Currency traders are having their worst start to a year since 2010 as a dearth of trends in major foreign-exchange markets crushes their investment strategies. Deutsche Bank AG’s Currency Returns Index has dropped 0.3 percent since Dec. 31, dragged down by momentum trading, where investors looks for consistent moves in one direction. The gauge, which is also based on techniques including carry and valuation, rose in 2013 by the most in four years. As emerging-market currencies from Argentina’s peso to South Africa’s rand plunge, managers are drawing little benefit from strategies designed to provide returns in times ... (full story)