Why Can a Commodity ETF's Return Differ Even When Spot Prices Rise?
Futures-based commodity ETFs replace contracts as expiration approaches. Distinguish contango, backwardation, convergence, and collateral income to understand returns that differ from spot prices.
Futures-based commodity ETFs continually replace contracts with expiration dates, so their performance can differ from products that follow spot prices alone. In contango, when longer-dated contracts cost more, convergence can weigh on long futures positions, all else equal. It is inaccurate to say that the entire price difference immediately becomes a realized loss at the moment of rolling.
First determine whether the product holds physical assets or futures exposure
A structure that physically holds precious metals has different cost sources from one that gains commodity exposure through futures contracts. An ETF holding mining companies also includes company costs, debt, and management risk in addition to commodity-price exposure. The shared commodity label does not justify expecting identical returns. Before comparing, check whether the prospectus specifies spot assets, a futures index, or a producer-company index as the target. Some U.S. exchange-traded commodity products have legal structures different from conventional registered investment companies, so the general ETF label alone does not establish the investor-protection framework.
Separate replacing contracts from profit or loss while holding them
Rolling means closing exposure in a contract with one expiration and continuing it in a contract with another. Maintaining the same notional exposure may require changing the contract quantity as prices differ. Subsequent convergence of futures prices toward spot and changes in the futures curve itself affect actual profit or loss. Assuming contango persists is different from observing a curve at one point in time. Backwardation can allow convergence effects in the opposite direction, but does not guarantee a positive overall return.
Read the index rules for which delivery months it rolls into
Results differ depending on whether the index uses only the nearest contract or spreads exposure across maturities, and whether it staggers the roll period. Check whether the price cited in spot-market news matches the delivery month the ETF actually holds. A total-return futures index may also include income on cash collateral. Currency movements, fees, and trading costs also affect investor returns. Rather than concluding from a daily spot chart alone that an ETF moved incorrectly, connect the index's return components to the actual contracts held.
Worked example
Hypothetical example: The spot price is 100 and a futures contract expiring in one month trades at 105. If spot stays at 100 and the expiring futures price converges to 100, the price loss on one unit of a long futures position is 5. Relative to its initial notional value of 105, that is approximately −4.76%, which differs from the return on margin. Calculating actual fund returns also requires contract quantities, collateral income, and other factors. Merely buying a new futures position at 105 does not mean a loss of 5 has been realized at that instant.
What to check
- Have you identified whether the actual investment is physical commodities, futures, or producers?
- Have you read the held contract months, roll schedule, and rules for spreading exposure?
- Have you distinguished the price gap at the roll from subsequent profit or loss?
- Have you avoided confusing returns on futures notional value with returns on margin?
Sources and primary materials
This is educational material about research methods. For an actual company decision, verify the filings and primary sources for the relevant period.