At the open, the Thai baht was at Bt35.58 per US dollar, down by 0.23 per cent from Monday closing of Bt35.50.
At 1.46pm, the Thai baht was traded at Bt35.56, the new 6-year low.
As the morning session ended, the Stock Exchange of Thailand index shed 28.08 points or 1.99 per cent, to 1,380.66 points. Only 207 stocks managed to advance while 825 stocks were down.