Option Greeks Explained: Delta, Gamma, Theta, Vega

What Are Option Greeks and Why They Matter

Option greeks are a family of numbers that measure how an option premium reacts to change. Each greek isolates one force: how the option moves with the underlying, how that movement itself speeds up, how much value time strips away each day, and how shifts in implied volatility push the premium around. Learn to read them and the premium stops being a mystery and becomes a set of moving parts you can reason about.

For most new traders in India, an option is just a cheap lottery ticket on NIFTY or BANKNIFTY. You buy a call because you feel bullish, watch the premium tick, and hope. The option greeks replace that hope with a model. They tell you, before you enter, roughly how many rupees you stand to make or lose for a given move, how fast that figure will change, and how much the clock is working against you.

There are five greeks worth knowing. Delta, gamma, theta and vega are the four that drive almost every decision. Rho, the sensitivity to interest rates, matters far less for the short dated weekly and monthly contracts that dominate Indian markets, so we cover it briefly at the end. The plan of this guide is simple: build each greek from intuition, attach a rupee example, then show how they combine into a real position.

One honest note before we begin. Everything here is educational. First Plan India is a paper trading platform built so you can practise with virtual money and learn how these forces behave without risking your savings. Nothing in this article is financial advice or a recommendation to buy or sell any specific contract.

Premium First: Intrinsic Value and Time Value

Before the greeks make sense, you need to know what they are measuring. An option premium has two parts: intrinsic value and time value. Intrinsic value is the part that is already in the money. For a NIFTY 23,000 call when NIFTY trades at 23,150, the intrinsic value is ₹150 per unit, because exercising would capture that much. Time value is everything above intrinsic value, the extra ₹80 or ₹100 the market charges for the chance that the option moves further your way before expiry.

An out of the money option has zero intrinsic value. Its entire premium is time value, pure hope priced by the market. A deep in the money option is almost all intrinsic value with very little time value left. This split matters because the greeks act mostly on the time value portion. Delta touches both, but gamma, theta and vega live and breathe inside the time value.

Think of time value as a melting ice block. The greeks describe how fast it melts (theta), how it grows or shrinks when the weather changes (vega), how sensitive its size is to where the underlying sits (delta), and how quickly that sensitivity itself changes (gamma). Keep this picture in mind and the rest follows naturally. These index options on the NSE, such as NIFTY and BANKNIFTY, are cash settled, which keeps the maths clean because you never deal in delivered shares.

Delta: How Far the Option Moves With the Market

Delta is the first and most intuitive greek. It measures how much the option premium changes for a one point move in the underlying. A call with a delta of 0.50 gains roughly ₹0.50 in premium for every one point NIFTY rises, and loses about the same when NIFTY falls. Call deltas run from 0 to 1. Put deltas run from 0 to minus 1, because puts gain value when the underlying falls.

Put a rupee figure on it. Suppose NIFTY trades at 23,000 and you buy the 23,000 call, an at the money option, with a delta near 0.50. The NIFTY lot size is 65 (the exchange revises lot sizes from time to time, so always check the latest NSE circular before you size a trade). If NIFTY climbs 100 points to 23,100, the premium rises by about 100 times 0.50, which is ₹50 per unit. Across one lot that is ₹50 times 65, or ₹3,250, before we account for the other greeks. If instead NIFTY drops 100 points, you lose roughly the same ₹3,250.

Puts mirror calls. Suppose you are worried about a fall and you buy the NIFTY 23,000 put with a delta of minus 0.50. If NIFTY drops 100 points to 22,900, the put gains about 100 times 0.50, or ₹50 per unit, which is ₹50 times 65, about ₹3,250 across one lot. The minus sign simply records direction: the put profits when the index falls. This is why traders who hold a stock portfolio or index futures sometimes buy puts as insurance, paying a premium to cap their downside while keeping their upside open.

Delta is not fixed. As the underlying moves and time passes, delta changes, which is exactly what gamma measures. A deep in the money call behaves almost like holding the index itself, with a delta close to 1, so it moves nearly rupee for rupee with NIFTY. A far out of the money call has a delta near 0.10 or less, so it barely twitches on a small move, which is why cheap weekly options can feel dead until a big move finally arrives.

One practical reading: delta is your directional exposure. A position delta tells you how many index points of exposure you are carrying. If your whole position has a net delta of plus 65 on NIFTY, you are effectively long one lot of the index, and you will gain or lose about ₹65 for every one point NIFTY moves in your favour or against you.

Delta as Probability and Directional Exposure

Delta carries a second meaning that experienced traders lean on heavily. The delta of an option is a rough estimate of the probability that it finishes in the money at expiry. A 0.30 delta out of the money call has, very approximately, a 30 percent chance of expiring with some intrinsic value. This is an approximation, not a guarantee, but it is a useful lens.

This is why an at the money option sits near 0.50 delta: it is close to a coin flip whether it finishes in or out of the money. It also explains why far out of the money options are cheap. A NIFTY call 500 points away with a delta of 0.08 is priced for an event the market thinks is unlikely, so you pay little, but you are also unlikely to be paid.

