Total Access Communication Pcl, Thailand’s second-largest mobile-phone operator, said it is not aware of any change in its business that could cause a surge in the stock yesterday.

Shares traded in Singapore jumped 22% yesterday to US$1.10 ($1.59), the biggest rise since August 2007. The city’s exchange today asked Total Access to explain the gain.

“There is no change in the company that would have that kind of impact on the stock,” Thavit Sangudomlert, head of Total Access’s investor relations department, said by phone today in Bangkok.
   
Thavit said the company will issue a statement later today to explain the stock’s movement. The shares lost 2.7% to US$1.07 at the midday break in Singapore. Total Access’s shares traded in Bangkok rose 2.3%. The markets were closed in Thailand yesterday for a holiday.