Effect of Changes, Foreign Exchange Market

SECTION 1

Historical Context & Motivation

The foreign exchange market (often abbreviated as forex or FX) is the largest and most liquid financial market on the planet, with daily trading volumes exceeding $7.5 trillion as of 2022. Unlike equity or bond markets that emerged from centralized exchanges, the forex market evolved organically from the practical need for nations and merchants to convert currencies in order to conduct cross-border trade and investment. Understanding how government policies and macroeconomic conditions shift supply and demand for currencies is essential for any business professional operating in a globalized economy, whether managing multinational operations, hedging foreign receivables, or evaluating sovereign risk in an investment portfolio.

For most of modern economic history, currency values were not determined by market forces at all. The prevailing international monetary arrangements—first the gold standard, then the Bretton Woods system—pegged exchange rates to gold or the U.S. dollar. When the Bretton Woods system collapsed in the early 1970s, the world transitioned to a regime of floating exchange rates in which currency values fluctuate based on supply and demand in decentralized global markets. This transition made it critically important for economists, policymakers, and business leaders to understand the determinants of exchange rate movements.

1870–1914

Classical Gold Standard

Major economies fixed their currencies to gold at set parities, creating stable exchange rates but limiting domestic monetary policy flexibility. Capital flowed freely across borders under this regime.

1944

Bretton Woods Agreement

Post-WWII delegates at Bretton Woods, New Hampshire, established a system of fixed exchange rates anchored to the U.S. dollar, which was convertible to gold at $35 per ounce. The IMF was created to oversee the system.

1971

Nixon Shock & End of Convertibility

President Nixon suspended the dollar's gold convertibility, effectively ending Bretton Woods. Major currencies began floating against one another, giving rise to the modern foreign exchange market.

1992

ERM Crisis & Black Wednesday

Speculator George Soros famously shorted the British pound, forcing the UK's exit from the European Exchange Rate Mechanism. The crisis illustrated how macroeconomic fundamentals and policy credibility can overwhelm fixed-rate regimes.

2008–Present

Quantitative Easing & Policy Divergence

The global financial crisis ushered in an era of unconventional monetary policy—zero interest rates, quantitative easing, and forward guidance—creating dramatic currency movements driven by policy divergence among the Fed, ECB, and BOJ.

The central question this lesson addresses is straightforward yet far-reaching: How do changes in fiscal policy, monetary policy, trade policy, and underlying economic conditions shift the supply and demand curves in the foreign exchange market, and what are the resulting effects on equilibrium exchange rates? By mastering this framework, you will be equipped to predict the direction of currency movements when you read news about interest rate changes, budget deficits, inflation reports, or shifts in trade balances.

SECTION 2

Core Principles & Definitions

Before analyzing how policies and conditions affect exchange rates, we must establish a precise vocabulary for the foreign exchange market. The exchange rate is the price of one currency expressed in terms of another. In macroeconomics, we typically graph the exchange rate on the vertical axis and the quantity of currency on the horizontal axis, treating the domestic currency like any other good whose price is determined by supply and demand. When the domestic currency rises in value relative to a foreign currency, we say it has appreciated; when it falls, it has depreciated.

Demand for a Currency

Foreign entities demand a domestic currency when they want to buy that country's goods, services, or financial assets. Higher demand (rightward shift of the demand curve) causes the currency to appreciate.

Supply of a Currency

Domestic residents supply their own currency when they want to purchase foreign goods, services, or assets. An increase in supply (rightward shift of the supply curve) causes the currency to depreciate.

Nominal vs. Real Exchange Rate

The nominal exchange rate is the quoted market price (e.g., 1 USD = 0.92 EUR). The real exchange rate adjusts for relative price levels, measuring actual purchasing power across borders.

Interest Rate Parity

Capital flows toward higher real returns. When a country's interest rates rise relative to others, foreign investors demand more of its currency, driving appreciation—a core channel for monetary policy transmission to the FX market.

