The European Union has fined four major banks a total of $390 million for colluding in a foreign exchange spot trading cartel that allowed them to reduce the risks inherent in foreign exchange transactions, the AP reports.

HSBC was fined nearly $200 million, while Credit Suisse, RBS and Barclays received smaller fines. UBS was not fined because it disclosed the cartel.

"The collusion of the five banks has undermined the integrity of the financial sector at the expense of the European economy and consumers," said Commission Vice-President Margrethe Vestager.

The European Commission said in a statement that several spot currency traders“exchanged sensitive information and trading plans, and occasionally coordinated their trading strategies through an online professional chatroom called Sterling Lads.”