Because there is no debt settlement system on the day of futures. Under this system, futures companies will calculate the profit and loss of each transaction on that day according to the settlement price after closing at 3 pm every day, and make adjustments in their respective margin accounts. The profit and loss of individual investors' futures trading is ultimately related to the price difference between the opening price and the flat price. Therefore, buying futures in the later period shows that the price has lost a lot.