Trading Methods

Automatic Order Matching (AOM)

1. Price then Time Priority
AOM trading performs the order matching process according to price-then-time priority based on algorithms and without human intervention. After brokerage houses electronically send buy or sell orders to the SET mainframe computer, the SET CONNECT system queues the orders and arranges them according to a price-then-time priority. This means orders are first grouped according to price, with the best price taking precedence. Then, within each price group, orders are arranged according to time.

2. Matching
There are two matching methods: continuous order matching and auction method. Continuous order matching procedures operate during the regular trading sessions. The SET CONNECT trading system continuously matches the first buy and sell orders in the queue, and at the same time confirms each executed transaction via the member's (broker's) terminal. Auction matching is utilized in calculating the opening and closing prices of a security at the opening and closing of the trading hours. This method allows brokers to enter their bid/ask orders to be queued for matching at a specified time at the price that generates the greatest trading volumes for that particular stock.

3. Minimum resting time
When entering order to the exchange, the order will be able to amend or cancel after order have stay in order book for at least 250 milliseconds. SET may reject the amendment or the cancellation if an order stays in system less than 250 milliseconds.
Effective from 2 September 2024