Well if i were a betting man (which I am) I'd bet wallstreet does do this all the time in the "real" markets (granted this is illegal)...
You got to think scalability... It was easy to turn $500, $1000, or even $10,000 into 2x, 3x, even 10x that amount with bitcoins. If the "big boys" of wallstreet wanted to influence our market they would be looking to double $10 million, $15 million, truthfully it's usually $billions of dollars and the market cap for bitcoins just couldn't support that kind of move.
I just don't think bit finance cares that much about doubling $50,000 with bitcoins.