To stay in business as a stock trader in the long run... And have any chance of growing your business.. You profit margins MUST be around 50%... Or 30-40% as an absolute minimum... Plus reasonable fixed costs. Over 15 years my margins are 52%... Any lower and I would have gone bankrupt. But because of the collapse in costs... And automation... And windfall profits from the Subprime Crisis... My margins for 2007-8 have been > 80%. Last 20 months... Average net profit = $58,000 Average commission paid IB = $9,000 Profit margin = 86% Do the math... And I been grossing about $0.02/share... while paying IB $0.0032/share. But this is ONLY because after 15 years... I've learned how to exploit a "liquidity crunch"... And I'm sure I'll never match this stretch again numbers wise... Even though my profits will escalate from here... As my hedge fund continues to grows. And you could ONLY do this with a 7 figure fund... it will not scale.