Quantitative easing is an unconventional monetary policy where a central bank purchases securities to increase the flow of credit in financial markets when nominal interest rates are near zero. If quantitative easing is successful in making it easier for firms to obtain credit, the premium that firms pay above the federal funds rate would fall. In an IS-LM diagram, quantitative easing would cause a shift of the IS curve to the right, representing increased aggregate demand and output as access to credit improves.