Scnerios like this are probably beyond one's control, but needs to be planned. 1. Trading ES, CME can go down. 2. CBOT down 3. IB or your broker down 4. Internet down 5. Computer problems any and all of this though pretty rare are the backbone of trading and could result in significant losses. Thoughts on how you prepare for this?
3,4,and 5 are easy to prepare for. 1 and 2 unfortunatley you have NO control over and if it happens you are at the mercy of the exchange. The ONLY thing that you can do in that case is hedge with PIT traded commodities if you can or use SPY's or DIA for example if you are trading the indexes.