Effects of Policy and Shocks on the Foreign Exchange Market — AP Macroeconomics Study Guide

For: AP Macroeconomics candidates sitting AP Macroeconomics.

Covers: Covers how domestic fiscal policy, monetary policy, and external market shocks shift currency supply and demand, change equilibrium exchange rates, and alter net exports under both flexible and fixed exchange rate regimes. It includes step-by-step graphing and causal chain analysis for exam questions.

You should already know: How supply and demand determine foreign exchange equilibrium, the difference between flexible and fixed exchange rate regimes, the structure of balance of payments accounts.

A note on the practice questions: All worked questions in the "Practice Questions" section below are original problems written by us in the AP Macroeconomics style for educational use. They are not reproductions of past College Board / Cambridge / IB papers and may differ in wording, numerical values, or context. Use them to practise the technique; cross-check with official mark schemes for grading conventions.

1. What Is Effects of Policy and Shocks on the Foreign Exchange Market?

This topic is a core application of foreign exchange (forex) market fundamentals to real-world economic events and policy actions, accounting for roughly 15-20% of Unit 6 exam weight on the AP Macroeconomics exam. It appears regularly in both multiple-choice (MCQ) questions (often as a graph shift or concept application question) and free-response (FRQ) questions, where you will typically be asked to draw a forex graph, identify the change in the exchange rate, and connect that change to domestic output and prices. This topic builds on static forex equilibrium by linking shifts in supply and demand curves to specific causal events: intentional domestic policy changes (fiscal and monetary) and unanticipated external shocks (changes in tastes, income, price levels, or interest rates). Unlike basic forex problems, this topic requires you to walk through a full logical chain of causation: starting from the shock or policy change, identifying which curve shifts, what happens to the exchange rate, and what the resulting impact is on net exports and aggregate demand. Mastery of causal linkages, not just memorization of outcomes, is required to earn full credit on AP exam questions.

2. Effects of Monetary Policy under Flexible Exchange Rates

Monetary policy changes impact the foreign exchange market primarily through the interest rate effect. When a central bank engages in expansionary monetary policy, it increases the domestic money supply, which lowers the nominal (and real, in the short run) interest rate. Lower domestic interest rates mean foreign assets now have a higher relative return compared to domestic assets. This causes two parallel shifts in the forex market: 1) domestic investors want to buy more foreign assets, so they supply more of the domestic currency to the forex market to exchange for foreign currency; 2) foreign investors demand less domestic currency to buy domestic assets, since returns are now lower. Both the increase in supply of domestic currency and the decrease in demand lead to domestic currency depreciation, or a decrease in the equilibrium exchange rate (where exchange rate is defined as units of foreign currency per unit of domestic currency, the standard AP definition). Depreciation of the domestic currency makes domestic exports cheaper for foreigners and imports more expensive for domestic consumers, so net exports increase, which boosts aggregate demand. Conversely, contractionary monetary policy raises interest rates, causes currency appreciation, reduces net exports, and dampens aggregate demand. This is the core result of the Mundell-Fleming model, which finds monetary policy is highly effective at changing output under flexible exchange rates.

Worked Example

Problem: The Reserve Bank of New Zealand engages in expansionary monetary policy to boost employment after a recession. All else equal, what happens to the value of the New Zealand dollar (NZD) against the Japanese yen (JPY) under a flexible exchange rate regime? What is the impact on New Zealand net exports?

1. Step 1: Expansionary monetary policy increases New Zealand's money supply, which lowers New Zealand's interest rates relative to interest rates in Japan.
2. Step 2: Lower relative returns on New Zealand assets cause Japanese investors to demand less NZD to buy New Zealand assets, and New Zealand investors supply more NZD to exchange for JPY to buy Japanese assets.
3. Step 3: On a forex graph for NZD, with exchange rate (JPY per 1 NZD) on the y-axis, demand for NZD shifts left and supply of NZD shifts right.
4. Step 4: The new equilibrium exchange rate is lower, meaning 1 NZD now buys fewer JPY. Outcome: the NZD depreciates against the JPY.
5. Step 5: NZD depreciation makes New Zealand exports cheaper for Japanese consumers and Japanese imports more expensive for New Zealand consumers, so New Zealand net exports increase.

Exam tip: Always label your exchange rate on the y-axis of your forex graph for FRQs; AP graders require this to accept your shift analysis, and defining it upfront prevents confusion about whether depreciation means a higher or lower y-value.

