The Stock Exchange of Thailand index plunged on Monday as the number of infections linked to the coronavirus outbreak in Samut Sakhon continued to rise.
The SET main index plunged 38.81 points, or 2.62%, to 1,443.57 in turnover of 30 billion baht shortly after it opened.
The SET50 index dropped 28.58 points or 3.02% to 918.70.
Kasikornbank led the losses, down 5 baht, or 4.20%, to 114, while rubber glove maker Sri Trang Gloves (Thailand) jumped 2.75 baht, or 3.73%, to 76.50 baht.
The stock market dropped after the virus outbreak in Muang district of Samut Sakhon that started at the Central Shrimp Market last week.
The new infections rose to one-day high on Sunday at 576, with 516 of them related to the shrimp market, according to the Centre for Covid-19 Situation Administration.
The Public Health Ministry said the figures were expected to continue rising as more labourers were checked for the virus.