You might want to read this paper from Vanguard's research department on the utility of major macro approaches to predicting future stock
returns. The conclusions are so well
stated I’ll reprint a long quote from the article:
Asset allocation and the difficulty
of predicting the future
We’ve shown that forecasting stock returns
is a
difficult endeavor, and essentially
impossible in the
short term. Even over longer time horizons,
many
metrics and rough “rules of thumb” commonly
assumed to have predictive ability have had
little
or no power in explaining the long-run
equity return
over inflation. Although valuations have
been the
most useful measure in this regard, even
they
have performed modestly, leaving nearly 60%
of the variation in long-term returns
unexplained.
What predictive power valuations do have is
further clouded by our observation that
different
valuations, although statistically
equivalent, can
produce different “point forecasts” for
future
stock returns.
This underscores a key principle in
Vanguard’s
approach to investing: The future is
difficult to
predict. As such, we encourage investors not
to
focus on the “point forecasts” that result
from
various forecasting models and instead turn
their
attention to the distribution of potential
future
outcomes.
Once future prospects are viewed in a
distributional
framework, the benefits of strategic asset
allocation
become clear. A focus on the distribution of
possible
outcomes highlights the benefits and trade-offs
of
changing a stock allocation: Stocks have a
higher
average expected return than many less-risky
asset
classes, but with a much wider distribution,
or level
of risk. Diversifying equities with an
allocation to
fixed income assets can be an attractive
option for
those investors interested in mitigating the
“tails” in
this wide distribution, and thereby treating
the future
with the humility it deserves
A couple
points from the article:
·
In the short term markets are basically
unpredictable.
·
In the longer term p/e ratios offer some
predictability high p/e ratios predict lower long term returns as they revert
to the mean and vice versa. But even this measure had only correlation of .40
to future returns meaning even in the best case 60% of market returns were
unpredictable.
Some
Implications for Investors:
1. These
relationships between p/e ratios and future returns might argue for a bit of a
“value tilt” in a portfolio overweighting low p/e stocks. But such a strategy
can only be expected to generate a higher long term return if the investor is
willing to stick with the strategy for a long period.
However….
During the tech boom of the 1990s with growth
significantly outperforming value many investors sold their value stocks. And
since there is a herding (momentum) factor in the shorter term markets can
“overshoot” taking prices and p/e ratios higher before they revert to the mean
and fall. This makes it even harder for value investors to hold on. In light of human nature and well known factors
in behavioral finance one might be well advised not to weight too highly to
value stocks.
Professional
investors are not immune to the tendency to join the move to high p/e stocks
and abandon value investing …even if their basic instincts tell them not to do
so. Professional investors face “benchmark risk” which translates into “career
risk”. A period of 3,2, or even 1 year of underperformance vs. a benchmark such as the S+P 500 will lose to outflows of
funds from the pool of assets under management. Less assets under management =
lower compensation for the manager and the fund company in turn raising “career
risk” for the manager. Hence a tendency for even the more knowledgeable
professional investor to join the herd in a bubble rather than “fight the
tape”.
Recognizing
these tendencies it’s not hard to see why bubbles and busts can occur in the
short term and why virtually all the great (few as they are) long term investors
have been value investors and why all the
most successful factor based investing strategies (used by passive
vehicles such as ETFs and index funds) use some variant of a value tilt even
while they may differ on exact methodology.
2. Point forecasts are basically useless but
longer term probabilistic approaches can be useful.
I am in the midst of reading Nate Silver’s The Signal and
the Noise and he reinforces this
approach. While it is extremely difficult to make a point forecast it is far
easier to forecast a range of returns and a probability of outcomes. Although
people focused on his highly successful forecasts for the results of the last
two elections they might have overlooked the fact that he always gave his
forecasts in terms of probabilities
rather than a point forecast. He has some interesting things to say about financial
markets
In this interview (interestingly the motley fool which hosts the interview promotes exactly the
approach Silver argues against)
He pretty much lines up with the view the
view that one can forecast the long term
probability of a range of return with much greater success than trying to make
a point forecast
probability of identifying the probability
of returns over a ten year period far more useful than a point forecast. While
it may disappoint those looking for a point forecast here is how Vanguard views
the outlook for future returns:
Turning to real returns, we estimate a
slightly greater than 50% likelihood that
over the
2012–2022 period, the broad U.S. stock
market
will earn at least a 5% average annualized
real
return. As such, we feel our expectation for
the
forward real return is quite in line with
the historical
average of 6.8% that has been observed since
1926,
and does not represent a drastic change in
the
risk–reward characteristics of the equity
market.
Match that up with a commonly held approach
that current yields represent the best forecast of future nominal bond returns one could get an idea of
a portfolios expected return. A strong case has been made that this argues for
a negative real return on treasury securities. As a consequence it would argue
for a significant weighting in corporate bonds as well avoiding long duration
since a low future inflation expectation is built into future corporate and
treasury bond yields.
So final thought: skip the end of year
forecast articles, instead spend your time enjoying family and friends over the
holidays.