By using Thai nominee shareholders and preference share structures foreigners have been able to circumvent foreign ownership and business restrictions through Thai limited companies. The use of preference shares issued to foreigners is allowed under the current Foreign Business Act, however the use of nominees by foreigners is and always has been illegal (sections 36 & 37 FBA).
A nominee under the foreign business act is a Thai person or Thai company registered as shareholder in the company but who holds the shares on behalf of the foreigner.