Dollar Index (DXY)
The Dollar Index measures the US dollar's value against a basket of major foreign currencies, and its swings ripple through stocks, commodities, and emerging markets far beyond the currency desk.
What DXY actually measures
The Dollar Index tracks the dollar's value against six major currencies, with the euro carrying the largest weight, alongside the yen, pound, Canadian dollar, Swedish krona, and Swiss franc. It doesn't tell you what the dollar is worth in absolute terms, only how it's trending relative to that basket.
A rising DXY means the dollar is strengthening against those currencies; a falling DXY means it's weakening. Because the euro dominates the weighting, DXY often behaves like a mirror image of the euro-dollar exchange rate.
Why the world's reserve currency matters
The dollar underpins global trade and finance in a way no other currency does. Oil, most commodities, and a large share of international debt are priced and settled in dollars, so dollar moves affect countries that have nothing to do with the United States directly.
When the dollar strengthens, it becomes more expensive for foreign borrowers and importers to service dollar-denominated debt or buy dollar-priced goods, which is why a sharp dollar rally can tighten financial conditions well beyond US borders.
How dollar swings move other markets
A stronger dollar tends to pressure commodities, since oil, gold, and industrial metals are priced in dollars and become more expensive for holders of other currencies, dampening demand. It can also weigh on the earnings of large US multinationals, since revenue earned abroad converts back into fewer dollars.
A weaker dollar tends to do the opposite: it makes US exports more competitive, lifts dollar-priced commodities, and often eases pressure on emerging markets that carry dollar debt.
What drives the dollar itself
Interest rate differentials are the biggest driver: capital tends to flow toward whichever major economy offers the best risk-adjusted return, so when US rates rise relative to other countries, the dollar often strengthens. The dollar also acts as a safe haven during periods of global stress, since investors flock to it even when the news is bad for the US economy itself.
Relative growth expectations matter too. If the US economy is expected to outperform Europe or Japan, capital tends to gravitate toward dollar assets in search of better returns, which lifts the currency independent of what the Fed is doing with rates in that moment. Trade flows and current account balances play a smaller but persistent role as well, since a country that imports far more than it exports tends to see steady structural pressure on its currency over time.
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Quick answers
What currencies make up the Dollar Index?
Six currencies: the euro, Japanese yen, British pound, Canadian dollar, Swedish krona, and Swiss franc, with the euro carrying the heaviest weight by far.
Why does a strong dollar hurt commodity prices?
Commodities are priced in dollars, so when the dollar strengthens they become costlier for buyers using other currencies, which tends to reduce demand and pressure prices lower.
Is DXY the same as the dollar's value against every currency?
No. It only reflects the dollar against a fixed basket of six major currencies, so it can miss moves against currencies outside that basket, like the Chinese yuan.