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August 24th, 2009
Options traders provide one community of opinions worth considering when evaluating
short-term prospects for stocks. While they as a group could be totally wrong,
they differ importantly from analysts and academics, because they are risking
their money on their opinions.
It is mathematically possible to extrapolate the probable range of future
prices through a specified period using the implied volatility of the near-term, "at
the money" options associated with particular securities. We published the
formula in a prior posting.
It is important to note that the probability ranges make no suggestion
as to direction, just the level of variation from the market price either
positively or negatively. Other information is needed to inform your opinion
as to whether prices will move into the upper or lower section of the probability
ranges.
Key US Stock Indexes:
The chart below computes the 68% and 95% probably price ranges (one and two
standard deviations of implied volatility) for key US stock indexes out 30
days based on the implied volatility from published volatility indexes.

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In short, the future prices changes over 30 days for the S&P 500 and NASDAQ
100 have a 68% probability of about +/- 7%, and a 95% probability of about
+/- 14%. The Dow Jones Industrial Average has a somewhat narrower probable
price range. The Russell 2000 small-cap index has a wider probability price
range (about +/- 9% and +/- 18%).
Miscellaneous ETFs:
The next chart below utilizes the implied volatility of the near month Call
option for the associated securities. Published volatility indexes are not
available for those securities (with the possible exception of Japan, but we
are not yet familiar with the Japan volatility index, so we didn't use it).

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The miscellaneous selection of ETFs in the chart above shows widely varying
probability ranges for prices over the next 30 days.
China and Brazil have wider probability ranges than emerging markets overall,
and US equity REITs have a yet wider range of probable prices than China and
Brazil.
Japan has a comparatively low probable price range, as do long-term Treasuries.
However, for a bond investor, the +/- 4.7% to +/- 9.3% range of 68% to 95%
probable prices over the next 30 days for long-term Treasuries is quite large
for fixed income securities.
Uses For Probable Price Ranges:
Two important potential uses for the probability price ranges are:
- thinking about stop loss points or percentages (setting stops outside of
the ranges, if not greater than your absolute risk tolerance -- or avoiding
positions with probable price ranges outside of your risk tolerance)
- thinking about strike prices for selling covered calls (sell strikes outside
of the ranges).
Certainly prices could move outside of the probability ranges (that's why
they are not 100% probability), but to the extent that odds are important to
short-term decisions, implied volatility derived price probability ranges could
be useful as one tool in an overall decision toolbox.
Relationship to Chart Support and Resistance:
Let's look at how the volatility implied probable price ranges relate to graphical
charts and some other kinds of clues to future prices.

The upside 68% and 95% range would put the S&P 500 index back to the levels
it experienced in mid-free fall during last October. There is no particular
encouragement there, except for the investor who feels the crisis is over and
that the near-death stage is past -- that the 2008 summer, pre-crisis index
price levels make sense today.
The downside 68% corresponds fairly closely to June-July, 20-day price channel
highs, which could be seen as support levels. Those prices are also the approximate
20-day price channel highs in early January, which could also be seen as support
levels.
The downside 95% corresponds to the July low which could be seen as a support
level, and to the January/February double top, which could be seen as a support
level.
Relationship to Fundamental Earnings Estimates:
Let's look at how the volatility implied probable price ranges relate to fundamental
estimates of price/earnings ratios:
Standard and Poor's estimates 2010 12-month operating earnings on a bottom
up basis to be $73.05. The 68% probability range would represent about 13 to
15 times 2010 operating earnings (average to somewhat below average). The 95%
probability range would represent about 12 to 16 times 2010 operating earnings
(well below average to above average).
Securities mentioned:
SPY, QQQQ, DIA, IWM, EFA, EEM, FXI, EWJ, EWZ, TLT, GLD, IYR.
Disclosure:
We own SPY, IWM, EFA, EEM, FXI, EWZ and GLD in some accounts.
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