USD is negatively correlated with the US stock markets. US stock markets have an effect on the value of the USD everybody selling stock to buy USD everybody wants cash or USD even though US has trillions in debt. I guess there are no safe currencies to hold. that is how powerful or important the stock market is. stocks markets can mover currency markets or value of USD the question what will people do when the USD has it's day of reckoning and they need to sell USD. what are they going to hold. the only thing cash produce is paper. even foreign investors and institutions are buying USD. it'll be the day when US companies and gov't start own Chinese Treasuries and currency.