(About 8 years ago I developed a really nice scalping system on super high volume/liquid DOT exchange traded funds. This is now long gone and due to the fact that I could not develop jack squat after this time, I basically in a nutshell became an equities "gambler.") I was wondering for folks presently scalping equities and the now evolution of rebate pricing structures, are you adding liquidity by basically selling at the ask or buying at the bid & or say selling as close to the bid as possible below anyone else and if so at that moment are you able to turn around and sell it on the bid within a milisecond, thereby profiting a small margin between the loss on the spread of the bid/ask versus the rebate credit? Or are you actually taking on risk, so to speak, needing and waiting for the price to move in your direction so you can then sell it in a matter of 30 seconds or say two minutes? I am only asking because I do not mind the stability of grunt work like this day in and day out. Those penny round trip margins on thousands and thousands of trades add up at the end of the month.