Two prominent hacking groups have reportedly stolen “around $1 billion to date”, according to a new report released by Chainalysis – a cryptocurrency fraud detection company.

The two groups, dubbed Alpha and Beta by the researchers, allegedly teamed up to conduct phishing schemes and ransomware targeting security soft spots.

The analysis of transaction flows has shown that in order to launder the funds, the groups established a network of digital wallets then made transactions within them at an average of about 5,000 times before being converted into cash through online exchanges.

According to the report, Alpha preferred to move the stolen funds immediately, while Beta opted to delay transferring the stolen funds for as long as 18 months, possibly waiting for any media attention surrounding the breach to fade away.

Upon closer inspection, both groups may also differ in their overall network structure and motivation. The report purportedly states while Beta is smaller and less organized, whose goals heavily focused on the money, Alpha is a more systematic organization and “partly driven by non-monetary goals.”

The Wall Street Journal cites Philip Gradwell, the chief economist at Chainalysis, as saying that the two hacker groups are likely still at large.