U.S. Dollar Index (USDX)

What Is the U.S. Dollar Index (USDX)?

The U.S. Dollar Index (USDX) is a benchmark index that measures the value of the U.S. dollar against a fixed basket of major foreign currencies. It is commonly used by traders, analysts, and market commentators as a shorthand gauge of broad dollar strength or weakness.

The index is administered by ICE Data Indices, and USDX futures trade on ICE Futures U.S. The index began in 1973, after the Bretton Woods fixed-exchange-rate system broke down and major currencies moved toward floating exchange rates.

How the Index Works

USDX compares the dollar with a set of currencies using fixed weights. The basket includes the euro, Japanese yen, British pound, Canadian dollar, Swedish krona, and Swiss franc. Because the weights are fixed, the index is consistent as a historical benchmark, but it does not constantly update to reflect today's full trade patterns.

If the index rises, the dollar has strengthened against the basket overall. If it falls, the dollar has weakened. The index level itself is less intuitive than the direction and percentage change. A move from 100 to 105 means the dollar has gained 5% against the weighted basket from that starting point.

What Traders Watch

Currency traders watch USDX because it condenses several major exchange-rate relationships into one number. Bond investors watch it because dollar strength can interact with inflation, capital flows, and demand for U.S. assets. Commodity traders watch it because many commodities are priced in dollars, and dollar moves can influence global purchasing power.

Equity investors also pay attention. A stronger dollar can reduce the translated value of foreign earnings for U.S. multinationals and make U.S. exports more expensive abroad. A weaker dollar can have the opposite effect, though company-specific hedging and supply chains matter.

Limits of the USDX

The USDX is not the whole dollar. It does not include every major U.S. trading partner, and its currency weights reflect the index design rather than a live map of global trade. The euro's large weight means euro-dollar moves can dominate the index even when the dollar's move against other currencies is more mixed.

For broader economic analysis, the Federal Reserve's trade-weighted dollar indexes may be more useful. For trading a narrow benchmark, USDX remains widely recognized. The right tool depends on whether the reader is looking at futures, market sentiment, import prices, trade competitiveness, or portfolio currency exposure.

Example

If the dollar rises strongly against the euro and yen but falls slightly against the Canadian dollar, USDX may still rise because the euro and yen carry meaningful weight. A headline that says the dollar is stronger may therefore be true for the basket while still hiding mixed bilateral exchange-rate moves.

Reading the Level

The index is also a relative measure, not a statement about domestic purchasing power. A rising USDX can coexist with domestic inflation if the dollar is losing less purchasing power than other currencies or if foreign demand for dollar assets is strong. A falling USDX can occur even when the U.S. economy is growing if other currencies strengthen faster.

The Bottom Line

The U.S. Dollar Index is a market benchmark for broad dollar movement against a fixed major-currency basket. It is useful for quick dollar context, but it should be read with its composition in mind. A dollar view based only on USDX can miss trade-weighted, emerging-market, and country-specific currency exposure.