These two charts present the monthly and daily percentage price changes in the S&P 500 from January 1950 through the most recent period in 2009, roughly 60 years.
After the exceptional experiences of the past year, a long-term look back may be helpful. Of course, we are in a different environment than the U.S. has seen since 1950, and the U.S. economy has been and is in continual change. But an awareness of history is still a good thing to have.
Monthly Price Change (click image to enlarge)
If you take the 80% of months in the middle, the extremes of monthly change were -4.40% and +5.35%.
If you take the 90% of months in the middle, the extremes of monthly change were -6.20% and +7.13%.
Daily Price Change
If you take the 80% of days in the middle, the extremes of daily change were -0.98% and +1.01%.
If you take the 90% of days in the middle, the extremes of daily change were -1.42% and +1.44%.
Neither of these charts provides data about back-to-back runs of monthly increases or declines.
Different investors will make different use of this sort of information, but we wanted to put it out there for those who may find it useful or insightful. It's good to have a sense of "the thing."
Investors often write to us for long-term data such as this. Then again, some will say "so what," and that's OK too. We think that in some way, at some time, it would be helpful to have these statistics available.
Disclosure: We own SPY in some managed accounts.