The Foreign Institutional Investors (FIIs) were net buyers to the tune of Rs 1,649.03 crore in the futures & option segment on Friday.According to data released by the NSE, FIIs were net buyers of index futures to the tune of Rs 918.61 crore and bought index options worth Rs 636.62 crore. They were net buyers of stock futures to the tune of Rs 85.50 crore and bought stock options worth Rs 8.30 crore.As per data available on the Sebi website - FIIs were net buyers of stocks worth Rs 159.20 crore in the cash market on Thursday. Mutual funds were net sellers of shares worth Rs 250.66 crore on the same day.