some gremlins are lurking about that harry the efficient-
market theory and make it impossible for anyone to state that
the theory is conclusively demonstrated. Finding
inconsistencies in the efficient-market theory became such a
cottage industry during the 1990s and early 2000s that I will
devote an entire chapter (chapter 11) to the market anomalies
and so-called predictable patterns that have been uncovered.
Moreover, I worry about accepting all the tenets of the
efficient-market theory. As the
quote from Paul Samuelson
indicates, the theory holds that, at any time, stocks sell at the
best estimates of their intrinsic values. Thus, uninformed
investors buying at the existing prices are really getting full
value for their money, whatever securities they purchase.
This line of reasoning is uncomfortably close to that of the
“greater fool” theory. We have seen ample evidence in Part
One that stocks sometimes do not sell on the basis of
anyone’s estimate of value (as hard as this is to measure)—
that purchasers are often swept up in waves of frenzy. It is
true that the market pros were largely responsible for several
twentieth-century
speculative crazes, including the turn-of-
the-century Internet bubble. But the existence of such
psychological influences on market prices at least raises the
possibility that investors may not want to accept the current
tableau of market prices as being the best reflection of
intrinsic values.
Another fragile assumption is that news travels
instantaneously. I doubt that there will ever be a time when
all useful inside information
is immediately disclosed to
everybody. Indeed, even if it can be argued that all relevant
news for the major stocks followed by institutional investors
is quickly reflected in their prices, it may well be that this is
not the case for all the thousands of small companies that are
not closely followed by the pros. Moreover, the efficient-
market theory implies that no one possesses monopolistic
power over the market and that stock recommendations based
on unfounded beliefs do not lead to large buying. But firms
specializing in research services and various institutional
investors wield considerable
power in the market and can
direct tremendous money flows in and out of stocks. In this
environment, it is quite possible that erroneous beliefs about
a stock by some professionals can for a considerable time be
self-fulfilling.
Finally, there is the enormous difficulty of translating
known information about a stock into an estimate of true
value. We have seen that the major determinants of a stock’s
value concern the extent and duration of its growth path far
into the future. Estimating this is extraordinarily difficult, and
there is considerable scope for an individual with superior
intellect and judgment to turn in a superior performance.
But although I believe in the possibility of superior
professional
investment performance, the evidence we have
thus far does not support the view that such competence
exists; and although I may be excommunicated from some
academic sects because of my only lukewarm endorsement of
the semi-strong and particularly the strong form of the
efficient-market theory, I make
no effort to disguise my
heresy in the financial church. It is clear that if there are
exceptional financial managers, they are very rare, and there is
no way of telling in advance who they will be. This is a fact
of life with which both individual and institutional investors
have to deal.