It appears that over the past 18 months the Federal Reserve has given itself a third, unofficial mandate.

In 1977, Congress gave the quasi-independent central bank what’s known as a dual mandate: It is supposed to promote “the goals of maximum employment, stable prices and moderate long-term interest rates.” In its monetary policy announcements, the Fed interprets the first two clauses as its goals, saying that it “seeks to foster maximum employment and price stability.”