Commodity Physical Markets Glossary: Basis, Storage, Grades and Futures Curves

Physical commodity prices describe specific products delivered at specific places and times. A barrel of crude oil, tonne of copper or bushel of grain cannot be analysed fully without considering its grade, location, storage needs, logistics and the relevant contract specification.

This commodity markets glossary focuses on the physical and commercial mechanisms behind futures prices, showing why local cash prices can diverge from benchmark contracts and why futures curves need careful interpretation.

Why this specialist terminology matters

Market commentary often compresses a complex mechanism into one familiar expression. The right question is not only what a term means, but which contract, accounting basis, measurement date or operational framework applies. A number without this context can be precise and still misleading. The definitions below include both the basic concept and a caution about practical interpretation.

Commodity Physical Markets Glossary: essential terms

Cash market

The market for the underlying physical commodity or prompt delivery arrangements under defined specifications. Prices depend on location, grade, freight and delivery conditions. A cash price is not necessarily an exchange-quoted global spot reference.

Basis

The difference between a specified physical cash price and relevant futures price; many grain markets define it as cash minus futures. Basis sign conventions vary. The comparison must use compatible units, delivery location, grade and contract month.

Basis risk

The risk that the cash-futures difference changes in a way that prevents a futures hedge from perfectly offsetting the physical price exposure. It may arise from transport, quality, seasonal demand or mismatched delivery dates even if futures markets are highly liquid.

Grade or specification

Contractual quality requirements such as oil sulphur content, metal purity, grain protein or moisture limits. A premium or discount may be earned for a different grade. A headline price without its specification can be misleading.

Delivery location

The port, terminal, warehouse or geographic area relevant to a physical commodity price or futures contract. Price differences can reflect freight, pipeline congestion, weather and regional supply imbalances.

Freight differential

The cost or price adjustment associated with transporting a commodity between markets or delivery points. Vessel availability, fuel costs and bottlenecks can shift regional spreads without changing the underlying global supply balance.

Storage cost

The expense of holding inventory, including warehousing, insurance, handling and financing. Physical inventories are not costless to carry, and some products are difficult or impossible to store economically for long periods.

Cost of carry

The combined cost of holding a commodity across time, typically incorporating financing, storage and other applicable expenses. It influences relative spot and futures prices but does not guarantee a positive return from a particular strategy.

Convenience yield

The economic benefit of having physical inventory available when needed, sometimes inferred indirectly from commodity futures pricing. It is not a coupon paid by an exchange and may increase when usable stocks are scarce or production disruption risk is elevated.

Contango

An upward-sloping specified comparison of a futures price to spot or nearer-dated prices. It can reflect carry and financing, but the curve shape alone does not determine expected total return.

Backwardation

A specified downward-sloping futures structure where nearby exposure trades above later delivery references or spot exceeds a forward contract. It may be associated with inventory scarcity, though contract conventions and expectations matter. Backwardation does not guarantee rising spot prices.

Calendar spread

The price difference between futures contracts for different delivery months on the same underlying market and compatible specifications. Its sign depends on the quoted spread order. Inventory, seasonal conditions and financing can drive it.

Front-month contract

The nearest eligible listed futures delivery month under an exchange or data-provider roll rule. It may not be the most liquid month as delivery approaches and it may not correspond to a physically relevant buyer’s delivery window.

Roll yield

A component of returns from maintaining futures exposure across expiries under a specified roll methodology. It interacts with spot price movements, collateral returns and trading costs; it is not simply the slope of the curve read in isolation.

Warehouse warrant

A document or electronic record evidencing qualifying inventory held under recognised warehouse or exchange rules. Legal rights, delivery eligibility and warehousing charges depend on the contract and clearing arrangements.

Deliverable supply

Physical inventory meeting contract grade, location, timing and documentation requirements for delivery. Total global production is not the same as deliverable stocks. Bottlenecks can constrain locally available supply.

Open interest

Outstanding derivative contracts under the exchange’s reporting convention. It is not a measure of immediately deliverable inventory and should not be read as a simple supply-demand balance.

Producer hedge

A commercial use of futures or another instrument to manage price risk tied to expected production or inventory. It reduces some exposure but can create margin-cash-flow and basis risks, and the physical quantity may differ from expectations.

Consumer hedge

A manufacturer’s or end user’s derivatives position intended to reduce price uncertainty for future purchases. A hedge may lock an unfavourable cost in hindsight; its purpose is managing uncertainty rather than guaranteeing the lowest price.

Crack spread

A simplified indicator of refinery margin based on the difference between refined-product values and crude oil input costs under a chosen product mix. Actual refinery economics include energy, yields, logistics and operating costs; benchmark crack spreads are not realised profit.

