Keep the units straight
The metaAndAssetCtxs response returns openInterest in base units. Comparing raw BTC and SOL values is meaningless, so Market Pulse derives USD open interest as base OI multiplied by mark price. It labels this transformation explicitly.
dayNtlVlm is 24-hour notional volume in USD terms. It measures turnover, not capital locked. A market can have large volume relative to OI when positions churn frequently.
estimated_OI_USD = openInterest_base × markPx
Impact spread is a size-aware proxy
The API’s impactPxs field provides bid and ask impact prices. We compute their distance around the mid price in basis points. This is not the visible best bid/ask and should not be described as a top-of-book spread.
For execution planning, request the L2 book and simulate the actual order size. The impact field is useful for cross-market scanning; a full depth walk is needed for a trade-specific estimate.
Mark, oracle and mid prices
Oracle price is built from weighted-median external feeds. Mark price uses a robust median of multiple inputs and is used for margining, liquidations, unrealized PnL and trigger orders. Mid price reflects the local book.
A gap between mid, mark and oracle can be informative during fast markets, but each field serves a different purpose. Never substitute a local last trade for the liquidation mark.
A practical market scan
Start with 24-hour notional volume to identify active products, then inspect estimated OI, funding and impact spread. Sort by the field that matches the decision: volume for activity, OI for outstanding exposure, funding for carry, impact spread for a rough liquidity screen.
Finally confirm the exact contract and venue. Hyperliquid can expose standard perps and separately deployed products; product identity matters for fees and risk.