In the morning session, Krungsri Securities forecast the day's index would fall to between 1,635-1,640 points.
It said the index would be under pressure due to a sharp fall in oil price amid uncertainty over the US and China would release their oil reserves, plus fund flow volatility due to CME FedWatch Tool forecast the US Federal Reserve would raise the interest rate in March next year.
"However, mass buy-ups of shares which gained specific positive sentiment would help boost the index," Krungsri Securities said.
The 10 stocks with the highest trade value today were TRUE, DTAC, EA, CBG, PTTEP, KBANK, PTT, SCB, ONEE and ADVANC.
Other Asian indices were down with one exception: