Dow Jones & Co., publisher of The Wall Street Journal and other influential financial publications, said Friday it was looking into a report that Russian hackers had used information stolen from its servers to trade on before it became public. Bloomberg, citing four sources it did not identify, said the FBI, Secret Service and the Securities and Exchange Commission were leading the investigation of the intrusion. The incident was said to be "far more serious" than a data breach disclosed by Dow Jones a week ago, according to the Bloomberg report. Dow Jones CEO William Lewis said last week that his company was the target of a hack that may have exposed the credit and debit card information of "fewer than 3,500 individuals." In a statement to NBC News on Friday, Dow Jones indicated it was unaware of the broader intrusion.