Well, the money comes in payments for flow, obviously. In the more volatile markets that flow will be worth even more.Considering they raised $176 million in venture financing to get that whole thing operational, Robinhood can certainly continue the free trading model for quite a while. But it will be interesting to see if their tune changes when that pile of borrowed cash starts dwindling down and the pressure to make profits like a real brokerage kicks in, especially when the inevitable market downturn happens and all the millennial mobile-phone traders start getting their asses handed to them.
of course, on the web site they never mention it outright: