A practical, India-specific guide to options Greeks with NIFTY and BANK NIFTY examples. Built for traders who want to actually use them, not just memorise definitions.
Options Greeks are the four numbers that explain how an option's price will change when something in the market moves. They're the difference between trading options blindly (everyone's first 18 months) and trading them as a coherent risk system. This guide is built for Indian-market traders specifically — every example uses NIFTY, BANK NIFTY, or a major NSE F&O stock.
Each Greek answers one question. Delta: how much does the option price change if the underlying moves ₹1? Gamma: how much does Delta itself change? Theta: how much value does the option lose per day from time decay alone? Vega: how much does the option price change if implied volatility moves 1%?
Once you can read Greeks, every option position becomes legible. You can see exactly which risks you're taking and which you're not — which is the prerequisite for ever managing a position correctly.
Delta is the most-watched Greek. It tells you how much the option's price will change for every ₹1 move in the underlying. A NIFTY call with Delta 0.50 will gain ₹0.50 if NIFTY rises ₹1. A NIFTY put with Delta -0.30 will lose ₹0.30 if NIFTY rises ₹1.
At-the-money options have Delta around ±0.50. Calls trend toward +1.0 as they go deep in-the-money; puts trend toward -1.0. OTM options have Delta close to zero — small moves in the underlying barely affect them.
Delta as probability of expiring ITM. A useful approximation: |Delta| roughly equals the probability that the option will expire in-the-money. A 0.30 Delta call has a ~30% chance of expiring ITM. This isn't mathematically exact (it ignores volatility skew) but it's good enough for quick risk reads.
Net Delta on a multi-leg position is the sum of each leg's Delta times the number of contracts. A long straddle (long ATM call + long ATM put) has Delta close to zero — it's a volatility bet, not a directional bet. An iron condor has Delta close to zero between the body strikes. Building positions to specific net-Delta targets is how professionals control directional exposure.
Gamma tells you how much Delta itself will change for every ₹1 move in the underlying. If a NIFTY call has Delta 0.40 and Gamma 0.05, then a ₹1 rise in NIFTY makes Delta become 0.45 — your directional exposure has increased.
Gamma is highest at the at-the-money strike and peaks on expiry day. On the last day of an options contract, ATM Gamma can be huge — small moves in the underlying produce massive Delta swings. This is why expiry-day option selling is so dangerous: your position can flip from short to long delta in minutes if the index ticks past your strike.
Gamma scalping. Some traders intentionally take long Gamma positions (long straddles) and hedge the resulting Delta by trading the underlying as the market moves. Each hedge harvests Gamma profit. Sophisticated, but real money is made this way during high-volatility periods.
For most retail Indian traders, the key point is: be aware of Gamma when selling options near expiry. The number on the screen looks great in the morning and ruinous by 2 PM if the index moves toward your strike.
Theta is the daily decay in option price assuming the underlying and IV stay the same. A NIFTY call with Theta -₹2 loses ₹2 of value per day just from time passing.
Theta is strongest at the at-the-money strike and accelerates as expiry approaches. An ATM weekly option loses very little value 7 days from expiry but bleeds out rapidly in the last 2-3 days. The classic 'last 3 days' decay curve is what makes Indian weekly option selling such an active strategy.
Theta is the option seller's edge. When you sell an option, you're long Theta — you make money every day from time decay alone. As long as the underlying doesn't move enough to overwhelm Theta with Delta+Gamma losses, time decay grinds in your favour.
Theta is roughly proportional to IV. Higher-IV options have higher Theta. BANK NIFTY options have higher Theta than NIFTY because BANK NIFTY IV runs higher. That's the source of the 'BANK NIFTY pays more for selling' folk wisdom.
Vega tells you how much the option price will change for every 1% change in implied volatility. A NIFTY call with Vega ₹15 gains ₹15 if NIFTY IV rises from 14% to 15%, all else equal.
Vega is highest at the at-the-money strike and longest-dated expiry. Monthly options have more Vega than weeklies — they're more sensitive to IV regime changes. Far OTM options have very little Vega.
IV expansion events. IV typically rises before major catalysts: RBI policy, US Fed announcements, election results, big earnings. Long Vega positions (long straddles, long calendars) profit from IV expansion. Selling premium just before such events is a common loss-making mistake.
IV crush. After a known event passes, IV typically drops sharply. Long premium positions get hurt; short positions benefit. This is the source of the well-known 'sell straddles after earnings' edge.
Every option position has all four Greeks at once. A long ATM NIFTY call: positive Delta (you make money if NIFTY rises), positive Gamma (your Delta grows as NIFTY rises), negative Theta (you lose money each day from decay), positive Vega (you make money if IV rises).
A short ATM NIFTY straddle (sell call + sell put at same strike): zero initial Delta (directional-neutral at entry), negative Gamma (your Delta becomes negative as NIFTY rises, positive as NIFTY falls — your loss grows in either direction), positive Theta (Theta is what you're harvesting), negative Vega (you get hurt if IV rises).
Reading any position through the four Greeks is the only way to know what risks you're actually carrying — and what risks you're not. Strota's strategy builder shows the net Greeks for any multi-leg position before you commit capital to it.
Theta is the seller's edge — the reason option selling works as a strategy. But Gamma is the seller's enemy, especially near expiry. The art of option selling is harvesting Theta while staying small enough in Gamma to survive sudden moves.
Delta gets you most of the directional gain. Vega matters around event catalysts. Theta is your daily cost — the longer you hold, the more you bleed. The classic option-buyer mistake is overpaying for Vega just before a known catalyst, then watching IV crush wipe out the directional profit.
From the Black-Scholes model (or a discrete-dividend variant for Indian markets). Inputs are the current option price, current spot price, time to expiry, strike, risk-free rate, and dividend yield. The implied volatility is derived from the option price first, then plugged back to compute the four Greeks.
No. Greeks are first-order partial derivatives — they describe how the option price will change given small instantaneous moves in the underlying or IV. They don't predict where the market will go. They tell you what risks you're carrying right now.
Theta is conventionally quoted as the change in option value per day. Since options lose value over time (all else equal), the change is negative. From the seller's perspective the same value is positive because they receive that decay.
On Monday-Tuesday, around -₹5 to -₹10 per day. By Wednesday-Thursday, it can rise to -₹20 to -₹40 per day as Gamma and Theta both peak into expiry. The exact value depends on current IV and spot level.