The Greeks · Lesson 01 of 7 · Concept
Delta
Delta is how much an option premium changes for a one-point move in the underlying. On 23 September 2026 the NIFTY 23,350 call carried a delta of 0.542 with six days to expiry, so a 89-point rise in the index implied a gain of about ₹48. The premium gained ₹18.30.
NIFTY 23,350 CE, 23 September 2026 · premiums from MarketCue’s chain capture, delta solved with Black-Scholes
Move it
Black-Scholes, not market data — the premiums elsewhere in this topic were traded, these are what the model returns for the inputs you set.
Black-Scholes, European exercise, 6.5% risk-free rate. These are model outputs, not traded prices.
A slope, not a promise
Delta is the first derivative of the option price with respect to the underlying. A call delta runs between 0 and 1, a put delta between −1 and 0, and the figure is read as rupees of premium per point of index.
In the lab above it is drawn rather than asserted: the violet line is the tangent to the premium curve at the current setting, and its slope is delta. Move the index control and watch the tangent tip. That tipping is gamma, and it is the next lesson.
Delta is also often read as a rough probability of finishing in the money. The two numbers are close for an at-the-money contract and drift apart at the wings, so it is a serviceable shorthand rather than an identity.
Why the index rose 89 points and the call gained 18
On 23 September 2026 NIFTY opened at 23,357.60 and closed at 23,446.80, a rise of 89.20 points. The at-the-money 23,350 call opened at ₹150.00 with a solved delta of 0.542 — which points at a gain of about ₹48.32. It closed at ₹168.30, up ₹18.30.
Delta was not wrong. It was incomplete. Delta describes the response to the index and holds everything else still, and on that session everything else did not hold still: implied volatility fell from 11.15% to 8.22%, and with vega at ₹11.88 per point that accounts for roughly −₹34.80.
The full attribution is the subject of the Greek interactions lesson. The point here is narrower: a delta figure is a statement about one variable, and a premium responds to four.
The 0.542 above is delta at the open. By the close the contract was in the money and its delta was higher, so even the delta term itself understates the move. Gamma is the correction for that, and it added about ₹4.73.
Common questions
What does delta mean in options?
Delta is the change in an option premium for a one-point change in the underlying. A call delta runs from 0 to 1 and a put delta from −1 to 0. An at-the-money option sits near 0.5 in absolute terms.
Is delta the same as probability of expiring in the money?
They are close but not identical. Delta approximates that probability well near the money and less well at the wings, so it is a useful shorthand rather than an equivalence.
Why did my option not move as much as delta said?
Delta holds everything but the underlying still. If implied volatility falls or time passes, vega and theta work against the delta gain. On 23 September 2026 a NIFTY call with delta 0.542 gained ₹18.30 on an 89-point rise, against roughly ₹48 from delta alone, because implied volatility fell almost three points.
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How these figures are produced
Every price on these pages was traded on the exchange and is read from our own option-chain capture, which records the NIFTY and SENSEX chains once a minute through the session. Each page names the session its figures come from.
Figures that a model produced rather than the market — the Greeks, implied volatility — are labelled as model outputs wherever they appear, and never presented beside traded prices without saying which is which. The pricing is checked against published reference values on every change.
Where our own data cannot support a claim, the page says so instead of generalising. MarketCue is not a registered investment adviser, research analyst or broker under SEBI regulations.