Where an economy's exports concentrate heavily in a few commodities, its overall economic activity, fiscal revenue, currency and corporate earnings all move with those commodity prices. When prices rise, all of these improve together in a mutually reinforcing expansion, and when prices fall they deteriorate together. This co-movement gives the cycle a larger amplitude than a diversified economy would show. Equity cyclicality is amplified as a result. Index composition usually centres on resource companies and related financials and transport, and the earnings of those sectors are highly sensitive to commodity prices. At a cyclical peak, their earnings and valuations sit high together, and both contract at the trough. This makes the amplitude of the index considerably larger than the amplitude of earnings alone. Currency plays a dual role here, amplifying or buffering.
When commodity prices rise, export revenue increases and the currency tends to appreciate, which amplifies equity returns measured in foreign currency further. In a downturn, currency depreciation and equity declines occur together, so foreign investors bear larger losses than local ones. This co-movement of currency and equities is a common feature of such markets. The procyclicality of fiscal policy complicates matters further. When prices are high, fiscal revenue is abundant and spending expands easily, and when prices are low, revenue contracts while cutting spending is politically difficult. Many resource exporters therefore run procyclical rather than countercyclical fiscal policy, which amplifies the economic cycle and increases the risk of fiscal strain at the trough. One category of economy uses institutional design to buffer the cycle.
A sovereign wealth fund stores revenue from commodity peaks and provides a fiscal buffer at the trough, converting procyclical fiscal policy into a countercyclical one. Whether such an institution exists is an important distinction in assessing the macroeconomic stability of a resource exporter, and its effect is quite visible across several cases. From a global allocation perspective, such markets offer a specific exposure: exposure to the global commodity demand cycle, which correlates comparatively little with exposure to developed-market consumption or technology cycles. This gives them some diversification value at the cost of higher individual volatility. Their role sits closer to a cyclical allocation than to a core holding. For investors, the key to understanding this cycle is that its driver sits outside the market.
The direction of such markets is set mainly by global commodity demand, which in turn depends on growth and industrial activity in the major economies. Using local economic data to judge these markets omits the true driver, and that driver is located somewhere else entirely. One further point concerns the shape of these cycles rather than their amplitude. Commodity cycles tend to be long and to overshoot in both directions, since supply responds slowly to price. Building capacity takes years, so high prices persist while it arrives, and the eventual surplus then persists while it is worked off. The equity markets attached to these economies inherit that extended shape, which lengthens both the good periods and the difficult ones.