Your comment is quite a bit contradictive of the number 1 rule in investing. BUY LOW, SELL HIGHER. That is ALL that matters in the end. Buying something lower and selling it higher or shorting something higher and covering lower. The number 1 rule in investing relies soley and 100% on the PPS of any given security. (But those who use PPS alone... as you have intimated as teh ONLY true facts here. Usually lose.)