Thai stocks fell almost one percent on Thursday as concerns about new bird flu outbreaks and firming oil prices prompted investors to cash out to reduce risks, analysts said.
The benchmark Stock Exchange of Thailand (SET) composite index closed down 6.03 points, or 0.92 percent, at 646.76 points and the big-cap SET 50 index fell 1.1 percent to 43.98 points.
Turnover fell to 14.06 billion baht ($344.4 million), from 17.4 billion baht on Wednesday.
"The market had no good stories to help as investors were worrying again about oil prices and new bird flu outbreaks," Syrus Securities analyst Charoen Iampathanatham said as Thailand confirmed more outbreaks of the deadly bird flu among chickens.
Investors were cautious also because US oil prices rose to a six-week high above $41 on Thursday as concerns about security of supplies were heightened by a surprise fall in key fuel stockpiles in the United States, he said.
The market would weaken on Friday, with resistance on the main index seen at 654 points and support at 640 points, he said.
Shares in Tisco Finance, Thailand's number two finance firm, fell 1.8 percent to 27 baht after the company reported an 11 percent drop in second quarter net profit due to losses on securities investments despite an upbeat auto lending business.
The telecommunications sector was active, driven by speculation of a merger between mobile handset distributors Samart I-Mobile and M-link Asia Corp.
But profit taking ate into early gains by shares in Samart I-Mobile, which ended unchanged at 13.4 baht after rising to a two-month high of 13.70 baht. M-link shares jumped 2.6 percent to 5.9 baht.
Shares in telecom group Samart Corp, which holds a 86.5 percent stake in Samart I-Mobile, rose 5.96 percent to eight baht. Shares in oil refiners Bangchak Petroleum and Rayong Purifier fell after Energy Minister Prommin Lertsuridej said he was asking refineries to accept lower subsidies the government pays them to maintain ceilings on retail product prices.
Bangchak shares fell 1.27 percent to 15.60 baht, while Rayong Purifier shares were down 1.67 percent at 29.5 baht.
Analysts said investors took profit on banks, which are in the middle of reporting second-quarter results. Big banks are expected to release their performance figures next week. The sector fell 0.08 percent.