Gamma scalping

Definition

Gamma scalping is the active management of a long-options position by re-hedging its delta as the underlying moves: long gamma means the position gets longer as prices rise and shorter as they fall, so re-flattening delta mechanically sells rises and buys dips. The harvested scalps are not free money — they are the realized- volatility payout of a position that pays theta daily for the privilege. The strategy is therefore a pure form of the KB’s central options identity: long options profit when REALIZED vol exceeds the IMPLIED vol paid (indicator-realized-vs-implied-vol).

How it works / structure

• The P&L identity (Hull/Sinclair exposition): a delta-hedged long option earns approximately ½ × gamma × (move)² per re-hedge and pays theta per day; break-even is the move whose square matches the theta bill — the option’s implied daily move restated (opt-expected-move). Realized > implied → scalps exceed decay; realized < implied → decay wins.
• The construction (engine-parameterizable): long straddle or strangle (strategy-straddle chassis), delta re-hedged with stock/futures; parameters — hedge trigger (re-hedge at fixed delta bands vs fixed time intervals: band hedging captures more in trending chop, time hedging is friction-predictable), tenor (short tenor = high gamma, high theta — the aggressive end), and moneyness (ATM maximizes gamma/theta density — greek-gamma).
• The friction reality: every scalp pays spread and fees — hedge-band width must exceed round-trip cost meaningfully or the harvest goes to the market makers; documented as the retail-scale binding constraint.
• Event applications: long gamma into known-volatility windows (earnings weeks held OPEN rather than through the print, high-uncertainty macro regimes) where realized chop is the thesis.

When it applies

Regimes where realized vol is expected to exceed implied (post-crush windows, choppy high-uncertainty periods — the thesis is a VOL FORECAST, stated falsifiably); as the management layer on any long straddle thesis (unmanaged straddles need the terminal move; scalped straddles monetize the path); market-maker literacy (dealers run this book constantly — their hedging is the flow behind greek-gamma regime effects).

Risk profile & failure modes

• The quiet grind (the base case): implied vol usually exceeds realized (the documented premium) — the strategy’s default state is paying theta and under-harvesting; it is a countertrend thesis against a documented premium, deployed selectively, not standing.
• Scalp-the-trend regret: re-flattening delta in a sustained trend sells the winner repeatedly — long gamma monetizes CHOP, not trends; the trend case favors letting delta run (a stated parameter choice, not an accident).
• Friction underestimate: paper scalping ignores spreads; live scalping at retail size in wide-spread options documents negative even in favorable vol — instrument liquidity is an entry criterion.
• Discipline decay: manual re-hedging under P&L emotion drifts from the rule — the strategy is rule-density heavy and suits automation (mgmt-delta-hedging cadence machinery).

Evidence & limits

The gamma-theta identity is standard derivatives mathematics (Hull); the practitioner P&L decomposition is Sinclair’s exposition; the vol-premium headwind is the documented base rate. No standalone edge claim: the strategy converts a volatility forecast into P&L — the forecast carries the thesis burden.

Falsifiable-thesis examples

Illustrations only, not signals:

• “Realized vol will exceed current implied by 20%+ over the next month in X (the gamma-scalp thesis proper)” — falsified by the realized measurement.
• “Band-triggered hedging at ±0.10 delta harvests more net-of-friction than daily time-based hedging in choppy-regime replays (parameter check)” — falsified by the paired replay.

Cross-references

• The identity’s parts: greek-gamma, greek-theta, opt-implied-volatility
• The chassis: strategy-straddle; the machinery: mgmt-delta-hedging
• The premium headwind: indicator-realized-vs-implied-vol
• The dealer-flow mirror: indicator-options-flow