As tools grow more sophisticated, hackers may be turning to insider trading for a payoff. A group of Russia-based hackers broke into Dow Jones & Co's internal computer network in search of unreleased, market-moving information, according to a new report from Bloomberg. Dow Jones had reported a smaller compromise earlier this week, in which financial data on 3,500 employees was compromised. But this breach is far greater in scope, reaching back at least a year.

It's not the first time hackers have turned to insider trading to make money. In August, federal prosecutors brought charges against a Ukrainian group for compromising BusinessWire, MarketWired, and PR Newswire in search of embargoed announcements to trade against. A related civil lawsuit alleged more than $100 million in illegal profit from the theft.