Generally, each trading unit, called a "board lot," contains 100 units of each security; however, for a security priced at 500 baht or more per unit for 6 consecutive months, one board lot is equivalent to 50 units.
Though, One Board Lot of Depository Receipts shall be equal to one unit of Depository Receipts.
Minimum price movements, as prescribed by the SET for securities trading, vary according to each market price level as follows:
Market Price Level (THB)
Tick sizes (THB)
(effective since March 30, 2009)
Less than 2
2 up to less than 5
5 up to less than 10
10 up to less than 25
25 up to less than 100
100 up to less than 200
200 up to less than 400
The above Tick sizess do not apply to trading of unit trusts and ETFs, whose Tick sizes is THB 0.01
Floor & Ceiling Limits(Effective from March 18,2020 not later than 30 September 2020)
Prices of stocks traded on SET are allowed to fluctuate within a range of ±15 percent of the previous closing price of the local shares. Foreign shares traded by individual shareholders can have price changes to a maximum of ±30 percent from the previous day's closing price of the local shares.
There are exceptions for Ceiling & Floor rule as follows,
First trading day
First day trading when the Exchange announces the posting of a sign (XD,XR or XA)
Ceiling and Floor for Transferable Subscription Rights (Warrant, Derivative warrant and Derivative Warrant Convertible), the price of warrant can increase or fall from the closing price on the preceding Trading day, not exceeding 15% of the closing price of the Underlying Asset on the preceding Trading day, multiplied by a Conversion Ratio.
In case of first day of trading, the ceiling price of security cannot exceed three times the IPO price and the floor price of security must be no lower than Baht 0.01 of IPO price. In addition, the price of warrant can increase from the IPO price, not exceeding one time the closing price of the underlying asset on the preceding Trading day, multiplied by a Conversion Ratio and can fall from the IPO price, not exceeding one time the closing price of the underlying asset on the preceding Trading day, multiplied by a Conversion Ratio; provided that it will not be less than Baht 0.01.