The Chicago Fed National Activity Index, a broad measure of the national economy slumped sharply in August. Remember, the dollar rebound was not predicated on the idea of a strengthening US economy but the deleveraging of the global economy and a return to the US of capital flows that had moved overseas seeking better returns. Once it became clear that the global economy had not decoupled from the US economy as had been assumed, money gushed out of emerging markets like a firehose.