The foreign institutional investors (FIIs) were net buyers to the tune of Rs 430.58 crore in the futures & option segment on Thursday.According to data released on the NSE website, FIIs were net sellers of index futures to the tune of Rs 152.87 crore, while they sold index options worth Rs 167.40 crore. They were net buyers of stock futures to the tune of Rs 756.43 crore and they sold stock options worth Rs 5.58 crore.As per data available on the Sebi website - FIIs were net sellers of stocks worth Rs 423.50 crore in the spot market on the Wednesday. Domestic mutual funds (MFs) were net buyers of shares worth Rs 193.30 crore on the same day.