Ask a currency trader in today’s market how the US dollar is likely to react to positive news on the economy and the response is likely to be a blank stare.

Just as the forex market has managed to wash its hands of the confusing question of how to trade the euro, a new conundrum has reared its head. The US dollar now has the dubious honour of being the currency that is the most difficult to predict, after defying expectations that it would get weaker when the Federal Reserve launched its third round of monetary easing, or QE3.

“People have turned from euro speculation to dollar speculation since QE3 but that’s not working out as they hoped – people aren’t getting bang for their bucks,” says Richard Usher, JPMorgan’s head of spot forex trading in London.