The foreign institutional investors (FIIs) were net sellers to the tune of Rs 308.41 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 388.47 crore while they bought index options worth Rs 44.18 crore. They were net buyers of stock futures to the tune of Rs 41.26 crore while they sold stock options worth Rs 5.38 crore.