The Foreign Institutional Investors (FIIs) were net buyers to the tune of Rs 340.78 crore in the futures & option segment on Wednesday.According to data released by the NSE, FIIs were net buyers of index futures to the tune of Rs 327.68 crore and bought index options worth Rs 91.08 crore. They were net sellers of stock futures to the tune of Rs 70.56 crore while sold stock options worth Rs 7.42 crore.As per data available on the Sebi website - FIIs were net buyers of stocks worth Rs 656 crore in the cash market on Tuesday. Mutual funds were net sellers of shares worth Rs 330.57 crore on the same day.