In the morning session, a stock analyst at Krungsri Securities expected the US Federal Reserve's move to relax inflation policy while maintaining a low interest rate would push the index up to 1,335 before it fell back.
"Also, the index gained positive sentiment from news of a Covid-19 test kit," he said.
The 10 stocks with the highest trade value today were MINT, PTT, KBANK, BBL, AOT, GULF, BAM, CPALL, SCB and SCC.
As of 4.30pm, the price of oil fell by US$0.02 or 0.05 per cent to $43.02 per barrel, while gold rose by $34.70 or 1.80 per cent, to $1,967.30 per ounce.
Other Asian indices were mixed:
Japan’s Nikkei Index closed at 22,882.65, down 326.21 points or 1.41 per cent.
China’s Shang Hai SE Composite Index closed at 3,403.81, up 53.69 points or 1.60 per cent, while the Shenzhen SE Component Index closed at 13,851.32, up 316.23 points or 2.34 per cent.
Hong Kong’s Hang Seng Index closed at 25,422.06, up 140.91 points or 0.56 per cent.
South Korea’s KOSPI Index closed at 2,353.80, up 9.35 points or 0.40 per cent.
Taiwan’s TAIEX Index closed at 12,728.85, down 68.46 points or 0.53 per cent.