Because of the capital costs of holding commodities directly, investing is almost exclusively done using futures (exceptions include commodity producers, consumers, etc.) Commodity indices, ETFs, ETNs and mutual funds manage their portfolios very similarly when using futures contracts. For the most part, they construct the portfolio by purchasing near-dated futures contracts. As the contracts near maturity, they sell the contract at or near the spot price of the commodity and purchase new near-dated contracts and the process repeats itself. The frequency and magnitude of this roll leads to the importance of the yield it generates.
Unfortunately, investing in commodity futures contracts can be complicated since total returns are comprised of three return components:
- Collateral Yield: Futures contracts require very little collateralization (~10%). The remainder is frequently invested in high-quality, short-term instruments such as a 90-Day T-Bill. The yield from these investments is often very small relative to the total return and is known as the collateral yield.
- Spot Price Change/Yield: This represents the price change in the underlying commodity contract and is often quoted during a discussion of a commodity’s return. Investors are usually seeking exposure to these returns when choosing to invest in commodities.
- Roll Yield: This component of return is the focal point of the recent articles and is a little more complicated. Commodity investors (e.g. indices, funds, etc.) tend to buy near-dated contracts (e.g. 1-month from expiration) and sell them just prior to settlement. The revenue generated is immediately used to purchase another near-dated contract to maintain exposure to the commodity. This process continues indefinitely and represents the roll yield (sale price less purchase price). If the subsequent purchase cost is less than the revenue gained from the sale, then the roll yield is positive; if the sale prices is less than the purchase price the roll yield is negative. A positive roll yield is referred to as backwardation while a negative yield is called contango.