Foreign institutional investors (FIIs) were net buyers of Rs 1,193.21 crore in the futures & options segment on Tuesday.According to data released by the NSE, FIIs were net buyers of index futures of Rs 646.57 crore and index options worth Rs 325.76 crore. They were net buyers of stock futures of Rs 225.79 crore and sold stock options worth Rs 4.91 crore.