Crush spread

A measure comparing the value of agricultural processing outputs with the cost of the input crop, often applied to soybeans. Processing efficiencies, by-products and contract multipliers affect the calculation and its interpretation.

Inventory report

A scheduled dataset describing estimated stocks held within a defined geography, survey and reporting method. A reported build or draw must be interpreted against expectations, seasonal norms, revisions and coverage limitations.

Worked example and interpretation

Imagine a fictional grain market where local cash wheat trades at £195 per tonne and a comparable futures contract trades at £200. Under the cash-minus-futures convention, basis is £195 − £200 = −£5 per tonne. A month later, the cash price rises to £205 while futures rise to £207: basis becomes −£2. Both prices rose, but basis also strengthened by £3. For a physical hedger, this basis change can affect the net realised price even if the broad futures direction was anticipated correctly. The example assumes compatible quality and delivery conditions.

Analytical extension: storage economics and the shape of the futures curve

A simplified commodity carrying-cost framework relates forward price to spot price through financing, storage and the benefit of access to physical inventory. Under continuous rates, a stylised expression is F ≈ S × exp((r + u − y) × T), where r is financing cost, u storage and insurance cost, y convenience yield and T time in years. The relationship is a teaching model, not a universal price law; deliverability, seasonality and contract specifications can change the economics substantially.

Illustrative calculation: Suppose an eligible commodity has a spot reference of £100 per unit, annual financing cost of 4%, annual storage and insurance of 3%, and an assumed convenience yield of 2%. The model’s net carry is 5% annually. For six months, the theoretical forward value is £100 × exp(0.05 × 0.5), or approximately £102.53. This does not predict the spot price in six months or imply that a speculative investor can collect £2.53 without risk. Actual trading costs, collateral, taxes and the physical delivery process matter.

Physical scarcity can reshape the curve. A refinery that needs immediate crude oil for continuous production may value prompt barrels more than a distant delivery claim even when financing and storage cost money. Similarly, grain futures may reflect harvest seasonality and local transport constraints. An inventory report showing aggregate stocks rising does not necessarily mean deliverable inventory at the relevant location and grade is abundant. The right comparison is the economically eligible inventory, not a broad headline total.

Hedging check: A producer shorting futures against expected production may be exposed to basis strengthening or weakening independently of the overall price direction. It may also face variation-margin calls before the physical sale occurs. Futures can reduce benchmark price uncertainty while increasing short-term cash-flow management demands. A comprehensive hedge review follows both derivatives settlements and physical sale or purchase obligations.

Concept comparison

Applying the terms in a structured research process

First identify the exact exposure or decision being studied. Record the relevant market or institution, contract specification, valuation basis and observation date. Separate directly observed data from estimates and from judgements. If the research question concerns the future, state more than one possible scenario rather than implying that a past relationship must continue.

Second, translate the terminology into its economic consequences. Ask which party receives or pays cash, what changes if the quoted price moves, what financing or collateral may be required and which risk remains after any hedge or mitigation. Whenever figures are compared, match units, timing and direction before doing the arithmetic.

Third, explain what would make the conclusion unreliable. A market can become less liquid, an estimated coefficient can shift, operational rules can change and the available data can be incomplete. Checking these limitations is part of professional analysis, not a weakness in the explanation.

Common interpretation mistakes

• Comparing oil, metal or grain prices with different grades, quotation units or delivery locations.
• Assuming backwardation always implies an upcoming spot-price rise or a guaranteed positive roll return.
• Interpreting an inventory statistic without checking what geography, product or stock class it actually covers.

Frequently asked questions

Why is the local cash price different from futures?

Transport, storage, quality, location, time to delivery and local supply conditions create a basis between the two reference prices.

Is the front-month futures price the same as spot?

Not necessarily. Contract months, delivery conditions, financing and timing mean that a near-month futures quote is not a universal spot price.

Do physical hedges eliminate price risk completely?

They can offset part of the benchmark exposure, but basis, volume, timing, margin and operational risks remain.

Related education

Explore Contango and Backwardation Explained; Commodity Futures Explained; Commodity Producer Hedging, the Trading Glossary or the complete Education Hub.

Sources and further reading

• CME Group — Understanding Grain Basis
• CME Group — Contango and Backwardation
• CME Group — Grain Convergence

Important notice: General financial education only, not personalised advice or a recommendation to buy, sell or hold any financial instrument. All numerical scenarios are hypothetical. Investments and derivatives may incur significant losses and applicable product terms determine actual outcomes.