US, British and Swiss regulators have fined six major banks more than 4-billion US dollars for attempting to manipulate foreign exchange markets.
Citibank, JPMorgan Chase, Royal Bank of Scotland, HSBC, UBS and Bank of America all faced penalties resulting from the inquiry.
Regulators contend the six banks have failed to adequately train and supervise foreign currency traders since the start of the global financial crisis in 2008.
Martin Wheatley is the head of UK Financial Conduct Authority.
"The banks' failures to establish adequate systems and controls are what allowed the traders to manipulate the fixed rates across the world's largest currencies and failings like this seriously undermine confidence in the market and undermine the attempts to genuinely reform banking culture."
British bank Barclays is also included in the probe.
But it hasn't agreed to any settlement as of yet.
