GMAB gamma levels
From the closing options book · October 20, 2026
GMAB closed at 39.07 on October 20, 2026. Its call wall was 40, put wall 35, the Apex (the strike with the most dealer gamma) 40, and the gamma flip 37.5. Net dealer gamma was positive, so hedging tends to absorb moves.
These are the October 20, 2026 closing levels. Members see GMAB's board live all session, with the odds of reaching each level.
GMAB's closing options book on October 20, 2026 carried +$144K of net dealer gamma spread across 5 expirations and 5 contracts. The sign is positive, so hedging leans against the move rather than with it.
The heaviest call-side strike sits at 40 and the heaviest put-side strike at 35, a band 13% wide. GMAB has averaged 2.55% between its high and its low over the last 73 sessions, which makes the full width of that band about 5.0 average sessions of travel. It closed in the upper third of that band.
GMAB closed at 39.07 — 2.4% below the call wall and 10% above the put wall. The call side is the nearer of the two at 2.4% away, which is the only reason it is worth watching more closely than the other. Most levels drawn on a chart are never reached at all, and the distance is what separates them.
The gamma flip is at 37.5, 4% below the close. It is the price where the summed book changes sign — an estimate read from the chain, shown as a price rather than a line price respects.
GMAB's apex — the strike carrying the most gamma in absolute terms — is 40, the same strike as its call wall. When those stack on one level the book is concentrated rather than spread, and that single strike is doing most of the work.
Across the last 10 recorded sessions its call wall has not moved off 40 once, and its put wall has printed two different strikes. Walls that stay put and walls that migrate every session are different objects.
What GMAB's walls are — and aren't
GMAB's book has been recorded on 73 sessions. Its average daily range over that stretch was 2.55% of price. Walls are where dealer hedging is heaviest — positive gamma absorbs moves, negative gamma amplifies them. They are not bounce points, and across our grading they contained price no better than a same-width band around the prior close.
GMAB levels, last 10 sessions
| Session | Close | Apex | Call wall | Put wall |
|---|---|---|---|---|
| Oct 20 | 39.07 | 40 | 40 | 35 |
| Oct 19 | 38.50 | 40 | 40 | 35 |
| Oct 16 | 37.00 | 40 | 40 | 30 |
| Oct 15 | 37.82 | 40 | 40 | — |
| Oct 14 | 36.89 | 40 | 40 | 30 |
| Oct 13 | 36.57 | 40 | 40 | 30 |
| Oct 12 | 37.37 | 40 | 40 | 30 |
| Oct 9 | 37.07 | 35 | 40 | 35 |
| Oct 8 | 36.05 | 40 | 40 | 30 |
| Oct 7 | 36.65 | 40 | 40 | 30 |
Common questions
GMAB's heaviest call-side gamma strike is 40, measured from the closing options book on October 20, 2026. That is 2.4% above where it closed, against an average daily range of 2.55%.
The heaviest put-side strike is 35, 10% below the October 20, 2026 close. Together with the 40 call wall it brackets a band 13% wide.
GMAB's gamma flip is at 37.5, 4% below the close. Above it the book is net positive gamma; below it, net negative.
Not reliably. Walls mark where dealer hedging is heaviest — positive gamma absorbs moves, negative gamma amplifies them — but levels are not bounce points, and across our grading walls contained price no better than a same-width band around the prior close (GMAB's book has been recorded on 73 sessions).
No. This page is built from the closing options book and rebuilt each night, so it describes October 20, 2026. Walls build and dissolve through a session — the live intraday board is inside FlowMonkey, and a free 15-minute delayed SPY board is public at flowmonkey.net/spy-gamma-heatmap.
These are closing levels. The board moves all day.
Walls build and dissolve through the session. FlowMonkey shows the live board on 400+ symbols, with every level priced by whether price can actually reach it today. Start with the free SPY board — no account needed.
Levels are measured from the closing options book and rebuilt nightly. Gamma is an estimate of dealer hedging pressure, not a forecast of direction. Not investment advice.