For those who are not aware, just to bring your attention to new portfolio margin rules by SEC wef 2 Apr 07. In short, the new portfolio margining rules align the amount of margin money required to TOTAL PORTFOLIO RISK and expands the scope of products eligible for portfolio margining to include equities, equity options, narrow-based index options, certain security futures products (such as single stock futures), and unlisted derivative. So we are no longer looking at standalone strategies and can 'enjoy' the netting off effects on margin requirement on a portfolio basis. See press release by CBOE.
In plain simple English, these are the resulting benefits: -Lower margin requirements => lower cost of trading => increase in trading volume => more liquidity and better bid/ask spreads