Purchasing Power Parity (PPP)

In the long run, exchange rates should adjust so that identical goods cost the same across countries. Higher domestic inflation relative to trading partners erodes purchasing power and tends to cause currency depreciation.

✦ KEY TAKEAWAY

Think of a currency as a commodity traded in a marketplace—like coffee beans. Anything that makes foreigners want more of your country's 'product' (higher interest rates, attractive investment opportunities, desirable exports) increases demand for your currency and bids up its price. Anything that makes your own citizens eager to spend abroad increases the supply of your currency on the market and pushes its price down. Every policy or economic change we analyze in this lesson operates through one of these two channels: shifting the demand curve, the supply curve, or both.

SECTION 3

Visual Explanation — The Foreign Exchange Market Model

The standard graphical model of the foreign exchange market plots the exchange rate (the price of the domestic currency in terms of a foreign currency) on the vertical axis and the quantity of the domestic currency exchanged on the horizontal axis. The demand curve slopes downward because as the domestic currency becomes cheaper (depreciates), foreign buyers find domestic goods, services, and assets more affordable. The supply curve slopes upward because as the domestic currency becomes more expensive (appreciates), domestic residents find foreign goods cheaper, incentivizing them to sell more domestic currency in exchange for foreign currency.

The diagram shows the standard foreign exchange market for U.S. dollars. The downward-sloping demand curve (D$) and upward-sloping supply curve (S$) intersect at the equilibrium exchange rate e* and quantity Q*. The dashed green line (S$') illustrates a rightward shift in supply—for example, from U.S. residents buying more foreign goods—which causes the dollar to depreciate to e*'.

This model is the analytical workhorse for every scenario we will examine. When a policy change or economic condition shifts demand to the right, the domestic currency appreciates (the exchange rate rises on the vertical axis). When demand shifts left, the currency depreciates. A rightward shift in supply causes depreciation because more domestic currency is being offered for sale; a leftward shift in supply causes appreciation. Many real-world events shift both curves simultaneously, and the net effect on the exchange rate depends on the relative magnitudes of the shifts.

SECTION 4

How Policies & Conditions Transmit to the FX Market

Monetary Policy Channel

When a central bank raises its policy interest rate (such as the Federal Reserve raising the federal funds rate), domestic financial assets become more attractive to global investors seeking higher returns. This triggers an inflow of foreign capital: investors must first purchase the domestic currency before buying domestic bonds or deposits, which shifts the demand for the domestic currency to the right. Simultaneously, domestic residents find foreign assets relatively less attractive, so they supply less of their own currency on the FX market, shifting the supply curve to the left. Both effects work in the same direction: the domestic currency appreciates. Conversely, a rate cut leads to depreciation.

UNCOVERED INTEREST RATE PARITY (UIP)

i_domestic − i_foreign ≈ (E_expected − E_spot) / E_spot

Where i = nominal interest rate, E_spot = current exchange rate, and E_expected = expected future exchange rate. The condition implies that if domestic rates exceed foreign rates, the market expects the domestic currency to depreciate by a corresponding amount—but in the short run, the initial capital inflow typically causes appreciation before any expected depreciation materializes.

Fiscal Policy Channel

Expansionary fiscal policy—increased government spending or tax cuts—stimulates aggregate demand, which raises national income and, through money-market effects, can push up interest rates (the crowding-out effect). Higher interest rates attract foreign capital, increasing demand for the domestic currency and causing appreciation. However, the higher income also increases imports, which raises the supply of domestic currency on the FX market—an offsetting effect. In most standard macroeconomic models, the interest rate effect dominates, producing net appreciation of the domestic currency, at least in the short to medium run.

Inflation & Relative Price Level Channel

If a country experiences higher inflation than its trading partners, its goods become relatively more expensive. Foreigners reduce purchases of those goods, decreasing their demand for the domestic currency. At the same time, domestic consumers shift toward cheaper imports, increasing the supply of domestic currency on the FX market. Both curves move in a direction that produces depreciation of the domestic currency.

