此为1984年演讲原文,略去表格
THE SUPERINVESTORS OF GRAHAM-AND-DODDSVILLE
by Warren Buffett
Is the
Graham and Dodd "look for values with a significant margin of
safety relative to prices" approach to security analysis out of
date? Many of the professors who
write textbooks today say
yes. They argue that the stock
market is efficient; that is, that stock prices reflect everything
that is known about a company's prospects and about the state of
the economy. There are no
undervalued stocks, these theorists argue, because there are smart
security analysts who utilize all available information to ensure
unfailingly appropriate
prices. Investors who seem to
beat the market year after year are just
lucky. "If prices fully reflect
available information, this sort of investment adeptness is ruled
out," writes one of today's textbook authors.
Well,
maybe. But I want to present to
you a group of investors who have, year in and year out, beaten the
Standard & Poor's 500 stock
index. The hypothesis that they
do this by pure chance is at least worth
examining. Crucial to this
examination is the fact that these winners were all well known to
me and pre-identified as superior investors, the most recent
identification occurring over fifteen years
ago. Absent this condition -
that is, if I had just recently searched among thousands of records
to select a few names for you this morning -- I would advise you to
stop reading right here. I
should add that all of these records have been
audited. And I should further
add that I have known many of those who have invested with these
managers, and the checks received by those participants over the
years have matched the stated records.
Before we
begin this examination, I would like you to imagine a national
coin-flipping contest. Let's
assume we get 225 million Americans up tomorrow morning and we ask
them all to wager a dollar. They
go out in the morning at sunrise, and they all call the flip of a
coin. If they call correctly,
they win a dollar from those who called
wrong. Each day the losers drop
out, and on the subsequent day the stakes build as all previous
winnings are put on the
line. After ten flips on ten
mornings, there will be approximately 220,000 people in the
United States who have correctly called ten flips in a
row. They each will have won a
little over $1,000.
Now this
group will probably start getting a little puffed up about this,
human nature being what it
is. They may try to be modest,
but at cocktail parties they will occasionally admit to attractive
members of the opposite sex what their technique is, and what
marvelous insights they bring to the field of flipping.
Assuming
that the winners are getting the appropriate rewards from the
losers, in another ten days we will have 215 people who have
successfully called their coin flips 20 times in a row and who, by
this exercise, each have turned one dollar into a little over $1
million. $225 million would have
been lost, $225 million would have been won.
By then,
this group will really lose their
heads. They will probably write
books on "How I turned a Dollar into a Million in Twenty Days
Working Thirty Seconds a
Morning." Worse yet, they'll
probably start jetting around the country attending seminars on
efficient coin-flipping and tackling skeptical professors with, "
If it can't be done, why are there 215 of us?"
By then some
business school professor will probably be rude enough to bring up
the fact that if 225 million orangutans had engaged in a similar
exercise, the results would be much the same - 215 egotistical
orangutans with 20 straight winning flips.
I would
argue, however, that there are some important differences in the
examples I am going to
present. For one thing, if (a)
you had taken 225 million orangutans distributed roughly as the
U.S. population is; if (b) 215 winners were left after 20 days; and
if (c) you found that 40 came from a particular zoo in Omaha, you
would be pretty sure you were on to
something. So you would probably
go out and ask the zookeeper about what he's feeding them, whether
they had special exercises, what books they read, and who knows
what else. That is, if you found
any really extraordinary concentrations of success, you might want
to see if you could identify concentrations of unusual
characteristics that might be causal factors.
Scientific
inquiry naturally follows such a
pattern. If you were trying to
analyze possible causes of a rare type of cancer -- with, say,
1,500 cases a year in the United States -- and you found that 400
of them occurred in some little mining town in Montana, you would
get very interested in the water there, or the occupation of those
afflicted, or other
variables. You know it's not
random chance that 400 come from a small
area. You would not necessarily
know the causal factors, but you would know where to search.
