You are using an outdated browser and your browsing experience will not be optimal. Please update to the latest version of Microsoft Edge, Google Chrome or Mozilla Firefox. Install Microsoft Edge

February 13, 2019

Stock Manipulation and Class Actions in Thailand

Informed Counsel

Since 2017, the Anti Money Laundering Office (AMLO), the Securities and Exchange Commission (SEC), and the Stock Exchange of Thailand (SET) have been engaged in an active drive to monitor and pursue many charges related to stock manipulation against high-level executives of security-issuing companies. These authorities, particularly the SEC, have the duties to regulate, monitor, and sanction any traders who act in contravention of the Securities and Exchange Act B.E. 2535 (1992) (the Act), which prohibits, among other things, insider trading and stock manipulation. Executives charged by the SEC for engaging in such conduct could be required to pay substantial civil fines, and could also be barred from holding an executive position in securities-issuing companies. Investors who suffer losses from such manipulations also have the right to file a claim against the stock manipulators to seek compensation.  

Stock Manipulation

Stock manipulations occur when a person with inside information causes stock to behave abnormally in order to manipulate its price or value. Principally, the Act prohibits anyone with inside information related to the securities-issuing company from purchasing or selling securities, or entering into a derivative contract with respect to the securities, for themselves or for others, except as allowed by law. The disclosure of inside information to another person, directly or indirectly, is also prohibited under the Act.

Certain groups of people are presumed under the Act to have inside information by the nature of their roles or positions in the company, including directors, executives, auditors, advisors, and employees who are responsible for or capable of accessing inside information. Any such persons found to have traded securities, or entered into derivatives contracts, in a different manner from their normal practice, are presumed to have known or possessed inside information.

The impact of insider trading can be substantial, and cautionary tales abound. In one very recent high-profile case, executives of a securities-issuing airline manipulated stocks by jointly trading shares with the public while trading shares among themselves by matching orders. The transaction appeared to the public to be a bid, thereby masking the true price and volume of securities being traded. This trading scheme caused the price and the volume of the shares to behave abnormally in the market, with the prices ultimately rising 22.5 percent.

The SEC charged the executives who participated in this scheme with offences under the Act, ordered them to pay massive civil fines (nearly USD 16 million in total), and barred them from becoming executives or directors of listed companies and securities-issuing companies.

Rights of Injured Investors to Claim through Class Actions

The fines and penalties in the case above are an example of the robust protections against unscrupulous trading practices in the arsenal of the SEC. However, the risks of insider trading no longer end with SEC sanctions. Recent legislation has also empowered affected investors to recover their losses from such practices directly.

In stock manipulation cases, even when vast sums have been unlawfully procured by a stock manipulator, the individual traders that have been misled may only have suffered comparatively small amounts of individual loss. This means that claim amounts have often been too small for investors to justify the cost of litigation.

Thailand’s recently enacted class action legislation, chiefly the Act to Amend the Civil Procedure Code (No.26) B.E. 2558 (2015), changes that, by allowing plaintiffs in cases related to securities and stock exchanges, including stock manipulation, to apply for class proceedings.

This means that a representative of a large group (or “class”) of injured parties can file a claim against the same defendant or defendants, on behalf of the group, in a single lawsuit. In a stock manipulation case for example, a class may include all those who purchased stock at an artificially inflated price. If the claim is successful, the damages awarded by the court can then be calculated based on the number of members of that class (if appropriate).

Strengthening that protection further, Thailand’s class action regime is an “opt-out” system, which allows for passive participation by class members. Class action cases are initiated and driven by lawyers and representatives of the class members who suffered similar losses, based on the same legal violations and other facts. When the parameters of such a class are fixed by the court, it will issue notices of proceedings to the class members. These notices include essential information such as a summary of claims, the details of claimants and lawyers, the rights of the class members, the binding effect of any court decision on those class members, and, crucially, the period for opting out from the proceedings. Those who do not do so are included in the plaintiff class, will be bound by the court’s decision, and will may be included in the multiplier for calculating the award of damages.

