Operators of US stock exchanges, Nasdaq and BATS have confirmed that their respective public websites became victims of a denial of service (DOS) attack on Tuesday.

Nasdaq site was showing only the banner carrying the logo, according to Reuters.

Trading activity, however, remained unaffected since Nasdaq’s websites are separate from their trading systems, Nasdaq spokesman Joseph Christinat said.

"The website wasn’t hacked, nobody got any information. What they did was try to block access for our users," said Christinat.

The BATS too experienced a similar attack. A BATS spokeswoman, confirming a denial of service incident, said its trading systems were not affected and there were no exchange customer disruptions associated with the incident.

"Our website is used to display general information about our market activity for the casual user, and there are no critical functions supported through our general public site," she told AFP.

"We worked with our Internet Service Provider and swiftly returned our website to a normal operating state," she added.