# Dollar Gamma Exposure: Converting Curvature into Portfolio P/L

Learn how to convert option Gamma into estimated P/L for a percentage move, distinguish competing dollar-Gamma conventions, and aggregate positions without hiding scenario assumptions.

Canonical: https://wiki.fcontext.com/options/dollar-gamma-exposure/
Fact checked: 2026-07-22

> For educational purposes only; not investment advice.

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## Direct answer

**Dollar Gamma exposure** converts model Gamma into a monetary risk measure for a stated underlying-price scenario. It answers a more useful question than raw Gamma alone: approximately how much second-order P/L would this position gain or lose if its underlying moved by a specified percentage?

The name has no universal formula. Some systems report the Gamma contribution to P/L, some report the change in Dollar Delta, and some omit the `0.5` Taylor-series factor. A risk report must show its formula, price-move unit, multiplier, position sign, and currency before values can be compared.

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## Two measures that must not be confused

Let `Γ` be option Gamma per share for a `$1` underlying move, `S` the underlying price, `q` signed contract quantity, `M` contract multiplier, and `m` the scenario return in decimal form.

The local second-order option P/L for price change `ΔS=mS` is

`Gamma P/L ≈ 0.5 × Γ × (mS)² × q × M`.

This guide calls the result at `m=0.01` **1% Gamma P/L**. It scales with the square of the assumed move. Long options have positive Gamma and short options negative Gamma, subject to the signed quantity convention.

A different measure estimates how much share-equivalent Delta changes:

`Change in Delta shares ≈ Γ × (mS) × q × M`.

Multiplying that by `S` gives a change in Dollar Delta. This is not the same as Gamma P/L. A dashboard labeled “Dollar Gamma,” “Gamma Cash,” or “GEX” may use either family of measures, so reconstruct its units rather than relying on its label.

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## One percent versus five percent

Suppose a stock is `$100`, one option has Gamma `0.04`, the position is long 10 contracts, and the multiplier is 100. For a `1%` move, `ΔS=$1`:

`1% Gamma P/L ≈ 0.5×0.04×1²×10×100 = $20`.

The corresponding local change in Delta is `0.04×1×10×100=40` share equivalents. These numbers describe different quantities and should not be substituted for each other.

For a `5%` move, holding Gamma artificially constant:

`Gamma P/L ≈ 0.5×0.04×5²×10×100 = $500`.

The five-percent estimate is 25 times the one-percent estimate, not five times, because the curvature term is squared. But Gamma will usually change across a `$5` move, so `$500` is a local approximation, not a full revaluation. A repricing model that updates Delta, Gamma, volatility, skew, time, and rates is more appropriate for large moves.

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## Portfolio checklist

- Confirm whether each feed's Gamma is per share, per contract, per point, or already position-scaled.
- Apply long/short signs, quantities, multipliers, adjusted deliverables, currencies, and FX conversion once and only once.
- Calculate percentage scenarios with each underlying's own spot price; identical raw Gamma on `$20` and `$500` stocks is not identical risk.
- Sum legs on the same underlying first, then state the joint-move and correlation assumptions used across underlyings.
- Report both upward and downward full revaluations because Gamma, skew, and volatility need not behave symmetrically.
- Pair Gamma with Delta, Theta, Vega, financing, dividends, and transaction costs; positive Gamma does not guarantee positive total P/L.
- Update near at-the-money strikes and expiration frequently, especially for 0DTE positions where Gamma can move quickly.
- Stress gaps and illiquidity in which continuous Delta hedging is impossible.
- Separate known account positions from dealer-GEX estimates inferred from open interest and assumed customer direction.

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## Common misconceptions

- “Dollar Gamma has one standard definition.” Vendors use materially different formulas and scaling.
- “A five-percent move is five times a one-percent Gamma result.” Under constant Gamma, the P/L curvature term is 25 times as large.
- “Positive Gamma guarantees profit.” Theta, Vega, Delta, and execution can outweigh its contribution.
- “Initial Gamma is valid through a large jump.” Gamma itself changes with spot, time, and volatility.
- “Dollar Gamma can simply be added across stocks.” The sum represents only a stated joint percentage-move scenario.
- “Public dealer GEX reveals dealer positions.” Open interest alone does not identify who is long or short.

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## Related topics

- [Delta and Gamma](/options/delta-and-gamma/)
- [Delta-Gamma approximation](/options/delta-gamma-approximation/)
- [Delta neutral](/options/delta-neutral/)
- [Dealer Gamma exposure](/options/dealer-gamma-exposure/)

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## Authoritative sources

- [Options Industry Council: Gamma](https://www.optionseducation.org/advancedconcepts/gamma)
- [Options Industry Council: Understanding Options Greeks](https://www.optionseducation.org/advancedconcepts/understanding-options-greeks)
- [Options Industry Council: Volatility and the Greeks](https://www.optionseducation.org/advancedconcepts/volatility-the-greeks)
- [Cboe Research: 0DTE Index Options and Market Volatility](https://cdn.cboe.com/resources/education/research_publications/gammasqueezes.pdf)