Open interest is not trading volume

Learn why turnover and outstanding perp positions tell different stories, with a worked example and a source-matched research checklist.

Two questions, two measurements

Volume asks how much trading took place during a specified interval. Open interest asks how many contracts remain open at a point in time. A completed transaction has a buyer and a seller, but standard futures open interest counts the resulting contract once, not twice. CME Group defines the two measures separately; a perp venue may publish the same idea as dollar notional rather than contract count. Always check the provider’s unit before comparing numbers.

A worked example: large volume without new positions

Imagine a market starts with 100 open contracts. During the day, 500 contracts change hands as existing holders transfer positions to new traders. Under the simplified assumption that each transaction replaces an existing holder without creating or extinguishing a contract, daily volume is 500 contracts and ending open interest is still 100. If 50 additional contracts are then opened by matched new long and short positions, volume rises to 550 and open interest rises to 150. These are illustrative contract counts, not observations from a live exchange. Trading can be busy while the stock of outstanding exposure hardly changes.

What makes open interest rise or fall

When both sides open a new matched contract, open interest increases by one. When both sides close an existing matched contract, it decreases by one. When an existing participant exits and another takes over the position, a trade contributes to volume while open interest can remain unchanged. The direction of the price move does not tell you which of these happened. Even rising open interest alone cannot reveal whether the new exposure is mostly directional speculation, hedging or market making.

Dollar figures need a price and a product boundary

A venue may report open interest in base units and separately display a mark price; a data provider may report a USD estimate. Hyperliquid’s documented perpetual asset-context response, for example, has separate openInterest, markPx and dayNtlVlm fields, and its request distinguishes the first perp venue from a named HIP-3 deployment. A dollar OI series can move when the mark price changes even if base-unit contracts do not. A reported 24-hour notional volume and a point-in-time dollar OI therefore should not be subtracted as if they were two account balances.

How to compare two venues without doubling a market

Record exactly which markets each figure includes: native perps, builder-deployed perps, options, spot, or an interface that routes into another venue. Use one consistent provider definition across peers or explicitly reconcile venue-native figures to the common basis. Confirm the OI timestamp and compare volume over complete, matching UTC intervals. For a weekly change, compare the same market set and the same observation time; an incomplete current day is not a substitute for a completed previous day.

Interpret the divergence cautiously

Higher volume with flat OI is consistent with turnover, but can also coincide with short-lived positions or repeated incentive-driven trades. Higher OI with little extra volume could indicate longer-held exposure, but does not prove more unique users, deeper liquidity or a stronger business. Check bid-ask spread, order-book depth, liquidation activity, fees and revenue, and what incentives were active. None of these measures alone establishes value for a venue’s token.

A repeatable five-line research note

For each venue, write down: (1) the exact product set and provider; (2) the OI value, unit and timestamp; (3) volume over 24 hours and a complete 30-day window; (4) comparable fee or revenue windows; and (5) any market launch or reward programme that could explain a jump. Then state what changed and what remains unknown. On PerpsAtlas, the metric source detail beside each project value is the starting point; token rights and supply require separate evidence.