The SET index at noon stayed at 1,371.12 points, shedding 8 points or 0.58 per cent, on turnover of Bt23.58 billion.
On Wednesday, the index gained 0.47 per cent, rebounding from the 2.56 per cent loss on Tuesday.
The Thai baht slightly weakened to Bt35.55 against US dollar at 2.14pm, from Bt35.53 yesterday.