Hedge Benefit

Why does the system block full margin if I execute only one leg on Basket order?

If you have hedge position the system blocks full margin due to the placement of limit order. Because until execution, the system cannot confirm whether a hedge will exist. To safeguard risk, it blocks the full margin first and only releases the excess once the hedge is established.  This is only in the case of limit order.

Under market order the system executes the order for only required margin.