The Foreign Institutional Investors (FIIs) were net buyers to the tune of Rs 801.42 crore in the futures & options segment on Friday.According to data released by the NSE, FIIs were net buyers of index futures to the tune of Rs 353.89 crore and bought index options worth Rs 171.05 crore. They were net buyers of stock futures to the tune of Rs 280.07 crore and sold stock options worth Rs 3.59 crore.