Russian Hackers of Dow Jones Said to Have Sought Trading Tips

A group of Russian hackers infiltrated the servers of Dow Jones & Co., owner of the Wall Street Journal and several other news publications, and stole information to trade on before it became public, according to four people familiar with the matter.

The Federal Bureau of Investigation, Secret Service and the Securities and Exchange Commission are leading an investigation of the infiltration, according to the people. The probe began at least a year ago, one of them said. The breach is described by the people as far more serious than a lower-grade intrusion disclosed a week ago by Dow Jones, a unit of Rupert Murdoch’s News Corp. The company said last week that it was working with a cybersecurity firm and law enforcement after learning that hackers had sought contact and payment information of about 3,500 customers. It is unclear if the incursions are related.