With its interest rate instrument at the zero lower bound, the Federal Open Market Committee has turned to unconventional methods to stimulate economic growth and increase employment. Prominent among these is quantitative easing (QE) — the purchase of a large quantity of longer-term debt....

It is widely believed that the Fed controls the funds rate by altering the degree of pressure in the reserve market through open market operations when it changes its target for the federal funds rate. Recently, however, several economists have suggested that open market operations may not be...