3. Effects of Fiscal Policy under Flexible Exchange Rates

Expansionary fiscal policy (increased government spending or tax cuts) increases domestic aggregate demand and income, and also raises domestic interest rates because a larger budget deficit increases government borrowing demand, pushing up market interest rates. Higher domestic interest rates attract foreign capital, increasing demand for domestic currency and leading to currency appreciation. At the same time, higher domestic income increases demand for imports, since consumers have more disposable income to spend on foreign goods, which increases the supply of domestic currency on the forex market (as consumers exchange domestic for foreign currency to buy imports). What is the net effect on the exchange rate? In the short run, the interest rate effect dominates the income effect for most economies, so the overall result is currency appreciation. Appreciation then reduces net exports, offsetting some of the expansionary effect of fiscal policy — this outcome is called crowding out of net exports, a key open-economy result. Conversely, contractionary fiscal policy lowers interest rates, leads to currency depreciation, increases net exports, and offsets some of the contractionary effect of fiscal policy. Unlike monetary policy, fiscal policy is less effective at changing output under flexible exchange rates because of this crowding out effect.

Worked Example

Problem: The Swedish government passes a large increase in government spending on public healthcare, financed by new borrowing with no change in taxes. All else equal, what is the impact on the value of the Swedish krona (SEK) relative to the U.S. dollar (USD) under flexible exchange rates, and what is the impact on Swedish net exports?

1. Step 1: The policy is expansionary fiscal policy, which increases Swedish aggregate demand and disposable income, leading to higher interest rates from increased government borrowing.
2. Step 2: Higher Swedish interest rates increase demand for SEK from U.S. investors, while higher domestic income increases supply of SEK as Swedish consumers import more U.S. goods.
3. Step 3: The interest rate effect dominates the income effect in the short run, so the net shift leads to a higher equilibrium exchange rate (USD per SEK), meaning the SEK appreciates against the USD.
4. Step 4: SEK appreciation makes Swedish exports more expensive for U.S. consumers and U.S. imports cheaper for Swedish consumers, so Swedish net exports decrease.

Exam tip: When asked for the effect of fiscal policy, never forget the income effect on imports in addition to the interest rate effect on capital flows; AP exam questions often test whether you recognize both effects, even when the interest rate effect dominates overall.

4. Effects of External Shocks on the Foreign Exchange Market

External shocks are changes in economic conditions or preferences that shift currency supply or demand independent of intentional domestic policy. Common external shocks tested on the AP exam include: (1) changes in foreign income, (2) changes in relative price levels, (3) changes in consumer tastes for goods, (4) changes in foreign interest rates, and (5) changes in expected future exchange rates. The core logic for analyzing these shocks follows the same supply and demand framework as policy changes: if foreign income increases, foreigners demand more imports, so they demand more domestic currency to buy domestic exports, leading to domestic currency appreciation. If domestic price levels rise faster than foreign price levels, domestic goods become more expensive, so foreigners demand less domestic currency and domestic consumers supply more domestic currency to buy cheaper foreign goods, leading to domestic currency depreciation. If global consumer tastes shift toward domestic goods (e.g., a global trend makes Brazilian coffee more popular), demand for the Brazilian real increases, leading to real appreciation. If foreign interest rates rise, capital flows out of the domestic economy to earn higher returns, leading to domestic currency depreciation.

Worked Example

Problem: Global consumer tastes shift away from Spanish wine and toward Australian wine. All else equal, what happens to the value of the euro (EUR, Spain's currency) relative to the Australian dollar (AUD) under flexible exchange rates?

1. Step 1: Foreign consumers (including Australian consumers) now want less Spanish wine, so they need less EUR to buy Spanish exports.
2. Step 2: This decreases the demand for EUR on the forex market, with no change in the supply of EUR in this scenario.
3. Step 3: On a forex graph for EUR, with exchange rate (AUD per 1 EUR) on the y-axis, the demand curve for EUR shifts left.
4. Step 4: The new equilibrium exchange rate is lower, so 1 EUR buys fewer AUD. Outcome: the EUR depreciates relative to the AUD.

Exam tip: When identifying which curve shifts, always ask: who is changing their behavior? If foreign consumers want less of our goods, demand for our currency shifts, not supply.

