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What is the US dollar and why does it matter to traders?
The Editorial Desk
9/6/2026
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Part one of GO's educational series, designed to help new traders understand the key forces that shape global markets.

Every day, traders watch gold, oil and equities move, looking for the next catalyst. But behind almost every major market move is an invisible force shaping the direction: the US dollar.

Many traders treat it as just another pair to trade. That can leave a major part of the market story out. When traders look at gold, oil or the Australian dollar, they may also be taking a view on the US dollar, whether they realise it or not.

Why the US dollar matters

The US dollar is the world’s reserve currency. It is the denominator for global trade, commodities and risk, so when the dollar moves, the impact can ripple across almost every market traders watch.

What the US dollar actually is

In financial markets, the dollar is typically measured by the US Dollar Index (DXY): a benchmark that tracks the value of the US dollar against a basket of six major currencies. The Euro carries the heaviest weighting, followed by the Japanese yen, British pound, Canadian dollar, Swedish krona, and Swiss franc.

Because the US dollar is the world's reserve currency, it acts as the backbone of the global financial system. Central banks hold it in their reserves. International trade is settled in it. Major commodities are priced in it.

When commentators talk about "dollar strength" or "dollar weakness," they are referring to the DXY moving up or down against these peers.

DXY
100%
Index Composition
EUR 57.6%
JPY 13.6%
GBP 11.9%
CAD 9.1%
SEK 4.2%
CHF 3.6%

Why traders watch the dollar, even when they don't realise it

Because the dollar is the pricing unit for so many global assets, its movement mechanically affects their prices. Four connections matter most for traders already active in these markets.

1. Gold (XAU/USD) is priced in dollars. A stronger dollar can make gold more expensive for buyers holding other currencies, which may weigh on price. The reverse can also apply when the dollar weakens.

2. Oil (WTI and Brent) often follows a similar dynamic. USD strength tends to weigh on crude prices; USD weakness often provides support.

3. AUD/USD is a risk-sensitive currency pair with strong links to commodities and global growth sentiment. It typically falls when the US dollar strengthens and global risk appetite weakens, creating a double headwind for the pair.

4. US equities, including the S&P 500, can also feel the pressure. A persistently strong dollar weighs on the earnings of US multinationals because their overseas revenues translate back into fewer dollars at home. That earnings drag flows into index valuations.

Gold · XAU/USD
More expensive for foreign buyers
Oil · WTI/Brent
Dollar pricing creates headwind
AUD/USD
Risk + commodity currency double hit
S&P 500
Multinational earnings drag

Typical directional impacts when the US dollar strengthens. Tendencies, not guarantees.

What moves the US dollar

The dollar does not move in a vacuum, rather, it responds to five main forces. Understanding these forces can help traders move beyond reacting to price and start reading the context behind it.

What moves the US dollar
Fed/US interest rates

Rate differentials drive capital flows. Higher US rates attract capital into USD assets, increasing demand for the currency.

↓ tap to expand
Strengthens

The Fed raises rates or signals fewer cuts than markets expected

Weakens

The Fed cuts rates or signals a more dovish path

US economic growth

Strong growth attracts foreign investment and sustains demand for USD. Growth divergence is one of the most persistent drivers of currency trends.

↓ tap to expand
Strengthens

US grows faster than other major economies

Weakens

US growth slows or disappoints relative to peers

Risk sentiment (safe haven)

The dollar is often treated as one of the world’s key safe-haven currencies. In genuine crises, USD demand surges as institutions sell risk assets and hoard cash.

↓ tap to expand
Strengthens

Global panic, equity sell-offs, credit stress

Weakens

Risk appetite returns; traders move into higher-yield assets

Inflation data (CPI/PCE)

Inflation can move markets because it changes expectations for the Fed, which can then flow through to the dollar. Watch what the data implies for rates, not just the headline number.

↓ tap to expand
Strengthens

Inflation runs hot and the Fed is expected to hike

Weakens

Inflation cools and rate cut expectations rise

Global dollar liquidity

Strong offshore demand for USD, used to settle trade and service debt, can drive the currency independently of US domestic fundamentals.

↓ tap to expand
Strengthens

Dollar funding stress; shortage of USD offshore

Weakens

Abundant liquidity; Fed QE or swap lines activated

Watch this, not just that

Don't just watch whether the dollar is rising or falling. Watch why it is moving.

A dollar rally driven by US growth is different from a dollar rally driven by global panic. The first is a risk-on signal. The second is a risk-off signal. The markets that may benefit, and the ones that may come under pressure, can be very different in each case.

Three common US dollar scenarios to recognise

The diagram below maps a simple if and then chain: macro catalyst, dollar mechanism and potential asset impact.

Macro Catalyst
Fed holds or hikes rates
Dollar Mechanism
USD strengthens
Capital flows into USD assets
Asset Impact
Gold ↓ Oil ↓ AUD/USD ↓
Macro Catalyst
Fed pivots dovish
Dollar Mechanism
USD weakens
Capital flows out of USD assets
Asset Impact
Gold ↑ Oil ↑ AUD/USD ↑
Macro Catalyst
Global panic/risk-off
Dollar Mechanism
USD spikes
Safe-haven demand surges
Asset Impact
Equities ↓ Risk FX ↓ Gold ↕
Common trap

Assuming that a stronger US dollar is always good news.

For traders with long exposure to gold, oil, AUD/USD or emerging market equities, a rising dollar can act as a headwind. It may push commodity prices lower, pressure resource-linked currencies and weigh on markets priced in USD. USD strength may benefit USD cash holders and some domestic US equity investors. But for traders exposed to commodities and FX, the effect is often more complicated.

The mistake is treating the dollar as a neutral barometer. It is not neutral. It has a direction, and that direction can affect almost every position you hold.

When the dollar may deserve closer attention

The dollar may deserve closer attention around events that shift Federal Reserve expectations or rattle global risk appetite.

  • CPI/inflation releases: Inflation can move markets because it changes expectations for the Fed, which can then flow through to the dollar. Watch what the data implies for rates, not just the headline number.
  • Federal Reserve meetings: Rate decisions and forward guidance directly reprice the dollar. The statement and press conference often matter more than the actual decision.
  • Non-Farm Payrolls and jobs data: Strong employment can reduce expectations for near-term rate cuts. Weak jobs data can increase expectations for Fed easing. Both move USD significantly.
  • Major risk-off event: Geopolitical shocks, banking stress, or sharp equity sell-offs can trigger sudden safe-haven demand for USD, causing rapid spikes in dollar strength regardless of underlying US fundamentals.

Test your knowledge

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Key takeaway

The US dollar is not just another market input. It is one of the main reference points global markets keep coming back to.

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