1. Money, Banking & Financial Assets
Money makes the modern economy possible. But what actually is money? It's not wealth, it's not income β it's a very specific tool that serves three critical functions.
The Three Functions of Money
| Function | What It Means |
|---|---|
| 1. Medium of Exchange | Money is accepted in trade for goods and services. Without it, we'd need barter β which requires a "double coincidence of wants" (you want what I have AND I want what you have). Money eliminates this problem. |
| 2. Unit of Account | Money provides a common measure to price everything. Instead of expressing the value of a car in chickens, we use dollars. It makes comparison shopping possible. |
| 3. Store of Value | Money holds its purchasing power over time (imperfectly β inflation erodes it). You can earn money today and spend it next month. |
Types of Money
Commodity Money
Has intrinsic value β the material itself is valuable.
Examples: Gold coins, silver, salt, cigarettes in prison.
Fiat Money
Has no intrinsic value β it's valuable because the government says so and people trust it.
Examples: US dollar bills, euros, yen. This is what all modern economies use.
Measuring the Money Supply
The money supply is divided into categories based on liquidity (how quickly an asset can be converted to cash):
| Measure | What's Included | Key Detail |
|---|---|---|
| M1 |
Most liquid assets: β’ Currency in circulation (cash) β’ Checkable deposits (checking accounts) β’ Traveler's checks |
This is the "spending money" β things you can use to make purchases immediately. |
| M2 |
M1 plus near-money assets: β’ Savings accounts β’ Money market accounts β’ Small time deposits (CDs under $100k) |
M2 includes everything in M1 plus assets that are easy to convert to cash but can't be spent directly. Exam Tip: M2 is always larger than M1. M2 includes M1. |
Financial Assets: Bonds, Stocks & Their Relationship to Interest Rates
Bond: An IOU. When you buy a bond, you are lending money to the issuer (government or corporation). They promise to pay you back with interest. Bonds have a fixed face value (par value) and pay a fixed coupon.
Stock: A share of ownership in a company. Returns come from dividends and price appreciation. Stocks are riskier than bonds.
The Bond PriceβInterest Rate Inverse Relationship
This is one of the most tested concepts in Unit 4. Bond prices and interest rates move in opposite directions:
Why? A bond pays a fixed dollar amount (say $50/year). If the bond's market price rises from $1,000 to $1,250, the effective interest rate falls: $50 / $1,250 = 4% instead of $50 / $1,000 = 5%. Higher price β lower yield.
Exam Tip: When the Fed buys bonds β bond prices rise β interest rates fall. When the Fed sells bonds β bond prices fall β interest rates rise. This is the core mechanism of monetary policy.2. The Money Market
The Money Market is the graph that shows how the nominal interest rate is determined by the interaction of money supply and money demand. Master this graph β it appears on nearly every AP Macro exam.
Key Components
| Component | Details |
|---|---|
| Money Supply (MS) |
A vertical line β the quantity of money is set by the Federal Reserve and does not change with the interest rate. The Fed shifts MS right (β money supply) or left (β money supply) using monetary policy tools. |
| Money Demand (MD) |
Downward sloping β when interest rates are low, the opportunity cost of holding money is low, so people hold more money (instead of bonds). When rates are high, people prefer to buy bonds and hold less cash. Exam Tip: MD slopes down because of the opportunity cost of holding money. Money earns 0% interest; bonds earn the nominal rate. |
| Equilibrium | Where MS and MD intersect β determines the nominal interest rate. |
What Shifts Money Demand?
| MD Shifts Right (β Demand for Money) | MD Shifts Left (β Demand for Money) |
|---|---|
|
β’ β Price level (need more $ to buy same stuff) β’ β Real GDP / income (more transactions) β’ β Uncertainty about the future |
β’ β Price level β’ β Real GDP / income β’ Advances in payment technology (less need for cash) |
π― The Chain Reaction: β MS β β interest rate β β Investment (I) β β AD β β Real GDP & β Price Level. This is the monetary transmission mechanism β know it step by step for the FRQ.
