Learn · Currency Mechanics
How Does a Currency Trade Work?
A currency trade buys one currency and sells another at the same moment, so every position is a bet on the relationship between two currencies. The result depends on three things: how the exchange rate moves, the difference between the two currencies' interest rates, and the cost of holding the position. This article covers how currency prices are quoted, the main ways to trade them, why a forward price differs from today's price, how companies hedge, how the carry trade works, and what happens when a central bank stops defending its currency.
How do you read a currency quote?
Currencies are priced in pairs. In EUR/USD, the euro is the base currency and the U.S. dollar is the quote currency, so a price of 1.10 means one euro costs $1.10. A rise to 1.15 means the euro has strengthened against the dollar, and a fall to 1.05 means it has weakened. Buying EUR/USD means buying euros and paying in dollars; selling it means the reverse.
Some pairs run the other way. USD/JPY at 150 means one dollar buys 150 yen, so a higher number there means a stronger dollar and a weaker yen. Price moves are counted in pips. One pip on EUR/USD is 0.0001, which is $10 on a €100,000 position, and pairs quoted in yen use a pip of 0.01. Many trading venues now quote in fractions of a pip.
Who trades currencies, and how big is the market?
Currencies make up the largest financial market in the world. The Bank for International Settlements, which surveys trading every three years, counted an average of about $9.5 trillion changing hands each day in April 2025, up from $7.5 trillion in 2022. The U.S. dollar was on one side of 89% of all trades, and euros against dollars made up about a fifth of the total.
Most of that volume is ordinary business. Importers buy the currency they owe suppliers, and exporters convert what they earn. Investors who own foreign shares and bonds manage the currency that comes with them, and central banks manage their reserves. Hedge funds trade currencies to remove the currency risk from foreign holdings or as positions in their own right, and the article on what a hedge fund actually owns shows where currencies sit in that wider range.
What are the main ways to trade a currency?
A spot trade exchanges currencies at today's price. Despite the name, most spot trades settle two business days later, because the payments have to move through banks in two countries; U.S. dollars against Canadian dollars settle in one.
A forward fixes a rate today for an exchange on a later date, anywhere from a few days to more than a year away. Forwards are private contracts with a bank, so the amount and date can be matched to a specific bill. A futures contract does the same job in standard sizes and dates, traded on an exchange that stands between buyer and seller. The Chicago Mercantile Exchange launched seven currency futures contracts in May 1972.
An option gives the right, without the obligation, to exchange at a set rate by a set date. The buyer pays an upfront premium, and that premium is the most the buyer can lose. Forwards and futures have no such ceiling: their gains and losses move one for one with the exchange rate for as long as the position is open.
Why is a forward rate different from today's rate?
A forward rate comes from interest rates. Suppose, using invented round numbers, that a euro costs $1.10 today, a one-year dollar deposit pays 4%, and a one-year euro deposit pays 2%. A bank asked to deliver euros in a year can borrow dollars, buy the euros now, and hold them on deposit until the delivery date. Its cost is the dollar interest it pays minus the euro interest it earns, so it quotes a one-year forward near $1.1216, which is $1.10 × 1.04 ÷ 1.02.
The forward sits above today's price because dollars pay more interest than euros. The bank would quote the same rate whether its economists expected the euro to rise, fall, or stay where it is, so a forward rate says very little about where the currency is heading. This relationship is called covered interest parity. Since the 2008 financial crisis it has held less tightly, and the BIS has documented persistent deviations from it, known as the cross-currency basis.
The same arithmetic explains why a higher interest rate abroad is not free money. An investor who converts dollars into a higher-yielding currency and locks in the rate to convert back gives up the extra interest through the forward price. Keeping the extra interest means leaving the currency exposure open, and that is a different trade with a different risk.
How does a company use a currency trade to hedge?
Take an invented American company that owes a German supplier €100,000 in three months. At $1.10 per euro the bill is worth $110,000 today, but the company pays on delivery and nobody knows what a euro will cost then. If the euro rises to $1.20, the same bill costs $120,000; if it falls to $1.00, the bill costs $100,000.
A forward removes the uncertainty. If the company locks in $1.10, it pays $110,000 on the day whatever the euro does. When the euro rises, the forward looks like a good decision, and when it falls, the company pays $10,000 more than it would have by waiting. Both outcomes are the hedge doing its job, because the company bought a known bill and received one.
What does locking in the rate buy?
An invented American company owes a supplier €100,000 in three months. A forward can lock in $1.10 per euro for some or all of the bill. Choose what a euro costs on payment day and how much of the bill is locked in.
Invented figures for illustration. The arithmetic leaves out bank spreads, fees, and collateral.
Hedges carry their own risk. A delayed shipment or a smaller order can leave the company holding a forward for euros it no longer needs, and closing the contract early can mean a gain, a loss, or a fee. Matching the amount and the payment date matters as much as the rate.
What is a carry trade?
A carry trade borrows in a currency with low interest rates, invests in one with higher rates, and leaves the currency exposure open on purpose. The investor earns the gap between the two rates for as long as the exchange rate holds steady or moves in the investor's favor.
