Mechanism and definitions
An exchange rate like EUR USD is the price of 1 euro in US dollars. GBP USD is the price of 1 pound in US dollars. Because both include USD, movements often reflect how the US dollar is repriced versus each non-USD currency.
A useful way to think about “what moves” these pairs is relative drivers:
- Relative rate expectations: If markets expect US interest rates to rise relative to euro-area rates, USD tends to strengthen versus EUR, pressuring EUR USD lower. The same logic applies for GBP USD using UK versus US expectations.
- Macro surprises: New information about inflation, growth, employment, and fiscal policy can change expectations for future policy rates and bond yields.
- Risk sentiment: In “risk-off” periods, investors may prefer USD liquidity and perceived safety, which can push both EUR USD and GBP USD down (or change their relative moves depending on which side is hit more by domestic news).
- Liquidity and market conditions: Even without “new information,” volatility can increase when liquidity is thinner (for example, around major economic releases or outside peak trading hours). Wider effective bid-ask spreads, larger price impact per trade, and changes in dealer positioning can affect observed price moves.
Evidence and a self-check example (no forecast)
You can verify the logic using a simple, non-predictive decomposition. Suppose a week of releases increases expectations that US policy will stay higher for longer, while euro-area expectations are unchanged. That typically implies US yields rise relative to euro-area yields. With USD priced higher, EUR USD is more likely to weaken, even if nothing “EUR-specific” changed.
Now compare that to the UK case. If, during the same period, UK inflation data is stronger than expected and shifts UK rate expectations upward relative to the US, GBP USD may weaken less (or even move differently) because GBP’s “rate support” partially offsets USD strength. The key is that each pair reflects USD plus the relative attractiveness of EUR or GBP versus USD, driven by shifting expectations and market positioning.
Limitations and risks (what can fail)
- Rate-story oversimplification: Correlation to yields can break when other forces dominate—such as large USD funding needs, policy communication shocks, or hedging flows.
- Risk sentiment is not one-way: “Risk-off” can strengthen USD, but the magnitude and direction can differ across EUR and GBP if the euro-area or UK event risk is larger or if investors already positioned differently.
- Market microstructure distorts observation: Short-term moves can be amplified by low liquidity or order-flow dynamics, making it easy to over-attribute price changes to macro news.
- Historical relationships don’t guarantee outcomes: Past reactions to inflation or central-bank headlines do not ensure the same response next time.
Verification and next question
To explain movements responsibly, track what changed rather than assuming a single cause: (1) how expectations for US versus euro/UK policy rates shifted, (2) which macro releases surprised, and (3) whether overall liquidity/risk conditions changed. A good next question is: which specific set of releases and expectation shifts occurred during the period you are analyzing?