The Securities and Exchange Commission, Thailand has launched a public consultation on proposed principles to revise how “major shareholders” are defined for derivatives business operators, aiming to ensure supervisory oversight extends to individuals who exercise ultimate control and aligns with the approach used for securities and digital asset businesses. The proposed changes would treat as a major shareholder any person who can directly or indirectly control the appointment or removal of at least half of all directors. The determination would also aggregate shareholdings of spouses and minor children and cover acting-in-concert situations, including coordinated voting, arrangements authorising another person to exercise one’s voting rights, and couples cohabiting without legal marriage registration regardless of gender identity. Practical guidance is also planned for applying the definition to different ownership structures, including use of a proportional (pro-rata) method for calculating shareholdings. Comments can be submitted through the SEC’s consultation channels, with the public hearing open until 13 February 2026.