PDI : SET posted "H" sign on PDI The Stock Exchange of Thailand (SET) posted "H" (Halt) sign on PDI's securities in the first trading session of May 9, 1996 at 9.45 a.m. The reason of "H" sign posting is that the material information has not been disclosed to the public through the exchange, and the SET has asked and, now, is waiting for its disclosure from the company.