America's National Security Agency (NSA) has been called in to help investigate last October's cyber-attack on Nasdaq OMX, according to Bloomberg.
The exchange operator confirmed last month that hackers had breached its computer systems and placed "suspicious files" to gain access to highly confidential data on publicly listed companies.
Nasdaq OMX and the FBI have now called on the electronic intelligence expertise of the NSA which has some of the world's most powerful computers.
Ex-NSA analyst Ira Winkler told Bloomberg that the organisation may be helping to unscramble encrypted messages used to extract data while Joel Brenner, former head of US counter-intelligence says NSA's involvement suggests a state-sponsored attack or an "extraordinarily capable criminal organisation".
An unnamed source told the wire that the attack was more extensive than initially reported and it could take months to determine which systems were hit and why.
US Spy Agency Is Said to Investigate Nasdaq Hacker Attack - Bloomberg