The Four That MatterHow fast does my exposure change?

The rate at which delta itself changes. Selling options means being short gamma, and that is the single honest description of what the risk in this strategy actually is.

Where you see it: The Gamma (ours) figure in the Assign tooltip and on AI Trader position cards.

Gamma is the second derivative: how much delta moves for a $1 move in the stock. If delta is your speed, gamma is your acceleration. A gamma of 0.03 means a $1 move changes delta by about 0.03.

Gamma is concentrated rather than spread out. It peaks right at the strike and falls away on both sides, and the peak grows dramatically as expiry approaches — the tall spike in the diagram is roughly a week out, the flat line months out, same strike and same stock.

When you sell an option you are short gamma. Your delta moves against you in both directions: as the stock falls toward your short put, delta rises and the position becomes more stock-like just as the stock is falling. As it rallies away, delta shrinks and you participate less in the recovery. Short gamma is the price paid for collecting theta, and the two are inseparable.

The platform shows position gamma, so it reads negative on every short leg. That negative sign is not an error and not a warning — it is the structural description of a premium-selling position.

Large negative gamma concentrated near expiry is the configuration that moves fastest. A position at the strike with days to go can swing from comfortable to assigned on a single session, and gamma is the number that says so before it happens.

Because gamma peaks at the strike, a position far out of the money carries very little of it — which is another way of saying a distant strike is stable and a near one is not.

Gamma explains why the last week feels different. The same contract that has behaved calmly for a month becomes sensitive as expiry approaches, and nothing about the stock has to change for that to happen — only the calendar.

It is also the reason a wheel seller who is content with assignment has an easier time than one who is not. If taking the shares at your strike is an acceptable outcome, short gamma near expiry is a mechanism rather than a threat. If it is not acceptable, that is the exposure to be aware of well before the final days.

Rolling a position further out reduces gamma — a longer-dated contract has a flatter hump. That is a description of what rolling does to the risk profile, not a recommendation to do it.

Like everything in this guide, these are descriptions of conditions and reference levels — context for your own decisions, not instructions to trade.