The US Dollar Index (DXY), Explained: What It Is and Why It Moves
The DXY is a trade-weighted index measuring the US dollar against six currencies, with the euro carrying 57.6% of the weight. Here's what it is, what moves it, and why it isn't a complete picture of global dollar strength.
The US Dollar Index (DXY), Explained: What It Is and Why It Moves
The DXY — the US Dollar Index — is one of the most-cited numbers in global finance. It tells you, in a single figure, how the US dollar is performing against a basket of six peer currencies. When traders say "the dollar is at 104" or "the dollar hit a 20-year high," they almost always mean the DXY. Understanding what the DXY is, how it is built, and where it falls short is foundational to reading macro currency analysis.
- The DXY measures the US dollar against six currencies, with the euro at 57.6% of the weight.
- It launched at 100.000 in March 1973, shortly after the Bretton Woods system collapsed.
- The basket has only changed once — when the euro replaced several European currencies in 1999.
- Fed policy, rate differentials, and risk sentiment are the primary drivers of DXY moves.
- The DXY is euro-heavy and does not capture dollar strength against Asia, Latin America, or emerging markets — for that, use the Fed's Nominal Broad Dollar Index.
What is the DXY?
The DXY is a geometrically weighted index of the US dollar against six foreign currencies: the euro, Japanese yen, British pound, Canadian dollar, Swedish krona, and Swiss franc. The index is designed, maintained, and published by ICE (Intercontinental Exchange), and futures on the index are traded on the New York Board of Trade (NYBOT), a subsidiary of ICE.
The index launched in March 1973 with a base value of 100.000, timed to coincide with the collapse of the Bretton Woods fixed exchange rate system — the moment when the world shifted to floating exchange rates. A DXY reading above 100 means the dollar is stronger than it was at that 1973 baseline; below 100 means it is weaker.
How is the DXY calculated?
The DXY uses a geometric weighted average — each currency is raised to the power of its weight, and the products are multiplied together. The six currency weights are:
| Currency | Ticker | Weight |
|---|---|---|
| Euro | EUR | 57.6% |
| Japanese Yen | JPY | 13.6% |
| British Pound | GBP | 11.9% |
| Canadian Dollar | CAD | 9.1% |
| Swedish Krona | SEK | 4.2% |
| Swiss Franc | CHF | 3.6% |
The practical implication is stark: EUR/USD accounts for more than half the index. When the euro moves, the DXY almost always moves in the opposite direction. The index basket has changed only once since inception — when the euro replaced the Deutsche Mark, French franc, Italian lira, Dutch guilder, Belgian franc, and Spanish peseta at the start of 1999.
What moves the DXY?
The DXY is the dollar's score against a peer-currency basket, so the same forces that move the US dollar drive it. Three forces dominate.
Federal Reserve policy and rate differentials
The single most powerful driver of the DXY is the Federal Reserve's interest rate setting relative to the central banks of the basket currencies — primarily the ECB and the Bank of Japan. When the Fed raises rates faster or higher than the ECB, capital flows toward dollar-denominated assets to capture the yield premium, bidding up the dollar and the DXY. The 2022 episode illustrated this vividly: the Fed took the federal funds rate from zero to 4.25% inside nine months, while the ECB only began hiking in July 2022 and the Bank of Japan held yield curve control throughout. The result was the DXY's sharpest multi-month rally in decades.
Relative economic growth
Capital flows to where it earns the best returns on a risk-adjusted basis. When US economic growth outpaces Europe and Japan — measured by PMIs, GDP prints, or labour market data — global investors shift assets to the US, lifting the dollar. The reverse also holds: a US growth slowdown relative to Europe tends to narrow the DXY's advantage.
Risk sentiment (safe-haven flows)
In times of global financial stress, the dollar often rises sharply as investors flee to the world's deepest and most liquid markets — US Treasuries and dollar cash. This "flight to safety" is one reason the DXY can spike during crises even when US fundamentals are not obviously superior. See the dollar's safe-haven behaviour in 2022 for a case study, and read more about the gold–dollar correlation, which often inverts during these episodes.
The DXY's key limitation: it is not the whole dollar story
The DXY is widely cited, widely traded, and genuinely useful for tracking the dollar's broad trend — but it has a structural flaw that every macro trader should understand: it only covers six currencies, and more than half the weight is the euro.
The basket contains no Chinese yuan, no Mexican peso, no Korean won, no Australian dollar. China and Mexico are the United States' two largest goods trading partners. The DXY barely registers them. If the yuan weakens sharply while the euro holds firm, the DXY may show "dollar stability" while the actual trade-competitiveness picture for US exporters has shifted considerably.
DXY vs the Fed's Broad Dollar Index — a comparison
| DXY | Fed Broad Dollar Index | |
|---|---|---|
| Maintained by | ICE (Intercontinental Exchange) | US Federal Reserve |
| Number of currencies | 6 | ~26 |
| Includes China / EM? | No | Yes |
| Last basket change | 1999 (euro introduction) | Updated periodically by trade share |
| Best for | Liquid futures trading; euro-dollar trend | Macro trade competitiveness analysis |
| Primary limitation | Euro-heavy; misses EM | Trade-weighted only; excludes financial flows |
The DXY in practice: the 2022 "wrecking ball"
The most dramatic DXY move of the modern era unfolded in 2022. The index rallied from around 95 in January to 114.78 on 27 September 2022 — its highest level since 2002. Three forces combined: the Fed's fastest tightening cycle since the 1980s, a European energy crisis triggered by the Russian invasion of Ukraine that hammered the euro and turned it into a recession hedge, and a Bank of Japan that refused to abandon yield curve control while every other major central bank hiked. The dollar, effectively fighting on all three fronts simultaneously, became one of the most disruptive forces in global markets that year — strengthening so aggressively it threatened emerging-market debt, commodity prices, and US corporate earnings all at once.
For a full breakdown of that episode, see the deep-dive on the 2022 strong-dollar cycle and on reserve currencies, which explains why demand for dollar-denominated assets runs structurally deep.
Reading the DXY alongside a macro currency meter
Because the DXY is so euro-centric, macro currency analysts typically watch it alongside broader measures. The Pip Theory macro strength meter scores all eight major currencies — including JPY, GBP, AUD, NZD, CHF, CAD, and EUR — on fundamental drivers: interest rates, growth differentials, positioning, risk sentiment, and commodities. That gives a fuller picture than any single bilateral index. When the DXY is rising sharply but the fundamental strength score for the US dollar has already plateaued, the divergence can be a useful signal that the move is running on inertia rather than fresh macro tailwinds.
The DXY is, in short, a useful but imperfect barometer. It captures the dollar's most liquid, most-traded bilateral relationships. What it cannot capture is the full geometry of a reserve currency that underpins roughly half of all global trade invoicing, half of all cross-border lending, and the lion's share of foreign central bank reserves — a role explored in detail in Reserve Currencies Explained.
Educational macro context only — not investment advice.