In my opinion the commissions and the cost of doing Trades, as is the cost of doing business, is extremely important. If it at the end of the year say has caused your cost to have risen or your profits reduced by 15% or more, it would mean your very net profits have been reduced by 15% or more, as in if you break even with one broker in one year whereby another broker would have ended you up in the green by 15% NET. IB does not make their comm structure readily all obvious and in a different thread it took a few of us shooting different understanding of these comms led me to posting the the below table that shows the comms fully revealed for easy and fast understanding and utilization. The table is 100% correct, although if any errors noted, I'll immediately post a corrected version. Notes: CUM. = Cumulative, Tot. = Total RT = Round Turns/Trip All other none comm costs are calculated at $2.30 Important, IB has a free API and Free Data.