Goldman Sachs and its fellow defendants have 30 days to respond to the summons, either by submitting a notice of appearance or a complaint. In a statement emailed to CNBC on Thursday, a Goldman Sachs spokesperson said: "We are in the process of assessing the details of allegations and fully expect to contest the claim vigorously." Earlier this month, the U.S. Justice Department arrested two former Goldman Sachs bankers on multiple criminal charges in relation to the 1MDB scandal.