Welcome to the World of Global Currencies!

Welcome! If you’ve ever traveled abroad and wondered why your money bought more one year than the next, or if you’ve followed news about "the strengthening Dollar," you’re already thinking like an economist. In this chapter, we are going to dive deep into how exchange rates are determined, how they stay in balance, and how professional traders spot opportunities. Don't worry if this seems tricky at first—we will break it down piece by piece!

1. The Basics: Reading the Quote

Before we dive into the complex math, we must be 100% sure we are reading the "price" correctly. In the CFA curriculum, an exchange rate is usually shown as Price Currency / Base Currency.

For example, if the USD/EUR rate is 1.10, the EUR is the Base Currency (the "thing" you are buying) and the USD is the Price Currency (how much you pay for it). Think of it like buying an apple: if an apple costs $1.10, the apple is the "base" and the dollars are the "price."

The Bid-Ask Spread

Banks and dealers don't exchange money for free. They make money on the spread.

  • Bid: The price the dealer will buy the base currency from you.
  • Ask: The price the dealer will sell the base currency to you.

Quick Tip: From your perspective as a student/customer, you always get the "worse" price. You will always buy at the higher price (Ask) and sell at the lower price (Bid). The dealer follows the rule: Buy low, sell high.

Calculating the Spread in Percent

To find the percentage spread, use this formula:
\( \% \text{Spread} = \frac{\text{Ask} - \text{Bid}}{\text{Ask}} \times 100 \)

Key Takeaway: Always identify the Base Currency first. Everything—the bid, the ask, and the interest rates—revolves around that base unit.

2. Cross Rates and Triangular Arbitrage

Sometimes you want to trade two currencies that aren't quoted against each other directly. To find that rate, we use a third "common" currency to create a Cross Rate.

How to Calculate a Cross Rate

If you have USD/EUR and JPY/USD, and you want to find JPY/EUR, you simply multiply them:
\( \frac{JPY}{EUR} = \frac{JPY}{USD} \times \frac{USD}{EUR} \)

Triangular Arbitrage: Finding "Free Money"

If the cross rate offered by a dealer is different from the cross rate you calculated, an arbitrage opportunity exists. This is a risk-less profit.
Example: If a dealer's JPY/EUR quote is lower than your calculated "implied" rate, the EUR is "cheap" at that dealer. You would buy EUR from them and sell it elsewhere for a profit.

Common Mistake: Forgetting to account for the bid-ask spread when calculating arbitrage. You must use the dealer's Ask to buy and their Bid to sell!

3. Forward Markets and "Points"

A Forward Contract is an agreement to swap currencies at a specific date in the future (e.g., 30, 60, or 90 days) at a price set today. This helps businesses "lock in" prices so they don't have to worry about fluctuations.

Forward Points

Forward rates are often quoted in "points" or "pips." These are small fractions added to or subtracted from the Spot Rate (the current price).
If a spot rate is 1.3500 and the 90-day forward points are +25, the forward rate is:
\( 1.3500 + 0.0025 = 1.3525 \)

Memory Aid: If the points are positive, the base currency is at a Forward Premium. If negative, it is at a Forward Discount.

4. International Parity Conditions: The Core Equilibrium

This is the most important part of the chapter. "Parity" means equality. These concepts explain how interest rates, inflation, and exchange rates all link together. Don't worry if these formulas look scary; they are all based on the idea of fairness between countries.

A. Covered Interest Rate Parity (CIRP)

CIRP says that you shouldn't be able to make extra money by borrowing in one country and investing in another if you use a forward contract to lock in the exchange rate. The formula is:
\( F = S \times \frac{1 + r_{price} \times (\frac{days}{360})}{1 + r_{base} \times (\frac{days}{360})} \)

Did you know? If the interest rate in the Price currency is higher than the Base currency, the Base currency must trade at a forward premium to offset that advantage.

B. Uncovered Interest Rate Parity (UIRP)

UIRP is similar, but it deals with expected future spot rates rather than forward contracts. It suggests that the currency with the higher interest rate is expected to depreciate (lose value) against the lower-interest-rate currency by the amount of the interest differential.

C. Purchasing Power Parity (PPP)

PPP is based on the "Law of One Price." It says a basket of goods (like a Big Mac) should cost the same everywhere when converted to the same currency.

  • Absolute PPP: The exchange rate is simply the ratio of price levels.
  • Relative PPP: Changes in exchange rates are driven by differences in inflation. If the UK has higher inflation than the US, the GBP should weaken against the USD.
D. The International Fisher Effect

This links interest rates and inflation. It states that Nominal Interest Rates = Real Interest Rates + Expected Inflation. Since real rates tend to equalize globally, countries with high nominal interest rates are usually just countries with high expected inflation.

Key Takeaway Summary:
- Higher Interest Rate \(\rightarrow\) Forward Discount (CIRP)
- Higher Inflation \(\rightarrow\) Currency Depreciation (PPP)

5. The Influence of the Balance of Payments

The Current Account tracks a country's trade (exports vs. imports). If a country has a Current Account Deficit, it is buying more from the world than it is selling. Generally, this puts downward pressure on the currency because the country must sell its own currency to buy foreign goods.

The Flow Mechanisms
  1. Current Account Mechanism: A deficit leads to a weaker currency, which eventually makes exports cheaper and fixes the deficit (over the long term).
  2. Capital Account Mechanism: If a country is attractive to investors (high growth, stable government), money flows in, which strengthens the currency, even if there is a trade deficit.

6. Monetary and Fiscal Policy (The Mundell-Fleming Model)

How do government decisions affect the exchange rate? This depends on how easily money can move across borders (Capital Mobility).

High Capital Mobility (The standard for most developed nations)
  • Expansionary Monetary Policy: Lower interest rates \(\rightarrow\) Money flows out \(\rightarrow\) Currency Weakens.
  • Expansionary Fiscal Policy: More government spending \(\rightarrow\) Higher interest rates (to attract lenders) \(\rightarrow\) Money flows in \(\rightarrow\) Currency Strengthens.
Low Capital Mobility (Emerging markets with restrictions)

In these cases, trade flows matter more than interest rates. Expansionary policy (fiscal or monetary) leads to more spending on imports, which causes the Currency to Weaken.

Quick Review Box:
- Monetary Expansion: Usually weakens currency.
- Fiscal Expansion: Usually strengthens currency (if capital can move freely).
- Portfolio Balance Approach: Focuses on the long-term risk of government debt. If a government prints too much money to pay off debt, the currency will eventually crash.

Closing Encouragement

You've made it through one of the most technical chapters in Economics! The secret to mastering FX is always keeping track of which currency is the "Base" and remembering that money flows toward higher real returns and lower inflation. Keep practicing those cross-rate calculations, and the logic will become second nature!