I assume IB allows 4 times equity intraday margin for stock daytrading. I know they basically follow exchange minimums for futures margin and allow half margin for intraday futures trades. My question is whether or not you can use stock equity for futures margin. In other words, if you have an account with $100k in stock equity but no cash, could you trade futures with that, and if so, how much futures margin would it support? And would you incur margin interest?