The Foreign Institutional Investors (FIIs) were net buyers to the tune of Rs 156.56 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 128.25 crore while sold index options worth Rs 6.53 crore. They were net buyers of stock futures to the tune of Rs 43.03 crore while sold stock options worth Rs 8.19 crore.