money laundering = changing the owner of the money = non legal.
Giving money to a company (with different owner structure) = changing owner of the money = possible money laundering.
If money stays in the hand of the money owner (= investor, and you just get trader) there is no legal problem.
Just you have to talk to the indivudal prop firm, there are firms which accept 3rd party trader (why not).
Mav seems to make sense. But I still don't understand why it's illegal if the owner of the actual money stays the owner and all i'm doing is setting up the trading strategy.. which obviously trades on it's own since its automated. Which firms are you talking about.