Preet Bharara, the U.S. Attorney for the Southern District of New York, announced that three Chinese citizens have been charged for attempting to hack into seven law firms involved in mergers and acquisitions to pilfer information to use for insider trading.

The suspected hackers were successful in hacking into the information systems of two unidentified New York law firms, steal information related to M&A deals, and make $4 million.

Bharara said in a statement, “This case of cyber meets securities fraud should serve as a wake-up call for law firms around the world: You are and will be targets of cyber hacking, because you have information valuable to would-be criminals.” According to investigators, the hackers were able to buy shares cheaply before anyone else knew how much they would increase in value from the acquisition. The hackers were looking to infiltrate the IT systems of the lawyers who were helping complete the deals.