This video answered all my questions on what happens when you don't have the funds, or the shares to cover an assigment. At the end he mentions he uses TD Ameritrade which I think uses the ThinkorSwim platform, and he gives basically 2 scenarios with brokers.
- They will deposit the shares from a short put, or short you the shares from a short call, and you get a margin call where you can either close the position yourself or satisfy the margin.
- They force close your position.
Anyway with a spread there is virtually no risk since you have protection of the long option.
So I think I am going to do all my options trading with think or swim TD now, since it is all automated, and my broker doesn't seem to understand their own procedures...I have had conflicting information thus far. I was able to do a test trade today that is an ITM credit spread, expiring today. The net cost for me to deliver the shares on the (naked) short call is over $4 million dollars, and I only have 100k in my paper trading account, and it put the trade through np. Well see what happens...my guess is the platform will just close the position and post my loss.
I bet no one will do a 4m trade with you with merely 100k in cash. Try and see what happens, the worst case is reducing to 10% of the positions.