Blockchain analytics companies like Chainalysis work with major cryptocurrency exchanges to stop suspicious transactions from entering the system ...
source https://www.google.com/url?rct=j&sa=t&url=https://www.ccn.com/1-billion-in-crypto-stolen-by-just-2-groups-how-do-they-cash-out/&ct=ga&cd=CAIyGmM2Nzk3ODA2ZWViNjVjODI6Y29tOmVuOlVT&usg=AFQjCNFaFrM7cXL3kdY2SlDhKriKjQ9qrA
