Commodity currency

An informal grouping of currencies issued by economies whose export earnings are concentrated in raw materials. The Australian dollar is habitually discussed alongside iron ore and coal, the Canadian dollar alongside crude oil, the New Zealand dollar alongside dairy, and the Norwegian krone alongside oil and gas. Membership of the group is a market habit rather than a classification anyone maintains.

The mechanism behind the label is the terms of trade. When the price of a dominant export rises, export revenue rises, the trade balance improves, foreign buyers of that export need more of the currency to pay for it, and the domestic economy runs warmer, which in turn shapes the central bank's rate path. Each link is real, and each takes time, which is why the relationship shows up more clearly in months of data than in a single session.

The relationship is a tendency and not a rule, and it breaks in predictable places. During episodes of falling risk appetite, flows into currencies treated as safe havens can dominate the commodity link entirely, and an interest rate differential moving the other way can hold a commodity currency up while the commodity itself falls. A correlation calculated over a long window can therefore describe a relationship that is absent in the window that matters.