Quote from Jay_Ap:
Here is the thinking behind this assertion:
The net delta of the strangle position would start to move to maybe somewhere around 0.7 (just a guess at this point) due to the imp vol stress move and the 15% stress move on the goog price. This means you would be incurring a loss at about 0.7 multiplied by the stress move (0.7 * 15% = 10.5%). GOOG is trading at around $632 and $632 times 10.5% equals $66.36. We then multiply this by 100 shares and end up with $6636.
So, $6636 should be the PM margin requirement just for the GOOG strangle. Using similar calcs for the other positions (and making adjustments based on index type, etc) I get:
AAPL = $6,405
GOOG = $6,636
SPY = $767
This means the total Portfolio Margin requirement should be somewhere around $13,808. So, yes, I think there may be some IB position concentration pixie dust being sprinkled onto your margin requirements.
-Jason