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- The US dollar is held in roughly 57% of disclosed global foreign exchange reserves, making it the dominant store of value for central banks worldwide.
- Oil is primarily priced and settled in dollars, meaning every country that imports energy must first acquire the currency. This creates structural global demand independent of any single nation’s trade balance.
- Federal Reserve rate decisions, US fiscal policy shifts, and dollar index movements affect asset prices across oil, commodities, and emerging market debt, regardless of geography.
The US dollar functions as the world’s reference point for global trade, energy markets, and international finance.
When the dollar moves, markets respond across asset classes and geographies simultaneously. Understanding why requires looking at three mechanisms that give the dollar its reach, and at the forces that constrain it.
How the Dollar Shapes Global Markets
The first mechanism is reserve holdings. Central banks hold foreign exchange reserves to manage their currencies and settle international obligations.
As of Q2 2025, approximately 57% of disclosed global foreign exchange reserves were held in US dollars ⁽¹⁾. That figure has declined from a peak of 72% in 2001 ⁽¹⁾, but it still exceeds double the share held in euros, the second-ranked reserve currency.
The second mechanism is transactional dominance. According to the Bank for International Settlements 2022 Triennial Survey, the US dollar appeared on one side of 88% of all global foreign exchange transactions ⁽²⁾.
Even when two non-US counterparties are trading with each other, the dollar frequently functions as the bridge currency. This creates a base level of structural dollar demand that persists regardless of the US economic cycle.
The Petrodollar System
In 1974, the United States and Saudi Arabia reached an agreement to price and settle oil exports in US dollars. That arrangement gave rise to the petrodollar system, which embedded the dollar in the global energy supply chain at its foundation.
Today, roughly 80% of global oil transactions are denominated in dollars ⁽³⁾.
The mechanism operates as a self-reinforcing loop. Many oil importers need to acquire dollars to complete the transaction.
That dollar demand supports global liquidity. Greater dollar liquidity makes dollar-denominated trade financing and commodity contracts more efficient, which deepens the dollar’s role as the dominant invoicing currency.
The connection between oil market risk pricing and dollar demand signals illustrates how energy disruptions translate directly into currency market dynamics.
When Dollar Dominance Has Limits
Reserve status does not insulate the dollar from depreciation or structural erosion. The decline from 72% to 57% of global reserves over two decades reflects a gradual but consistent move by central banks toward diversification into euros, Japanese yen, and gold. The pace is slow, but the direction has been persistent.
US fiscal policy also matters. Persistent budget deficits increase the stock of outstanding US Treasury securities and can weigh on long-term confidence in the currency. The most immediate near-term constraint, however, is Federal Reserve rate policy.
When the Fed raises rates, the relative return on dollar-denominated assets rises and draws capital inflows. When rates hold steady or fall, that advantage narrows, and the dollar typically faces downward pressure from shifting rate differentials.
Dollar Weakness and What It Signals
Dollar weakness transmits quickly into commodity prices, emerging market dynamics, and global risk appetite.
The DXY fell approximately 9% in 2025, its steepest annual decline since 2017 ⁽⁴⁾, as tariff uncertainty, narrowing US rate differentials, and concerns about the trajectory of US fiscal policy converged.
A weaker dollar provides structural support to oil prices, because the commodity is priced in dollars and becomes cheaper in foreign-currency terms as the dollar falls. Emerging market economies carrying dollar-denominated debt also gain relief, as the local-currency cost of debt service declines.
Markets interpreted the 2025 DXY decline as a repricing of near-term US growth and policy expectations. It did not register as a signal that the dollar was losing reserve status.
That distinction matters: dollar weakness as a cyclical policy signal behaves very differently from structural reserve diversification, and conflating the two produces misread market conditions.
Conclusion
The dollar’s position as the world’s most closely watched currency rests on three reinforcing pillars:
- Its dominant share of global reserve holdings
- Its function as the bridge currency in the majority of international transactions
- Its role as the settlement currency for the global oil market
Federal Reserve decisions and US fiscal signals therefore carry weight far beyond US borders. For traders reading oil markets, emerging market currency dynamics, or broader risk signals, the dollar is the common variable connecting them.
The mechanism that gives it this reach is structural and durable, even as its share of global reserves contracts gradually over time.
