Usually most traders track gains and losses. Lets say you use a 10 point stop on the YM and on one trade you lose -10 and the next trade you make +20. So your PF is 2.0. But you actually had a max risk exposure of -20 (if both trades got stopped out) and you ended up +10. So basically you risked -20 and made +10. And looking at it this way doesn't make you look as profitable as a PF of 2.0 makes you look - you're actually making less than your maximum risk exposure.