What drives USO and SPY prices differently? USO is tied to crude-oil futures and the forces shaping oil supply and demand; SPY is tied to the S&P 500, whose float-adjusted market-cap weighting gives larger companies more influence. USO is not a direct investment in spot oil, and each fund’s exchange price can differ from its net asset value (NAV).
What USO represents—and what it does not
The United States Oil Fund (USO) seeks to reflect daily percentage changes in a benchmark based on the near-month NYMEX light sweet crude oil futures contract, transitioning to the next-month contract. Its stated objective also accounts for interest earned on collateral and fund expenses. USO may use futures and, to a lesser extent, swaps and forwards.
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That structure matters: USO does not own barrels of crude oil, and its sponsor cautions against treating it as an investment in physical oil or in the benchmark futures contract itself. Its objective is tied to a futures benchmark, not a promise to match spot crude prices.
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Oil supply, demand, and inventories
Crude prices respond to the global balance between supply and demand. Economic growth and petroleum consumption influence demand; production by OPEC and non-OPEC countries affects supply. Inventories can cushion temporary imbalances and provide a signal of how tight the market is. The U.S. Energy Information Administration (EIA) discusses these factors in its pages on oil-market balance, oil prices and outlook, non-OPEC supply, and OPEC supply.
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Because production capacity and petroleum-using equipment cannot adjust quickly, short-run supply and demand are relatively inelastic. A disruption or a change in expectations can therefore prompt a sharp repricing. The EIA notes that spare production capacity and inventories influence how strongly markets may react to a potential disruption. Its explanation of crude-oil spot prices puts the mechanism plainly: “The volatility of oil prices is inherently tied to the low responsiveness or ‘inelasticity’ of both supply and demand to price changes in the short run.”
Geopolitical events, severe weather, refinery outages, and pipeline problems can affect actual flows or perceptions of future supply and demand. The price response depends on the disruption’s likely effect on the balance, as well as the market’s available buffers—not simply on the event’s headline.
Futures pricing and the roll
USO’s futures exposure introduces a factor beyond the movement in spot crude. When later-dated futures cost more than nearer-dated contracts, the curve is in contango; when nearer contracts cost more, it is in backwardation. As USO rolls exposure from one contract to another, the curve’s shape can affect returns over time relative to a simple spot-price comparison. It does not guarantee a particular result: contract movements, other holdings, collateral income, and expenses also contribute.
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USCF’s USO ETP Document Library describes a five-day roll process beginning January 1, 2026. The fund’s disclosures are the place to check the current details of its objective and structure.
What moves SPY
The SPDR S&P 500 ETF Trust (SPY) seeks, before expenses, to correspond generally to the price and yield performance of the S&P 500. The index is float-adjusted market-cap weighted, according to S&P Dow Jones Indices. A company’s influence therefore depends on its index weight: constituents do not contribute equally, and changes in larger-weighted stocks have more impact on the index than changes in smaller-weighted stocks, all else equal.
S&P Dow Jones Indices reported 503 constituents as of August 31, 2026. That is a dated snapshot, not a permanent count; index membership and weights can change. The benchmark and weighting method explain how constituent share-price changes feed into the index, but they do not by themselves quantify how much any particular factor—such as earnings, interest rates, or valuations—moves SPY at a given time.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How the price drivers compare
| Factor | USO | SPY |
|---|---|---|
| Underlying exposure | Benchmark crude-oil futures exposure; collateral income and expenses also affect NAV. | S&P 500 exposure, tracked generally before expenses. |
| Main market inputs | Oil supply, demand, inventories, producer output and capacity, disruptions, and expectations. | Prices of S&P 500 constituent companies, weighted by float-adjusted market capitalization. |
| Structure-specific factor | Futures-curve relationships and rolling exposure can affect results relative to spot crude. | Index composition and constituent weights determine each stock’s influence on index movement. |
| Trading-price consideration | Exchange price can be above or below NAV. | Exchange price can be above or below NAV. |
Fund structure and benchmark details are described by USCF and State Street; the S&P weighting method and dated constituent count are documented by S&P Dow Jones Indices.
Why the two funds can diverge
USO reflects an oil-futures exposure shaped by physical-market conditions and the futures curve. SPY reflects an equity index shaped by the share prices and changing weights of its large U.S. company constituents. Their underlying markets, benchmarks, and fund structures differ, so there is no reason to expect their prices to move together or to react to the same event in the same way.
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