For position management, you can add deltas across every leg you hold. Long one at the money call (delta plus 0.50) and short one further out call (delta minus 0.30, because you sold it) leaves a net delta of plus 0.20 per unit, or plus 13 across a 65 lot. That single number tells you the net direction of a multi leg trade at a glance, which is far more useful than staring at several separate premiums.

Gamma: The Acceleration Behind Delta

If delta is your speed, gamma is your acceleration. Gamma measures how much delta itself changes for a one point move in the underlying. Because NIFTY trades around 23,000, a single index point is small, so gamma per point is a small number, perhaps 0.0015 for an at the money call. The figure looks tiny, but multiply it across a real move and it bites: a 50 point rise lifts delta by about 50 times 0.0015, roughly 0.075, so a delta of 0.50 becomes about 0.575. Gamma is the reason a winning position starts making money faster than a static delta would suggest.

Gamma is highest for at the money options and lowest for deep in the money or far out of the money options. The intuition: an at the money option is balanced on a knife edge, so small moves swing its delta sharply between behaving like nothing and behaving like the index. Deep in or far out, the delta is already pinned near 1 or near 0, so there is little room for it to change.

Gamma is also why hedging is never a one time act. A desk that sells options and wants to stay delta neutral must keep rebuying or reselling the underlying as the market moves, because gamma keeps changing the delta out from under them. The larger the gamma, the more often they must adjust, and every adjustment costs something in charges and slippage. For a retail trader the lesson is gentler: do not assume the delta you saw at entry is the delta you hold an hour later, especially on a fast day or close to expiry.

Gamma also rises as expiry approaches, and this is one of the most important and most punishing facts in NIFTY weekly options. On the morning of expiry, an at the money NIFTY option can have enormous gamma, which means its delta flips violently with every swing of the index. A seller who looked safe an hour earlier can be deep in trouble after a 60 point move, because gamma turned a small delta into a large one almost instantly.

Buyers of options own positive gamma, which is a friend: their position accelerates in their favour and decelerates against them. Sellers carry negative gamma, which is the danger: their losses accelerate and their gains slow down. This asymmetry is the heart of why selling options can feel like picking up coins and occasionally meeting a steamroller.

Theta: Paying Rent on Time

Theta is the cost of time, and for option buyers it is the silent leak in the boat. Theta measures how much premium the option loses for each day that passes, assuming the underlying and volatility stay still. It is quoted as a negative number for anything you are long. A weekly at the money NIFTY call priced at ₹120 might carry a theta of about minus ₹15, meaning that if nothing else changes, tomorrow it will be worth roughly ₹105.

Put it in lot terms. That minus ₹15 of theta across a 65 lot is about ₹975 of value evaporating in a single day, purely from the calendar. Hold that option over a quiet weekend and you can lose two or three days of theta while the market is shut. This is why buying far out of the money weekly options and simply holding them is so often a slow bleed: the move you need has to arrive faster than theta drains your premium.

Theta is highest in rupee terms for at the money options, and it accelerates sharply into expiry. Far from expiry, an at the money option loses its time value gently. In the final days, the decay curve steepens dramatically, and on expiry day an at the money option can shed most of its remaining time value within hours. This is the engine behind option selling strategies: sellers collect theta every day, which is why they are sometimes described as being paid rent for taking on risk.

It also helps to read theta as a percentage of the premium rather than a raw rupee figure. A theta of minus ₹15 on a ₹120 option is losing about 12 percent of its value a day, a ferocious rate that no directional edge can outrun for long. The same minus ₹15 on a ₹300 monthly option is only about 5 percent a day, far more survivable. This is the real reason monthly options suit slower theses: the daily decay is a smaller slice of what you paid, so you can afford to be patient while your view plays out.

The flip side is buyer versus seller. If you are long an option, theta works against you every single day. If you are short, theta works for you. Neither is free: the buyer pays theta in exchange for limited risk and large upside, while the seller earns theta in exchange for limited upside and large, sometimes unlimited, risk. The greeks make this trade off precise rather than vague.

Vega: The Volatility Sensitivity

Vega measures how much the option premium changes when implied volatility moves by one percentage point. Implied volatility, or IV, is the market estimate of how much the underlying will swing in the future, baked into the option price. A vega of ₹8 means that if IV rises by one point, say from 14 percent to 15 percent, the premium rises by about ₹8 per unit, even if NIFTY itself has not moved at all.

This is the greek that catches new traders by surprise. You buy a call, NIFTY moves up exactly as you predicted, and yet your option barely gains or even loses value. The culprit is usually a fall in implied volatility, often after an event like the Union Budget, an RBI policy decision, or a major result. Before the event IV is pumped up and premiums are expensive. Once the uncertainty clears, IV collapses, vega drags the premium down, and your correct directional call still loses money. Traders call this an IV crush.

