American, British and Swiss regulators levied hefty fines, totaling up to over $3 billion, on five global banks on Wednesday for the attempted manipulation of benchmark rates in foreign exchange markets. The fines follow a year-long investigation into allegations that foreign exchange markets, in which over $5.3 trillion worth of currencies are traded daily, was being rigged by traders.

The U.S. Commodity Futures Trading Commission, or CFTC, the U.K. Financial Conduct Authority, or FCA, and the Swiss Financial Market Supervisory Authority, or FINMA, fined Citibank, JPMorgan Chase, Royal Bank of Scotland, HSBC and UBS a total sum of $3.4 billion. The single-largest penalty was meted out to Switzerland’s UBS, which paid a total of $803 million to the CFTC, FCA and FINMA. UBS also paid the highest single penalty, of $371 million, to the FCA, according to a statement issued by the regulator.

“Today’s record fines mark the gravity of the failings we found and firms need to take responsibility for putting it right. They must make sure their traders do not game the system to boost profits or leave the ethics of their conduct to compliance to worry about,” Martin Wheatley, FCA's CEO, said, in the statement.

The “failings” were found to have occurred between January 2008 and October 2013, during which “ineffective controls” at the banks allowed traders to “put their banks’ interests ahead of those of their clients, other market participants and the wider UK financial system,” FCA said. In its investigation, the FCA found that bank employees had formed groups in which information was shared about client activity in a direct breach of market rules.

“In addition to taking enforcement action against and investigating the six firms where we found the worst misconduct, we are launching an industry-wide remediation programme to ensure firms address the root causes of these failings and drive up standards across the market,” FCA said, in the statement.  

Barclays, which is also facing a similar probe and has not reached a settlement yet, reportedly said that it would seek a more “general coordinated settlement” from the regulators.