This is a strictly hypothetical question, since of course.. interest is as close to zero as you can possibly get. But I'm curious... (this is from the perspective of a CPO / fund) - if I have, let's say, $1 million deposited at a FCM, - if I proceed to sell $200k in options (so total cash $1.2 million), - but this brings it margin requirement of $500k. How much "money" would be available to collect interest on? Is it just the $1 million net equity? Or is it the current $1.2 million in cash? Is it $1.2 million - $500k? (Should I leave only $500k at the FCM, and sweep the rest into an interest-bearing account somewhere else?)