lol, D70 is right, GFC.....london whale........ erm!!
Maybe not so much day trading though....also you don't make billions every year and not have any money in the bank (no pun intended)......
For what it's worth, I'm fairly certain that banks won't be able to just spin off their prop desks and create a hedge fund but stay invested. If i understand current proposals, banks won't be allowed to own hedge funds. And in reality they won't be able to "sell" the prop desk as it's only people so a buyer would be better off just offering said traders a standalone package to join their fund....