3. The Federal Reserve & Monetary Policy
The Federal Reserve (the "Fed") is the central bank of the United States. Its job is to manage the money supply and interest rates to keep the economy stable β pursuing maximum employment and stable prices (its "dual mandate").
Monetary Policy: Actions taken by the central bank (the Fed) to change the money supply and interest rates to influence the economy. Unlike fiscal policy (Congress), monetary policy is implemented by an independent body.
The Fed's Three Tools
| Tool | How It Works | Expansionary / Contractionary |
|---|---|---|
| 1. Open Market Operations (OMO) |
The Fed buys or sells government bonds on the open market. This is the most commonly used and most important tool. β’ Buy bonds β money flows from Fed to banks β β bank reserves β β money supply β β interest rates β’ Sell bonds β money flows from banks to Fed β β bank reserves β β money supply β β interest rates |
Expansionary: Buy bonds Contractionary: Sell bonds Exam Tip: "Buy = Big (money supply)" / "Sell = Small (money supply)" β easy memory trick. |
| 2. Discount Rate |
The interest rate the Fed charges commercial banks that borrow directly from the Fed (the "lender of last resort"). β’ β Discount rate β borrowing is cheaper β banks borrow more β β reserves β β money supply β’ β Discount rate β borrowing is more expensive β banks borrow less β β money supply |
Expansionary: β Discount rate Contractionary: β Discount rate |
| 3. Reserve Requirement (RR) |
The fraction of deposits that banks must hold and cannot lend out. β’ β RR β banks can lend more of each deposit β β money creation β β money supply β’ β RR β banks must hold more β β lending β β money supply Rarely changed in practice β too disruptive. But heavily tested on the AP exam. |
Expansionary: β Reserve Requirement Contractionary: β Reserve Requirement |
The Federal Funds Rate
Federal Funds Rate: The interest rate that banks charge each other for overnight loans of reserves. This is the Fed's target rate β the rate it tries to influence through OMO. When you hear "the Fed raised/lowered rates," they mean the federal funds rate.
Expansionary vs. Contractionary β The Full Chain
Expansionary ("Easy Money")
Goal: Fight recession / close recessionary gap.
Fed buys bonds (or β discount rate / β RR)
β β Bank reserves
β β Money supply (MS shifts right)
β β Nominal interest rate
β β Investment (I) & β Consumer borrowing
β AD shifts right
β β Real GDP, β Unemployment, β PL
Contractionary ("Tight Money")
Goal: Fight inflation / close inflationary gap.
Fed sells bonds (or β discount rate / β RR)
β β Bank reserves
β β Money supply (MS shifts left)
β β Nominal interest rate
β β Investment (I) & β Consumer borrowing
β AD shifts left
β β Real GDP, β Unemployment, β PL
π― FRQ Gold: The AP exam will ask you to trace the full chain from the Fed's action β money market β investment β AD-AS β output & price level. Practice writing out every link. Missing a single step costs points.
4. The Money Multiplier
When the Fed adds $1 to the banking system, the total money supply increases by more than $1. This is because banks lend out most of each deposit, and that money gets re-deposited and re-lent β creating new money at every step.
How Banks Create Money
Let's trace a $1,000 deposit through the banking system with a 10% reserve requirement:
| Round | Deposit | Required Reserves (10%) | Lent Out (New Money) |
|---|---|---|---|
| 1st | $1,000 | $100 | $900 |
| 2nd | $900 | $90 | $810 |
| 3rd | $810 | $81 | $729 |
| 4th | $729 | $72.90 | $656.10 |
| β¦ | β¦ | β¦ | β¦ |
| Total | $10,000 | $1,000 | $9,000 |
The initial $1,000 deposit turned into $10,000 of total money in the economy. The banking system created $9,000 of new money through lending.
The Formulas
The Simple Money Multiplier
Example: Reserve requirement = 10% (0.10) β Money Multiplier = 1 / 0.10 = 10.
