Japanese Yen's Drop Raises Potential for Broader Market Trouble

The Japanese yen has tumbled to a 20-year low against the U.S. dollar. That might be bad news for markets far beyond Tokyo.

Traders around the world watch the yens rise and fall not just to follow Japanese markets but also to gauge how investors globally are feeling. Usually, when markets are rallying, the yen tends to weaken against other currencies. When markets get turbulent, the yen tends to gain ground.