Once the class is fixed, the plaintiff benefits from all the tools of civil litigation, including a document discovery process, in which parties are required to disclose their documentary evidence and witnesses to the opposing party. Uniquely among Thai civil proceedings, class action legislation enhances this discovery process by granting the court powers to interrogate the parties prior to witness hearings, and to search for additional facts beyond what has been disclosed by the parties.

This means that in addition to facing substantial fines by the SEC, and being prevented from holding future executive positions, those involved in unscrupulous trading activities may also find themselves facing an enhanced civil litigation process culminating in an award of damages based on the losses of hundreds, or even thousands, of defendants.

This powerful advantage for wronged investors should encourage companies to be even more cautious in their approach to preventing insider trading. More importantly, this protection should increase the confidence of traders, large and small, seeking to trade in Thailand free from the fear of unrecoverable losses caused by shady dealings.

RELATED INSIGHTS​ 

June 29, 2026
Thailand’s cabinet has approved the draft Act on Liability for Defective Goods, commonly called Thailand’s “Lemon Law.” The Draft Act is currently pending consideration by Parliament. The draft law aims to strengthen buyers’ position in pursuing cases against sellers. While the Civil and Commercial Code offers provisions governing liability for defective goods, it is difficult in practice for buyers to successfully make a claim against sellers, particularly where defects are latent and not discoverable at the time of sale or delivery. By introducing product-specific rules and clearer remedies, the new law is intended to modernize Thailand’s consumer protection framework and align it more closely with international standards, and to help relieve the buyer’s burden of proof against the seller in product liability cases. If enacted, the draft act will take effect 180 days after publication in the Government Gazette, giving businesses a transition period to assess their compliance obligations. This article provides an overview of the key provisions of the draft act and highlights some practical considerations for businesses operating in Thailand. Scope and Key Definitions The draft act applies to sellers—defined as persons who sell goods in the ordinary course of business—and protects buyers, a term defined broadly to include not just the original purchaser but also transferees and successors in title. This expands the class of people who can bring claims. The law does not apply to used goods, live animals, or goods exempted by future ministerial regulation. It also leaves intact any separate warranties, promises, advertisements, or other guarantees a seller has given; those remain enforceable alongside the new statutory rights. General Liability for Defective Goods Sellers are liable for defects that exist at the time of delivery, regardless of whether the seller knew about them. Liability arises where a defect reduces: The benefit intended under
June 22, 2026
Arbitrator independence and impartiality form the cornerstone of a legitimate arbitral process. Under section 19 of the Thai Arbitration Act B.E. 2545 (2002), prospective arbitrators must disclose circumstances likely to give rise to justifiable doubts as to their impartiality or independence, and existing arbitrators must do so throughout proceedings. This mirrors article 12 of the UNCITRAL Model Law. Yet despite this clear mandate, practical implementation varies significantly across Thailand’s arbitration landscape. Background Thailand’s two principal arbitration institutions, the Thai Arbitration Institute (TAI) and the Thailand Arbitration Center (THAC), both maintain procedures for addressing arbitrator challenges and require compliance with the statutory disclosure obligation. Under both sets of rules, any party wishing to challenge an arbitrator must submit a challenge application within fifteen days of becoming aware of the relevant facts, and a committee is appointed to consider the matter on a case-by-case basis. The TAI additionally prescribes its Code of Ethics and Conduct for Arbitrators to further emphasize the expectation of impartiality and transparency. However, Thailand’s arbitration ecosystem extends well beyond the TAI and THAC. Several sector-specific institutions also administer arbitral proceedings, including the Thai Commercial Arbitration Office under the Board of Trade of Thailand, the Arbitration Centre of the Office of the Insurance Commission, the Arbitration Centre of the Securities and Exchange Commission, the Office for the Prevention and Resolution of Disputes regarding Intellectual Property, and the Arbitration Centre of the Thai General Insurance Association. These institutions each operate under their own procedural rules, which were developed to serve particular industries and dispute profiles. The procedural mechanisms for securing and documenting an independence declaration are not uniformly established across these forums. Consequences of Procedural Inconsistency This creates a notable gap. Not all arbitration bodies have a formalized procedure requiring written independence statements before proceedings commence. Some tribunals proceed
