In futures markets, a calendar spread is a position that is long one contract month and short another contract month of the same futures product, usually in equal contract quantities. Its primary exposure is to the change in the price difference between the two expiries—the relative shape of the futures term structure—rather than to the outright price level alone. The same phrase is also used for options strategies, but this glossary term refers to futures calendar spreads.
The trade is the relationship between maturities
Suppose a nearby contract is priced at 100 and a deferred contract at 103. If a trader is long the nearby month and short the deferred month, the spread is -3 when expressed as nearby minus deferred. If the prices later become 105 and 106, the outright market has risen, but the spread has narrowed to -1; before transaction costs, the position has gained 2 price units because the nearby contract outperformed the deferred contract. The same position could also profit while both contracts fall. Correctly forecasting the direction of the outright market is therefore neither necessary nor sufficient for a profitable calendar spread; relative performance between maturities determines the result.
What drives that relative movement depends on the market. In storable commodities, calendar spreads can reflect financing and storage costs, inventories, seasonal availability, convenience yield, and constraints around delivery. A nearby contract strengthening relative to later months may be consistent with tighter immediate availability, but it is not by itself proof of a shortage or a forecast that spot prices must rise. In financial futures, the mechanism can be different. FX calendar spreads can represent pricing between two future dates and can be economically comparable to forward-starting FX swaps, while Treasury calendar spreads are widely used to transfer exposure from an expiring contract into a deferred contract during the roll.
Convention matters before interpretation
A practical trap is assuming that “buying the calendar spread” always means buying the same leg. Exchange conventions can differ by product. CME FX calendar spreads are quoted as far expiry minus near expiry, so buying the spread buys the far contract and sells the near contract. CME Treasury roll conventions use the opposite leg direction: buying the calendar spread buys the expiring contract and sells the deferred contract. A researcher should therefore record the exact leg convention and price-difference formula rather than infer position direction from the sign or label of a spread series.
Calendar spreads often receive lower margin requirements than the two standalone futures legs would require separately because clearing models recognize offsetting risk. The offset is not treated as perfect: SPAN can apply an intra-commodity spread charge for basis risk between expiries and delivery-risk parameters as physically deliverable contracts approach delivery. Lower margin therefore does not mean negligible risk. A calendar spread reduces much of the common outright-price exposure, but it remains a leveraged position in the relationship between maturities, and that relationship can move sharply when inventories, financing, liquidity, delivery conditions, or market expectations change.