Misfiring Models Leave Wall Street Currency Traders Flying Blind

Some of Wall Street’s tried-and-true currency strategies aren’t working anymore, and it’s baffling even the most seasoned traders.

Before President Donald Trump’s policies sent the dollar plunging, investors could reliably use a number of indicators to figure out how to trade. Europe cuts interest rates? Sell euros. Markets look jittery? Buy dollars. Oil prices spike? Time to snap up currencies from commodity exporters.