Hehe, the two upstairs didn't write the purpose. Futures adopt daily settlement system. After the close of each day, every customer's daily profit and loss should be settled and reflected in his capital account. If the closing price is adopted, a small amount of funds can be used to sweep the closing price to the daily limit or to the daily limit at the end of the day, resulting in a false high settlement of one type of account and a false loss or even short position of another type of account. If the average price is used for settlement, this result cannot be caused. The average price is beyond the control of small money.