Delta: Directional Sensitivity in Option Trading

Definition

Delta estimates how much an option's premium changes when the underlying index moves one point. A call with delta 0.40 gains roughly ₹40 per lot per point of Nifty rise (subject to other Greeks). Puts have negative delta — they gain when the index falls.

Delta also approximates the probability of expiring ITM under simplified models — useful intuition, not a forecast.

Delta by Moneyness

ATM options carry delta near ±0.50. Deep ITM options approach ±1.00 and behave like futures with less leverage per rupee. OTM options have low delta — cheap but need large moves.

As spot rises, call delta increases (delta of calls is always positive). This acceleration is gamma.

• High delta: more directional exposure, higher premium
• Low delta: lottery tickets, need explosive moves
• ATM: balance for intraday breakout trades
• Portfolio delta: sum exposures across legs

Practical Use

Match delta to conviction. Strong breakout thesis warrants higher delta; speculative event bets may use lower delta with smaller size.

Sellers watch delta to hedge — when short call delta grows, they may buy futures to stay neutral.