Trading Procedure

Auto Pause

Auto Pause

The Stock Exchange of Thailand ("SET") has established a measure to temporarily pause the buying or selling of securities automatically (Auto Pause) if the total buy volume or total sell volume for a security exceeds a threshold specified by SET. This measure allows securities companies and investors to verify their buy or sell orders and helps prevent potentially irregular order matching that could damage the market as a whole. The details are as follows:
SubjectDetail
Triggered conditionThe total buy volume or total sell volume for a security at all price levels on either side exceeds 15% of its registered shares.
Auto Pause PeriodNot exceeding 60 minutes
  • Post the Pause (P) sign for 40 minutes followed by Pre-open for 20 minutes, before resuming the normal session.
  • If the remaining time in the trading session is less than 60 minutes, trading will be paused for the remainder of the session without a Pre-open session.
  • Order updates and cancellations are allowed during the Auto Pause period.
Monitored securities
  • Common Stocks
  • Real Estate Investment Trusts (REITs)
  • Property Funds
  • Infrastructure Funds or Infrastructure Fund Project of Thailand Future Fund
Securities that will be halted from trading due to Auto Pause
  • Odd lot (-O)
  • Securities held by foreign nationals (-F)
  • Securities that use a monitored security as an underlying asset such as Warrant, Derivative Warrant
Auto Pause Trigger Session
  • Pre-open Session
  • Trading Session
Remark: Auto Pause of a security will be triggered once a day.

Mechanism

Example of the Auto Pause mechanism

ABC securities have 100,000 registered shares. Therefore, Auto Pause will be triggered when either the total buy volume or the total sell volume exceeds 15% of the registered shares, or 15,000 shares.
TimeTransactionTotal Buy VolumeTotal Sell VolumeAuto Pause mechanism
10:00Mr. A places buy order for 6,000 shares6,0000-
10:15Mr. B places sell order for 8,000 shares6,0008,000-
10:20Mr. C places buy order for 9,000 shares15,0008,000Auto Pause is not triggered because the total buy volume does not exceed 15,000 shares.
10:30Mr. D places sell order for 7,500 shares15,00015,500Auto Pause triggers.
10:30:Post “P” sign
11:10:Pre-open
11:30:Resuming trading as normal
10:50Mr. B cancels sell order for 8,000 shares15,0007,500-
11:40Mr. E places buy order for 5,000 shares20,0007,500Auto Pause is not triggered for ABC securities because it has already been triggered.

The Auto Pause measure may be exempted in the following case.

  • New securities on the first trading day (New Listing)
  • Securities that have resumed trading after being removed from the delisting criteria.
  • Securities that have temporarily resumed trading before a long period of suspension (SP) or delisting.
  • Other cases as specified by SET on a case-by-case basis.