A futures contract on a stock index. This type of futures entails the future delivery of a cash amount based on the value of a particular stock index (mostly, 500 times the index value). As opposed to regular futures which specify a specific commodity or instrument for delivery, the stock index futures are settled in cash because it is impossible to deliver the index in physical. In that sense, this futures allows investor to take a view on the future movement of a particular stock exchange and similarly to protect a portfolio of stocks from unfavorable movements in the broader market.