Raw materials on one side, share prices on the other
The commodity market and the equity market are strongly linked because some listed companies use commodities as their raw materials. When a commodity's price rises or falls, the profit margins of those companies move directly, and their share prices follow. The chain is mechanical: a rise in commodity prices increases input costs, which reduces profit margins; a fall in commodity prices can improve profitability and boost stock valuations.
The same commodity move creates winners and losers. Rising crude oil prices improve the profitability of oil-producing companies and, at the same time, reduce the profitability of airline and logistics companies, for whom fuel is a large input cost.
Crude rises 30%. An upstream oil producer sells the same barrels for 30% more, so its margins widen. An airline's fuel bill, often its largest single cost, jumps; unless it can raise fares in step, its margin shrinks. A trucking company sits in the same position as the airline. An analyst covering all three would move estimates in opposite directions off one input.
Commodities as a signal
Commodities are traded globally, so changes in the prices of crude, gold or copper often signal shifts in global demand and supply. Equity markets are sensitive to growth prospects and react to those signals even in sectors that never touch the commodity. The syllabus's example: a fall in copper prices may signal slowing industrial demand, dragging down metal and infrastructure stocks.
Two different mechanisms appear in questions. The input-cost mechanism runs through a company's own margins (fuel for an airline). The signal mechanism runs through what the price says about the world (copper as a read on industrial demand). Falling copper hurting an infrastructure stock is the signal mechanism, not an input-cost story, since cheaper copper would if anything help a builder's costs.
- Many listed companies use commodities as raw material, so a commodity price rise raises input costs and cuts profit margins, and a fall improves profitability and can lift valuations.
- The same move splits winners from losers: rising crude improves oil producers' profitability while reducing that of airlines and logistics companies.
- Commodities trade globally, so moves in crude, gold or copper signal shifts in worldwide demand and supply, and growth-sensitive equity markets react. A fall in copper can signal slowing industrial demand and drag metal and infrastructure stocks.