The foreign institutional investors (FIIs) were net buyers to the tune of Rs 751.29 crore in the futures & option segment on Friday.According to data released on the NSE website, FIIs were net buyers of index futures to the tune of Rs 496 crore and they bought index options worth Rs 266.23 crore. They were net sellers of stock futures to the tune of Rs 26.49 crore while they bought stock options worth Rs 15.55 crore.As per data available on the Sebi website - FIIs were net sellers of stocks worth Rs 1,632.80 crore in the spot market on Thursday. Domestic mutual funds (MFs) were net buyers of shares worth Rs 408.70 crore on the same day.