Quote from ScalperJoe:
Team Trading recruited over 500 independent traders over three years as an unregistered firm, marked up commissions, and eventually closed shop without returning approximately $2 million dollars of trader deposits.
So the basic questions a trader should ask if they wish to do business with the firm are simple:
1. Do you require traders to deposit capital?
2. Do you mark up commissions?
3. Are you a registered broker-dealer?
If they say "yes" to numbers 1 and 2, and "no" to #3, then simply ask "how do you avoid the registration requirements of a broker under Section 3(a)(4)(A) of the Securities and Exchange Act of 1934?"
As rmorse suggested, there are other ways to properly structure the model. Also, firms located outside of the U.S. may be subject to different jurisdictions, and therefore may not be registered with SEC.
Conducting simple due diligence now will save time and energy later if you end up fighting for the return of your capital.