An exchange traded fund pegged to the U.S. Dollar Index has broken out in May on Eurozone debt worries and pushed stocks and commodities ETFs lower.

PowerShares US Dollar Index Bullish (NYSEArca: UUP) is on track for a gain of nearly 5% in May. [Currency ETFs: Euro at 2012 Low]

The rally has been so strong and persistent that the dollar ETF has suffered only three down days the entire month. [Dollar ETF Rally Reveals Market Fear, Risks]

From the 2011 low in late July, the dollar has risen against all 16 of its major peers, according to a Bloomberg News report Tuesday. The Dollar Index has rallied 12% and is higher than when the Federal Reserve launched its first bond-buying program in late 2008.

“The dollar is proving scarce, even after the Federal Reserve flooded the financial system with an extra $2.3 trillion, as the amount of the highest-quality assets available worldwide shrinks,” according to the report.

“We’re seeing many more periods of dollar buying during these uncertain times,” Ken Dickson, an investment director of currencies at Standard Life Investments, told Bloomberg.