The Japanese yen was the standard funding currency for years. In early 2024 the Bank of Japan's policy rate was still below zero, at minus 0.1%, while the U.S. Federal Reserve held its target range at 5.25% to 5.50%, so borrowing yen to hold dollars earned more than five percentage points a year. In early July 2024 a dollar bought about 162 yen, then the weakest the yen had been since December 1986. The Bank of Japan raised rates on July 31, and by August 5 a dollar bought about 144 yen. That fall of about 11% in under a month erased roughly two years of the interest gap. Japan's Nikkei stock index fell 12.4% the same day, and the BIS later described the episode as an unwinding of carry trades.
What happens when a central bank defends a currency?
A central bank can hold its currency at a fixed rate or inside a band by buying and selling from its reserves, raising or cutting interest rates, or limiting how money crosses its borders. Hong Kong has held its dollar between 7.75 and 7.85 per U.S. dollar since 2005 this way. When traders doubt that a defense will last, they sell the defended currency, and the central bank must decide how much it is willing to spend. Britain's failed defense of sterling in September 1992 is the best-known case, and the article on global macro investing walks through it.
A defense can end in the other direction too. In September 2011 the Swiss National Bank set a minimum exchange rate of 1.20 francs per euro, promising to buy unlimited euros to stop the franc from strengthening past it. On January 15, 2015, it abandoned the minimum in a surprise announcement and said it would cut its deposit rate to minus 0.75%. Within minutes the euro fell from 1.20 francs to roughly 0.80 to 0.85, depending on the price source, and the franc ended the day about 15% stronger.
The price skipped the levels in between. A stop-loss order, an instruction to sell automatically if the price reaches a chosen level, gives no protection when the price never trades at that level, and orders placed just below 1.20 were filled far lower. The broker FXCM later put its clients' losses beyond their account balances at about $276 million and took a $300 million rescue loan. In London, the broker Alpari UK went into insolvency.
Where does the risk in a currency trade come from?
Leverage is the first source. A forward or futures contract needs only a small deposit, called margin, to control a much larger amount of currency, and the whole amount moves with the exchange rate. U.S. rules require individual traders to put down at least 2% of a position's value on major currency pairs, which is leverage of 50 to 1, so a 2% move against the position can wipe out the entire deposit.
Gaps are the second. Markets that trade continuously on an ordinary day can empty out around a surprise policy decision, as the franc showed. The third is the other side of the contract. A forward is a private agreement with a bank, so it is only as good as the bank's ability to pay; futures replace that exposure with a clearing house, in exchange for gains and losses settled in cash every day.
Every currency trade, from a traveler's cash to a fund's forward, comes down to the rate at the start, the rate at the end, and the interest paid or earned in between.
Sources and further reading
Bank for International Settlements: Triennial Central Bank Survey, April 2025
BIS Quarterly Review: Covered interest parity lost: understanding the cross-currency basis
Swiss National Bank: discontinuation of the minimum exchange rate, January 15, 2015
BIS Bulletin: the market turbulence and carry trade unwind of August 2024
Bank of England: the operation of monetary policy, 1992
Frequently asked questions
How big is the currency market?
Traders exchanged an average of about $9.5 trillion a day in April 2025, according to the Bank for International Settlements, which surveys the market every three years. That compares with $7.5 trillion in 2022. The U.S. dollar was on one side of 89% of all trades.
What is a pip in currency trading?
A pip is the standard unit for measuring a move in a currency price: 0.0001 for most pairs and 0.01 for pairs quoted in Japanese yen. On a €100,000 position in EUR/USD, one pip is worth $10. Many venues quote in fractions of a pip, and traders use pips to describe price moves and the gap between buying and selling prices.
What is a carry trade?
A carry trade borrows a currency with low interest rates and invests in one with higher rates, earning the difference while the exchange rate holds. The risk is that the higher-yielding currency falls by more than the interest earned. Between early July and August 5, 2024, the dollar lost about 11% against the yen as yen-funded positions were closed, roughly two years of the interest gap at the time.
What moves exchange rates?
Interest rates, inflation, economic growth, trade, and money moving into and out of a country's assets all play a part. Expectations matter as much as the numbers, so a currency can fall after an interest-rate rise if markets expected a bigger one. Central bank intervention and political events can move rates sharply and suddenly.
What is a currency peg?
A peg ties a currency to another currency, or holds it inside a narrow band, through central bank intervention and interest-rate policy. Hong Kong's dollar has been held between 7.75 and 7.85 per U.S. dollar since 2005. A peg lasts only as long as the central bank is able and willing to defend it, which is why Switzerland's sudden exit from its minimum exchange rate in 2015 moved the market so violently.
Does buying a foreign currency mean borrowing money?
No. Someone who swaps dollars they already own for euros has borrowed nothing; they hold euros and will gain or lose in dollar terms as the rate moves. Borrowing enters when a trader uses margin to control a larger position, or deliberately funds one currency by borrowing another, as in a carry trade.
Are currency trades only for hedge funds?
No. Most currency trading comes from companies paying and receiving foreign money, investors buying assets abroad, banks, and central banks. A traveler changing money at an airport is making a small spot trade. Individuals in the U.S. can also trade currencies through regulated brokers, with a minimum deposit of 2% of the position on major pairs.