June 16, 2026
The president of Thailand’s Supreme Court has issued new recommendations providing courts with criminal jurisdiction with a comprehensive framework for identifying and dismissing criminal cases brought in bad faith. Published in the Government Gazette on May 29, 2026, after being signed on May 25, the Recommendations of the President of the Supreme Court Concerning Bad-Faith Litigation in Criminal Cases B.E. 2569 were issued under Section 5 of the Act on the Organization of Courts of Justice. The recommendations took effect upon publication and represent a significant step in Thailand’s efforts to curb abusive criminal litigation, including strategic lawsuits against public participation (SLAPP). Background Section 161/1 of Thailand’s Criminal Procedure Code empowers courts to dismiss criminal cases filed dishonestly or with the intent to harass or take unfair advantage of a defendant. The new recommendations provide detailed guidance that courts previously lacked on identifying and handling such prosecutions. Definition of Bad-Faith Litigation Under recommendation 1, filing a criminal case in bad faith is defined broadly to encompass three categories: Harassment-type filings involving intimidation, threats, or creating unreasonable hardship for the defendant; Coercive filings designed to pressure the defendant into acting or refraining from acting for illegitimate benefit; and False or misleading filings that deliberately assert incorrect material facts or conceal such facts. Circumstances Indicating Bad Faith Recommendation 2 sets out specific circumstances that should raise a court’s suspicion that a filing may violate section 161/1. These include: Filing in a distant court far from the defendant’s domicile without benefiting the adjudication; Retaliation against the defendant’s advocacy for human rights, environmental protection, consumer rights, labor rights, or other public interests—effectively establishing an express anti-SLAPP framework; Retaliation against whistleblowers who disclosed corruption or unlawful conduct; Retaliation against individuals responsible for investigating the plaintiff’s wrongdoing or who concluded such an investigation; Filing multiple
June 10, 2026
For multinational franchisors operating in Thailand, a key risk after franchise termination is that former outlets may continue operating in ways that could easily mislead consumers into believing they remain within the authorized network. To justify such operations, former franchisees often argue that the termination was invalid or ineffective. As a result, these cases are often treated as contractual disputes, making it difficult for franchisors to obtain injunctive relief before a final judgment confirms that the termination was lawful. Franchisors face significant commercial and reputational harm during lengthy proceedings, including consumer confusion, disruption to franchise restructuring, and damage to brand reputation and customer trust. In an encouraging development, the Thai court in a 2025 case responded to the problem of unauthorized post-termination franchise operations by granting interim relief, recognizing broader brand and consumer harm, and awarding substantial damages, highlighting a successful litigation strategy of framing the dispute not merely as a contractual termination issue but as trademark infringement causing ongoing commercial injury. The Subway Case From December 2024 to mid-2025, an unauthorized “Subway®” franchise operation in Thailand attracted substantial public and media attention. Reports and online discussions about unauthorized Subway® stores circulated widely after complaints arose about food quality and customer experience at certain outlets that were allegedly operating after their franchise rights had expired. Because these stores continued to use Subway® trademarks, trade dress, and overall commercial appearance, many consumers were unable to distinguish them from authorized operations, resulting in reputational risks and customer confusion that affected the franchisor’s brand and franchise system in Thailand. Subway treated this matter with the utmost seriousness and moved promptly to protect its brand, franchise system, and customers. It filed a civil action with the IP&IT Court seeking a permanent injunction and damages. During the proceedings, the court granted a preliminary injunction