RELATIVE PURCHASING POWER PARITY

%ΔE ≈ π_domestic − π_foreign

Where %ΔE = percentage change in the exchange rate and π = inflation rate. If domestic inflation exceeds foreign inflation by 3 percentage points, the domestic currency should depreciate by approximately 3% over the same period.

Income & Growth Channel

An increase in national income or real GDP growth raises consumer spending, including spending on imports. As domestic consumers buy more foreign goods, they supply more domestic currency on the FX market. This rightward shift in currency supply leads to depreciation of the domestic currency, all else being equal. However, rapid GDP growth may simultaneously attract foreign direct investment, which shifts demand for the currency to the right. The net effect depends on which flow—imports or capital inflows—responds more strongly to the growth shock.

SECTION 5

Detailed Breakdown — Policy Scenarios & Their FX Effects

The following diagram and table consolidate the most common policy and economic scenarios into a reference framework. Each scenario is traced through its impact on the supply and demand for the domestic currency, culminating in either appreciation or depreciation. Business professionals routinely use this type of analysis when conducting scenario planning for treasury operations, setting hedging strategies, or advising clients on cross-border investments.

This flowchart traces five common policy or economic scenarios through their effects on the supply and demand for the domestic currency, arriving at the net effect on the exchange rate. Note that expansionary fiscal policy has offsetting effects (higher interest rates attract capital, but higher income raises imports); the standard conclusion is that the interest rate channel dominates, producing net appreciation.

Summary of policy and economic scenarios and their FX market effects

Scenario	Demand for $	Supply of $	Net FX Effect
Tight monetary policy (↑ i)	Increases (capital inflows)	Decreases (domestic capital stays home)	Appreciation
Loose monetary policy (↓ i)	Decreases (capital outflows)	Increases (seeking foreign returns)	Depreciation
Expansionary fiscal policy	Increases (crowding-out raises i)	Increases (higher Y → more imports)	Net appreciation (i effect dominates)
Higher domestic inflation	Decreases (exports less competitive)	Increases (imports cheaper relatively)	Depreciation
Increase in tariffs on imports	Unchanged or slightly up	Decreases (fewer imports)	Appreciation
Rise in domestic income (↑ GDP)	Ambiguous (may attract FDI)	Increases (more import spending)	Likely depreciation
Foreign country raises its rates	Decreases (capital flows abroad)	Increases (domestic investors go abroad)	Depreciation

SECTION 6

Worked Example — The Fed Raises Interest Rates

Suppose the U.S. Federal Reserve announces a 50-basis-point increase in the federal funds rate, raising it from 4.50% to 5.00%, while the European Central Bank holds its main refinancing rate steady at 3.75%. We will trace the effect on the USD/EUR exchange rate using the supply-and-demand framework for the foreign exchange market.

Tracing a Fed Rate Hike Through the FX Market

Step 1 — Identify the Policy ChangeThe Fed has raised the U.S. interest rate by 50 basis points (0.50 percentage points). The interest rate differential between the U.S. and the Eurozone widens from 0.75% to 1.25%. This is a contractionary monetary policy move that makes U.S. financial assets more attractive relative to European assets.

Interest rate differential: 5.00% − 3.75% = 1.25%

Step 2 — Determine the Demand ShiftEuropean and other foreign investors, seeking higher returns, will redirect capital toward U.S. Treasury bonds, corporate bonds, and money market instruments. To purchase these U.S.-denominated assets, they must first buy U.S. dollars with their euros. This increases the demand for dollars in the foreign exchange market, shifting the demand curve from D₁ to D₂ (to the right).

Demand curve shifts rightward

Step 3 — Determine the Supply ShiftU.S. investors, who might otherwise have sent capital to Europe for higher returns, now find domestic assets more competitive. They have less incentive to convert dollars into euros, so the supply of dollars on the FX market decreases. The supply curve shifts from S₁ to S₂ (to the left).

