The Foreign Institutional Investors (FIIs) were net buyers to the tune of Rs 343.51 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 268.08 crore and bought index options worth Rs 142.97 crore. They were net sellers of stock futures to the tune of Rs 62.23 crore and sold stock options worth Rs 5.31 crore.As per data available on the Sebi website - FIIs were net sellers of stocks worth Rs 520.20 crore in the cash market on Monday. Mutual funds were net buyers of shares worth Rs 22.80 crore on the same day.