Commodity ETFs provide exposure to physical goods like gold, oil, agricultural products, and metals — assets that traditionally required futures accounts, physical storage, or specialized brokerage relationships. But commodity ETFs come in three distinct flavors, each with very different mechanics and risk profiles.
Physically-Backed Commodity ETFs
The simplest structure holds the actual commodity in secure storage. Gold ETFs like GLD and IAU store gold bullion in bank vaults (primarily HSBC and JP Morgan in London). Each share represents a fractional ounce of gold. The ETF's price tracks the spot gold price minus the expense ratio. Silver ETFs like SLV work the same way.
The advantage is pristine tracking — the ETF's NAV directly reflects the metal's value. The limitation is that physical storage only works for storable, non-perishable commodities. You cannot physically store crude oil or natural gas in an ETF vault efficiently.
Futures-Based Commodity ETFs
For non-storable commodities, ETFs use futures contracts. A crude oil ETF holds near-term futures contracts and must "roll" them before expiration — selling the expiring contract and buying the next month. This roll process introduces costs that can significantly erode returns.
The Contango Problem
When future-month contracts cost more than near-month contracts (a condition called contango), each roll costs money. The ETF sells low and buys high every month. For oil ETFs, contango has historically cost investors 5-10% per year. This is why oil ETFs often dramatically underperform the actual spot price of oil over time.
Backwardation — when near-month prices exceed future-month prices — benefits the ETF on rolls. But contango is the more common condition for most commodities, making futures-based commodity ETFs a structural drag for long-term holders.
Equity-Based Commodity ETFs
The third approach holds shares of companies that produce commodities. A gold miners ETF holds mining company stocks rather than gold itself. An energy ETF might hold XLE or similar baskets of oil and gas producers. These ETFs avoid futures roll costs but introduce company-specific risks like management quality, mine accidents, and debt levels.
Tax Implications
Commodity ETFs have complex tax treatment. Physically-backed precious metal ETFs (GLD, SLV) are taxed as collectibles with a maximum 28% long-term capital gains rate. Futures-based commodity ETFs may issue K-1 forms and apply 60/40 tax treatment. Equity commodity ETFs are taxed like normal stock ETFs. Consult a tax advisor before investing. Explore more about ETF structures in our education center.
