A regulatory clampdown on foreign-exchange brokerages catering to retail investors is curtailing U.S. trading volumes for individuals, a study said Thursday. Currency trades by retail investors in the U.S. "have dwindled to their lowest levels in years," said the report by research firm LeapRate, which studies the retail foreign-exchange trading sector. In the third quarter, trading volumes at Gain Capital Holdings Inc. (GCAP) fell by 83%, to $12 billion, compared with the prior year's quarter. Volumes at Gain's chief rival, FXCM Inc. (FXCM), fell 47% year over year, to $30 billion, the report said. That's because ... (full story)