EU antitrust regulators have fined Barclays, Credit Suisse, HSBC and NatWest 344 million euros ($390 million) for rigging the foreign exchange spot trading market.
UBS had alerted the European Commission about the cartel, which was set up via a chatroom known as “Sterling Lads”.
HSBC’s fine was the largest at 174.3 million euros, followed by Credit Suisse at 83.3 million euros, Barclays at 54.3 million and RBS at 32.5 million.
RBS is now known as NatWest following a rebranding last year.
The EU competition enforcer said the forex rigging was done via the chatroom.
The traders involved exchanged sensitive information and trading plans and occasionally coordinated their trading strategies via the chatroom on whether and when to sell or buy the currencies in their portfolios, the Commission said.