Santander UK Plc was fined £107.7m ($132m) by the UK financial watchdog over repeated anti-money laundering failures.
The bank failed to ensure it had sufficient oversight and monitoring of its business customers and missed hundreds of millions of suspicious funds channelled through accounts between 2012 and and 2017, the Financial Conduct Authority said in a statement on Friday.
Santander fully cooperated with the FCA probe and accepted the watchdog's findings in exchange for a 30pc discount in the penalty.
"Santander's poor management of their anti-money laundering systems and their inadequate attempts to address the problems created a prolonged and severe risk of money laundering and financial crime," Mark Steward, the FCA's executive director of enforcement and market oversight, said.
The fine is the latest example of a concerted effort by the regulator to act more forcefully. It has previously fined HSBC Holdings Plc, Standard Chartered Plc and NatWest Group Plc a combined £431m for poor management of their AML systems.
"We are very sorry for the historical anti-money laundering related controls issues," Mike Regnier, Santander UK's chief executive officer, said in a statement. "We have since made significant changes to address this by overhauling our financial crime technology, systems and processes."
One business customer's account saw around £269m pass through during an almost four year period even though it was only opened on the basis of a monthly revenue of £5000. Even when it was suspected that the account was funnelling criminal funds, it was never closed.
Almost a year ago, the FCA fined NatWest for the criminal offense of failing to prevent money laundering in a case that heard details of hundreds of thousands of pounds being couriered in black garbage bags and branch vaults overflowing with bank notes.
