The FBI is investigating whether Russian hackers breached Dow Jones & Co. in an attempt to steal stock market information that could help them predict changes in U.S. markets, Bloomberg News reported. Outsiders first infiltrated the network more than a year ago and may have stolen information they hope to sell to stock traders, who stand to gain much from inside knowledge.

The White House, State Department and Securities and Exchange Commission have been briefed on the matter. While Dow Jones denied any knowledge of an investigation, Voice of America reported the FBI has confirmed an investigation is taking place.

The breach was discovered when the company hired cybersecurity investigators to examine whether payment details on 3,500 customers had been compromised. It's not clear whether that breach is related to the alleged Russian hack, though sources told Bloomberg the hack is “far more serious than a lower-grade intrusion.”

Russian hackers were previously blamed for an attack on the Nasdaq, with officials speculating at the time that Moscow was interested in constructing a similar stock exchange.

Cybercriminals who hack for financial gain have needed to explore new revenue streams as large U.S. corporations have increased how much they invest in cybersecurity. One way to do that is to target data providers or business journalists, who have access to embargoed information about financial markets. Dow Jones releases sensitive information to more than 10,000 industry insiders every day and publishes the Wall Street Journal.

This is the latest reported infiltration from Russian hackers, who have previously targeted email systems at the White House and the State Department, and are widely believed to be responsible for a breach at the Pentagon in August. It's often difficult for investigators to determine whether the party responsible is working on behalf of a government, is a gang of criminals, or both. Growing tension between the U.S. and Russia, combined with the lack of job opportunities in many of the former Soviet states, is believed to have contributed to the creation of a full-time hacking unit that launches attacks at the Kremlin's behest.

The Chinese government has been more receptive to U.S. complaints. It quietly arrested a handful of hackers in September at Washington's request. That came just weeks before President Barack Obama and Chinese President Xi Jinping announced they would work to slow (but certainly not eliminate) the constant flow of hacks launched against each other's private companies.