Either a decrease in the nominal money supply by the Federal Reserve, all else held constant. or an increase in the price level, all else held constant, will shift the aggregate demand [AD] curve to the left. The Keynesian portion of the short-run aggregate supply [5A5] curve would be relevant during a recessionary situation. Stagnation occurs when the aggregate demand [AD] curve shifts out on the upward sloping portion of the short-run aggregate supply [5A5] curve