Why Currency Demand and Supply Matter
A cross-border purchase usually requires someone to obtain one currency and give up another. A U.S. household buying a holiday in the euro area may need euros; a euro-area business buying U.S. equipment may need dollars. These transactions create demand for one currency and supply of another in the foreign-exchange market.
The key is to name the currency being analyzed before labeling an order as demand or supply. The same transaction is demand for one currency and, in exchange, supply of another. International payments can also arise from purchases of financial assets, not only from trade in goods and services. Expectations matter because a buyer or seller may choose to exchange currency now in response to what they anticipate later.
Set the Quotation Before Reading the Diagram
Suppose the market is for euros and the quotation is \(e=\$\,\text{per euro}\). Then \(e=\$1.25/\text{€}\) means that one euro exchanges for 1.25 U.S. dollars. The vertical axis measures dollars per euro; the horizontal axis measures the quantity of euros exchanged, perhaps in millions of euros per day.
At this quotation, a U.S. buyer who needs euros demands euros. A euro holder who gives up euros to obtain dollars supplies euros. If the quotation rises from \(1.25\) to \(1.30\) dollars per euro, each euro is priced at more dollars. That is a rise in the dollar price of a euro, not a fall. The quote must be read in its stated direction; if it were inverted to euros per dollar, the numerical movement would be different.
In the standard diagram, the demand schedule for euros slopes downward when the vertical axis is dollars per euro: other things equal, a higher dollar price of a euro tends to reduce the quantity of euros buyers choose to acquire. The supply schedule for euros slopes upward: other things equal, a higher dollar return for each euro tends to make holders more willing to supply euros in exchange for dollars. These are conventional relationships under the stated ceteris paribus condition, not claims that every transaction responds identically.
A higher exchange rate changes the quantity demanded or supplied along the corresponding schedule, with other influences held fixed. Changes in trade plans, asset decisions, or expectations can alter the amounts buyers and sellers plan to exchange at a given rate. The diagram is useful only if these distinctions are kept clear: a point on a schedule is a quantity at a particular exchange rate, while the reasons behind the schedule include more than the exchange rate itself.
Where Currency Demand and Supply Come From
For euros, demand can come from U.S. residents purchasing euro-area goods or services, traveling in the euro area, or buying euro-denominated financial assets. These buyers need euros to make payments or hold the assets. A U.S. importer does not necessarily conduct a separate exchange-market trade for every invoice—for example, a bank may handle the conversion—but the underlying payment creates a need for euros.
Supply of euros can come from euro-area residents buying U.S. goods or services, traveling in the United States, or acquiring dollar-denominated assets. To make those payments, they may exchange euros for dollars. The counterpart is demand for dollars. An export transaction does not always involve a currency exchange by the exporter: if the exporter is paid in euros and keeps the euros, there may be no immediate conversion. The market interpretation concerns who needs which currency, not simply which country’s name appears on an invoice.
Financial flows follow the same currency logic as trade flows. A U.S. investor purchasing a euro-denominated bond must obtain euros, so the transaction creates demand for euros. A euro-area investor purchasing a U.S. asset must obtain dollars, so the transaction can create supply of euros. When investors sell foreign assets and convert the proceeds back into their home currency, the direction of the currency order depends on which currency they are buying in that conversion.
| Transaction, with euros as the currency traded | Order affecting the euro market | Reason |
|---|---|---|
| A U.S. tourist pays for a euro-area hotel in euros | Demand for euros | The tourist must obtain euros to pay. |
| A U.S. fund buys a euro-denominated bond | Demand for euros | The fund needs euros to purchase the asset. |
| A euro-area business buys U.S. equipment using dollars | Supply of euros | The business exchanges euros to obtain dollars. |
| A euro-area investor buys a U.S. asset | Supply of euros | The investor needs dollars for the purchase. |
Worked Example: Classifying Trade and Asset Transactions
Use the market for euros, with the quotation \(e=\$1.25/\text{€}\). During one day, U.S. residents need \(€2.4\) million for imported machinery, \(€0.3\) million for travel, and \(€1.8\) million to buy euro-area bonds. Euro-area residents buy U.S. goods costing \(\$1.50\) million and U.S. shares costing \(\$0.75\) million. If those residents exchange euros to obtain the dollars, calculate the listed demand for and supply of euros.
