The foreign institutional investors (FIIs) were net sellers to the tune of Rs 453.78 crore in the futures & option segment on Monday.According to data released on the NSE website, FIIs were net sellers of index futures to the tune of Rs 372.78 crore while they sold index options worth Rs 71.94 crore. They were net buyers of stock futures to the tune of Rs 2.94 crore and they sold stock options worth Rs 12 crore.As per data available on the Sebi website - FIIs were net buyers of stocks worth Rs 659.50 crore in the spot market on Friday. Domestic mutual funds (MFs) were net sellers of shares worth Rs 79.63 crore on the same day.