While this op/ed is NOT on topic, and is merely about stock market investing in general, it is ,imho, one of the best written pieces on the subject -ever, and is therefore displayed here [where it surely doesn't belong], just so you aware of it & may chose to read it in your spare time as you wish:
http://www.zerohedge.com/article/jeremy-grantham-q4-letter-pavlovs-dogs