The Stock Exchange of Thailand Index declined 1.65 points from Thursday to close at 1,377.36, a decline of 3.1% from the previous Friday's close of 1,421.48. Turnover was 26.1 billion baht, with 4.27 billion shares traded.
The local market is up 6.2% from the end of 2013.
Foreign investors were net sellers on Friday of 1.88 billion baht worth of Thai shares, bringing their net sales for the month to 686.8 million baht. For the year to date they are net sellers of 5.6 billion baht.
Local institutions were net buyers of 565.2 million baht while brokers sold 124.3 million. Individual investors were net buyers of 1.44 billion baht.
Global stock markets were subdued on Friday, with investors weighing a fall in Chinese inflation and renewed tensions in Ukraine as pro-Russian militants pressed ahead with plans for an independence referendum.
Inflation in China eased in April to 1.8% in a mixed message for investors. The drop gives Beijing more leeway to stimulate the economy if needed, but also underlines that domestic demand is weak.
European shares opened lower, with Britain's FTSE 100 down 0.4%, France's CAC 40 off 0.6% and Germany's DAX shedding. On Wall Street, Dow and S&P 500 futures were both down 0.1% ahead of the market opening.
Trading in Asian markets was mixed. Hong Kong's Hang Seng fluctuated before closing up 0.1% at 21,862.99. Japan's Nikkei 225 gained 0.3% to 14,199.59. Investors, heartened by good results from Toyota, are now waiting for more earnings reports, including Nissan and Sony, next week.
"People are relieved about Toyota, but that's not enough for a major rally," said Shuji Hosoi, senior strategist at Daiwa Securities in Tokyo.
Elsewhere, South Korea's Kospi edged up 0.3% to 1,956.55, while Australia's S&P/ASX 200 shed 0.3% to 5,460.80.
In Bangkok, the SET50 index of blue chips ended at 935.41 points, unchanged, on turnover of 17.41 billion baht, and the SET100 lost 1.62 points to 2,049.59 in trade worth 20.04 billion. The SETHD index of high-dividend shares declined 0.63 to 1,113.51, with turnover of 7.33 billion baht. The Market for Alternative Investment gained 0.20 points to 407.00 points, with transaction value of 633.3 million baht.
The five most active shares by value were Jasmine International (CK), falling 10 satang to 7.90 baht; KBANK, up 1.50 baht to 189; Ichitan (ICHI), up 40 satang to 19.80 baht; KTB, down 10 satang to 17.80 baht; and BBL, up 50 satang to 186.50 baht.
In the currency markets, the baht continued to slide as protests intensified following the court-ordered exit earlier in the week of former premier Yingluck Shinawatra.
The baht was trading late Friday in Bangkok at 32.59/62 to the dollar, compared with 32.46/48 on Thursday and 32.36/38 a week earlier.
Bank of Thailand Governor Prasarn Trairatvorakul said the political stalemate remained the biggest risk to the economy.
"The Thai political situation is increasingly uncertain and that weighs on the economic outlook," said Koji Fukaya, CEO ofFPG Securities in Tokyo. "This underpins speculation of a further rate cut."
Currently, only 2 of 21 economists surveyed by Bloomberg predict the central bank will lower its policy rate by a further 25 basis points by year-end after a reduction in March that brought the benchmark rate to 2%.
In the bond market, the yield on 3.625% government notes due in June 2023 fell two basis points to 3.50%.
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