Using 50-Basis-Point Order-Book Depth to Assess Market Impact

Summary

The article explains how a large order can consume successive price levels and move its own average execution price, a cost it calls walking through the book. It argues that traders executing large size should examine resting liquidity within 50 basis points of the midpoint, not rely only on the best quote or shallower depth bands. The proposed check is to compare intended order size with that wider depth and estimate slippage before choosing a venue.

It presents venue depth figures for several semiconductor perpetual contracts, then compares a hypothetical million-dollar NVDA order across deeper and thinner books. A monthly illustration extends the assumed per-trade slippage difference over repeated executions. These examples clarify how market impact can dominate fees, but they are not a controlled execution study: the depth snapshot is time-specific, and actual fills depend on order direction, book changes, order type, and execution speed. The venue comparison and slippage estimates are presented by an exchange and should be treated as illustrative rather than independently validated.

Key ideas

• Large orders can consume multiple price levels and worsen their own average fill price.
• Depth within 50 basis points of midpoint can help assess whether a venue can absorb an intended order.
• The article compares semiconductor perpetual depth across venues and illustrates hypothetical NVDA slippage costs.
• Displayed depth is time-sensitive and does not guarantee the execution quality of a future order.
• Order impact also creates entry, information leakage, and urgent-exit concerns.

Tags

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.