The Foreign Institutional Investors (FIIs) were net buyers to the tune of Rs 90.15 crore in the futures & options segment on Monday.According to data released by the NSE, FIIs were net buyers of index futures to the tune of Rs 89.45 crore and sold index options worth Rs 21.38 crore. They were net buyers of stock futures to the tune of Rs 6.01 crore and bought stock options worth Rs 16.07 crore.