Here's an interesting topic from Barry Ritholtz's site, The Big Picture.
I just had an interesting conversation with Mike Panzner, Director of Institutional Sales Trading at Rabo Securities. Mike is a quant who has an interesting take on the markets. Assuming the SP 500 index finishes about where the markets are at the moment …
Here is a great example of how even two good thinkers like Barry Ritholtz and his friend Mike can get confused by probability. I'm sure if you asked either of them the odds of a coin coming up heads for a fourth time AFTER you already had three consecutive "heads" they would both give the right answer.
Well this is virtually the same problem. If you think that the market is always pretty close to fairly valued, then the odds of an up year are 50%. Actually, because of the long-term upward bias the odds are better than that. The fact that this is the fourth consecutive year is utterly irrelevant unless you think that the last three years have sent stocks into overvalued territory.
So we are back to the question of fundamentals and underlying value, not any sophisticated "quant" look at history or probability. Interestingly, none of the commenters on Barry's site point this out.
The market implication? To the extent that current prices reflect the thinking of people like Barry and his readers, current prices are a bargain.