Hong Kong shares of HSBC fell to their worst level since 1995 on Monday (September 21) after reports that it and other financial institutions had allegedly moved large sums of illicit money over two decades.
They revolve around documents leaked to Buzzfeed and shared with a global network of invetigative journalists.
Buzzfeed and other news outlets say it involves moving money for the likes of terrorists, drug kingpins and corrupt leaders.
The leak is reportedly made up of over 2,100 suspicious activity reports filed by banks and other financial firms with the U.S Treasury's Financial Crimes Enforcement Network, or Fincen.
The so-called Fincen Files allegedly show more than $2 trillion dollars worth of transactions from 1999 to 2017, all of it flagged as suspicious by the banks' own compliance departments.
The activity reports aren't necessarily proof of wrongdoing, but the leak paints a picture of a banking system that allows for vast amounts of money laundering.
Among the alleged activity are funds handled by JPMorgan for potentially corrupt individuals and companies in Venezuela, money from an investment scam, or Ponzi scheme, moving through HSBC and money linked to a Ukrainian billionaire processed by Deutsche Bank.
Five global banks appeared the most in the documents; HSBC, JPMorgan, Deutsche Bank, Standard Chartered and Bank of New York Mellon.
In a statement to Reuters, HSBC said the information was "historical" and that as of 2012, "HSBC embarked on a multi-year journey to overhaul its ability to combat financial crime."
Deutschebank also called the reports "historic issues" and that the bank had "devoted significant resources to strengthening" their controls.
Standard Chartered and JP Morgan both said they took the issue of fighting financial crime seriously, while BNY Mellon said it fully complies with laws and regulations.