There's nothing special about a stock price six months or a year ago. Investors want to make sure that the current price is high relative to what they paid for it.

We found that it is a type of psychological bias on the part of many investors that seems to drive momentum. Investors tend to hold on to their losing stocks too long and sell their winners too quickly. This triggers momentum.

The disposition effect plays a very important role in explaining this stock momentum.

I'm better than I was two months ago, better than I was six months ago, and certainly better than I was 17 months ago.

A year ago, it was not that difficult to predict six months in advance where they were going to be. That's going to be harder when you are at 5 percent and you think the economy is going to be weak enough to get them to cut rates.

They took my mother's stomach out six months ago.