01Two words for two shapes
A commodity does not have one price: it has one for each delivery date. Put those in order and you get the futures curve, and it can slope two ways.
- Contango: each contract further out costs more than the nearer one. Spot 91, three months 94, six months 96. Normal when there is plenty of supply, because someone has to be paid to store it.
- Backwardation: the opposite. Spot 91, three months 88. The market is paying a premium for oil today, which is what happens when it is scarce right now.
02Why it costs you money without you noticing
This is where the curve stops being theory. A commodity ETF does not own barrels sitting in a tank: it holds futures contracts, and it has to roll them forward before they expire — sell the expiring one, buy the next.
In contango, that roll is done at a loss every time: you sell the cheap contract and buy the expensive one. Over a year of steep contango the drag can run to double digits. The result is an ETF that loses value while the commodity it tracks goes up, and the holder never sees where it went, because nothing appears as a fee.
The arithmetic, with round numbers: rolling monthly with the next contract 2% more expensive costs about 2% a month, which compounds to roughly 26.8% over a year if the gap stays that wide. That assumes a constant spread, which never quite holds — but the order of magnitude is the point.
03Why almost nobody shows you the curve
Because the chain of contracts is genuinely hard to assemble. Each commodity has its own delivery months and its own contract sizes, and the data feeds that carry them are expensive and inconsistent.
When we built this, the raw chain came back empty for 20 of 33 commodities: the symbols exist, the provider knows them, and there is no chain behind them. The honest options are to show nothing, or to generate the maturities by convention — each commodity has a published delivery calendar — and label them as generated rather than observed.
The one thing that is not acceptable is showing a generated curve as if it had come off an exchange. If you are looking at a futures curve anywhere, it is worth asking which of the two it is.
04How to read it without overreaching
- Shape first, level second. Whether spot is above or below the next contract says more about today's market than the headline number.
- Steepness matters as much as direction. A 0.2% contango and a 3% contango are both contango and mean very different things for anyone holding an ETF.
- It is not a forecast. The curve is not the market predicting the price in six months; it is the cost of carry plus scarcity today. Curves in contango have been followed by falling prices plenty of times.
- Check whether it is observed or generated before you conclude anything from it.
Measured in September 2026 over 33 commodity symbols, of which 20 returned no contract chain from the provider. Curves generated by delivery convention are labelled as such in the product and are never presented as observed exchange data.
This is information and analysis, not financial advice, and it contains no recommendation to buy or sell. See the disclaimer.