Reserve Currency
The currency central banks hold as savings and the rest of the world uses to price and settle trade, which today means the dollar.
A reserve currency is one that central banks hold as savings and that businesses everywhere use to price, borrow, and settle even when neither party is from the issuing country. About 57 percent of the world's official foreign exchange reserves are held in dollars, against roughly 21 percent in euros, 6 percent in Japanese yen, and 2 percent in Chinese renminbi. Around half of world trade is invoiced in dollars, several times the American share of that trade. When an Indonesian firm buys Brazilian coffee, the price is usually set in a currency neither country issues.
Why the world settles on one
Money is a network, and networks concentrate. You want to be paid in whatever everybody else accepts, so the leading currency keeps winning for the same reason a common language does. Once oil, shipping, commodities, and half the world's bond market are priced in one currency, using another costs you money on every transaction.
Four things are needed to be that currency, and having all four at once is rare. Deep, liquid markets in a safe asset, which for the dollar means Treasury bonds, so anyone can park billions and sell them tomorrow. Free movement of capital in and out. Courts that will enforce a contract against your own government. And a willingness to supply the world with your currency, which in practice means running trade deficits so that foreigners can accumulate it.
That is why the renminbi is stuck near 2 percent. China is the largest trading nation on earth, but it maintains capital controls, and a currency you cannot freely take out of the country is not a store of value.
The privilege and the bill
Valery Giscard d'Estaing called it an exorbitant privilege when he was French finance minister in the 1960s, and the phrase stuck because it is accurate. The United States borrows more cheaply than it otherwise could because the world needs its bonds. It earns a small profit on every hundred-dollar bill circulating abroad. Most importantly it controls the plumbing: because dollar payments clear through American banks, Washington can cut a company, a bank, or a country out of the world economy without firing anything.
There are real costs. Global demand for dollars keeps the currency stronger than American trade alone would justify, which makes American exports expensive and has contributed to the hollowing of American manufacturing. And the Triffin dilemma sits underneath the whole arrangement: supplying the world with dollars requires deficits, and permanent deficits eventually eat away at confidence in the thing being supplied.
Does it last
Reserve currencies do change, but slowly, and usually because the issuer breaks. Sterling ran the world through the nineteenth century and was still more than half of global reserves in 1950, decades after Britain had stopped being the leading economy. It took two world wars and a bankruptcy to finish it off.
Talk of de-dollarization has been louder since 2022, when the United States and its allies froze roughly 300 billion dollars of Russian central bank reserves. That was a demonstration that reserves held in Western currencies are not fully yours if you fall out with the West. The visible response has not been a move into the renminbi, which has barely shifted, but a sustained wave of central bank gold buying and more bilateral trade settled in local currencies. Both are hedges, not replacements.
The dollar's position rests in the end on a belief that the United States will honor its obligations and let people move money in and out. Every sanction spends a little of that belief. The question is not whether an alternative exists today, because it does not. It is whether the incumbent keeps giving people reasons to look for one.