Supply curve shifts leftward

Step 4 — Determine the New EquilibriumBoth shifts work in the same direction. The rightward demand shift and leftward supply shift both put upward pressure on the exchange rate (the price of dollars in terms of euros). The dollar appreciates against the euro. For example, the exchange rate might move from €0.92 per dollar to €0.96 per dollar. The effect on quantity exchanged is ambiguous—it depends on the relative magnitudes of the two shifts.

Exchange rate rises: e* moves from €0.92/$ to approximately €0.96/$ — the dollar has appreciated.

Step 5 — Assess Real-World ImplicationsA stronger dollar means U.S. exports become more expensive for European buyers, potentially reducing U.S. net exports. For a U.S.-based multinational, revenues earned in euros translate into fewer dollars when repatriated. Conversely, imports become cheaper for American consumers. A U.S. firm considering hedging strategy should recognize that the rate hike creates short-term appreciation pressure, though UIP suggests the dollar may gradually depreciate back toward its long-run equilibrium.

USD appreciates; U.S. net exports likely decline; import costs fall for U.S. consumers.

SECTION 7

Strengths & Limitations of the Supply-Demand FX Framework

The supply-and-demand model of the foreign exchange market provides a powerful and intuitive analytical tool, but like all models, it simplifies a complex reality. Understanding its strengths and limitations is essential for applying it responsibly in business decision-making and policy analysis.

Strengths and limitations of the basic FX market supply-demand model

Strengths	Limitations
Provides a clear, graphical framework for predicting the direction of exchange rate movements in response to policy changes.	Does not predict the magnitude of exchange rate changes—only the direction (appreciation vs. depreciation).
Isolates the key channels (interest rates, inflation, income, trade policy) through which shocks transmit to the FX market.	Treats each channel in isolation (ceteris paribus), whereas real-world events trigger multiple simultaneous shifts that may offset one another.
Applicable to any currency pair and consistent with broader macroeconomic models (IS-LM-BP, AD-AS).	Ignores speculative dynamics, herding behavior, and market sentiment—which can dominate short-run exchange rate movements.
Intuitive for business professionals who are already familiar with supply and demand from microeconomics.	Assumes flexible exchange rates; the model requires significant adaptation for fixed or managed float regimes.
Useful for AP/college-level exams and as a foundation for more advanced international finance models.	Empirical performance of PPP and UIP is mixed—exchange rates often deviate from theoretical predictions for extended periods.

✦ KEY TAKEAWAY

Think of the supply-demand FX model as a compass rather than a GPS. A compass reliably tells you which direction you are heading—north or south, appreciation or depreciation—but it does not tell you exactly how many miles (or basis points) you will travel. In financial practice, traders and corporate treasurers combine this directional framework with quantitative tools like econometric models and option pricing to put precise numbers on expected moves.

SECTION 8

Connection to Advanced International Finance Theory

The supply-and-demand framework presented in this lesson provides the conceptual foundation upon which more sophisticated models of exchange rate determination are built. As you advance in international macroeconomics and finance, you will encounter models that incorporate expectations, asset-market dynamics, and general equilibrium effects. The table below maps the basic concepts from this lesson to their advanced counterparts, giving you a roadmap for further study.

Mapping basic FX concepts to advanced theory

Basic Concept (This Lesson)	Advanced Extension
Interest rate differential drives capital flows and currency demand	Mundell-Fleming Model (IS-LM-BP): Formalizes the interaction of goods, money, and FX markets under perfect capital mobility. Shows that monetary policy is effective under flexible rates while fiscal policy is partially offset by exchange rate changes.
Relative inflation causes depreciation (PPP)	Dornbusch Overshooting Model: Explains why exchange rates overshoot their long-run PPP equilibrium in the short run due to sticky goods prices and rapid financial-market adjustment. A monetary expansion causes immediate overshooting depreciation followed by gradual recovery.
Uncovered Interest Rate Parity (UIP)	Carry Trade & Forward Premium Puzzle: Empirically, UIP often fails: high-interest-rate currencies tend to appreciate rather than depreciate as UIP predicts. This anomaly gives rise to the carry trade strategy and remains an active area of financial research.
Supply-demand equilibrium in a single currency market	General Equilibrium & DSGE Models: Advanced models embed the FX market within a dynamic stochastic general equilibrium framework, capturing feedback loops between exchange rates, output, inflation, and policy rules (Taylor rules) across multiple countries simultaneously.

