Deutsche Bank AG was dethroned after a nine-year reign as theworld's biggest currency trader by Citigroup Inc., a EuromoneyInstitutional Investor Plc survey showed, as subdued volatilitydepressed trading in the euro.

Citigroup, which last led the ranking in 2002, claimed 16.04percent market share, beating Deutsche Bank's 15.67 percent,Euromoney said in a statement. The U.S. bank trailed its Germanrival by just 0.28 percentage point in the 2013 poll, thesecond-slimmest margin since it began in 1976. Barclays Plc was thethird-largest trader, with a 10.91 percent share.

The biggest dealers in the $5.3 trillion-a-day foreign-exchangemarket are facing reduced revenues after stimulus efforts bycentral banks around the world muffled many of the trends thattraders and investors use to make money. That's adding tocompetition among banks, which are pushing more trading ontoelectronic platforms to boost market share.