Stocks in Vietnam hit their lowest level in almost two weeks on Thursday after the central bank lowered the dong against the dollar to help exports, while Thai shares edged up as beaten-down telecoms regained some of their recent losses.
Vietnam's benchmark VN Index fell as much as 2 percent to its lowest since June 9, led by Viet Nhat Seafood Corp and Savimex Corp, before settling down 0.6 percent by the midday break.
Vietnam lowered the mid-point rate for trading its currency on the interbank market by 1 percent on Thursday to support exports, the key driver of the economy, the central bank said.
The dong's depreciation started in May due to escalating tensions between Vietnam and China over territory in the South China Sea, DBS said in a report.
"Despite its preference for a stable exchange rate this year, we reckoned that the central bank may need to adjust the dong weaker by 1-2 percent if the situation does not improve between Vietnam and its largest trading partner anytime soon," the broker said.
The Thai SET index rose 0.4 percent, snapping two days of falls, as shares of battered telecoms firms such as Advanced Info Service and True Corporation bounced back.
The benchmark index fell 1.3 percent on Wednesday, in part due to rumours about a possible capital gains tax, brokers said.
"After yesterday's unexpected correction on telecom sell-off and market rumours about capital gains tax, the SET index is likely to rebound on Thursday... The market talk on capital gains tax has no ground in our view," strategists with broker KGI Securities said in a report.
At present, investors at the Stock Exchange of Thailand are exempted from the tax, exchange officials said.
Shares in the Philippines eased slightly ahead of the central bank's meeting on interest rate.
The central bank will likely keep rates unchanged at 3.5 percent at its policy meeting on Thursday after growth unexpectedly slowed in the first quarter, a Reuters poll showed.
Other stock markets in Southeast Asia were little changed.
Asian stock markets rose after the U.S. Federal Reserve gave a positive assessment of the economy and committed to retaining accommodative monetary policy. MSCI's broadest index of Asia-Pacific shares outside Japan was up 0.8 percent.