Dow Jones servers were infiltrated by a group of Russian hackers looking for stock tips, Bloomberg reported Friday.
The Federal Bureau of Investigation's New York office confirmed to CNBC that it is aware of the hack and is investigating.
In a statement, Dow Jones said, "to the best of our knowledge, we have received no information from the authorities about any such alleged matter."
"We are looking into whether there is any truth whatsoever to this report by a competitor news organization," Dow Jones said.
The report describes the breach as more serious than the one reported last week, though it is still unclear if the two are related.
A Bloomberg spokesman said "we stand by our reporting."
Last week, the News Corp. unit said that hackers had breached its system and possibly stole payment information for some former and current subscribers between August 2012 and July 2015.
Click here to read Bloomberg's full report.