Discount Rate vs Open Market Operations
Discount Rate and Open Market Operations are two Money & Monetary Policy concepts in AP Economics that students often mix up. The discount rate is the interest rate the Federal Reserve charges commercial banks that borrow from it directly for the short term. Open market operations are the central bank's buying and selling of government bonds to change the money supply. Here is how they compare side by side.
When the Fed lowers the discount rate, it becomes cheaper for banks to borrow, encouraging more lending and increasing the money supply. Raising the discount rate has the opposite effect, tightening monetary policy. It is one of the Fed's tools to influence economic activity.
Buying bonds injects reserves and increases the money supply (expansionary); selling bonds removes reserves and decreases it (contractionary). They are the Federal Reserve's most-used monetary policy tool. They directly affect bank reserves and short-term interest rates.
Discount Rate vs Open Market Operations: Who Decides How Many Reserves Move
| Discount Rate | Open Market Operations | |
|---|---|---|
| What the central bank actually sets | A price: the rate charged on loans made at its lending window | A quantity: the value of government securities the trading desk buys or sells |
| Who starts the transaction | A commercial bank, by choosing to borrow | The central bank, by placing the order |
| Is the reserve change knowable in advance | No, it depends on how many banks show up and for how much | Yes, a purchase of a given size credits exactly that many reserves on settlement |
| How long the reserves stay | Until the loan matures, often the next morning, when they are debited back | Until the desk deliberately reverses the trade |
| How often it is used | Changed a few times a year, and borrowing at the window is episodic | Conducted continuously, in both directions |
| Position relative to the policy target | Priced above the target range, so it is an outside option | Sized to hold the overnight rate inside the target range |
| What a question is testing | Whether you know the quantity is chosen by banks, not by the central bank | Whether you can carry a known injection through the money multiplier |
A discount rate cut can move zero reserves, and a bond purchase never does
Cutting the discount rate is an offer. Buying securities is a done deal. Suppose the desk buys $75 of government securities from banks. On settlement the sellers' reserve accounts are credited, so reserves rise by exactly $75, and nothing about bank willingness enters the arithmetic. Now cut the discount rate by half a percentage point instead. Reserves rise by whatever banks choose to borrow, which could be $75, or $8, or nothing at all, and nobody at the central bank knows the figure until the lending is done. That asymmetry is why the desk trades every day while the discount rate is adjusted a handful of times a year. It also decides which tool a question is really about. A prompt that hands you a reserve ratio and a dollar figure and asks how far deposits can expand is an open market operations prompt, because only there is the opening injection a known number. A prompt that asks why a rate cut failed to increase lending is a discount window prompt, because only there does bank behavior sit between the announcement and the reserves. Run the injection arithmetic at /calculate/money-multiplier and the underlying stock at /glossary/monetary-base-high-powered-money.
One tool leaves reserves in the system; the other takes them back when the loan matures
Discount window loans undo themselves. A loan made at the window has a maturity, frequently overnight, and when it matures the borrowing bank's reserve account is debited and those reserves disappear. The effect on the monetary base is temporary by construction, so a bank that borrows on Monday has reversed the injection by Tuesday unless it borrows again. An open market purchase carries no such maturity. The securities sit on the central bank's balance sheet and the reserves stay in the system until the desk sells them back on purpose. That single difference explains why one tool steers the stance of policy across months while the other patches a single bank's shortfall across a night. It also explains a table row students regularly get backwards. Both tools change the monetary base, but only open market operations change it in a way that persists long enough for several rounds of lending and deposit creation to run. If a free response question asks which tool a central bank would use to raise the money supply and hold it there, naming the discount rate earns nothing, even though a lower rate genuinely does encourage borrowing. The window is a valve, not a pump.
Frequently asked questions
Which matters more for the money supply, the discount rate or open market operations?
Open market operations do almost all of the work. The central bank chooses the size of the trade, so the change in reserves is known before it happens and can be repeated daily until the overnight rate sits where the committee wants it. A discount rate change only alters the price of borrowing, and the quantity borrowed is left to banks, which may be zero. One tool sets an outcome; the other sets an incentive and waits.
Does lowering the discount rate increase the money supply?
Only if banks respond by borrowing. A lower rate makes window borrowing cheaper relative to the alternatives, and each dollar borrowed does add reserves that can support new lending. If banks already hold plenty of idle reserves, or if they fear that borrowing signals weakness, the cheaper price changes nothing and the money supply is unmoved. Write the conditional into an exam answer rather than asserting the increase outright.
Why keep a lending window at all if the central bank can buy bonds?
Because a securities purchase adds reserves to the system in aggregate and cannot aim them at the one bank that is short. The desk buys from whoever offers the best price, and the new reserves land wherever the sellers bank. A window loan goes to the specific institution that needs it, against that institution's collateral, and is repaid when the pressure passes. Aggregate tools and targeted tools solve different problems.
Live Money Market graph. Drag the curves, or open the full version.
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