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Survivorship Bias
By Larry Swedroe, Buckingham
Asset Management
In a recent article, we talked about how the market's woes have caused
record numbers of mutual funds to liquidate.
Of course, this is especially bad news if you happen to be a shareholder
in a fund that bites the dust. But when a fund is liquidated or merged
into another, it can skew the performance numbers of fund families to
paint a picture that isn't completely accurate.
Larry Swedroe, who is currently hard at work on his third book, exposes
the misleading effects of survivorship bias with typical gusto - The
New York Times dubs him "a fan of debunking myths and slaughtering
sacred cows."
"Warning: Returns Shown Contain Biases We Are Not Required to
Report"
The above headline should be an SEC-required disclosure for advertisements
of many mutual funds. The reported returns of many fund families and their
funds are often either misrepresentations (intentional or unintentional)
of the returns earned by investors, or are at the very least misleading
representations. This is because of biases in the data. Lets look
at one of the biases for which disclosures should be required - survivorship
bias.
Funds that have poor performance are made to disappear, most often by
the fund sponsor merging a poorly performing fund into a better performing
one. Unfortunately for investors, only the performance reporting disappears,
not the poor returns.
In the most comprehensive study ever done on mutual funds, covering the
period 1962-1993, Mark Carhart found that by 1993 fully one-third of all
funds in his sample had disappeared. (1)
In 1996, 242 (5%) of the 4,555 stock funds tracked by Lipper Analytical
Services were merged or liquidated. Lets see why survivorship
bias is so important. In 1986 the then existing 586 stock funds returned
13.4%. By 1996, the 1986 performance had magically improved to 14.7%.
How did this 1.4% improvement happen? Twenty four percent of the funds
disappeared. (2) As another example,
for the 10-year period ending in 1992, capital appreciation funds reported
an average appreciation of 18.08%, versus a return of only 17.52% for
the S&P
500 index. Once the survivorship bias is eliminated, the returns of
all capital appreciation funds that existed during the same 10-year period
drops to 16.32%. Actual returns to investors were not only almost 2% per
annum worse then they initially appeared to be, but they were also about
1% below the return available to investors in S&P 500 index funds.
(3)
Two other studies confirm this view. Lipper Analytical Services found
that the return of all general equity funds for the 10-year period they
studied was 15.7%. This was 1.5% below that of the funds that existed
at the end of the period (the survivors) and almost 2% below the return
of the S&P 500. (4) The second
study found that over the 15-year period ending December 1992, the annual
return of all equity mutual funds was 15.6% per annum. When you include
all the funds that failed to survive the entire period, the annual return
dropped to 14.8%. The cumulative difference in returns was 781% versus
689%. (5)
The survivorship bias problem has increased in recent years as mutual
fund families try to bury poor performance. In 1998 alone, 387 stock and
bond funds were merged out of existence, an increase of 43% over the previous
year. A further 250 funds were liquidated due to investor redemptions.
In the first quarter of 1999, the number of vanishing stock funds jumped
74%. (6) The trend managed to accelerate
even further in 2000 as 451 funds were shut down (223) or merged out of
existence (222). (7)
The following is a good illustration of the potential impact on reported
returns when funds are merged out of existence. Liberty Financial Cos.
had been experiencing a serious drain on their assets under management.
In 1999 net outflows were over $600 million. In the first three quarters
of 2000, outflows increased to over $850 million. In an effort to stem
investor defections from its funds, on October 5, 2000 Liberty announced
that it was planning to merge out of existence 17 of its 95 stock and
bond funds. The 17 funds represented $1.7 billion of investor assets.
The assets of the 17 funds were to be merged into 10 existing funds in
the Liberty family. (8) I think it
safe to assume that the funds that were merged out of existence were the
ones with the worst track records. By merging the funds out of existence,
Liberty magically made the performance statistics of those funds disappear.
The reported returns of the now merged funds will only contain the live
returns of the surviving fund. Of course, the poor returns investors received
from the defunct fund did not disappear, they just go unreported as if
they never were experienced (it's not due to respect for the dead). Future
investors in the Liberty funds are clearly not getting the whole story
on the returns earned by investors in the Liberty family of funds.
As you can see, while still playing within SEC rules there exists the
potential for significant distortion of both the actual returns received
by investors and also the potential for repeat performances. Better disclosures
might help, but since many investors dont read the fine print, the
public would be better served if these practices were prohibited.
(1) Journal of Finance, March
1997
(2) Wall Street Journal, April
4, 1997
(3) Dow Jones Asset Management, January/February
1998
(4) Burton G. Malkiel, A Random
Walk down Wall Street
(5) John Bogle, Bogle on Mutual
Funds
(6) Wall Street Journal, May
10, 1999
(7) St. Louis Post-Dispatch,
February 7, 2000
(8) Ibid.
04/13/2001
Larry Swedroe is the
author of
The Only Guide To A Winning Investment Strategy You Will Ever Need
and What
Wall Street Doesn't Want You to Know. He is also the Director of Research
and Principal for Buckingham
Asset Management, Inc. in St. Louis, Missouri. However, his opinions
and comments expressed within this column are his own, and may not accurately
reflect those of Buckingham Asset Management.
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