Maximum Change in the Money Supply
Example: The Fed buys $500 in bonds (adding $500 of excess reserves). rr = 20%. β ΞMS = (1/0.20) Γ $500 = 5 Γ $500 = $2,500 maximum increase in money supply.
Maximum Change in Loans (New Money Created)
Or equivalently: ΞLoans = (Multiplier β 1) Γ Initial Deposit.
Required Reserves vs. Excess Reserves
Required Reserves = Deposits Γ Reserve Requirement β the amount banks must keep.
Excess Reserves = Total Reserves β Required Reserves β the amount banks can lend.
Only excess reserves are multiplied. Required reserves are "locked up."
π― Common Exam Trap: If a person deposits $1,000 cash into a bank, the money supply doesn't change initially (cash moved from circulation into deposits β it's still M1). What changes is that the bank now has excess reserves it can lend, which then creates new money through the multiplier process.
5. The Loanable Funds Market
The Money Market determines the nominal interest rate. The Loanable Funds Market determines the real interest rate β the rate that affects long-term borrowing, investment, and saving decisions. Students often confuse these two graphs. Let's clear that up.
Loanable Funds Market: A model showing the supply of and demand for loanable funds (savings available for lending). The price in this market is the real interest rate.
Supply & Demand in the LF Market
| Component | Details |
|---|---|
| Supply of LF (SLF) |
Comes from savers β households, businesses, and foreign investors who save money in banks or buy bonds. Upward sloping: Higher real interest rates β greater reward for saving β more funds supplied. Also includes national saving = private saving + public saving. |
| Demand for LF (DLF) |
Comes from borrowers β businesses investing in capital, households buying homes, and the government running deficits. Downward sloping: Lower real interest rates β borrowing is cheaper β more funds demanded. |
What Shifts Supply and Demand?
| Curve | Shifts Right (β) | Shifts Left (β) |
|---|---|---|
| Supply (SLF) |
β’ β Savings rate / consumer thriftiness β’ β Foreign capital inflow β’ Government runs a budget surplus (public saving β) |
β’ β Savings rate β’ Capital outflow β’ Government runs a budget deficit (public saving β β government borrows from the pool) |
| Demand (DLF) |
β’ β Business optimism / expected returns β’ β Government borrowing (deficit spending) β’ β Investment tax credit |
β’ β Business confidence β’ β Government borrowing (surplus) β’ β Expected returns on investment |
Crowding Out β The LF Graph in Action
Crowding Out is best understood through the Loanable Funds Market:
Government runs a deficit (spends more than it collects in taxes)
β Government must borrow to cover the gap
β DLF shifts right (government joins the borrowing line)
β Real interest rate rises
β Private Investment falls (businesses can't afford higher rates)
β The increase in G is partially offset by the decrease in I.
Money Market vs. Loanable Funds β Don't Confuse Them!
| Money Market | Loanable Funds Market | |
|---|---|---|
| Y-axis | Nominal interest rate (i) | Real interest rate (r) |
| X-axis | Quantity of money | Quantity of loanable funds |
| Supply | Vertical (set by the Fed) | Upward sloping (savers respond to rates) |
| Demand | Downward sloping (opportunity cost of holding money) | Downward sloping (cost of borrowing) |
| Who controls supply? | The Fed | Savers (households, businesses, foreign investors) |
| Used to show⦠| Monetary policy effects | Fiscal policy effects (gov't borrowing, crowding out) |
π§ Memory Rule: Money Market = the Fed's playground (MS is vertical, the Fed moves it). Loanable Funds = the government borrowing / saving playground (deficit spending shifts demand). Different graphs, different interest rates, different stories.
Unit 4 Formula Cheat Sheet
Money Multiplier = 1 / rr
ΞMSmax = (1 / rr) Γ Ξ Excess Reserves
Required Reserves = Deposits Γ rr
Excess Reserves = Total Reserves β Required Reserves
Real Interest Rate = Nominal Rate β Inflation (Fisher Equation)
Bond prices β βΊ Interest rates β | Buy bonds = β MS | Sell bonds = β MS
End of Unit 4 Study Guide.