I submit to
you that there are ways of defining an origin other than
geography. In addition to
geographical origins, there can be what I call an intellectual
origin. I think you will find
that a disproportionate number of successful coin-flippers in the
investment world came from a very small intellectual village that
could be called
Graham-and-Doddsville. A
concentration of winners that simply cannot be explained by chance
can be traced to this particular intellectual village.
Conditions
could exist that would make even that concentration
unimportant. Perhaps 100 people
were simply imitating the coin-flipping call of some terribly
persuasive personality. When he
called heads, 100 followers automatically called that coin the same
way. If the leader was part of
the 215 left at the end, the fact that 100 came from the same
intellectual origin would mean
nothing. You would simply be
identifying one case as a hundred
cases. Similarly, let's assume
that you lived in a strongly patriarchal society and every family
in the United States conveniently consisted of ten
members. Further assume that the
patriarchal culture was so strong that, when the 225 million people
went out the first day, every member of the family identified with
the father's call. Now, at the
end of the 20-day period, you would have 215 winners, and you would
find that they came from only 21.5
families. Some naive types might
say that this indicates an enormous hereditary factor as an
explanation of successful
coin-flipping. But, of course,
it would have no significance at all because it would simply mean
that you didn't have 215 individual winners, but rather 21.5
randomly distributed families who were winners.
In this
group of successful investors that I want to consider, there has
been a common intellectual patriarch, Ben
Graham. But the children who
left the house of this intellectual patriarch have called their
"flips" in very different
ways. They have gone to
different places and bought and sold different stocks and
companies, yet they have had a combined record that simply cannot
be explained by the fact that they are all calling flips
identically because a leader is signaling the calls for them to
make. The patriarch has merely
set forth the intellectual theory for making coin-calling
decisions, but each student has decided on his own manner of
applying the theory.
The common
intellectual theme of the investors from Graham-and-Doddsville is
this: they search for discrepancies between the value of a business
and the price of small pieces of that business in the
market. Essentially, they
exploit those discrepancies without the efficient market theorist's
concern as to whether the stocks are bought on Monday or Thursday,
or whether it is January or July,
etc. Incidentally, when
businessmen buy businesses, which is just what our Graham &
Dodd investors are doing through the purchase of marketable stocks
-- I doubt that many are cranking into their purchase decision the
day of the week or the month in which the transaction is going to
occur. If it doesn't make any
difference whether all of a business is being bought on a Monday or
a Friday, I am baffled why academicians invest extensive time and
effort to see whether it makes a difference when buying small
pieces of those same
businesses. Our Graham &
Dodd investors, needless to say, do not discuss beta, the capital
asset pricing model, or covariance in returns among
securities. These are not
subjects of any interest to
them. In fact, most of them
would have difficulty defining those
terms. The investors simply
focus on two variables: price and value.
I always
find it extraordinary that so many studies are made of price and
volume behavior, the stuff of
chartists. Can you imagine
buying an entire business simply because the price of the business
had been marked up substantially last week and the week
before? Of course, the reason a
lot of studies are made of these price and volume variables is that
now, in the age of computers, there are almost endless data
available about them. It isn't
necessarily because such studies have any utility; it's simply that
the data are there and academicians have [worked] hard to learn the
mathematical skills needed to manipulate
them. Once these skills are
acquired, it seems sinful not to use them, even if the usage has no
utility or negative utility. As
a friend said, to a man with a hammer, everything looks like a
nail.
I think the
group that we have identified by a common intellectual home is
worthy of study. Incidentally,
despite all the academic studies of the influence of such variables
as price, volume, seasonality, capitalization size, etc., upon
stock performance, no interest has been evidenced in studying the
methods of this unusual concentration of value-oriented
winners.
I begin this study of results by going back to a group of four of
us who worked at Graham-Newman Corporation from 1954 through
1956. There were only four -- I
have not selected these names from among
thousands. I offered to go to
work at Graham-Newman for nothing after I took Ben Graham's class,
but he turned me down as
overvalued. He took this value
stuff very seriously! After much
pestering he finally hired
me. There were three partners
and four of us as the "peasant"
level. All four left between
1955 and 1957 when the firm was wound up, and it's possible to
trace the record of three.
加载中…