Shifts in Money Demand and Money Supply

The money market graph plots the nominal interest rate on the vertical axis and the quantity of money on the horizontal axis. Money demand slopes down because a higher interest rate raises the opportunity cost of holding cash instead of an interest-bearing asset, so people hold less of it. Money demand shifts, rather than slides, when something other than the interest rate changes how much money people need for transactions. A higher price level means the same basket of goods costs more dollars, so people need more cash on hand just to buy groceries and pay rent. That shifts money demand right. The same thing happens when real GDP grows: more output means more transactions, more paychecks, more purchases, so people want to hold more money at every interest rate.

Money supply is drawn as a vertical line, set by the central bank through tools like open market operations, independent of the interest rate. When money demand shifts right and supply stays fixed, the equilibrium nominal interest rate rises, because the fixed quantity of money now has more people competing to hold it. A change in the interest rate itself never shifts demand; it only moves you along the existing curve, since the curve already shows how quantity demanded responds to rate changes.

This nominal rate set in the money market is also the rate businesses and households face when borrowing to invest. A higher equilibrium rate makes borrowing more expensive, so planned investment falls, which pulls down aggregate demand. That link is how a shift inside the money market ripples out into the whole economy.