This marks a major year-end crackdown by the Securities and Exchange Commission (SEC), sending significant shockwaves through Thailand's capital market.
On 29 Dec 2025 GMT+7, the SEC announced legal actions against 48 individuals in multiple securities for stock price manipulation and insider trading.
These actions include charges filed with the Department of Special Investigation (DSI), the Economic Crime Suppression Division (ECD), the Anti-Money Laundering Office (AMLO), and civil penalties as follows.
The first case involves COMAN, or Comanchee International Public Company Limited. The SEC charged nine individuals with the ECD for manipulating price or trading volume. This group includes:
(1) Mr. Nithit Silamath
(2) Ms. Phatchanok Thanaruthairot
(3) Mr. Patsakorn Silamath
(4) Ms. Chayada Sukkasi
(5) Ms. Supha Wonganu
(6) Mr. Wasawat Prasertsilp
(7) Mr. Kiattisak Charoensuk
(8) Mr. Panpong Khidrukmuang
(9) Mr. Winai Wangpeng
Their misconduct occurred in three periods from late 2022 to mid-2023. They cooperated to place buy orders to push prices up and controlled bid offers to prevent others from buying easily, forcing purchases at higher prices.
They also engaged in matched trading at similar prices and volumes and manipulated pre-open and pre-close prices to mislead the market into thinking the stock price was rising. This violates the Securities Act.
The SEC referred the case to the ECD for criminal prosecution and notified AMLO since these unfair trading practices constitute predicate offenses under anti-money laundering laws.
Another major case involves OTO, formerly One To One Contacts Public Company Limited (now PEER). The SEC charged 18 individuals with the DSI. The accused include both individuals and entities:
(1) Mr. Sitthichai Pornsapanan
(2) Mr. Natthapong Sitwarat
(3) Ms. Ratha Weerapong
(4) Mr. Pakpoom Ternserikul
(5) Mr. Boonua Jitrothanom (6) Ms. Kittiya Uthakayot
(7) Next To Capital Company Limited (now Wealth Plus Holding Company Limited) (8) Mr. Pinyo Rukpanmethee
(9) Mr. Amorntep Watcharapruksaidee
(10) Mr. Adam Insawang
(11) Mr. Patipol Prawangsuk
(12) Mr. Chayanon Chaowkitjaroen
(13) Mr. Sathaporn Photong
(14) Mr. Suwit Cheewatham
(15) Mr. Boonlert Eawpornchai
(16) Ms. Nattakamon Namkaeng
(17) Mr. Pongpat Cheewatham
(18) Mr. Chaiwat Pitakraktham
This group operated over 438 trading days (13 Jul 2021 - 3 May 2023), pushing up stock prices by placing small buy orders to stimulate the market and placing bids to block other investors, forcing them to raise their buy orders.
Notably, they engaged in matched orders among themselves and manipulated pre-close prices to desired levels, misleading market participants about true price and volume. The SEC referred this for criminal prosecution with the DSI and notified AMLO as well.
Next is SA, or Saimis Asset Public Company Limited. The SEC charged eight individuals with the DSI for colluding to manipulate prices (commonly known as stock manipulation).
The accused in this group overlap clearly with the OTO case, including Mr. Boonua Jitrothanom, Ms. Kittiya Uthakayot, Mr. Pinyo Rukpanmethee, Mr. Pakpoom Ternserikul, and Mr. Sitthichai Pornsapanan.
The misconduct occurred during 2021-2022 over 167 trading days, involving price pushing, placing bids at multiple levels to block others, and controlling pre-open and pre-close prices to raise price levels.
These actions misled general investors and caused SA’s trading to deviate from normal market conditions. Due to the systematic nature and broad impact, the SEC filed charges with the DSI and reported to AMLO for predicate offenses of money laundering.
Next is insider trading involving SF, or Siam Future Development Public Company Limited. The SEC imposed civil penalties on seven individuals related to a major deal where CPN acquired SF from MAJOR and made a tender offer at 12 baht per share, positively affecting SF’s stock price.
Key figure Mr. Nopporn Vitoorachat, SF’s CEO and major shareholder, knew this deal and informed his mother, Ms. Suphan Vitoorachat, who bought shares in advance. Additionally, relatives of MAJOR’s directors, Ms. Napatsorn Suntornmanokul and Ms. Pentipa Ongwasit (both sisters of a MAJOR director), together with Ms. Papawarin Chatkul Na Ayudhya, bought SF shares in Ms. Papawarin’s account (daughter of Ms. Pentipa and niece of Ms. Napatsorn).
Ms. Napatsorn also used her daughter, Ms. Sirada Suntornmanokul’s trading account to buy unusually large amounts of SF shares. Furthermore, Ms. Napatsorn’s husband, Mr. Kiattisak Suntornmanokul, also bought unusually large amounts, constituting insider trading.
The SEC fined these seven individuals a total of over 8.6 million baht in civil penalties and banned them from serving as directors or executives for 12 to 14 months. For instance, Mr. Nopporn was banned for 14 months, as was Ms. Napatsorn.
The heaviest penalty in monetary terms was for TFG, or Thai Foods Group Public Company Limited. The SEC imposed civil penalties on six individuals for insider trading related to Q1 and Q2 2016 financial results showing sharply increased profits.
The main person is Mr. Winai Tiawsomboonkij (CEO, director, and chairman), along with Mr. Natthawut Tiawsomboonkij and four others, who used undisclosed net profit information to buy TFG and TFG-W1 shares through other accounts.
The penalty was severe: the SEC’s civil penalty committee ordered Mr. Winai to pay fines and disgorgement totaling over 1.122 billion baht and banned him from being a director or executive for 40 months. Other accomplices received graduated fines, totaling over 1.125 billion baht in penalties.
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