HSBC Holdings Plc, Europe's biggest bank by market value, andCitigroup Inc. suspended four traders as the probe into the alleged manipulation of currencies widens.

HSBC suspended two London-based foreign-exchange (FX) traders,according to a statement today. Citigroup put two spot traders whospecialized in G-10 currencies on leave, according to a person withknowledge of the matter who asked not to be identified because thematter is private.

The moves bring the total number of traders known to be fired,suspended or put on leave to at least 17 since Bloomberg Newsreported in June that employees at some firms said they sharedinformation about their positions with counterparts at other banksto try and manipulate the WM/Reuters rates, a key benchmark in the$5.3 trillion-a-day currency market.

The world's seven biggest foreign-exchange dealers have now alltaken action against their employees as regulators in Washington,London, and Switzerland investigate. Together, the firms accountfor about 70 percent of all currency trading globally, according toEuromoney Institutional Investor Plc.

Deutsche Bank AG has the biggest market share at 15.2 percent,followed by Citigroup with 14.9 percent, Barclays Plc at 10.2percent, UBS AG with 10.1 percent, HSBC at 6.9 percent, JPMorganChase & Co. at 6.1 percent, and Royal Bank of Scotland GroupPlc with 5.6 percent, according to the survey.

HSBC suspended London-based traders Edward Pinto and SergeSarramegna, said a person with knowledge of the decision who askednot to be identified because the matter is private.

Citigroup has put Anthony John in London and Andrew Amantia inNew York on leave, according to another person with knowledge ofthe matter who asked not to be identified. None of the tradersresponded to e-mails and telephone calls seeking comment, whileofficials at their employers declined to comment.

The traders are the first to be suspended by HSBC, whileCitigroup last week fired its head of European spot trading RohanRamchandani.

Deutsche Bank suspended several traders after combing throughemployees' electronic communications using search terms negotiatedwith regulators late last year, a person familiar with the mattersaid this week. UBS suspended its co-chief dealer, Niall O'Riordan,while JPMorgan has put its chief dealer in London, Richard Usher,on leave. Edinburgh-based RBS has suspended foreign-exchangetraders Paul Nash and Julian Munson. No individual or firm has beenaccused of any wrongdoing.

'The Cartel'

At the center of investigations are instant-message groups withnames such as “The Cartel,” “The Bandits' Club,” “One Team, OneDream,” and “The Mafia.” Their members exchanged information onclient orders and agreed how to trade at the fix through the messaging platforms,five people with knowledge of the investigations said lastmonth.

Traders on the chats say they were merely matching buyers andsellers ahead of the fix to minimize losses by avoiding trades at atime when prices typically fluctuate the most.

Still, many banks—including Deutsche Bank, Citigroup, JPMorgan,and Goldman Sachs Group Inc.—have clamped down on the use ofmulti-bank instant-message groups.

Senior currency dealers raised the issue of how they communicateto officials at the Bank of England in April 2012, telling themabout how they shared information about orders to reduce the riskof losses in the minutes before benchmarks are calculated, peoplewith knowledge of the meeting said this week. The traders wereconcerned because regulators were scrutinizing instant messages intheir investigations into rigging of the London interbank offeredrate, the people said.

The Bank of England said it's supporting the U.K. FinancialConduct Authority in its investigation into currency manipulation.In the U.S., the Federal Reserve is probing the matter, alongsidethe U.S. Justice Department. The European Union's CompetitionCommission and Swiss Competition Commission are alsoinvestigating.

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