The computer network that runs the Nasdaq Stock Market has been penetrated by hackers multiple times during the past year, according to a newspaper report.
The Wall Street Journal reported on its website late Friday that federal investigators are trying to identify the perpetrators and their motive.
People familiar with the investigation say the exchange's trading platform, the system which executes trades, was not compromised, according to the report.
A person involved in the Nasdaq investigation told the newspaper that so far the perpetrators "appear to have just been looking around."
Nasdaq officials declined to comment. A telephone message left with the FBI's office in New York was not immediately returned.