Method. Net GEX is full‑chain notional dealer gamma from the CBOE delayed chain, dealers assumed long calls and short puts (spot × gamma × open interest × 100 × spot × 0.01). Sign sets the regime: positive gamma dampens moves (dealers fade), negative gamma amplifies them (dealers chase).
Zero‑gamma is the cumulative‑by‑strike crossing inside ±15% of spot; when gamma does not cross within that band the flip sits outside it and the rail is marked accordingly.
Data is CBOE delayed by roughly 15 minutes and cached for 5 minutes per name.