The Pre-Open phase is a 30-minute session before regular trading starts at 0900 hrs. It comprises the Pre-Open and the Non-Cancel periods.
During the Pre-Open period (0830 - 0859 hrs), buy and sell orders can be entered, amended or withdrawn. However, they will not be matched and executed during this period.
The Non-Cancel period (0859 and 0900 hrs) does not allow input, amendment and withdrawal of orders. Orders are matched and executed at a single computed price, which will be the same as or better than the price at which the orders are entered. This computed price shall be the opening price for the day. Unmatched orders will be queued for regular trading.
During the Pre-Close phase (1645 - 1649 hrs), orders are still accepted and automatically updated in the order book, but no trades are executed. A theoretical Closing Price (TCP) based on orders entered, is dynamically calculated.