HONG KONG (AP) — Missing Chinese investment banker Bao Fan is co-operating with an investigation in China, his company China Renaissance said in a stock market filing Sunday.

Since Bao went missing, China Renaissance Holdings Ltd.’s Hong Kong-listed shares have slumped as much as 29%. They were up 2.3% on Monday.

“The Board has become aware that Mr. Bao is currently cooperating in an investigation being carried out by certain authorities in the People’s Republic of China,” the company filing said. “The board would like to reiterate that the business and operations of the group are continuing normally.”

Bao’s whereabouts are unclear. It is not unusual for Chinese authorities to detain people in the course of investigations without making any public announcements.

Bao is one of China’s top dealmakers in the technology industry, having worked on major deals including e-commerce company JD.com’s $2 billion initial public offering and the public listing of short video platform Kuaishou in Hong Kong.

After working at Credit Suisse and Morgan Stanley, Bao founded China Renaissance in 2005. He took it public in 2018, raising $346 million.

Bao’s disappearance follows a crackdown on big technology companies in the past two years. Anti-graft investigations targeting the financial sector have ensnared dozens of Chinese officials and finance executives at institutions such as Everbright Securities, China Construction Bank and major bank ICBC.