Authorities believe it to be the largest scheme of its kind discovered to date and part of a growing trend. Last winter, internet security firm, FireEye, warned the FBI about the activities of FIN4, a separate group of hackers that appear to only target specific pieces of information that could be used to gain various market advantages. "FIN4 is the first time we are seeing a group of very sophisticated attackers actually systematically acquire information that only has true value to a criminal when used in relation to the stock market," Dan McWhorter, FireEye's vice president of threat intelligence, told the FBI.

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