Curriculum Part 4 Chapters 22–24

Commodities

One idea runs through the whole part: you cannot hold a commodity, you hold a futures position — so the shape of the forward curve, not the spot price, decides what you earn.

Spot markets & trading firms

Economics of the spot market. Short-run supply is inelastic — mines, wells and farms cannot respond within a season — and demand is often inelastic too, which is why small imbalances produce violent price moves and why commodity volatility clusters. Inventory is the shock absorber: when inventories are high, a demand surprise is met from storage and prices barely move; when inventories are low, there is nothing to buffer with, so prices spike and volatility rises. Supply responds eventually through investment, which is the mechanism behind multi-year cycles and the tendency for commodity prices to mean-revert toward the marginal cost of production over long horizons.

Commodity trading firms are logistics businesses, not directional investors. They earn margins on transformation in space (transport), time (storage) and form (processing and blending). Their exposures are therefore basis, spread and freight risk rather than outright price risk, and they hedge flat price aggressively while carrying operational, credit, financing and counterparty risk. The exam angle is the distinction between hedging by commercial participants and speculation by financial participants, and the role speculators play in supplying liquidity and bearing risk that hedgers wish to shed.

Futures market mechanics

Because physical ownership is costly, institutional exposure comes through futures. The pieces to hold precisely:

Cost of carry
Financing plus storage plus insurance, less any benefit from holding the physical. A pure carry model gives F = S(1 + r + storage − convenience yield) over the period.
Convenience yield
The non-monetary benefit of holding inventory — the ability to keep a production line running or meet unexpected demand. It rises as inventories fall, which is why scarcity flattens then inverts the curve.
Basis
Spot minus futures. Basis converges to zero at expiry, and roll return is the profit or loss from that convergence as a position is rolled forward.
Contango
Upward-sloping curve: futures above spot. A long roll sells a cheap near contract and buys a more expensive far one — negative roll return.
Backwardation
Downward-sloping curve: futures below spot. Rolling a long position is accretive — positive roll return, typically associated with low inventories.

Collateral and leverage. A futures position requires only margin, so a fully collateralised commodity index return has three parts: the collateral (cash) return, the change in the price of the futures held, and the roll effect from moving between contracts. That decomposition is the single most tested structure in the part.

Theories of the forward curve

Three explanations, and the exam wants you to know that they are complements rather than rivals.

Theory of storage

Explains the curve through inventories and the convenience yield. High inventories imply a low convenience yield, so cost of carry dominates and the curve slopes upward; low inventories imply a high convenience yield and a downward-sloping curve. The relationship between the slope and inventory levels is the Working curve, which is non-linear — the slope becomes steeply negative as inventories approach zero, because there is a limit to how much a curve can be in contango (arbitrage caps it at full carry) but no limit on backwardation.

Insurance perspective / normal backwardation

Producers wish to hedge future output by selling futures, so speculators must be induced to take the long side. The futures price is therefore set below the expected future spot price, and the long earns a risk premium as the futures price rises to meet spot — Keynes's normal backwardation. Note the vocabulary trap: this is a statement about futures prices relative to expected spot, not about the observable slope of the curve.

Hedging pressure hypothesis

Generalises the insurance view: hedgers are not always net short. When consumers of a commodity are the dominant hedgers, their buying pressure pushes the futures price above the expected future spot price, and the risk premium accrues to the short side. So the sign of the risk premium depends on which side of the market has the greater hedging need — which makes long-short strategies conditioned on hedging pressure a legitimate strategy rather than a mispricing.

Seasonality sits across all three: agricultural curves reflect harvest cycles, natural gas and heating oil reflect the heating season, and comparing prices across seasons rather than across the same delivery month in different years is a standard error.

Return decomposition & inflation

The decomposition. Total return on a fully collateralised futures position = collateral return + excess return, where excess return divides into spot return (the change in the spot price) and roll return (the profit or loss from the basis converging as contracts are rolled). Roll return is positive on average in persistent backwardation and negative in persistent contango — gold, for instance, has almost always shown negative roll yield because its cost of carry exceeds any convenience yield.

Why spot return contributes little over long horizons. Because commodity prices mean-revert toward production cost, the long-run spot component is small; the durable sources of return are the collateral yield, the roll, and the rebalancing effect within a diversified index. That is the honest version of the "commodities have equity-like returns" claim, and stating it well is worth marks.

Inflation hedging. Commodities are among the few assets with a genuine sensitivity to unexpected inflation, because commodity prices are themselves an input to price indices and respond contemporaneously to supply shocks. The caveats matter: the hedge is strongest against energy-driven inflation, weaker against services and wage inflation; the relationship is unstable across periods; and the hedge comes with very high volatility per unit of protection. Commodities are also a natural exchange-rate exposure — a weaker dollar tends to accompany higher dollar-denominated commodity prices, so part of a US investor's commodity return is a currency story.

