On SPX, the margin required for a 1 lot 1150/1140 credit spread is $10 regardless of how far away the underlying is i.e. your $10 will be tied up until the spread is released.
On ES, for a comparable spread, the margin will be somewhat lower and is calculated based on how much risk the position is deemed to have on a daily basis and subject to minimums.
Both spreads obviously have the same maximum loss. However, over the lifetime of the positions, you will require less performance bond set aside for ES positions than for the SPX position. This is manifested as a better return on investment. Then there are possible cross-margin and hedging benefits too that have been discussed before.
In any event, depending on your disposition, prudence might dictate that you maintain neccessary equity to cover the full loss on the spread regardless of whether SPAN requires you to do so or not. There is room for abuse of SPAN or risk-based margin systems but there is also room for much better risk management.
The basics of how SPAN margin works
from the horses mouth.
Given the ever increasing liquidity of ES options, there are really not many reasons left to still be using SPX options IMO. You can hardly be any worse off on b/a spreads
Better still is MM haircut if you can get it....but if you predominantly trade SPX then this is a good place to start.
MoMoney.
Quote from domestic:
rally, regarding es options. clearly the margin is significantly less than spx naked, but can you clearly explain how a spread is different than standard spx? to me, an 1150/1140 credit put is the same (except that it represents half the value), but in real percentage terms how can it be any different than spx? tia