For business students, the most immediately practical extension is the Mundell-Fleming model, which formalizes a key insight: under a flexible exchange rate regime with high capital mobility, monetary policy is highly effective at influencing output because it operates through both the interest rate channel and the exchange rate channel. Fiscal policy, by contrast, is partially neutralized because the induced appreciation of the domestic currency crowds out net exports. This 'policy effectiveness' result has profound implications for how governments coordinate macroeconomic stabilization in open economies—a topic you will revisit in courses on international trade policy and global financial strategy.

SECTION 9

Practice Problems

PROBLEM 1 — CONCEPTUAL

Explain why the demand curve for a country's currency in the foreign exchange market slopes downward. In your answer, identify at least two types of transactions that generate demand for a currency and explain why the quantity demanded increases as the exchange rate falls.

PROBLEM 2 — BASIC CALCULATION

Suppose the U.S. inflation rate is 6% per year while the Japanese inflation rate is 1% per year. According to relative Purchasing Power Parity, by approximately what percentage should the U.S. dollar depreciate against the Japanese yen over one year? If the current spot rate is ¥130 per dollar, what rate does PPP predict one year from now?

PROBLEM 3 — INTERMEDIATE

The Bank of England unexpectedly cuts its benchmark interest rate by 75 basis points while the Federal Reserve holds U.S. rates steady. Using the supply-and-demand model for the British pound (with the exchange rate measured as dollars per pound on the vertical axis), (a) identify which curve(s) shift and in which direction, (b) determine whether the pound appreciates or depreciates, and (c) explain the effect on British net exports.

PROBLEM 4 — APPLIED

You are a financial analyst at a U.S. multinational that earns 40% of its revenue in euros. The ECB has just announced a large quantitative easing program (expanding its balance sheet by purchasing eurozone government bonds), while the Fed is simultaneously tightening policy. Using the FX market framework, predict the direction of the EUR/USD exchange rate and explain how this currency movement would affect your company's reported revenues and competitive position. What hedging strategy might you recommend?

PROBLEM 5 — CRITICAL THINKING

A country simultaneously implements (1) expansionary fiscal policy (a large infrastructure spending bill financed by borrowing) and (2) expansionary monetary policy (the central bank cuts rates to keep borrowing costs low). Analyze the combined effect on the foreign exchange market. Do the two policies reinforce or partially offset each other in terms of their exchange rate effects? Under what conditions might the net effect on the currency be ambiguous? Discuss with reference to the Mundell-Fleming framework.

SUMMARY

Lesson Summary

The foreign exchange market determines currency values through the interaction of supply and demand under a flexible exchange rate regime. Changes in monetary policy transmit to the FX market primarily through the interest rate channel: higher domestic rates attract foreign capital, increase demand for the currency, and cause appreciation. Expansionary fiscal policy raises interest rates via crowding out and also boosts imports; the standard result is net appreciation because the interest rate effect dominates. Higher domestic inflation reduces export competitiveness and raises import demand, leading to depreciation, consistent with relative purchasing power parity.

Rising national income increases import spending, shifting currency supply rightward and typically causing depreciation. Trade policies like tariffs reduce imports, decrease currency supply, and lead to appreciation. The uncovered interest rate parity condition provides a formal link between interest rate differentials and expected exchange rate movements. While this supply-and-demand framework accurately predicts the direction of currency movements, it does not quantify magnitudes, and real-world outcomes may be influenced by speculation, central bank intervention, and the simultaneous occurrence of multiple shocks. Advanced models such as the Mundell-Fleming model and the Dornbusch overshooting model build on this foundation to address dynamics, expectations, and general equilibrium interactions.