Global financial regulators are looking into allegations that traders at some of the world's biggest banks, including Deutsche Bank, colluded to manipulate benchmark foreign-exchange rates used to set the value of trillions of dollars of investments, or the so-called WM/Reuters "fix".
Previously, a separate source had told Reuters that several Deutsche Bank currency traders had been suspended at the bank's New York office.
The investigation by the consulting firm is ongoing, the source said, and it is still sending questions to the bank's traders around the world.
Last year, Britain's Financial Conduct Authority began a formal probe into possible manipulation in the global foreign exchange market.The U.S. Justice Department is also engaged in an active investigation of possible manipulation of the market, the world's largest.
Earlier this month, U.S. banking regulators from the Federal Reserve and Office of the Comptroller of the Currency visited Citigroup Inc's London offices in connection with the investigation.
A spokesperson for the Fed declined comment. While market manipulation isn't the Fed's remit, it does have enforcement powers in safety and soundness matters, an issue raised by this investigation.
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The Office of the Controller of the Currency and the U.S. Department of Justice both declined to comment.
Benchmark foreign exchange rates, often referred to as fixes, are a cornerstone of global financial markets, used to price trillions of dollars worth of investments and deals. They are relied on by companies, investors and central banks.
Deutsche Bank has been the biggest FX trader in the world for nine years running, seeing 15.18 percent of global daily turnover in 2013, according to Euromoney magazine.
The bank previously said it has received requests for information from regulatory authorities investigating trading in the foreign exchange market, and it is cooperating with these probes. It added that it will take disciplinary action with regard to individuals if merited.
As a result of the investigation, Deutsche has restricted the use of chatrooms, another source familiar with the issue said, only allowing conversations between two participants and banning multi-party chats.