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SPX gamma levels: call wall, put wall and gamma flip
The four SPX levels that describe dealer hedging: call wall, put wall, gamma flip and volatility trigger, with what each one means during the session.
Dealer gamma exposure is calculated from the prior session's closing chain, so the levels below are the ones the index opened against rather than a live reading. Spot moves through the session and the levels stay where the open interest put them.
For the ladder itself, Options Viz shows net gamma by strike. What the sign convention means, and where the whole measure stops being informative, is in the gamma exposure guide.
Levels at the last close
Levels publish before the US open on trading days.
How to read the levels
The call wall is the strike with the largest concentration of call open interest above spot. In a long-gamma book the hedging behind those calls leans against a rise, so price tends to stall near it. A long position takes profit into the wall rather than through it, and a close above it means the hedging that was leaning on the market is gone.
The put wall is the same thing below spot, built from puts. Hedging there leans against a decline, which is why it behaves as support on an ordinary day: the selling finds less room than it expects. It fails on the day the index gaps through it, and that is the day the level stops mattering.
The gamma flip is the price where net gamma changes sign. Above it the dealer book damps moves, below it the book amplifies them. It is a regime line, not a target: the useful question is which side of it spot is trading, not how close it is.
The volatility trigger marks where hedging turns with the move instead of against it. It usually sits near the flip and slightly below it. When spot crosses both, the same piece of news produces a much bigger range than it did the day before.
Questions
What are SPX gamma levels?
They are strikes where the options open interest produces a large amount of dealer hedging as the index moves: the call wall above spot, the put wall below it, the gamma flip between them and the volatility trigger where hedging starts pushing the move instead of damping it.
What is a call wall?
The strike carrying the most call open interest above spot. Hedging against those calls tends to lean on a rally, so price often stalls there. A close above the wall removes that hedging and the level stops acting as resistance.
What is the gamma flip?
The price where net dealer gamma changes sign. Above the flip the book dampens moves; below it the book amplifies them. Traders use it as a regime line for stop distance and position size, not as an entry signal.
Do these levels predict where SPX will close?
No. They describe how hedging is likely to respond to a move, not where the index will go. The dealer side is inferred from open interest, the numbers are stale by the time spot moves, and a wall that holds all week can be irrelevant in one session.
How often are the levels updated?
They are calculated at the prior close and replaced on this page before the US open on trading days when a snapshot is available. There is no intraday refresh here; Options Viz is the live view.
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