I don't the exact % but it is absolutely tiny... that's one advantage of position trading I suppose i.e. apart from absorbing trading losses as a cost of business, everything else [commissions, data etc] is, proportionately, a negligible cost of doing business...
I do not know exactly but a rough estimate is less than 0.15 %. I find slippage cost to be much greater than commission. I am a long term position trader.
