# Gamma Exposure > Compute or review a Gamma Exposure (GEX) / dealer-hedging-behavior estimate from options open interest before it gets reported as if it were an observed fact. Trigger for "GEX", "gamma exposure", "gamma squeeze", "gamma wall", "zero gamma flip", "dealer positioning", "做市商对冲", "伽马敞口", "波动率压制/放大", "0DTE flows", "净伽马", or whenever the user is inferring options-dealer hedging pressure from open interest and implied volatility, building a GEX chart/panel, or about to state a GEX regime call ("dealers are long/short gamma at X") as if it were measured rather than estimated under an assumption. Also trigger when reviewing GEX-computation code for a silent sign or scaling bug — the failure mode this skill exists to catch produces a plausible-looking wrong answer, not a crash. Do NOT trigger for a plain options-chain display (bid/ask/volume/greeks per contract, no hedging inference) or for risk exposure of options the user actually holds — that is `risk-assessment`. - Skill: `artherahq/gamma-exposure` (Agent Skill, multi-file: 6 files) - Install (CLI): `npx skillmds@latest add artherahq/gamma-exposure` - Raw SKILL.md: https://api.skillmd.com/api/skills/artherahq/gamma-exposure/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Marketing & Growth - Author: artherahq (https://skillmd.com/u/artherahq) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/artherahq/gamma-exposure --- # Gamma Exposure (GEX) GEX infers options-dealer hedging *behavior* — not dealer hedging *positions*, which are never public — from open interest, implied volatility, and one industry-standard but fundamentally unverifiable assumption. Every number this produces is an estimate under that assumption, and the single most common failure in this category is reporting it as a fact instead. ## The gap this closes GEX computations look deceptively easy to get right: sum some gammas, apply a scaling constant, done. Two things make it easy to get quietly wrong instead: 1. **The sign convention is an assumption, not a physical law.** The standard convention — customers are net buyers of options, dealers are net sellers, so call OI contributes positive gamma exposure and put OI contributes negative — is a public-GEX-calculator convention (the same one SqueezeMetrics-style tools use), not something derivable from the options data itself. Flip that one sign and the code still runs, still produces a smooth chart, and still gives a *confident* regime call — just the opposite one from what the data implies under the standard assumption. `scripts/gex_gate.py --demo` reproduces this exact bug on one synthetic chain: identical inputs, `net_gex_total` flips from -1.08M to +2.63M, regime flips from negative to positive. 2. **The assumption itself is presented as measured fact.** No public dataset shows dealers' actual positioning. A report that states "dealers are short gamma at 450" without the caveat is making a stronger claim than the data supports — the honest version is "under the standard assumption that dealers are net short customer flow, OI implies dealers are short gamma at 450." ## Workflow 1. Get a real option chain — strike, open interest, and implied volatility for both legs at each strike, for one expiration. Free listed-equity data (e.g. yfinance) is enough; do not fabricate OI/IV to fill gaps. 2. Compute gamma per strike with the standard Black-Scholes closed form (`scripts/gex_gate.py`'s `black_scholes_gamma`) — identical for calls and puts at the same (S, K, T, sigma), so there's no separate call/put gamma formula to get wrong. 3. Apply the standard sign convention (call OI: +, put OI: -) and the standard normalization (`Γ × OI × contract_multiplier × S² × 0.01`) — see `references/methodology.md` for why that specific scaling. Do not invent a different convention or scaling without calling it out as non-standard. 4. Attach both disclosures to the output every time, not just in an appendix: the dealer-positioning assumption, and what this snapshot does NOT cover (other expirations, intraday OI changes since the snapshot, OTC/index flow that free listed-equity data can't see). 5. Before sharing a GEX report, run it through the audit gate: `python scripts/gex_gate.py --audit report.json`. FAIL-severity flags (`missing_dealer_assumption_disclosure`, `missing_coverage_limitation`, `gex_sum_mismatch`, `regime_sign_mismatch`, `flip_point_out_of_range`, `gamma_walls_mismatch`) mean the report is either undisclosed or internally inconsistent — fix before sharing, don't caveat around it. 6. `sparse_chain` (WARN) does not block sharing, but disclose it: a zero-gamma flip or gamma-wall pick computed from fewer than 5 strikes has real resolution limits worth stating next to the number. 7. See the sign-bug and disclosure-gate mechanics with no data at all: `python scripts/gex_gate.py --demo`. ## Guardrails - Never state a GEX regime as an observed fact. It's always "under the standard assumption that dealers are net short customer flow, OI implies X" — not "dealers are X." - Never silently choose a non-standard sign convention or scaling constant. If you have a specific reason to deviate from the industry standard, say so explicitly and explain why — don't let it look like the same convention everyone else uses. - Never present GEX as a directional price forecast. It describes a hedging-flow *regime* (positive = dealer hedging tends to dampen volatility; negative = tends to amplify it), not a prediction of where price goes next. - Never claim free listed-equity-options GEX covers a symbol's full dealer hedging book — OTC and index-option flow are frequently the larger piece and are invisible to this data source. - A report with disclosures present is not automatically trustworthy — `audit_gex_report` also checks the numbers agree with each other (`gex_sum_mismatch`, `regime_sign_mismatch`) so a stale or hand-edited summary doesn't slip through just because the boilerplate caveat is there. ## Bundled resources - `scripts/gex_gate.py` — `compute_gex()` (Black-Scholes-based, standard sign convention and normalization) plus `audit_gex_report()`, the disclosure/consistency gate. `--demo` reproduces the sign-convention bug flipping a regime call on identical inputs, then shows the gate separate a compliant report from a hollow one and catch a tampered summary. - `references/methodology.md` — the gamma formula, the normalization constant and why it's there, the sign convention and its limits, zero-gamma-flip interpolation, gamma-wall selection, and what this estimate structurally cannot see.