I'd like to try trading index futures (ES or ER2) and am wondering what sort of risks I'm exposing myself to. If I hold, say, 5 contracts of the ES and while I'm in the bathroom terrorists bomb Chicago and I come back to find my positions down 600 points, can the broker come after my other assets? What if I open up a separate account for trading the futures, can I lose more than is in this account? I already have one account with IB that I'm using to trade equities and I don't want to put this at risk. Is there a way to put up a firewall to protect these funds - opening separate accounts, trading with different brokers, etc.?