The Thai baht slipped 0.3 percent to 31.36 against the dollar as of 1:09 p.m. in Bangkok. It has lost almost 5 percent in the past three months, after reaching its highest level since 1997 in April. The benchmark Stock Exchange of Thailand Index fell 2.1 percent, heading for its biggest drop since July 25.
The Thai central bank cut its 2013 GDP growth forecast to 4.2 percent from 5.1 percent on July 19, citing weakening exports. Shipments (THCTEXPY) grew 0.95 percent in the first six months.
The monetary authority lowered borrowing costs by 25 basis points in May. Singapore last week cut its forecast for exports this year, while Indonesia this month reported second-quarter GDP growth of less than 6 percent for the first time since 2010.
Thai consumer confidence fell to the lowest in seven months in July on rising political unrest and the weakening economic outlook. Prime Minister Yingluck Shinawatra imposed the Internal Security Act for eight days this month to contain protests as the parliament debated an amnesty bill for political protesters.