At its height, the DarkMarket forum counted 2,500 people as registered members, the FBI said in a statement. Authorities estimate the sting helped save $70 million in victim losses.
The statement did not say how the FBI got control of the forum, which was reportedly under the bureau's control for about two years. However, law enforcement said it worked with international partners to identify and track down culprits.
Wired reported that the FBI used the site as a way to create profiles of DarkMarket users. The agency tracked users' IP addresses and their activity on the site, along with transaction records from the E-Gold electronic currency service.
The FBI said the sting also netted new leads into other cybercrime cases, which now are being investigated by the FBI and international partners.