The foreign institutional investors (FIIs) were net buyers to the tune of Rs 251.03 crore in the futures & option segment on Tuesday.According to data released to the NSE, FIIs were net buyers of index futures to the tune of Rs 288.67 crore and they bought index options worth Rs 55.94 crore. They were net sellers of stock futures to the tune of Rs 85.53 crore and they sold stock options worth Rs 4.05 crore.As per data available on the Sebi website - FIIs were net buyers of stocks worth Rs 43.40 crore in the cash market on Monday. Domestic mutual funds (MFs) were net sellers of shares worth Rs 10.84 crore on the same day.