U.S., British and Swiss regulators fined five global banks more than $3 billion for attempted manipulation of foreign exchange markets.

The U.S. Commodity Futures Trading Commission, the U.K. Financial Conduct Authority and the Swiss Supervisory Markets Authority said Wednesday that they had fined Citibank, JPMorgan Chase Bank, Royal Bank of Scotland, HSBC Bank and UBS a total of $3.4 billion.

Martin Wheatley, chief executive of the FCA, says the record fines "mark the gravity of the failings we found and firms need to take responsibility for putting it right."