HONG KONG (AP) - The Hong Kong arm of one of China's biggest securities companies says its chairman has returned to work after disappearing a month ago.

HONG KONG (AP) The Hong Kong arm of one of China's biggest securities companies says its chairman has returned to work after disappearing a month ago.

Guotai Junan International Holdings said Wednesday that Yim Fung had been assisting in "certain investigations" by authorities in mainland China in a "personal capacity" and could not be reached during that time.

Neither Yim nor the company was the subject of the investigation, Guotai said in a filing to Hong Kong's stock exchange.

The company said Yim has resumed his duties as chairman and CEO.

He's one of a number of high-profile figures in China's securities industry who have disappeared or been detained after authorities began an investigation into a plunge in China's stock markets in the summer.