The index was at 1,407.70 points at the end of March.
It was driven mainly by foreign capital inflows. According to SET's data, foreign investors' net-buys of Thai shares in the month reached Bt26.5 billion.
A recent gain in oil prices boosted global markets yesterday, allowing the SET index to gain 12.95 points. At 4.33pm today, the index was at 1,371.93 points with Bt25.5 billion in turnover.
Tisco Securities said in a research note that trading would be lacklustre today, given the long holiday period ahead.