Thai stocks closed at a seven-week low on Wednesday as investors sold shares in banks and chemical firms, worried that higher global oil prices could affect their profitability, dealers said. Chemical firm Aromatics (Thailand), the most active stock, fell 2.7 percent to 54.50 baht as investors took profit on recent gains.
The stock hit a four-month high last week when the firm announced strong second-quarter earnings.
Late selling sent shares in Thai Petrochemical Industry, the country's biggest corporate debtor, down 4.4 percent to 7.6 baht after rising 0.6 percent on news that Finance Minister Somkid Jatusripitak had approved its debt restructuring plan.
The benchmark Stock Exchange of Thailand (SET) index closed down 11.62 points at 619.19 points, its lowest close since mid-June.
The big-cap SET 50 index fell 1.71 percent to 42.43 points and turnover was 9.09 billion baht ($219.4 million), down slightly from 9.64 billion baht on Tuesday.
"Basically, energy stocks should be good hedges against rising oil prices, but the overall poor market sentiment caused investors to panic too much," said Capital Nomura Securities strategist Sukit Udomsirikul.
Oil prices, which surged to another record high as US light sweet crude touched $44.28 a barrel, would weaken the market again on Thursday with the main index likely to fall to a support level of 615 points, he said.
The bank sector dropped 1.33 percent, led by a 2.35 percent decline to 8.3 baht by big-cap Krung Thai Bank.
Shares in PTT Exploration & Production (PTTEP), which rose more than three percent on Tuesday due to rising oil prices, fell 1.34 percent to 294 baht as investors took their gains.
The selling of PTTEP stocks came despite an upbeat view by Moody's Investors Service, which said it expected a positive rating trend for the firm over the next 18-24 months.
Major contractors fell more than five percent on concerns that rising building material costs could squeeze profit margins.
Sino-Thai Engineering and Construction dropped 8.3 percent to 8.25 baht and CH Karnchang fell 5.2 percent to 10.90 baht.
Fast food firm Minor Food Group, the top gainer, surged 27 percent to 105 baht after Royal Garden Resort, which owns 98.95 of its shares, said it would offer to buy the rest at 110 baht, 32 percent above Tuesday's close.