Money supply and demand

Welcome to the World of Money!

Hello there! Today, we are diving into one of the most fascinating parts of macroeconomics: Money Supply and Demand. Think of money as the "oil" that keeps the engine of the economy running smoothly. Without it, trading would be incredibly difficult (imagine trying to trade your laptop for 500 cups of coffee!).

In this chapter, we will explore what money actually is, how it is created by banks, and why people choose to hold onto it. Don't worry if this seems a bit abstract at first—we’ll use plenty of everyday examples to make it stick. By the end of these notes, you'll see "cash" in a whole new light!

1. What is Money? (Functions of Money)

In economics, Money is anything that is widely accepted as payment for goods and services. It isn't just the coins in your pocket; it’s a tool that performs four essential jobs:

• Medium of Exchange: It’s used to buy and sell things. This solves the "double coincidence of wants" problem in bartering.
• Unit of Account: It provides a common measure of value. Instead of saying a car is worth 10 cows, we say it’s worth \( \$200,000 \).
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• Store of Value: You can keep it and use it in the future. It holds its purchasing power over time (unless inflation is very high!).
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• Standard of Deferred Payment: It allows us to agree on a value for debts to be paid in the future.
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Quick Review: To be "money," an item must be divisible, portable, durable, and scarce.

2. Measuring the Money Supply

In Hong Kong, the Hong Kong Monetary Authority (HKMA) measures money supply using different categories based on liquidity (how quickly you can turn it into cash to spend).

The "M" Categories:

1. M1 (Narrow Money): The most liquid. It includes physical currency (notes and coins) plus demand deposits (money in current accounts that you can spend immediately via a debit card).

2. M2: Includes everything in M1 + savings deposits and time deposits with licensed banks.

3. M3 (Broad Money): Includes everything in M2 + deposits with restricted license banks and deposit-taking companies.

Memory Aid: Think of M1 as your "Wallet," M2 as your "Wallet + Savings Account," and M3 as the "Total Bank System." As you go from M1 to M3, the money becomes less liquid.

3. How is Money Created? (The Fractional Reserve System)

Did you know that most of the money in the world isn't printed by a central bank? It’s created by commercial banks when they give out loans! This is called the Credit Creation Process.

The Process:

1. You deposit \( \$1,000 \) in Bank A.
2. The bank is required to keep a small percentage (the Required Reserve Ratio) as cash.
3. The bank lends out the rest to someone else.
4. That person spends the money, and the receiver deposits it into Bank B.
5. Bank B lends out a portion of that deposit... and the cycle continues!

The Money Multiplier Formula:

The total amount of money created from an initial deposit depends on the Money Multiplier.

\( \text{Money Multiplier} = \frac{1}{\text{Required Reserve Ratio (R)}} \)

\( \text{Total Money Supply Change} = \text{Initial Deposit} \times \text{Money Multiplier} \)

Example: If the reserve ratio is \( 10\% \) (or \( 0.1 \)), the multiplier is \( 1 / 0.1 = 10 \). An initial deposit of \( \$1,000 \) could eventually create \( \$10,000 \) in the total money supply!

Common Mistake: Students often forget that if people choose to hold cash "under the mattress" instead of depositing it, the money multiplier effect weakens. This is called a cash leakage.

4. The Demand for Money

Why do people want to hold money (cash/bank balances) instead of investing it in stocks or bonds? John Maynard Keynes identified three main motives:

1. Transactions Motive

You need money to buy your morning coffee, pay rent, and commute. This depends mainly on your Income (Y). If you earn more, you spend more, so you need more liquid money.

2. Precautionary Motive

This is "saving for a rainy day." You keep some money aside for unexpected medical bills or a broken phone. This also increases as Income (Y) increases.

3. Speculative Motive

This is the tricky one! People hold money to avoid losses in other assets (like bonds).
- When interest rates are high, the "opportunity cost" of holding cash is high (you’re missing out on interest). So, demand for money falls.
- When interest rates are low, the cost of holding cash is low. So, demand for money rises.

Key Takeaway: There is an inverse (negative) relationship between the interest rate and the quantity of money demanded. This is why the Money Demand curve slopes downward!

5. The Money Market Equilibrium

In the money market, the Interest Rate acts as the "price" of money.

• Money Supply (Ms): Usually represented as a vertical line because it is controlled by the Central Bank (or the HKMA) and does not depend on the interest rate.
• Money Demand (Md): A downward-sloping curve.

The Equilibrium Interest Rate is found where the Supply of money meets the Demand for money.

What happens if the Interest Rate changes?

- If the interest rate is above equilibrium, there is an excess supply of money. People will use the extra cash to buy bonds, driving bond prices up and interest rates back down.
- If the interest rate is below equilibrium, there is an excess demand (shortage) of money. People will sell bonds to get cash, driving interest rates back up.

Did you know? Bond prices and interest rates have an inverse relationship. When one goes up, the other goes down!

6. Summary and Quick Review

To wrap up this chapter, remember these three core pillars:

1. Supply: Controlled by the central authority and expanded by commercial banks through the multiplier effect.
2. Demand: Driven by our need to spend (Transactions), our fear of the unknown (Precautionary), and our investment strategy (Speculative).
3. Equilibrium: The point where supply meets demand determines the interest rate in the economy.

Don't worry if the speculative motive feels confusing! Just remember: High Interest = Low Money Demand (because you'd rather have your money in a bank earning interest than sitting in your pocket).

Check your understanding:

1. If the HKMA increases the money supply, what happens to the interest rate? (Answer: It falls!)
2. If the reserve requirement increases, does the money multiplier get larger or smaller? (Answer: Smaller! Banks have to keep more and can lend less.)

Keep going! You're doing great. Understanding how money moves is a huge step toward mastering Macroeconomics!