Hello, I have 3 calendar spreads on ES futures open. They are using options expiring on Nov. 21st & 23rd and are currently out of the money. Current margin is around $300, but it shows post expiry margin of $4900. This does not make sense to me. Why would post expiry margin be so high. Assuming price stays the same, the 21st options would expire worthless, and I would be long the 23rd options. I can't understand why just being long a couple cheap options would have such a high margin requirement, unless the system at IB is making a mistake in its calculations.