Shares in gambling group Suncity Group Holdings were suspended from trade on Monday with its chief executive believed to be among 11 people arrested by Macau authorities over alleged links to cross-border gambling and money laundering.
Macau authorities said police were questioning Alvin Chau on Saturday after a Chinese city issued an arrest warrant for the mogul, accusing him of operating gambling activities in mainland China.
The South China Morning Post reported that Macau police said on Sunday a 47-year-old businessman surnamed Chau was among those arrested.
Hong Kong-listed Suncity Group Holdings operates gambling rooms across Asia. Chau is also founder of a separate junket operator, which is also called Suncity. Junket operators are go-betweens who bring high rollers to play at casinos, extending their credit and collecting on their debts.
Shares of Macau casino operators slid early on Monday, with Wynn Macau down more than 10%, Sands China falling more than 7% and MGM China dropping over 6%.
Casino gambling is illegal in China outside Macau, the world's largest gambling hub.
Authorities in the eastern Chinese city of Wenzhou said on Friday an investigation had found Chau formed a junket agent network in the mainland to help citizens engage in offshore and cross-border gambling activities.
Chau also set up an asset management company in the mainland to help gamblers to make cross-border fund transfers, the Wenzhou City Public Security Bureau in the coastal city in Zhejiang province said on its Weibo account.
Suncity could not be reached for comment. Shares of the company last closed at HK$0.255.
Chau is also a controlling shareholder in Sun Entertainment Group Ltd, a film production and cremation services firm, whose shares plunged 65% early on Monday.
Sun Entertainment said in a Sunday stock exchange filing its board had noted news coverage about the investigations in Wenzhou and Macau.
"The Board wishes to emphasize that the news coverage is relating to the personal affairs of Mr Chau. The Board is of the view that the incident does not have any material impact on the financial position, business nor operation of the group," the filing said.