Expansionary Monetary Policy vs Contractionary Monetary Policy
Expansionary Monetary Policy and Contractionary Monetary Policy are two Money & Monetary Policy concepts in AP Economics that students often mix up. Expansionary monetary policy increases the money supply to lower interest rates and stimulate aggregate demand. Contractionary monetary policy decreases the money supply to raise interest rates and reduce inflation. Here is how they compare side by side.
The central bank buys bonds, lowers the discount rate, or cuts the reserve requirement. Lower interest rates boost investment and interest-sensitive consumption, shifting aggregate demand right. It is used to fight recession and unemployment.
The central bank sells bonds, raises the discount rate, or increases the reserve requirement. Higher interest rates reduce investment and consumption, shifting aggregate demand left. It is used to fight high inflation.
Expansionary vs Contractionary Monetary Policy: Tracing Both Chains
| Expansionary Monetary Policy | Contractionary Monetary Policy | |
|---|---|---|
| Open market operation | The central bank buys bonds, adding reserves to the banking system | The central bank sells bonds, draining reserves from the banking system |
| Bond prices | Rise, because the central bank bids for a stock of bonds that cannot grow in the moment | Fall, because the central bank increases the supply of bonds private buyers have to absorb |
| Nominal interest rate | Falls, since the money supply curve shifts right and equilibrium slides down a downward-sloping money demand curve | Rises, since the money supply curve shifts left and equilibrium slides up the same curve |
| Other tools set the same way | Lower the discount rate, lower the reserve requirement, pay less interest on reserves | Raise the discount rate, raise the reserve requirement, pay more interest on reserves |
| Currency and net exports | Lower rates push financial capital out, the currency depreciates, and net exports rise | Higher rates pull financial capital in, the currency appreciates, and net exports fall |
| Where it runs out of room | Hits a floor near a zero nominal rate, where further bond buying may not lower the rate borrowers face | Has no ceiling, since a nominal rate can be raised as far as the central bank is willing to go |
The two policies stop being mirror images near a zero interest rate
Contractionary monetary policy has no upper limit, since a central bank can keep raising the policy rate until borrowing becomes painful. Expansionary monetary policy meets a floor, because a nominal rate cannot fall far below zero without savers preferring cash to deposits. The asymmetry is visible on the money market graph. In the normal case, shifting the money supply curve right slides equilibrium down a downward-sloping money demand curve, so the interest rate falls, investment rises, and aggregate demand shifts right. Once the rate is already near zero, money demand is flat over the relevant range, so the same rightward shift leaves the interest rate unchanged, investment unchanged, and aggregate demand unchanged. That is the liquidity trap, and a prompt that puts the policy rate at or near zero is usually asking you to say that monetary policy has lost its grip and that fiscal policy is the remaining lever.
The money multiplier gives a ceiling, not a forecast
With a required reserve ratio of 20 percent, the money multiplier is 1 divided by 0.20, which equals 5. A central bank purchase of $30 million in bonds can expand the money supply by at most $150 million, and a $30 million sale can shrink it by at most $150 million. Both figures are ceilings rather than predictions. Banks that sit on excess reserves lend less than the model assumes, and households that keep part of each new loan as cash pull dollars out of the deposit chain, so the realized change lands short of the ceiling. Notice which direction a bank can refuse. A purchase only creates the opportunity to lend, and a bank that wants to hold the new reserves may simply hold them, while a sale takes reserves out whether banks wanted to lend or not. Free-response prompts usually ask for the maximum possible change, so state the multiplier, show the arithmetic, and label the answer as a maximum.
Frequently asked questions
Does expansionary monetary policy raise or lower bond prices?
Expansionary monetary policy raises bond prices. The central bank enters the market as a buyer, bidding for a stock of bonds that cannot grow in the moment, and the extra demand pushes prices up. Because a bond's coupon is fixed in dollars, a higher price means a lower yield, which is the same thing as a lower interest rate. Contractionary policy runs the chain backward, since selling bonds pushes prices down and yields up. Learn the price and the rate as one movement, because exam questions test both in the same sentence.
Which monetary policy should a central bank use during stagflation?
Stagflation gives a central bank no clean answer, because output is falling while the price level is rising. Expansionary monetary policy would raise output and employment, but it pushes the price level higher still. Contractionary policy would bring inflation down, but it deepens the fall in output and raises unemployment further. A question about a negative supply shock usually wants that trade-off stated explicitly rather than a winner picked, followed by the point that only a rightward shift in short-run aggregate supply fixes both problems at once.
How does monetary policy change the exchange rate?
Expansionary monetary policy lowers the domestic real interest rate, which makes domestic financial assets less attractive, so financial capital flows out and demand for the currency falls. The currency depreciates, exports get cheaper for foreign buyers, imports get more expensive, and net exports rise, reinforcing the increase in aggregate demand. Contractionary monetary policy reverses every step. The real interest rate rises, capital flows in, the currency appreciates, and net exports fall. Trace all four links, since a chain that stops at the interest rate loses the later points.
Want the long version? Expansionary vs Contractionary Policy: Full Matrix walks through the same comparison as a full guide, with worked examples and the exam traps. This page is the quick side-by-side.
Live Money Market graph. Drag the curves, or open the full version.
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