I dont calculate things like that. I calculate just daily P%L's and then subtract commissions from that. Usually I run right around 75% margins, but I am always aware of what I am spending on commissions. I add liquidity when stocks so provide that they can do that, and I trade news alerts when the stocks that I have set on alert recieve good news. For example, EAG just got some news I grabbed 132,200 shares at .22 (tried to get 500k this was my fill) and I flipped them at .24 for some profit. This type of trading is what I do in addition to the regular LU,NT,ELN, and F trading.
When I trade listed stocks, I usually use size. Depending on the stock LU-usally around 100-200k at a time, NT the same, F and ELN i scale back because they move quicker and easier so I am usually 24k to 50k at a time. I keep my losses to a penny at a time or atleast I try to. I also try to buy size when there is something there to back me up to dump into if it does not work out for me. I.E. I buy 400k of LU on the bid using SDOT, but there is also CSE for 200k TRIM for another 200k ARCA INET and BRUT for an assorted 200k. I know I have 600k to dump into if it does not work out for me and I break even on the trade. I make sure I use routes that are either free to me or cost little to nothing to make the trades. It is a must in this type of trading. That is all that I am going to disclose, no need to let 8 years of knowledge and no how out of the bag. here is my updated blotter now with the eag profit.