The U.S. National Futures Association may change its rules for how much leverage retail clients trading currencies can take on, a spokeswoman said on Tuesday, after last week's emergency rescue of broker FXCM . The Chicago-based NFA, which oversees the trading of retail foreign exchange products, said any chances would be to make sure that its leverage requirements were in line with those of exchanges that trade currency products. "Any changes to our rules do require board approval. NFA's next board meeting is Feb. 19," the spokeswoman said in an emailed statement. Shares in retail currency broker FXCM lost two-thirds ... (full story)