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Trading Procedure

Types of Orders

Types of Orders
The main type of SET trading order is the limit-price order (or limit order), which is an order to buy or sell at a specified price. However, to accommodate the needs of all investors, SET has introduced a variety of order types as listed below.
Market Order
A market order is an order to buy or sell a stock at the best available price. A market order can be matched at more than one price level. Unmatched quantity (if any) will be automatically cancelled. Market orders are allowed only during open trading sessions.
Market to Limit Order
A market-to-limit order is submitted as a market order to execute at the current best market price only. Unmatched quantity (if any) will be converted to a limit order at price equal to the last executed price. Market-to-limit orders are allowed only during open trading sessions.
ATO (At the Open) / ATC (At the Close)
  • ATO is an to buy or sell a stock at the opening price.
  • ATC is an order to buy or sell a stock at the closing price.
  • ATO and ATC order are Market order with condition Fill and Kill (FAK) which sent during the pre-open or pre-close session. The unmatched ATO or ATC order will be cancelled.
  • Execution price of ATO and ATC orders can fall outside ceiling & floor but not exceeding ±1 tick.
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FAK (Fill and Kill)
An order to buy or sell a stock immediately on the condition that any remaining portion of the trade which is unmatched will be cancelled.
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FOK (Fill or Kill)
An order to place a trade immediately and completely; if the specified conditions cannot be met immediately, the order is cancelled. FOK orders are allowed only during open trading sessions.
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Iceberg
An iceberg order is a high volume order that has been equally subdivided into smaller lots so that only the portion of the total order which is currently being executed is visible. The broker specifies the subdivided portion of the order to be published in the order book. When the published portion of the order is executed, the next remaining suborder is made available for trade until the entire high-volume order has been executed.

Iceberg order must be divided into no more than 100 suborders. 
Overnight Order
Investors can send Overnight Order to kept in SET’s trading system. The queue for Overnight Order is based on order entry time at first place.
The allowed order types are:
  1. Good till Cancel (GTC): Orders are valid until cancelled.
  2. Good till Date (GTD): Orders are valid until specified date or cancelled.

The additional conditions for Overnight Order are:

  1. The order will be kept in SET’s trading system for 30 calendar days at maximum. (The order entry date is the first date.)
  2. Overnight Orders will be cancelled in one of the following cases:
    • When the order price is outside ceiling and floor of each day.
    • On The first day when the ex-beneficial sign is posted on the securities* such as dividend payment (XD), Right to subscribe newly issued shares (XR), Right to receive a warrant(XW) and Capital return payment (XN), etc.
    • When there is a change of the securities details in the Trading System as determined by the Exchange e.g. change of securities symbol, change of par value of shares which results in the increase or decrease in the number of shares, etc.
  3. Overnight Order for odd lot trade is not permitted.
  4. In case SET imposes a measure to buy securities with advanced fully-deposit cash (or Case Balance account) due to trading supervision measures or where C (Caution) sign is posted etc., members need to supervise the overnight order to comply with such measures.
*Refer to Practice Guideline regarding Trading, Clearing and Settlement of Securities in the Exchange about Announcement of sign indicating Trading price with no rights or benefits