I have a couple of IB accounts. One is tiny and the other not. In the tiny account, I hold one ES put and one ES call, both short and expiring next week. The standard margin on one ES contract should be around 3500. Lately it's been more like 4000 - 4200. When you hold a put and a call, SPAN drops a few hundred off the margin...at least that's the way all of this used to work. A few days ago, the initial margin on this account started creeping up, through the 4000's and then over 5000. At yesterday's close the initial was 5400, dropped to 5200 this morning and is now almost 5700. Even stranger, buying a call or put further out to create a spread has little to no effect on the overall margin. Two other notes: margin on the larger acct has remained static, despite having a comparable ratio of positions and the VIX does not seem to be in play - when the VIX was near 30, my margin was a bit over 4000 for this account. Is anyone else seeing this?