AP Macroeconomics Unit 6 ReviewOpen Economy – International Trade and Finance

AP Macro Unit 6 covers what happens when an economy opens its doors to the rest of the world, with currency exchange, the balance of payments, and international capital flows at the center. The single biggest idea is that a country's currency has a price like anything else, set by supply and demand in the foreign exchange market, and that price feeds back into net exports, aggregate demand, and capital flows. This unit makes up 10-13% of the AP exam and leans heavily on one new graph, the foreign exchange market.

What this unit covers

The balance of payments: tracking every dollar that crosses the border

• The balance of payments (BOP) is the full accounting record of a country's transactions with the rest of the world. Every international transaction lands in one of two accounts.
• The current account (CA) records net exports of goods and services, net income earned from abroad (like dividends a US investor earns on a Japanese stock), and net unilateral transfers (like foreign aid or remittances).
• The capital and financial account (CFA) records purchases and sales of assets between countries, including financial capital flows like a German investor buying US Treasury bonds.
• Neither account has to balance on its own. The US can run a current account deficit (importing more than it exports) as long as it runs a matching financial account surplus (foreigners buying US assets). The two accounts mirror each other, so under the AP framework CA + CFA = 0.
• You need to be able to calculate the CA, the CFA, and the BOP from a list of transactions, and to identify which account a transaction belongs in. A Brazilian tourist spending money in Miami goes in the US current account as an export of services. A Canadian firm buying a US factory goes in the CFA.

Exchange rates and the foreign exchange market

• An exchange rate is the price of one currency in terms of another. If 1 dollar trades for 100 yen, the dollar's price is 100 yen and the yen's price is 1/100 of a dollar. The two rates are always reciprocals, which is exactly how the calculation questions test you.
• Appreciation means a currency becomes more valuable relative to another. Depreciation means it becomes less valuable. When the dollar appreciates against the yen, the yen automatically depreciates against the dollar. It is a seesaw, and both ends move at once.
• The foreign exchange market graph works like any supply and demand graph, but the "good" is a currency. Demand for dollars comes from foreigners who want US goods, services, or financial assets. Supply of dollars comes from Americans making payments in other currencies (buying imports or foreign assets).
• Demand for a currency slopes downward and supply slopes upward, with the exchange rate on the vertical axis and the quantity of the currency on the horizontal axis. Equilibrium is where they cross, and surpluses or shortages of a currency push the exchange rate back toward equilibrium.

What shifts currency demand and supply

• Anything that changes foreign demand for a country's goods, services, or assets shifts the demand for its currency. If US tech products get popular in Europe, demand for dollars rises and the dollar appreciates.
• Trade policy matters too. Tariffs or quotas on imports reduce the supply of the domestic currency (fewer dollars flowing out to pay for imports), which appreciates the currency.
• Fiscal and monetary policy reach into this market through interest rates and income. Expansionary monetary policy lowers domestic interest rates, making domestic bonds less attractive to foreign investors, so demand for the currency falls and it depreciates. Contractionary monetary policy does the opposite.
• Relative price levels matter as well. Higher inflation at home makes domestic goods less attractive, lowering demand for the currency.

The feedback loop: currency value, net exports, and aggregate demand

• This is where Unit 6 plugs back into the AD-AS model. When a currency appreciates, that country's goods get more expensive for foreigners, so exports fall and imports rise. Net exports decrease, which shifts aggregate demand left.
• When a currency depreciates, exports get cheaper for foreigners, exports rise and imports fall, net exports increase, and aggregate demand shifts right.
• A clean way to remember it is that a "strong" currency is actually bad news for exporters. Appreciation shrinks net exports; depreciation grows them.

Real interest rates and international capital flows

• Financial capital flows toward the country with the relatively higher real interest rate, because investors chase the better return on bonds and other assets.
• If US real interest rates rise relative to other countries, foreign investors buy US assets. That increases demand for dollars (dollar appreciates) and increases the supply of loanable funds in the US (which pushes the US real interest rate back down a bit).
• Central banks can influence the domestic interest rate in the short run, so monetary policy in one country ripples through exchange rates and capital flows everywhere. A Fed rate hike appreciates the dollar, attracts capital inflows, and reduces US net exports. That full chain is a classic FRQ sequence.

Unit 6, Open Economy, International Trade and Finance at a glance

Why Unit 6, Open Economy, International Trade and Finance matters in AP Macro

Unit 6 is where the whole course goes global. Everything you learned in a "closed economy" setting now has an international channel, and the exam loves testing whether you can trace effects across borders.

