Singapore shares dropped for a sixth straight session, hitting a two-week low, dragged down by financial and real estate stocks.
Most other Southeast Asian stock markets were sluggish in lacklustre trade, in line with Asian peers as investors have already factored in the benefits to company bottom lines from U.S. tax cuts.
The Republican-controlled U.S. House of Representatives gave final approval on Wednesday to the biggest overhaul of the U.S. tax code in 30 years, sending a sweeping $1.5 trillion tax bill to President Donald Trump for his signature.
The Bank of Japan left monetary stimulus unchanged in the final policy meeting of 2017. Governor Haruhiko Kuroda holds a press conference at 3:30 p.m in Tokyo, and traders will be eager for insights into the policy path for 2018, as well as any hints as to whether he wants to stay at the helm after his term ends in April.
At 0510 GMT, the Straits Times Index lost 0.09 percent or 36 points to 3,391. It ended 0.28 percent lower on Wednesday, taking the year-to-date performance to about 18 percent.
Shares of United Overseas Bank lost 0.3 percent and Oversea-Chinese Banking declined 0.6 percent. DBS Group Holdings edged up 0.2 percent.
CapitaLand Commercial Trust dropped over 3 percent.
Brewing group Thai Beverage lost 0.5 percent after it won an auction earlier this week to buy a $4.8 billion stake in Vietnam's top brewer Sabeco.
But Noble Group jumped 4 percent after lenders agreed to extend the waiver for its $1.1 billion revolving credit facility until May 18.
About 643 million shares worth S$382 million changed hands, with losers outnumbering gainers 166 to 165.
