Bangkok: The Stock Exchange of Thailand (SET) has revised the criteria for securities that High-Frequency Trading (HFT) investors can purchase to reduce the price volatility of medium- and small-cap securities that may not have sufficient liquidity for trading, effective from 7 July 2025.

According to Thai News Agency, the SET has introduced measures to enhance supervision and increase investor confidence by specifying that HFT investors are allowed to purchase only securities that are large and highly liquid. This move aims to mitigate the price volatility of smaller securities with insufficient trading liquidity. The securities eligible for HFT investor purchases include common stock securities, such as those held by foreigners and NVDRs, specifically stocks in the SET100 Index and reference stocks of DW and Single Stock Futures within the SET100 Index. If these reference stocks are removed from the index, they can still be purchased until the DW expires or the Single Stock Futures cease trading.

Other types of securities available for HFT investors include DW, DR, and ETF. However, HFT investors currently holding securities outside of these categories may continue to hold or sell them but are prohibited from purchasing additional shares once the criteria take effect.

Interested parties can find detailed information about the revised criteria on the Stock Exchange of Thailand website under the headings ‘Rules/Supervision’ and ‘Rules – Circulars on Securities Trading’ in the section ‘Specifying Securities Allowed for Purchase by High-Frequency Trading (HFT) Investors’.