• It completes the policy story. Monetary and fiscal policy from Units 4 and 5 do not stop at the border; they change exchange rates, capital flows, and net exports, and you need the full chain.
• It adds the third major market of the course. After the AD-AS model and the money/loanable funds markets, the foreign exchange market is the last graph in your toolkit, and it links to both of the others.
• It explains real headlines. Why a Fed rate hike strengthens the dollar, why a strong dollar hurts US manufacturers, and why trade deficits pair with financial account surpluses all come straight from this unit.

How this unit connects across the course

• Comparative advantage, specialization, and the gains from trade (Unit 1) are the reason countries trade at all. Unit 6 builds the financial plumbing on top of that foundation.
• Net exports are a component of GDP and aggregate demand (Units 2 and 3). Unit 6 explains what makes net exports move, so a currency depreciation becomes a rightward AD shift you already know how to analyze.
• The loanable funds market and interest rates (Unit 4) drive international capital flows. A higher domestic real interest rate pulls in foreign capital, which appreciates the currency and adds to the supply of loanable funds.
• Monetary and fiscal policy effects (Unit 5) get an international extension here. Expansionary monetary policy now depreciates the currency and boosts net exports, partially reinforcing the domestic stimulus.

Key models and graphs to know

• Foreign exchange market graph: supply and demand for a single currency, with the exchange rate (price of that currency in terms of another) on the vertical axis. Use it for any appreciation or depreciation question.
• Loanable funds market (open economy version): capital inflows shift the supply of loanable funds right, lowering the domestic real interest rate. Use it when interest rate differences move capital across borders.
• AD-AS model linked to net exports: depreciation raises net exports and shifts AD right; appreciation lowers net exports and shifts AD left. Use it to finish any "what happens to real GDP and the price level" chain.
• Balance of payments accounting: CA + CFA = 0. Use it to calculate one account when given the other, or to sort transactions.
• Exchange rate conversion: if 1 dollar = 100 yen, then 1 yen = 1/100 dollar. The two rates are reciprocals, and "more yen per dollar" means the dollar appreciated.

Unit 6, Open Economy, International Trade and Finance on the AP exam

Unit 6 is 10-13% of the exam, and it shows up in both multiple choice and free response. Multiple-choice questions ask you to classify transactions into the current account or the capital and financial account, calculate exchange rate conversions, identify which way a currency moves after a given event, and predict the effect on net exports.

Free-response questions almost always make you draw the foreign exchange market graph, correctly label the axes (the exchange rate as the price of one currency in terms of the other), shift the right curve, and show the new equilibrium. The most common FRQ pattern is a multi-step chain. A typical sequence looks like this: a central bank raises interest rates, so you show capital flowing in, demand for the currency rising, the currency appreciating, net exports falling, and aggregate demand shifting left. Practice writing each link explicitly, because points are awarded for the reasoning, not just the final answer. Getting the axis label wrong on the forex graph is one of the most common ways to lose an otherwise earned point.

Essential questions

• Why does a country's currency have a price, and what determines it?
• How can a country run a trade deficit year after year without "running out" of money?
• How do one country's interest rate decisions ripple through exchange rates and economies around the world?
• Why might a "weak" currency actually help a country's economy in the short run?

Key terms to know

• Balance of payments (BOP): the record of all transactions between a country and the rest of the world, made up of the current account and the capital and financial account.
• Current account (CA): the account recording net exports, net income from abroad, and net unilateral transfers.
• Capital and financial account (CFA): the account recording purchases and sales of assets and financial capital flows between countries.
• Exchange rate: the price of one currency expressed in terms of another currency.
• Appreciation: an increase in a currency's value relative to another currency.
• Depreciation: a decrease in a currency's value relative to another currency.
• Foreign exchange market: the market where one currency is traded for another, determining the equilibrium exchange rate.
• Demand for a currency: arises from foreign demand for that country's goods, services, and financial assets; inversely related to the exchange rate.
• Supply of a currency: arises from residents making payments in foreign currencies; positively related to the exchange rate.
• Net exports: exports minus imports; falls when the currency appreciates and rises when it depreciates.
• Capital inflow: foreign financial capital entering a country, attracted by a relatively higher real interest rate.
• Trade deficit: when imports exceed exports, producing negative net exports within the current account.

Common mix-ups

• Appreciation sounds good but reduces net exports. A stronger currency makes your exports pricier for foreigners, so "strong currency" means weaker export sales.
• When one currency appreciates, the other depreciates automatically. If a question gives you the dollar-yen market, the yen graph is the mirror image; do not shift both demand curves the same direction.
• Buying foreign goods goes in the current account; buying foreign assets goes in the capital and financial account. A US resident buying a Toyota is an import (CA). A US resident buying Toyota stock is a financial outflow (CFA).
• Supplying dollars and demanding euros are the same action. When Americans buy European goods, they supply dollars and demand euros simultaneously. Identify which currency's market the graph shows before you shift anything.