Three Sources of Return
Investing in commodity futures generates returns from three distinct sources, and understanding the distinction matters enormously for realistic expectations.
Spot price appreciation is what most people think of: the underlying commodity price rising. Oil going from $60 to $80, gold rising from $1,800 to $2,200. This component drives headlines but is also the hardest to predict — it depends on the complex interplay of global supply, demand, geopolitics, and technology.
Collateral yield arises because futures contracts require only a margin deposit, not full payment upfront. The remaining capital can be invested in short-term government securities, earning the risk-free rate. In an era of near-zero interest rates, this was negligible. When short-term rates rise — as they did sharply in 2022-2023 — collateral yield becomes a meaningful positive return component.
Roll yield is the gain or loss from rolling expiring futures contracts into the next month. As discussed in the prior leaf, roll yield is positive in backwardated markets and negative in contango. Over long periods, the structure of commodity markets determines whether roll yield adds to or subtracts from returns.
The Gorton-Rouwenhorst Research
The academic case for commodities as a strategic portfolio allocation rests heavily on a landmark 2006 paper by Gary Gorton (University of Pennsylvania) and K. Geert Rouwenhorst (Yale School of Management): "Facts and Fantasies About Commodity Futures" (Yale International Center for Finance, 2006).
Gorton and Rouwenhorst examined a diversified portfolio of commodity futures over the period 1959 to 2004. Their findings were striking:
- Commodity futures delivered equity-like returns over the full period.
- They exhibited low or negative correlation with equities and bonds — meaning they tended to zig when stocks and bonds zagged.
- They showed positive correlation to inflation, particularly unexpected inflation — the condition in which equities and bonds typically struggle most.
- They exhibited positive correlation to inflation at both short and long horizons.
The combination of equity-like returns with inflation-hedging properties and low correlation to financial assets made commodities appear to be an unusually attractive diversifier — one that improved a portfolio's risk-adjusted return without simply adding more of the same risks already present in stocks and bonds.
Commodities as an Inflation Hedge
The inflation-hedging argument for commodities has an intuitive logic. Commodities are upstream inputs in the production process: oil feeds into transport and manufacturing; wheat and corn feed into food prices; copper and steel feed into construction costs. When commodity prices rise, those cost increases eventually flow through the supply chain and push up the general price level. Consumer price indices are, to a significant degree, downstream of commodity prices.
This means that when inflation is rising, commodity prices are often already rising — and the investment in commodities gains value precisely when other assets (bonds especially, but often equities too) are under pressure from rising inflation and the rising interest rates that typically follow.
The classic painful scenario for a traditional 60/40 (stocks/bonds) portfolio is an inflationary recession: growth falling while inflation rises simultaneously. Bonds lose value as rates rise; equities struggle with the growth slowdown. Commodities, particularly energy and agricultural products, often continue to appreciate in this environment.
Supply Constraints and the Super-Cycle
Over the very long run, a structural bull case for commodities rests on finite physical supply. Unlike financial assets, commodities cannot be created by central banks or corporate boardrooms — they must be found, extracted, grown, or raised. New mining discoveries take ten to fifteen years to bring to production. Agricultural land is limited. This supply inelasticity creates a long-run floor under prices.
The commodity super-cycle is a concept used to describe extended periods — often two to three decades — of above-trend commodity prices driven by massive, sustained demand growth. The most recent super-cycle was widely attributed to China's rapid industrialisation from roughly 2000 to 2015, during which China's demand for steel, copper, coal, and oil grew at rates that global supply struggled to match. A new potential super-cycle is discussed today in the context of the green energy transition's enormous demand for copper, lithium, cobalt, and nickel.