TOKYO—In carrying out their first joint effort in a generation to boost the yen, the U.S. and Japan are seeking to contain ...

The U.S. Treasury's foray into the foreign exchange market on Friday to buy Japanese yen wasn't its first FX intervention and won't be its last. But it was one of its most unusual.

The US Treasury intervened in the foreign exchange market for the first time since 2011, buying Japanese yen to prop up the ...