The Option Greeks near expiry

The Greeks are never more dramatic than in the final days of a contract's life. Theta accelerates, gamma spikes, delta turns binary and vega fades to nothing. These pages explain each Greek's behaviour near expiry and how they interact — the mechanics behind every expiry-day surprise.

Expiry & Option Greeks: Approaching expiry, theta (time decay) accelerates and is steepest for at-the-money options, gamma spikes so delta changes violently on small moves, delta becomes increasingly binary (near 0 or 1), and vega collapses because there is little time left for volatility to matter. Understanding these shifts explains expiry-day price action.

Theta Near Expiry

Time decay

Theta near expiry is the accelerating rate at which an option's time value erodes as its remaining life shrinks — for an at-the-money option, time va…

→

Gamma Near Expiry

Gamma

Gamma near expiry is the sharp rise in an at-the-money option's rate-of-change-of-delta as the contract's final days approach — because delta must co…

→

Delta Behaviour Near Expiry

Delta

Delta near expiry becomes increasingly binary — an option that is clearly in-the-money is pulled toward a delta of 1, one clearly out-of-the-money is…

→

Vega Collapse Into Expiry

Vega

Vega collapse is the sharp decline in an option's sensitivity to changes in implied volatility as expiry approaches — with little time left for the u…

→

Implied Volatility Before Expiry

Implied volatility

Implied volatility before expiry is the market's evolving estimate of how much the underlying might move before the contract ends — it can build up a…

→

Implied Volatility After Expiry

Implied volatility

Implied volatility after expiry has no meaning for the contract that just expired — it ceased to exist — so market attention, liquidity and pricing s…

→

The Time Decay Curve

Time decay

The time-decay curve is the shape traced by an option's remaining time value as it falls from its starting level toward zero at expiry — for an at-th…

→

How the Greeks Interact During Expiry

Greeks

Near expiry, the Greeks stop behaving independently: for at-the-money options, gamma and theta rise together (they are mathematically linked through …

→

Frequently asked questions

Why does theta increase near expiry?

Theta measures time decay, and an at-the-money option's remaining time value decays along a curve that steepens as expiry nears — roughly proportional to the square root of time left. With little time remaining, each passing day removes a larger share of the option's value, so theta is largest in the final days.

Why is gamma so high near expiry?

Gamma peaks for at-the-money options close to expiry because the option's delta must transition from near 0 to near 1 over a shrinking price range. That makes delta extremely sensitive to the underlying — a small Nifty move can swing an ATM option from nearly worthless to deep in-the-money.

What happens to implied volatility after expiry?

For the expiring contract, implied volatility becomes meaningless at expiry because there is no time left. Attention shifts to the next series, whose IV reflects fresh uncertainty. A post-event IV crush often occurs when an anticipated event passes and uncertainty resolves.