5. Effects of Policy and Shocks under Fixed Exchange Rates

Under a fixed exchange rate regime, the central bank pegs the value of the domestic currency at a specific target exchange rate against a foreign currency (usually the U.S. dollar). If a policy change or external shock pushes the free-market equilibrium exchange rate away from the target, the central bank is required to intervene in the forex market to maintain the peg. For example, if a shock leads to downward pressure on the domestic currency (the free-market value is below the target, meaning the currency would depreciate if left alone), the central bank must buy domestic currency and sell its foreign currency reserves to increase demand for domestic currency and push the exchange rate back up to the target. Conversely, if the currency faces upward pressure to appreciate, the central bank sells domestic currency and buys foreign reserves to increase supply of domestic currency and keep the exchange rate at the target. A key policy result: under fixed exchange rates, monetary policy is ineffective, because any change in the money supply to change domestic output is offset by intervention to maintain the peg. Fiscal policy, by contrast, is highly effective under fixed exchange rates, because the crowding out of net exports that occurs under flexible rates is eliminated by central bank intervention.

Worked Example

Problem: Hong Kong pegs the Hong Kong dollar (HKD) to the U.S. dollar at a target of 7.8 HKD per 1 USD. U.S. interest rates fall unexpectedly, putting pressure on the HKD exchange rate. What action must the Hong Kong Monetary Authority take to maintain the peg, and what is the impact on Hong Kong's money supply?

1. Step 1: Lower U.S. interest rates mean HKD assets now have higher relative returns, so investors sell USD and buy HKD, increasing demand for HKD on the forex market.
2. Step 2: The free-market exchange rate would fall below the 7.8 HKD per 1 USD target (meaning 1 USD buys fewer HKD, so HKD appreciates above the target).
3. Step 3: To maintain the peg, the Hong Kong Monetary Authority must sell excess HKD to the market, buying USD foreign reserves in exchange.
4. Step 4: Selling HKD adds HKD to circulation, so Hong Kong's domestic money supply increases, which lowers Hong Kong interest rates to match the lower U.S. rates, ending the pressure on the peg.

Exam tip: Always remember that central bank intervention to maintain a fixed exchange rate automatically changes the domestic money supply; AP FRQs almost always ask for this impact after you identify the intervention action.

6. Common Pitfalls (and how to avoid them)

• Wrong move: Drawing a forex graph for the domestic currency and shifting the supply/demand of foreign currency instead, leading to the opposite shift outcome. Why: Students often confuse which currency the graph is denominated in, especially when the question asks about the value of one currency relative to another. Correct move: Always draw the graph for the currency whose value you are asked to analyze, with the exchange rate as [foreign currency] per 1 [domestic currency] on the y-axis.
• Wrong move: Claiming expansionary monetary policy causes currency appreciation because it boosts the economy. Why: Students confuse the long-run growth effect with the short-run interest rate effect that drives exchange rate changes. Correct move: Walk the chain explicitly for every question: expansionary monetary → lower interest rates → capital outflow → domestic currency depreciation.
• Wrong move: Claiming the income and interest rate effects of fiscal policy always cancel out, so there is no change in the exchange rate. Why: Students remember both effects have opposite pushes, so incorrectly assume they offset. Correct move: State that the interest rate effect dominates the income effect in the short run, so expansionary fiscal policy always leads to appreciation in basic AP analysis.
• Wrong move: Under fixed exchange rates, claiming the central bank does not need to intervene after a shock. Why: Students confuse flexible and fixed exchange rate regime rules, applying flexible outcomes to fixed rates. Correct move: Any time a question specifies a fixed exchange rate, automatically add a step for central bank intervention and the resulting change in the domestic money supply.
• Wrong move: Claiming currency depreciation leads to a decrease in net exports. Why: Students mix up how exchange rate changes impact export and import prices. Correct move: Memorize the link explicitly: depreciation makes exports cheaper and imports more expensive → net exports increase; appreciation → net exports decrease.
• Wrong move: Shifting the supply of domestic currency when foreign tastes shift toward domestic exports. Why: Students mix up who is transacting: domestic consumers shift supply, foreign consumers shift demand. Correct move: If foreigners want more domestic goods, demand for domestic currency shifts right, leading to appreciation. If domestic consumers want more foreign goods, supply of domestic currency shifts right, leading to depreciation.

7. Practice Questions (AP Macroeconomics Style)

Question 1 (Multiple Choice)

If the Central Bank of Chile engages in contractionary monetary policy to reduce domestic inflation, all else equal, which of the following will occur under a flexible exchange rate regime?

