Traders in F&O always look at the ROI% for the trades they place. In ICICIdirect, your ROI becomes better as you can create positions using your Holdings in Demat at no cost. This facility is Shares as Margin.
With Shares as Margin, you can make use of your existing shares that you own in your Demat to generate instant limits to trade in F&O. No interest is charged for the limits generated through Shares as Margin.