Hong Kong police said on Friday they had arrested a 29-year-old man over a cyber attack on the city's stock exchange website which halted trading in the shares of seven companies.
Police said they detained the man on Thursday, seizing five computers, two mobile phones and other items, a police spokesman told AFP.
"He is being investigated under the offence of access to a computer with criminal or dishonest intent," the spokesman said, adding that the man was being held for questioning.
The bourse was hit last week by what it called a "malicious" attack which caused firms including banking giant HSBC and flag carrier Cathay Pacific to suspend trading for half a day.
The website of the Hong Kong bourse, the world's most valuable exchange operator, displays listed companies' regulatory filings. The bourse said it had to suspend the trading to ensure investors had equal access to the filings.
The exchange had said its other systems were not affected and trading in its securities and derivatives markets were operating normally.
The hacking was detected after HSBC announced the sale of its United States credit card and retail services business as part of an overhaul to streamline its operations, while Cathay reported its 2011 half-year earning results.
The incident was the second cyber attack on stock exchanges within days after hackers targeted the Zimbabwe stock exchange website two weeks ago, forcing a shutdown of the site.
Explore further: Hong Kong bourse hit by 'malicious hacking'