Stock index futures are traded between buying and selling, forming a trading price. Suppose there are only you and me in the market at present, you have 1 many hands and I have 1 hands. You judge that the market outlook is down, you want to sell, and you offer multiple closing prices of 100. I judge that the market outlook is rising, and I want to close the empty order, but I will release an empty order closing price of 90, then we will definitely not close the deal.

There is no price on the market at present. You are in a hurry to close the deal, so you have to change the price to 90 to cooperate with me. After the transaction, the market price will show 90. Of course, there are a large number of people in the market who are constantly hanging out the buying and selling prices. It is precisely because there are so many people doing transactions that the market prices are constantly fluctuating and getting closer to the reasonable prices. This is one of the functions of futures: price discovery.