My best guess is that they would make more in OTC derivatives which have higher margins rather than just plain old forwards and swaps. I mean, the more expertise is required, the higher the profit margin. Just like any other business. Also, ever since the LTCM debacle, most banks are moving away from prop trading. It's viewed as risky. Have you talked to any institutional traders? There are a lot that hang out on vault.com under the company message boards (like goldman sachs). They would be able to give you really good info that's better than anything you'll get on elitetrader.