Delta (Option Greek)
Delta is one of the most important option Greeks. It measures how much an option’s premium changes for a one-rupee move in the underlying. Delta ranges from 0 to 1 for calls and 0 to −1 for puts. Understanding delta lets Indian options traders size positions correctly, choose appropriate strikes, and quantify portfolio exposure.
Key takeaways:
- Delta measures the rate of change of premium relative to the underlying.
- Calls have positive delta (0 to 1); puts have negative delta (0 to −1).
- ATM options have delta close to ±0.5; deep ITM approaches ±1; deep OTM approaches 0.
- Delta is also a rough probability estimate of finishing ITM.
- Position delta sums across multiple legs for overall directional exposure.
What Delta means in practice
If you hold a Nifty call with delta 0.5, a 100-point rise in Nifty will (approximately) raise the option premium by 50 points (per unit). For a lot size of 25, that is ₹1,250 of profit per lot. Delta gives you a quick translation between underlying moves and your option P&L.
Delta by moneyness
| Status | Call delta | Put delta |
|---|---|---|
| Deep ITM | ~+1.0 | ~−1.0 |
| ATM | ~+0.5 | ~−0.5 |
| Deep OTM | ~0 | ~0 |
Delta as probability
Many practitioners use absolute delta as a quick proxy for the probability that an option expires ITM. A delta of 0.3 implies roughly a 30% chance of finishing in the money — though this is an approximation that breaks down at extreme moneyness or during very high volatility regimes.
Delta and position sizing
Position delta is the sum of deltas across all legs. If you hold long 2 Nifty calls each with delta 0.5 and short 1 future, your position delta is 2 × 0.5 × 25 − 25 = 0. You are delta-neutral. Adjusting your trade to maintain target delta is the basis of dynamic hedging.
Delta changes — meet Gamma
Delta itself changes as the underlying moves. The rate at which delta changes is Gamma. ATM options have the highest gamma; their delta swings fastest as the underlying moves. ITM/OTM options have lower gamma. Active option traders watch both delta and gamma to stay on top of position changes.
Delta vs other Greeks
- Theta — measures time decay.
- Vega — measures sensitivity to implied volatility.
- Rho — measures sensitivity to interest rates.
- Gamma — rate of change of delta.
Frequently asked questions
Is delta the same for calls and puts of the same strike?
Almost — they sum to ±1 at the same strike (e.g., 0.6 call delta + −0.4 put delta = +1 in absolute terms when adjusted for sign).
Does delta change during the day?
Yes. As spot and IV move, delta moves too.
What is delta-neutral trading?
A strategy where position delta is approximately zero, eliminating direction risk and isolating volatility or time decay.
Does Lemonn show delta on the option chain?
Yes. Modern Indian brokers including Lemonn display all major Greeks in their option chain interfaces.