Method. Classify each order by the currency the buyer needs. Add euro amounts directly. Convert dollar purchases into euros using the stated quotation before adding them to euro supply.
The three U.S. transactions require euros, so listed demand is:
The euro-area residents need dollars. At \(\$1.25\) per euro, the euro amount exchanged for the goods payment is:
The euro amount exchanged for the shares payment is:
Thus listed euro supply is \(€1.20\text{ million}+€0.60\text{ million}=€1.80\text{ million}\). At the stated quotation, listed demand exceeds listed supply by \(€4.50\text{ million}-€1.80\text{ million}=€2.70\text{ million}\). This is a comparison of the transactions given, not a claim that all market orders have been counted.
Check. Multiplying each euro supply amount by \(\$1.25/\text{€}\) gives \(\$1.50\) million and \(\$0.75\) million, the original dollar payments. A common mistake is to divide the U.S. demand total by the exchange rate even though it is already stated in euros.
Why the Schedules Respond to the Exchange Rate
A simple budget relationship explains the usual downward slope of currency demand. Assume a buyer has a fixed dollar budget \(B\) for obtaining euros, faces the quotation \(e\) dollars per euro, and has no other constraint. If the buyer spends the entire budget, the quantity of euros purchasable is \(Q=B/e\). As \(e\) rises, each euro costs more dollars, so the same budget buys fewer euros.
For example, with a fixed budget of \(\$14.4\) million, a buyer can obtain \(€12\) million at \(\$1.20\) per euro, but only \(€9.6\) million at \(\$1.50\) per euro. The budget calculation demonstrates a price-and-quantity relationship; it does not say that every buyer has a fixed budget or that aggregate currency demand is determined by this one buyer.
The usual upward slope of supply can be understood from the seller’s return. At a higher number of dollars per euro, selling one euro yields more dollars. Under the conventional assumption that some holders are more willing to exchange euros when the dollar return is higher, the quantity supplied rises. The exact response depends on holders’ plans, constraints, and expectations; the slope is a standard model assumption for interpreting the basic diagram.
Worked Example: Reading Quantities at Two Exchange Rates
A hypothetical market has the following schedules, measured in millions of euros per day. At \(e=\$1.20/\text{€}\), buyers plan to acquire \(12\) million euros and holders plan to supply \(5\) million. At \(e=\$1.50/\text{€}\), buyers plan to acquire \(9\) million and holders plan to supply \(8\) million. Interpret both entries and explain the direction of each schedule.
At \(e=\$1.20/\text{€}\), the point on the demand schedule is \((Q_D,e)=(12,\$1.20/\text{€})\); the point on supply is \((Q_S,e)=(5,\$1.20/\text{€})\). These mean planned purchases of \(€12\) million and planned sales of \(€5\) million per day at that quotation.
At \(e=\$1.50/\text{€}\), the corresponding quantities are \(Q_D=9\) million and \(Q_S=8\) million euros per day. The quotation has risen by \(\$0.30\) per euro. Across these schedule entries, demand quantity has fallen by \(12-9=3\) million euros per day, while supply quantity has risen by \(8-5=3\) million euros per day. This is consistent with the conventional downward-sloping demand and upward-sloping supply schedules.
Check. At both quotations, the units on the vertical axis remain dollars per euro and the quantities remain euros per day. A common mistake is to read \(e=\$1.50/\text{€}\) as the dollar value of one dollar; it is the dollar price of one euro. This example interprets schedule points; it does not identify a market-clearing exchange rate.
Expectations and Current Currency Orders
Currency decisions can depend on anticipated future exchange rates as well as current payments. If investors expect the euro to become more valuable in dollars, some may choose to buy euros now to hold euro-denominated assets or currency. That adds current demand for euros. If holders expect the euro to lose value, some may prefer to exchange euros for dollars sooner, adding current euro supply. These are possible behavioral responses, not mechanical rules: the direction and size depend on the investors’ actual decisions and on other relevant considerations.
