The European Commission has fined five banks a total €1.07 billion ($1.2 billion) for manipulating the foreign exchange market in 11 currencies.

Citigroup Inc., Barclays, JPMorgan Chase & Co., and the Royal Bank of Scotland were fined €811.197 million ($906.8 million); and Barclays, RBS and MUFG Bank (formerly Bank of Tokyo-Mitsubishi) were fined €257.682 million ($288 million).

UBS was also included in the commission's decision but wasn't fined, as it had revealed the existence of the cartels to the authorities.

"Today we have fined Barclays, The Royal Bank of Scotland, Citigroup, JPMorgan and MUFG Bank, and these cartel decisions send a clear message that the commission will not tolerate collusive behaviour in any sector of the financial markets," said Margrethe Vestager, the EU's antitrust chief. "The behaviour of these banks undermined the integrity of the sector at the expense of the European economy and consumers."

The commission found that foreign exchange traders at the banks had operated cartels that manipulated the prices of currencies. The traders, who were nominally rivals in the forex market, shared confidential information about their clients' needs and their trading plans in confidential chatrooms.

Traders exchanged information about customers' future orders, the spreads between the prices for buying and selling a currency (known as the bid-ask spread), and their risk positions. The information enabled the traders to make decisions about whether to buy or sell certain currencies and at what price.

The traders gave the chatrooms names that reflected the fact that they knew each other personally. One of the chatrooms was known as "Essex Express 'n the Jimmy", because all the traders except for one named James lived in Essex, an area just outside London, and met on a train into work in the City. Another was called the "Three-Way Banana Split".

The two cartels, known as "Forex – Three-Way Banana Split" and "Forex – Essex Express", ran from December 2007 to January 2014 and from December 2009 to July 2012, respectively.

Several of the banks had their fines reduced because they cooperated with the investigation. UBS escaped fines altogether because it revealed the existence of the cartels to the authorities.

JPMorgan, Citi, Barclays and RBS settled a similar inquiry with the U.S. Department of Justice in 2015. The banks agreed then to pay fines of more than $2.5 billion.

Companies and individuals affected by the cartels have the right to apply for damages in their national courts, the EC said.