You can buy and sell before the contract expires, and the last trading day is the third Friday of the contract expiration month, which will be postponed in case of national legal holidays.

Contract time: the contract time of stock index futures refers to the expiration month of stock index futures contracts. May, June, September, 65438+February is the contract time.

According to your analysis of the possible ups and downs of the Shanghai and Shenzhen 300 index in the next few months, such as IF 1809, it means that the stock index futures contract will expire in September of 20 18. The last trading day is on the third Friday in September.