Stock index futures are settled every trading day. But every contract has a time limit, during which you can close your position in advance, depending on the stock index. If the price goes up and you are short, you will lose money. Stock index futures contracts can be sold short very conveniently. Only when the price falls, can you make a profit by shorting. Sometimes, the price of stock index futures is at its lowest point. If you do more, you will make a profit, which depends on your judgment of the market, because stock index futures fluctuate greatly and are risky. Compared with stocks, the risks of stock index futures and stock investment are just like the flexibility of the mouse in CS. Stock index futures are risky but highly flexible. The risk of stock is smaller than that of stock index futures, but it is not easy to control and cannot be short easily.