Back to the stock market closing 15, so 15 is a price settlement time point, which can be divided into pre-trading and post-trading.

The previous transaction was from 15 of the previous trading day to 15 of the current day, and the price was calculated according to 15 of the current day.

Post-traders are from 15 o'clock on the current day to 15 o'clock on the second trading day, and the price during this period is calculated according to 15 o'clock on the second trading day.