You have already been informed that StrategyBuilder sucks. So do some homework, find another way, and get to it. Do your own analysis, away from the keyboard, and rely upon those TWS numbers which match your own. TWS was made for TRADING, not for analysis, and not for hand-holding. Speaking of trading, the numbers you've shown above indicate a 2-option ES FOP spread commission of $3 -- which is impossible. The one below that, which indicates what you intend as two identical vertical spreads, comes out at $11 -- which is impossible. So, go into your specs, find the one that controls the display of commissions in StrategyBuilder, and give it 3 decimal places. At that point, what is shown as "$3" will make sense; what is more is that you can then decompose the $11 figure to find what StrategyBuilder took as inputs (from you, and from whatever default values remain). The difference between your two vertical spread StrategyBuilder attempts are manifested most simply in the commissions charged -- it's taking quantities you did not intend. Solve that, and the profit, margin impact, and max loss will all be solved as well.