The last trading day refers to the last day of trading of stock index futures contracts in the expiration month. After the closing of the last trading day, all open contracts must be delivered. The final settlement date of most contracts in the world is the end of the weekend or the expiration month, and the last trading day is often set on the working day before the final settlement date.

The final transaction Et design of the CSI 300 contract is different from that of foreign countries. It is initially set on the third Friday of each month in the simulated transaction to avoid some special time points in the spot, such as the time point with strong holiday effect. Therefore, the last trading day of stock index futures contracts basically falls in the period of 15-22 every month.