Rebalancing and diversification return. Individual commodities are highly volatile and weakly correlated with one another, which means a periodically rebalanced basket earns a rebalancing premium that the individual constituents do not — the mechanical benefit of selling what rose and buying what fell in a mean-reverting universe. This is an examinable reason why commodity index performance is not the average of commodity performances.

Allocation to commodities

The beneficial characteristics a candidate should be able to list and qualify: diversification against stocks and bonds through a different risk driver; a hedge against unexpected inflation; the opportunity for a risk premium from hedging pressure and roll; event-risk protection, since supply disruptions that harm equities often raise commodity prices; and — for a leveraged instrument — capital efficiency, because exposure requires only margin, leaving the balance in collateral.

The costs to state alongside them: very high standalone volatility, no income and no earnings — nothing accrues while you wait; negative roll in contango markets, which can erode returns for years; capacity and liquidity limits in individual contracts; regulatory position limits; and the practical governance requirement of managing a derivatives programme with margin and collateral.

Strategy taxonomy. Directional strategies take outright long or short exposure, often driven by momentum, macro views, or term-structure signals. Relative value strategies trade one contract against another, isolating a spread: calendar spreads along one curve, inter-commodity spreads such as the crack (crude versus refined products), crush (soybeans versus meal and oil) and spark spread (gas versus power), and location or quality spreads. The attraction is that a spread strips out the common flat-price factor, leaving a more stable and more analysable relationship; the risk is that spreads are usually implemented with leverage and can break when a physical constraint binds.

Commodity-linked equity is not commodity exposure. A producer's equity carries operating and financial leverage, hedging policy, cost inflation, governance and equity-market beta — so its correlation with the commodity is far from one, and it often behaves more like equity than like the underlying. Say that whenever a question offers producer equities as a substitute for futures.

Accessing commodity investments

Direct physical
Practical only for precious metals and a few storable commodities; costs are storage, insurance, assay and financing, and there is no roll to manage. Not viable for perishables or bulk energy.
Futures and options
The institutional standard: liquid, exchange-cleared, capital-efficient. Requires margin management, roll decisions and derivatives authority.
Swaps and forwards
Customisable exposure and maturity, no exchange roll mechanics, but bilateral counterparty and collateral risk.
ETFs / ETNs / ETCs
Convenient wrappers. Futures-based funds inherit roll drag; notes carry issuer credit risk; physically-backed products carry storage cost. Tracking error against spot is the norm, not a defect.
Structured and leveraged notes
Embedded options and leverage, path dependency, and daily-reset products whose long-run return diverges sharply from the multiple of the index return.
Managed futures / CTAs
Active, often trend-following exposure across commodities and financials — a different return driver from a long-only index, and covered with hedge funds.

Commodity-linked corporate structures (producer equity, royalty and streaming companies, master limited partnerships) give indirect exposure with the qualifications above; understanding where the investor sits in the capital structure determines whether they own the commodity's upside or merely the operator's margin on it.

Index construction & the eight sources of return

Two commodity indices holding the same commodities can produce materially different returns, because construction choices are the strategy. The curriculum lists eight sources of index return:

Commodity beta
The return to holding the front-month contract and rolling it at the roll date — the transparent, liquid benchmark against which other approaches are judged.
Roll return
Profit or loss from the change in basis as the position is rolled. Positive in persistent backwardation, negative in contango — but a curve can flip, and designing an index purely on roll return concentrates it in low-inventory, high-volatility, highly correlated commodities.
Spot return
Excess return less roll return: the part attributable to spot price change. Expected to contribute little over long horizons outside a supercycle.
Dynamic asset allocation
Rules that over- and under-weight commodities through time — momentum (typically short-horizon), mean reversion (typically over a year or more), or term-structure signals that overweight backwardated markets.
Diversification
More constituents and more subsectors lower sensitivity to any one commodity; because subsectors are weakly correlated and constituents very volatile, diversification plus rebalancing is a real source of index return.
Component weights
The weighting rule must have an economic rationale — the S&P GSCI, for example, weights by average global production over a trailing five-year period. Concentrated weights raise volatility.
Maturity
Holding longer-dated contracts changes both roll and spot exposure: longer maturities are less sensitive to spot moves and less volatile, giving lower commodity beta — and materially less liquidity, which caps capacity.
Collateral return
In a total-return index the notional is assumed invested in short-term instruments, so the cash rate is part of the reported return — which is why total-return and excess-return index versions diverge whenever rates are not near zero.

Design issues the exam asks about directly: production versus liquidity versus economic weighting; the roll window and schedule (a predictable roll on fixed dates is front-runnable, which motivated later index generations to diversify the roll across dates and maturities); rebalancing frequency; sector caps; and eligibility rules. So-called second- and third-generation indices are precisely attempts to improve roll and weighting mechanics — and the honest caveat is that many of their advantages were identified in-sample.

