Compared with stocks, stock index futures have several distinct characteristics, which are particularly important for stock investors: 1. Futures contracts have an expiration date and cannot be held indefinitely. Stocks can be held all the time after buying, and the number of stocks will not decrease under normal circumstances. However, stock index futures have a fixed expiration date and will be delisted when it expires. Therefore, trading stock index futures cannot be equated with buying and selling stocks. You must pay attention to the expiration date of the contract to decide whether to close the position in advance or wait for the expiration of the contract (fortunately, stock index futures are settled in cash, and there is no need to actually deliver the stock), or transfer the position to next month. 2. Futures contracts are margin transactions, and stock index futures contracts must be settled every day. Generally, a contract can be bought and sold as long as the face value of the contract is about 10- 15%, which improves the profit space, but on the other hand, the risk will increase, so the profit and loss will be settled every day. After buying a stock, the book profit and loss are not settled before selling. However, stock index futures are different. After the transaction, the contract held in hand should be settled at the settlement price every day, and the book profit can be withdrawn, but the book loss (that is, additional margin) must be made up before the opening of the next day. And because it is a margin transaction, the loss may even exceed your investment principal, which is different from stock trading. 3. Futures contracts can be sold short. Stock index futures contracts can be easily sold short and then bought back after the price falls. It is ok to short stocks, but it is relatively difficult. Of course, once the price rises instead of falling after short selling, investors will face losses.