The Foreign Institutional Investors (FIIs) were net buyers to the tune of Rs 617.57 crore in the futures & options segment on Tuesday.According to data released by the NSE, FIIs were net buyers of index futures to the tune of Rs 280.09 crore and bought index options worth Rs 558.10 crore. They were net sellers of stock futures to the tune of Rs 214.48 crore and sold stock options worth Rs 6.15 crore.