Leaked documents involving about $2tn of transactions have revealed how some of the world's biggest banks have allowed criminals to move dirty money around the world.
They also show how Russian oligarchs have used banks to avoid sanctions that were supposed to stop them getting their money into the West.
It's the latest in a string of leaks over the past five years that have exposed secret deals, money laundering and financial crime.
What are the FinCEN files?
The FinCEN files are more than 2,500 documents, most of which were files that banks sent to the US authorities between 2000 and 2017. They raise concerns about what their clients might be doing.
These documents are some of the international banking system's most closely guarded secrets.
Banks use them to report suspicious behaviour but they are not proof of wrongdoing or crime.
They were leaked to Buzzfeed News and shared with a group that brings together investigative journalists from around the world, which distributed them to 108 news organisations in 88 countries, including the BBC's Panorama programme.
Hundreds of journalists have been sifting through the dense, technical documentation, uncovering some of the activities that banks would prefer the public not to know about.
Two acronyms you need to know
FinCEN is the US Financial Crimes Enforcement Network. These are the people at the US Treasury who combat financial crime. Concerns about transactions made in US dollars need to be sent to FinCEN, even if they took place outside the US.
Suspicious activity reports, or SARs, are an example of how those concerns are recorded. A bank must fill in one of these reports if it is worried one of its clients might be up to no good. The report is sent to the authorities.
Source : https://www.bbc.com/news/uk-54226107?at_medium=custom7...