In a rare coordinated move, Japan and the United States confirmed they jointly intervened in foreign exchange markets last week to halt a sharp slide in the yen after the currency plummeted to a new 40-year low.This marks the first joint FX intervention between Washington and Tokyo since 2011, when the two nations took coordinated action to weaken the yen following the catastrophic earthquake and tsunami in eastern Japan.Why Both Nations Stepped InThe joint effort underscores growing concerns th...