The timing distinction matters. An expectation about a future exchange rate affects today’s market only when it changes current orders. It is not itself a completed cross-border payment. An asset purchase can generate a currency order today even though the asset’s return will be received later.
Worked Example: Expectations and an Asset Purchase
At \(e=\$1.25/\text{€}\), suppose U.S. investors expect the euro to appreciate and, as a result, a fund buys \(€4\) million of euro-area securities. At the same time, a euro-area insurer sells a U.S. asset and converts its \(\$2.50\) million proceeds into euros. Euro-area importers also need \(\$1.25\) million for U.S. goods and exchange euros for those dollars. Find the listed demand for and supply of euros, and identify the role of expectations.
The U.S. fund needs euros to buy the securities. Its order is \(€4\) million of euro demand. The insurer also buys euros when converting its dollar proceeds. Its euro purchase is:
The importers need dollars, so they supply euros. The euro amount needed for their dollar payment is:
Listed demand is \(€4.00\text{ million}+€2.00\text{ million}=€6.00\text{ million}\); listed supply is \(€1.00\text{ million}\). The fund’s expectation helps explain why it buys the securities now, creating current euro demand. The insurer’s conversion creates euro demand because it is buying euros with dollars, even though the dollars came from selling a U.S. asset.
Check. At the quoted rate, the insurer’s \(€2.00\) million costs \(\$2.50\) million, and the importers’ \(€1.00\) million yields \(\$1.25\) million. The common mistake is to label the insurer’s order as euro supply simply because it sold a U.S. asset; the relevant step is the currency it buys with the proceeds.
Common Diagram Traps
- Ignoring the quote direction. With dollars per euro on the vertical axis, a higher value means a higher dollar price of a euro. Read the units before describing appreciation, depreciation, or a price change.
- Calling every cross-border payment demand for the home currency. Identify the market’s traded currency first. A buyer who needs euros creates euro demand; a holder exchanging euros for dollars supplies euros.
- Confusing a currency order with a goods purchase. A U.S. purchase of an imported good can require euros, but the demand being described on a euro-market diagram is demand for the currency, not demand for the good itself.
- Reversing the direction of an asset conversion. Selling a foreign asset does not alone tell you whether the investor supplies or demands euros. Trace the currency of the proceeds and the currency being acquired.
- Treating expectations as completed trades. Expectations influence the diagram through the current buying and selling decisions they prompt.
Check Your Understanding
For each problem, state the currency market and quotation before interpreting the orders.
- In the market for euros, \(e=\$1.40/\text{€}\). A U.S. firm needs \(€2.1\) million for equipment. A euro-area household buys U.S. services costing \(\$1.12\) million and exchanges euros to obtain the dollars. Calculate the two listed quantities. (Answer: demand for euros is \(€2.1\) million; supply is \(€0.8\) million.)
- A buyer has a fixed dollar budget of \(\$15\) million for euros. Calculate the amount purchasable at \(\$1.25/\text{€}\) and at \(\$1.50/\text{€}\), then state the direction of the relationship. (Answer: \(€12\) million at \(\$1.25/\text{€}\), \(€10\) million at \(\$1.50/\text{€}\); the quantity falls as the dollar price of a euro rises.)
- U.S. investors expect the euro to appreciate and buy \(€3\) million of euro-denominated assets. Separately, euro-area investors buy U.S. assets and exchange \(€2.4\) million for dollars. Classify each order in the euro market and explain which order is linked to expectations. (Answer: U.S. investors demand \(€3\) million; euro-area investors supply \(€2.4\) million; the expected appreciation motivates the current U.S. demand.)
- At \(e=\$1.30/\text{€}\), a diagram shows planned euro demand of \(€7.5\) million per day and planned euro supply of \(€9.0\) million per day. Calculate the difference and identify its direction. (Answer: planned supply exceeds planned demand by \(€1.5\) million per day.)
- The quotation rises from \(\$1.20/\text{€}\) to \(\$1.32/\text{€}\). Calculate the percentage change in the quoted dollar price of a euro and state the usual direction of movement along the euro demand schedule, holding other influences fixed. (Answer: the quoted price rises by \(10\%\); the usual quantity demanded of euros falls.)