Thai stocks fell in sluggish trade on Friday with sentiment hit by an outbreak of bird flu in domestic cats and by fears new investment rules will reduce market trade.
But investors were encouraged in afternoon trade by reports tests showed an anti-human flu drug developed by Australia's Biota Holdings Ltd was also effective against avian flu.
"The news about an Australian firm's drug that can treat bird flu had a positive psychological effect on the market so there was some buying in the afternoon session," said BT Securities analyst Piti Ketsiri.
The benchmark Stock Exchange of Thailand (SET) composite index closed down 4.33 points, or 0.59 percent, at 428.64 points, its lowest close in two weeks.
The big-cap SET 50 index fell 0.37 percent to 48.27 points.