Trading Procedure

Auto Pause

Auto Pause

The Stock Exchange of Thailand ("SET") has established a measurement to temporarily pause the buying or selling of any securities automatically (Auto Pause) if the volume of bid or offer of any security exceeds the threshold specified by SET. This is to allow securities companies and investors time to verify their buy or sell orders and to prevent potentially irregular order matching that may cause damage to the industry as a whole. The details can be summarized as follows:
SubjectDetail
Triggered thresholdWhen the total volume of buy orders or sell orders for a security at all price levels exceeds 15% of the number of its Listed Shares (Calculate from Automated Order Matching: AOM only)
Auto Pause PeriodNot exceeding 60 minutes
Monitored securities
  • Common Stocks
  • Real Estate Investment Trusts (REITs)
  • Property Funds
  • Infrastructure Funds
Applied Session
  • Pre-open Session
  • Trading Session

Mechanism

  • When a security has a total volume of buy orders or sell orders at all price levels exceeding 15% of the number of its Listed Shares, SET may pause trading of such securities (including odd lot and foreign securities) and securities that use such securities as their underlying asset not more than 60 minutes by posting the Pause (P) sign for 40 minutes followed by Pre-Open for 20 minutes before resuming to normal session.
  • In case an Auto Pause is triggered and the remaining time of that trading session is not more than 60 minutes, trading will be paused for the rest of that session without Pre-Open Session.
  • During Auto Pause period, member companies and investors are requested to verify and manage their trading orders if any abnormalities are found. Investors can modify or cancel their orders during this period.
  • Auto Pause of a security will be triggered once per day.

Example of Monitoring the Total Volume of Buy or Sell Orders

Securities ABC has 1,000,000 registered shares. Therefore, Auto Pause will be triggered when total order volume exceeds > 15% (15,000 shares)
TimeTransactionTotal Buy VolumeTotal Sell VolumeAction
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 shares15,0008,000-
10:30Mr. D places sell order for 7,500 shares15,00015,500Auto Pause
Post “P” sign=10:30
Pre-open=11:10
Pre-open=11:30
10:50Mr. B cancels sell order for 8,000 shares15,0007,500-
11:40Mr. E places buy order for 5,000 shares20,0007,500No Auto Pause triggered as it has already been triggered once

Exemptions

  • New Listing
  • In cases where there are other causes that may result in the volume with potentially higher-than-usual trading, and SET considers that the cause of the said high volume does not violate the normal market conditions according to guidelines specified by SET, such as the temporary trading resumption period (prior to a long suspension (SP) period or delisting).
  • Trade Report Orders
  • Other instances as may be prescribed or determined by SET on a case-by-case basis.
This measure will be effective from May 6, 2025 onwards.