A) Chilean interest rates rise, the Chilean peso appreciates, and Chilean net exports fall B) Chilean interest rates rise, the Chilean peso depreciates, and Chilean net exports rise C) Chilean interest rates fall, the Chilean peso appreciates, and Chilean net exports fall D) Chilean interest rates fall, the Chilean peso depreciates, and Chilean net exports rise

Worked Solution: Contractionary monetary policy reduces the Chilean money supply, which increases short-run domestic interest rates, eliminating options C and D. Higher relative Chilean interest rates attract foreign capital, increasing demand for the Chilean peso and leading to peso appreciation. Peso appreciation makes Chilean exports more expensive for foreigners and imports cheaper for Chilean consumers, so net exports decrease. The correct answer is A.

Question 2 (Free Response)

Canada has a flexible exchange rate regime and is currently in long-run equilibrium. The Canadian government cuts personal income taxes, increasing disposable income, and finances the resulting budget deficit with new borrowing. Answer the following: (a) Using a correctly labeled foreign exchange graph for the Canadian dollar (CAD) against the Chinese yuan (CNY), show the effect of this policy on the equilibrium exchange rate, defined as CNY per 1 CAD. (b) Explain how this change in the exchange rate affects Canadian net exports and aggregate demand. (c) Suppose instead Canada pegs the CAD to the CNY at the original equilibrium exchange rate. After the tax cut, what action must the Bank of Canada take to maintain the peg, and how does this action affect the Canadian money supply?

Worked Solution: (a) Correct graph labels: y-axis = Exchange Rate (CNY per 1 CAD), x-axis = Quantity of CAD. The tax cut is expansionary fiscal policy, which raises Canadian interest rates. Higher rates increase demand for CAD from Chinese investors and decrease supply of CAD from Canadian investors, so demand shifts right and supply shifts left. The new equilibrium exchange rate is higher than the original, indicating CAD appreciation. (b) CAD appreciation means 1 CAD now buys more CNY, so Canadian exports become more expensive for Chinese consumers and Chinese imports become cheaper for Canadian consumers. This leads to a decrease in Canadian net exports. The decrease in net exports shifts aggregate demand left partially, offsetting the rightward shift from the expansionary tax cut. (c) The tax cut puts upward pressure on the CAD exchange rate, so the CAD would appreciate above the pegged target. To maintain the peg, the Bank of Canada must sell CAD and buy CNY foreign reserves. Selling CAD increases the supply of CAD on the forex market and in the domestic economy, so the Canadian money supply increases.

Question 3 (Application / Real-World Style)

In 2023, a severe drought destroyed a large share of Brazil's domestic coffee crop, leading to a sharp increase in global coffee prices. Brazil is the world's largest coffee exporter, has a flexible exchange rate, and uses the Brazilian real (BRL) as its currency. All else equal, what is the impact of this drought shock on the value of BRL against the Euro, and what is the overall impact on Brazilian net exports?

Worked Solution:

1. The drought reduces the quantity of Brazilian coffee available, but the increase in global coffee prices means the total value of Brazilian coffee exports increases (demand for coffee is relatively price inelastic, so higher prices raise total export revenue). This means European importers need more BRL to pay for Brazilian coffee exports, so demand for BRL on the forex market shifts right.
2. The demand shift leads to an increase in the equilibrium exchange rate (EUR per BRL), so the BRL appreciates against the Euro.
3. The higher value of BRL makes non-coffee Brazilian exports more expensive for European consumers, but the initial increase in the value of coffee exports is larger than the decline in non-coffee net exports. In context, this drought shock leads to BRL appreciation and an overall increase in Brazilian net exports, driven by the higher global price of Brazil's core export.

8. Quick Reference Cheatsheet

9. What's Next

This topic is the foundational application for all open-economy macro analysis, and it is a prerequisite for the next topics in Unit 6 focused on the effect of exchange rate changes on domestic output and inflation, and the comparison of policy effectiveness under flexible vs fixed exchange rates. Without mastering how policy and shocks shift exchange rates, you will not be able to correctly analyze the impact of international events on domestic unemployment and inflation, a common high-weight FRQ topic on the AP exam. This topic also feeds into the bigger macro theme of how open economies differ from closed economies, changing the effectiveness of fiscal and monetary policy you learned in earlier units on aggregate demand and supply. Up next, you can study related topics: Policy effectiveness under flexible and fixed exchange rates Purchasing power parity and interest rate parity Balance of payments adjustments