The euro hit its highest level since early February vs. the U.S. dollar Tuesday, bringing its gain against the greenback to more than 2 percent in March.
If the losses for the dollar continue, it should kick-start the S&P 500 and gold, which have stalled this month, history shows.
An emerging markets ETF should continue its monster March breakout, past trading patterns indicate.
Using hedge fund analytics tool Kensho, CNBC PRO analyzed which ETFs thrived when the dollar declined 5 percent or more vs. the euro in one month.
Here are the top performing ETFs, on average:
Here is the average performance of ETFs tracking the S&P 500, gold and emerging markets:
Right now in March, the S&P 500 is little changed but heading lower in midday trading Tuesday. Gold is off by about 1 percent. These should reverse if the dollar keeps falling and if history is any guide. The iShares MSCI Emerging Markets ETF is already up 4 percent this month.
Disclosure: NBCUniversal, parent of CNBC, is a minority investor in Kensho.