The foreign institutional investors (FIIs) were net buyers to the tune of Rs 100.08 crore in the futures & option segment on Tuesday.According to data released on the NSE website, FIIs were net buyers of index futures to the tune of Rs 117.18 crore and they bought index options worth Rs 19.38 crore. They were net sellers of stock futures to the tune of Rs 35.57 crore and they sold stock options worth Rs 0.91 crore.As per data available on the Sebi website - FIIs were net buyers of stocks worth Rs 355.80 crore in the cash market on Monday. Domestic mutual funds (MFs) were net sellers of shares worth Rs 40.84 crore on the same day.