Why the US economy doesn't need to improve for the US dollar to rally

Deutsche Bank estimates there are around $47 trillion dollars in private and official investment in emerging markets.

That money slowly moved out of US dollars (mostly), euros and other currencies over a number of years. As the tide turned against emerging markets last year and continues to do so now, that money rushes home.

Deutsche Bank estimates there is at least $1 trillion invested in unhedged ETFs.