According to Europol, international investigators have dug up one of the largest hacker forums in the world.
The illegal marketplace "RaidForums" has been closed and the infrastructure has been confiscated, Europol announced on Tuesday in The Hague.
The administrator of the forum and two henchmen were arrested.
The US Department of Justice in Washington announced that data for millions of people, for example for credit cards or bank accounts, was traded on the platform.
According to the information, investigators from the USA, Great Britain, Sweden, Portugal, Romania and the German Federal Criminal Police Office were involved in the "Tourniquet" operation.
The main administrator of the forum is a 21-year-old Portuguese, according to the US Department of Justice.
He was arrested in Britain in January.
The US requested his extradition.
It is unclear where the other two suspects were arrested.
According to Europol, "RaidForums" was set up in 2015 and had more than half a million users.
Access to large databases from numerous US companies was sold on this platform.
It was about millions of credit cards, bank accounts and access data for online accounts.
The leaked databases had been collected through previous hacks and other illegal ways over the past few years.
According to the US Department of Justice, it involved more than ten million pieces of data from citizens of the United States and other countries.
These had previously been stolen by companies, universities or government institutions.
The investigators had been preparing the action for a year.
It was coordinated by Europol's cybercrime specialists.