Node classification and velocity

Every strike in a /v1/heatmap or /v1/historical response carries a nodeType. /v1/gex/levels returns only the classified strikes. This page defines exactly how those labels and the live velocityPct are computed.

The value being classified

value is the strike's net, signed exposure for the requested metric (gamma or vanna), summed across the returned expirations:

• By default the response nets the nearest 5 expirations.
• Use maxExpirations to net more or fewer, or expirations to name the exact ones.
• The expirations array in the response tells you which ones were included.

The sign is kept. Ranking for King and Gatekeeper uses the absolute value; Pika and Barney use the sign.

Classification runs over the strikes returned: 92 around spot by default, or set maxStrikes. The King is the largest strike in that window, not across the whole chain.

One expiration on its own

• Pass a single date, for example expirations=2026-10-02. value and nodeType are then computed from that expiration alone.
• Or add layout=matrix to receive the full grid (one row per strike, one column per expiration) with each strike × expiration value. value and nodeType still use the summed total.

Node types

Each strike gets exactly one type, assigned in this order of precedence:

So the Gatekeeper threshold is a percent of the King's magnitude (the same idea as "P25" in the web app's Nodes setting), not a percentile of the strike distribution.

velocityPct

velocityPct is the live percent change of a strike's value versus the snapshot 5 minutes earlier, matched by strike:

velocityPct = (value - value_5_minutes_ago) / |value_5_minutes_ago| * 100

• Returned on /v1/heatmap (live) only. It is omitted on /v1/historical.
• It reads 0 when there is no snapshot from 5 minutes earlier yet (for example right after the open), for a strike that did not exist 5 minutes ago, or when that strike's value 5 minutes ago was 0.