The New York Stock Exchange halted trading in all securities around 11:32 a.m. in New York, citing a computer malfunction. Stocks continued to change hands on other venues, such as the Nasdaq Stock Market and Bats Global Markets.
A number of cybersecurity stocks moved sharply higher on the news, although the NYSE has since said that the outage was due to an "internal technical issue."
One was Cyberark Software, which provides services meant to protect organizations from cyber attacks.
Imperva provides data security and other services for a number of industries, such as energy and finance, as well as the government.
AVG Technologies is an antivirus and Internet security firm that operates worldwide.
Then there is Palo Alto Networks, a security solutions company that provides firewalls that help prevent data leaks and other threats.
Finally there is the ISE Cyber Security index, which acts as a benchmark for a bunch of cybersecurity-related companies.
The sharp moves highlight how even the perception of a hacking attack can benefit cybersecurity technology companies. Security specialists have long lamented that many companies don't take anti-hacking protections seriously until they've been breached or a major incident hits their industry. For instance, technology vendors described a boon of business from retailers after Target was hacked in 2013 and attackers stole personal information on as many as 110 million customers.