Confusion pairs

Contango vs normal contango
An observable upward-sloping curve vs futures priced above the expected future spot price. The first is a fact; the second is a claim about a risk premium.
Backwardation vs normal backwardation
Curve slopes downward vs futures below expected future spot, so the long earns a premium. Do not infer one from the other.
Convenience yield vs storage cost
Benefit of holding physical inventory (rises as inventory falls) vs the monetary cost of holding it. Their net decides the curve's slope.
Roll return vs spot return
From basis convergence as contracts are rolled vs from the spot price itself. Roll dominates over long horizons; spot mean-reverts.
Total vs excess return index
Includes the collateral (cash) return vs futures price and roll only.
Producer equity vs futures
Operating and financial leverage, hedging policy and equity beta vs direct exposure to the commodity price and curve.
Hedging pressure vs normal backwardation
Premium accrues to whichever side hedgers are not on — either sign vs the special case where producers dominate and the long is paid.

Practice

Six multiple-choice questions in exam style, with the reasoning — not just the letter.

1. Inventories of a storable commodity fall sharply. The most likely effect on the forward curve is:

A. Steeper contango as storage costs rise
B. A move toward backwardation as convenience yield rises
C. No change; the curve depends only on interest rates
D. Parallel upward shift with unchanged slope
B. The theory of storage: scarce inventory raises the convenience yield, which subtracts from cost of carry and pushes the curve toward backwardation. The Working curve captures this relationship, and it is non-linear — contango is capped by arbitrage, backwardation is not.

2. Under the hedging pressure hypothesis, if commodity consumers are the dominant hedgers:

A. Futures prices lie below expected future spot and longs earn a premium
B. Futures prices lie above expected future spot and shorts earn a premium
C. No risk premium exists
D. The curve must be in backwardation
B. Consumers hedge by buying futures, and their pressure raises the futures price above the expected spot; the compensation therefore accrues to the party taking the short side. A describes the producer-dominated case (normal backwardation).

3. Over long horizons, the least important contributor to a diversified, fully collateralised commodity index return is generally:

A. Collateral return
B. Roll return
C. Spot return
D. Rebalancing/diversification effects
C. Because commodity prices mean-revert toward production cost, spot appreciation contributes little over long periods outside a supercycle; collateral, roll and rebalancing dominate.

4. An index is redesigned to hold longer-dated rather than front-month contracts. The most likely consequences are:

A. Higher volatility and higher commodity beta
B. Lower volatility, lower commodity beta, and reduced liquidity/capacity
C. Elimination of roll return
D. Higher collateral return
B. Deferred contracts are less sensitive to spot moves, so volatility and beta fall — meaning the index lags in a sharp spot rally. Liquidity in longer maturities is much thinner, which limits institutional capacity.

5. A committee proposes energy producer equities instead of futures to gain commodity exposure. The best objection is:

A. Producer equities are less liquid than futures
B. They add equity beta, leverage and hedging-policy risk, so correlation with the commodity is well below one
C. They provide no inflation sensitivity at all
D. They cannot be held by institutional investors
B. Producer equity returns are diluted by market beta, capital structure, cost inflation and corporate hedging — the exposure is to the operator's margin, not to the price and curve.

6. The main criticism of designing a commodity index primarily to maximise roll return is:

A. Roll return cannot be measured
B. Backwardated commodities are low-inventory, high-volatility and mutually correlated, so the index sacrifices diversification and stability
C. It increases collateral return excessively
D. It violates exchange position limits
B. Roll return also changes over time with rates, storage costs and convenience yields, so a curve can flip from backwardation to contango — making a roll-maximising rule both concentrated and unstable.

Constructed-response practice

Write these under time. Each outline is the shape the rubric rewards, not a model answer to memorise.

Prompt A (12 minutes). A pension plan holds a long-only front-month commodity index and is disappointed that its five-year return has lagged spot commodity prices. Explain the likely causes and recommend two implementation changes.

Outline:
  • Decompose index return into collateral, spot and roll; identify persistent contango as the likely drag.
  • Explain the mechanism: rolling a long position sells cheap near contracts and buys richer deferred ones.
  • Note secondary causes: weighting concentration, a predictable roll window that is front-run, and low collateral yield in a low-rate period.
  • Change 1 — a diversified roll schedule and/or deferred maturities; state the trade-off (lower beta, less liquidity).
  • Change 2 — term-structure-aware weighting or an active/CTA allocation; state the trade-off (fees, tracking error, in-sample design risk).
  • Close by re-stating the honest expectation: commodities are held for unexpected-inflation sensitivity and diversification, not for spot appreciation.

Prompt B (10 minutes). Assess whether commodities are a suitable inflation hedge for an endowment with a 5% real spending requirement.

Outline:
  • Distinguish expected from unexpected inflation and explain why commodities respond to the latter (they are an input to price indices).
  • State the limits: strongest against energy-driven inflation, weak against services and wage inflation, unstable through time.
  • Quantify the cost: high volatility per unit of protection, no income, potential multi-year roll drag.
  • Recommend sizing and structure — a modest allocation, diversified index or term-structure-aware implementation, funded from equities rather than from the liquidity reserve.
  • Compare against alternatives (TIPS, infrastructure with escalators, short-lease real estate) and say when each is preferable.
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