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Delta, gamma, theta and vega — without formulas, only what each one does to your money
Published by The Retail Trader · AUG 09, 2026 · Features
An option's premium is not made from just one thing. That is why the experience of 'the market went in my direction but the premium fell' happens to every new option buyer. The Greeks are exactly the four dials that turn this premium — and to understand them you need not maths, only intent.
Delta tells roughly how much the option's premium will move if the underlying moves 1 rupee. A deep OTM option has a very low delta, around ATM it is moderate, and at deep ITM it starts behaving almost like futures.
The practical meaning: a cheap OTM option is cheap because it captures a very small part of the underlying's move. You can be right on direction and still not earn much, because the instrument you chose picked up only a small part of the move.
Gamma is the delta of delta. It tells how fast your delta will change as spot moves. Gamma is highest at ATM strikes and gets faster as expiry nears.
This is why on expiry day an ATM option looks like zero one minute and double the next. That is not madness, it is gamma. For option sellers this is the most dangerous Greek, because the character of the position changes without their doing anything.
Theta tells how much the premium will fall just from one day passing, even if spot does not move at all. For a buyer theta is a daily cost; for a seller it is daily income.
Theta does not fall in a straight line — its speed increases as expiry approaches. That is why the thinking of 'wait a little more, it will come back' is the most expensive in weekly options.
Vega tells how much the premium will change when the expectation of volatility changes. Before a big event everyone's fear rises, so the premium swells. As soon as the event passes, that air goes out.
That is why buying an expensive option a day before a result or policy is a double bet: the direction has to be right, and the move has to be big enough to cover even the loss from vega falling.
In one line, here is who stands against an option buyer:
• Theta — cutting money with every passing day.
• Vega — lets the air out of the premium after the event.
• Delta — if the strike is far, it gives you a very small part of the move.
• Gamma — the only Greek that can bring speed in the buyer's favour, but it wakes up only very close to expiry.
That is why the case for option buying exists only when the move is big, fast and early. A slow but correct move defeats even the option buyer.
This article is for educational purposes only — it is not a buy or sell recommendation, makes no claim of guaranteed returns, and is not advisory. Rules, rates and mechanics are changed by the exchange, SEBI and RBI from time to time, so verify every number yourself with your broker or an official source.