accruals 0.035 0.024 -0.003 3.464 10.829
Industry Adjusted 0.021 0.013 0.000 4.602 12.883
Sales Growth 0.181 0.153 0.170 3.280 1.306
Raw 0.087 0.080 0.092 1.905 -1.532
Sales Growth 0.116 0.084 0.064 3.769 6.163
Industry Adjusted 0.023 0.010 -0.004 3.458 9.650
Beta 1.43 1.33 1.39 4.47 1.21
1.18 1.05 1.02 4.97 5.80
Return 0.17 0.16 0.18 3.88 -5.08
Standard Deviation 0.15 0.14 0.15 4.94 0.74
Table III. Abnormal returns to stocks that are shorted by domestic equity funds.
In this table, we evaluate the returns to portfolios of stocks that are shorted by domestic equity funds. For
each month from 200307 through 200512, all the stocks that are shorted by at least one domestic equity
funds over the preceding holding period (3-month, 6-month, or 12-month) are included in the portfolio.
RSI-weighted portfolio returns are obtained by assigning each stock with the proportion of each stock that
is shorted by each fund. When there are several funds shorting the same stock, each fund is given different
weight in the analysis. For equally-weighted portfolio returns, each stock is only included once no matter
how many funds take short positions in the stocks. The 30-month time series of portfolio returns are then
regressed on the Carhart four factors, and the results are reported below. In each cell, the top row is the
regression coefficient, and the bottom row is the corresponding t-statistic, testing the null hypothesis that
the coefficient is zero.
Holding Intercept RmRf SMB HML MOM Adj. R2
-0.297 1.215 0.564 -0.028 -0.085
-2.138 20.046 7.300 -0.328 -1.476
-0.756 1.344 0.789 0.079 -0.116
-3.606 14.672 6.751 0.622 -1.328
-0.276 1.185 0.569 0.028 -0.069
-2.120 20.870 7.850 0.352 -1.273
-0.650 1.261 0.804 0.087 -0.114
-3.480 15.449 7.721 0.769 -1.459
a, b, and c denote significance at 1, 5, and 10 percent levels, respectively.
Table IV. Abnormal returns to short portfolios of domestic equity funds
We evaluate the performance of the short positions taken by the domestic equity funds. Starting from the
second quarter of 2003, we construct a portfolio of short positions for each domestic equity fund that has
established short positions, and trace the portfolio return until the hypothetical holding period ends, or until
the next portfolio holdings information becomes available, whichever occurs first. The time-series of these
individual portfolio returns are then regressed on the four factors from Carhart model, the averages of the
regression coefficients, along with their corresponding t-statistics are then reported. In order for a portfolio
to be included in the average, we require that at least 24-month of returns data be available for the
estimation of the regression model. In each cell, the top row is the regression coefficient, and the bottom
row is the corresponding t-statistic, testing the null hypothesis that the coefficient is zero.
Holding # of Adj. # Stocks
intercept rmrf smb hml mom
Period Funds R2 Shorted
b a a
-0.453 1.169 0.496 -0.135 -0.020
6 24 0.679 >1
-2.117 12.483 3.207 -1.609 -0.173
b a a b
-0.401 1.162 0.537 -0.162 -0.042
12 27 0.683 >1
-2.114 13.945 3.522 -2.064 -0.387
b a a
-0.491 1.240 0.426 -0.132 0.018
6 23 0.697 >5
-2.229 19.586 2.954 -1.502 0.154
b a a c
-0.417 1.230 0.411 -0.162 0.018
12 25 0.711 >5
-2.065 20.873 3.041 -1.909 0.165
a, b, and c denote significance at 1, 5, and 10 percent levels, respectively.
Table V. Abnormal returns to long positions for the domestic equity funds that use short
We evaluate performance of the long positions taken by the domestic equity funds that take short positions.
Starting from the second quarter of 2003, we construct a portfolio of long positions for each domestic
equity fund that have established short positions at least once over our sample period, and trace the
portfolio return until the hypothetical holding period ends, or until the next portfolio holdings information
becomes available, whichever occurs first. The time-series of these individual portfolio returns are then
regressed on the four factors from Carhart model, the averages of the regression coefficients, along with
their corresponding t-statistics are then reported. In order for a portfolio to be included in the average, we
require at least 24-month of returns data. The performance of our sample funds is compared with the
performance of their corresponding TNA-matched funds. In each cell, the first number is the regression
coefficient, and the second number is the corresponding t-statistics for testing the null hypothesis that the
coefficient is zero.
Holding # of Adj. # Stocks
intercept rmrf smb hml mom
Period Funds R2 Shorted
a a a c
0.200 1.047 0.345 -0.009 0.082
6 48 0.747 >1
2.771 24.669 7.426 -0.115 1.917
b a a b
0.160 1.078 0.339 -0.036 0.086
12 55 0.755 >1
2.497 26.969 8.305 -0.544 2.298
a a a b
0.215 1.015 0.388 0.151 0.112
6 27 0.787 >5
3.127 25.488 6.773 1.642 2.384
a a a c b
0.211 1.017 0.382 0.140 0.116
12 29 0.799 >5
3.308 29.012 6.967 1.702 2.697
Four Factor Carhart (1997) Alpha Total Net Assets
Holding # of Paired Paired # Stocks
Sample Matches Sample Matches
Period Funds Difference Difference Shorted
0.200 -0.076 0.276 464.454 463.369 1.085
6 48 >1
2.771 -1.284 2.975 3.146 3.143 1.226
0.160 -0.083 0.243 455.942 455.038 0.903
12 55 >1
2.497 -1.567 2.895 3.413 3.411 1.165
0.215 -0.104 0.319 437.796 436.878 0.918
6 27 >5
3.127 -1.426 3.291 2.141 2.135 0.693
a c a
0.211 -0.127 0.338 424.841 423.976 0.865
12 29 >5
3.308 -1.969 3.780 2.229 2.223 0.702
a, b, and c denote significance at 1, 5, and 10 percent levels, respectively.