The Foreign Institutional Investors (FIIs) were net buyers to the tune of Rs 617.07 crore in the futures & options segment on Friday.According to data released by the NSE, FIIs were net sellers of index futures to the tune of Rs 170.28 crore and bought index options worth Rs 235.52 crore. They were net sellers of stock futures to the tune of Rs 553.24 crore and sold stock options worth Rs 1.40 crore.