The Foreign Institutional Investors (FIIs) were net buyers to the tune of Rs 989.54 crore in the futures & option segment on Tuesday.According to data released by the NSE, FIIs were net buyers of index futures to the tune of Rs 629.97 crore and bought index options worth Rs 353.49 crore. They were net buyers of stock futures to the tune of Rs 31.05 crore while sold stock options worth Rs 24.97 crore.As per data available on the Sebi website - FIIs were net buyers of stocks worth Rs 58 crore in the cash market on Monday. Mutual funds were net sellers of shares worth Rs 285.78 crore on the same day.