
Prasong Vinaiphat, deputy secretary-general of SEC, said the agency is investigating the issue jointly with the exchange after the company's share price fell to the floor levels for three consecutive trading days.
During Monday and Tuesday, it also fell near the floor levels. On Friday, it ended the week at Bt4.42 per share, down from Bt8 a week earlier. During the week, its price peaked at Bt15.80.
Brokerage houses are instructed to allow only cash transactions.
Sakkarin Ruamrangsri, chief regulatory officer of the exchange, said 10 brokerage houses are summoned to submit information. Then, the SET will finalise if the company's price has been manipulated.