The index fell sharply after rising by 5.58 points or 0.34 per cent on Monday.
In the morning session, Krungsri Securities forecast the SET Index on Tuesday would fluctuate between 1,635 and 1,655 points.
It said the index still gained positive sentiment from rising oil price and hopes over Thailand economic recovery after the country reopening on November 1.
"However, uncertainty over inflation, the US Federal Reserve's plan to taper its quantitative easing programme this year and signs of stock downward trend would pressure the index," Krungsri Securities said.
The 10 stocks with the highest trade value today were HENG, KBANK, SCC, AOT, BANPU, TRUE, PTT, CPALL, ADVANC and GULF.
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Other Asian indices were on the rise:
Japan's Nikkei Index closed at 29,215.52, up 190.06 points or 0.65 per cent.
China's Shanghai SE Composite closed at 3,593.15, up 25.02 points or 0.70 per cent, while the Shenzhen SE Component closed at 14,499.77, up 149.75 points or 1.04 per cent.
Hong Kong's Hang Seng Index closed at 25,787.21, up 377.46 points or 1.49 per cent.
South Korea's KOSPI Index closed at 3,029.04, up 22.36 points or 0.74 per cent.
Taiwan's TAIEX Index closed at 16,900.67, up 195.21 points or 1.17 per cent.