Has the vise started tightening on the UUP shorts? Granted the move today was not huge, the UUP bid most of the day with daily volume being 4,060,000 higher than average of around 1.8 mil. The clear inverse relationship between the UUP and S&P500 is demonstrated by the chart to the left. 



You see as the UUP(blue) traded up, as equities(red) came under pressure. If you take volume into consideration, you can argue UUP moved FIRST then equities moved inversely. I personally did not watch trading close enough to see this anomaly, but one thing is true, if one moves the other moves opposite.



Over time the relationship can become inverted on a daily chart, I.E. fall of 08' when traders flocked to the dollar as the "safe trade". This trade moves like this because the dollar is clearly front and center in traders minds and they know the USD rules the roost. Traders who are in these markets every day are tired of the same grind and are looking for volatility to show its head again, not because traders want the market to fall, they want the market to come to it senses. The USD is clearly the catalyst which can snap this market back into reality.