The argument is that stock market returns are not a random process but exhibit mean reversion: http://en.wikipedia.org/wiki/Mean_reversion_%28finance%29 http:/

The argument is that stock market returns are not a random process but exhibit mean reversion: http://en.wikipedia.org/wiki/Mean_reversion_%28finance%29 http://en.wikipedia.org/wiki/Mean_reversion_%28finance%29 In short, large deviations one way are more often followed by large deviations the other. If mean reversion is true, the coin flipping analogy is not an accurate one.