Vega is largest for at the money options and for options with more time to expiry. A monthly option has far more vega than a weekly option, because there is more time for volatility to matter. This is why traders who expect a volatility spike often prefer slightly longer dated or at the money contracts, and why sellers who want to harvest an IV crush look to sell when IV is high and expected to fall.

Two refinements turn vega from a single number into a fuller picture. First, different strikes carry different implied volatilities, a pattern called the volatility skew, so out of the money puts on NIFTY often trade at a higher IV than equally distant calls because traders pay up for crash protection. Second, IV itself changes with time to expiry, the volatility term structure, so a weekly and a monthly contract can move on different volatility stories even on the same index. You do not need to model these to trade, but knowing they exist explains why two options on the same underlying can behave so differently.

Long options have positive vega: rising volatility helps you. Short options have negative vega: rising volatility hurts you. A long straddle, buying both a call and a put at the same strike, is a pure positive vega and positive gamma bet that the market will move a lot, while the seller of that straddle is betting the opposite, that things stay calm and IV drifts lower.

Rho: The Interest Rate Greek in Brief

Rho is the forgotten greek for most Indian retail traders, and for good reason. Rho measures how much the option premium changes when interest rates move by one percentage point. Calls generally have positive rho and puts have negative rho, because the cost of carrying a position is tied to interest rates. For long dated options, rho can matter. For the weekly and monthly contracts that make up the vast majority of Indian options volume, rho is tiny compared with delta, gamma, theta and vega.

A practical way to hold it: over the few days or few weeks that a typical Indian options trade lives, interest rates rarely move enough to shift your premium in a way you would notice next to the daily theta bleed or a swing in IV. Rho becomes meaningful mainly for very long dated instruments, which are uncommon in the Indian retail options market. Know that rho exists, understand its direction, and then spend your attention on the four greeks that actually drive your profit and loss.

ATM, OTM and ITM: How the Greeks Shift Across Strikes

The single most useful skill with the greeks is knowing how they shift as you move across strikes. Take NIFTY at 23,000 and line up three calls: the 22,800 call (in the money), the 23,000 call (at the money), and the 23,200 call (out of the money). Each one carries a very different greek profile, and choosing between them is really a choice about which greeks you want.

The pattern to memorise is this: gamma, theta and vega all peak at the money and fall away as you move in either direction. Delta is the exception, climbing steadily from near 0 for far out options to near 1 for deep in options, passing through about 0.50 at the money. Once you can picture these curves, you can predict how any option on the chain will behave before you ever look at the price.

This is why the at the money strike is where the action is. It is the most sensitive point on the chain to every force at once: the underlying, time and volatility. Out of the money options feel cheap and tempting, but their low delta means you need a large move just to make them pay, and their decay relative to premium is brutal. In the money options feel safer and move more reliably, but you pay for that with a larger premium and more capital at risk.

• In the money 22,800 call: high delta (around 0.65 to 0.75), low gamma, lower theta as a share of premium, moderate vega. It behaves more like the index and costs more.
• At the money 23,000 call: delta near 0.50, the highest gamma, the highest theta in rupee terms, the highest vega. It is the most reactive option on the board.
• Out of the money 23,200 call: low delta (around 0.30), modest gamma, low absolute theta but heavy decay relative to its small premium, lower vega. It is cheap, but the odds are against it.

Into Expiry: How the Greeks Turn Sharp

Time does not affect the greeks evenly. As expiry approaches, the curves we just described do not just shift, they sharpen into spikes, and this transformation is where most weekly option accidents happen. Two greeks turn dangerous near expiry: gamma and theta.

Gamma near expiry becomes enormous for at the money options. With only hours left, a small move in NIFTY can flip an option from out of the money to in the money, swinging its delta from 0.20 to 0.80 almost instantly. For a seller, this means a position that was comfortably profitable can blow up in minutes on expiry day. This is the famous expiry day gamma risk, and it is amplified in India because NIFTY weekly options concentrate huge volume into the final hours.

Theta near expiry accelerates to its steepest. The time value that decayed gently over the week now collapses in a rush. For a buyer holding an out of the money option into the last day, this is often a near total loss, the premium melting to almost nothing as the clock runs out. For a seller, these final hours are when the bulk of the theta is collected, which is precisely why so many sellers concentrate on the expiry session, accepting the gamma risk in exchange for the fast decay.

Vega, by contrast, shrinks into expiry, because there is less and less time for volatility to express itself. A one point change in IV that mattered a lot three weeks before expiry barely registers on the last day. The lesson across all of this: the same strike is a completely different animal with three weeks left versus three hours left, and you must trade the greeks for the time you actually have, not the comfortable picture from earlier in the cycle.

Buyer Versus Seller: Who Holds Which Greek

Every greek has two sides, and which side you are on flips the sign. When you buy an option you are long the greeks that come with it. When you sell, you inherit the mirror image. Getting this clear in your head prevents a huge share of beginner confusion.

The list below explains the personality of each style. Buyers are paying rent (theta) for the right to a large, accelerating payoff if a big move arrives (positive gamma) or if fear spikes (positive vega). They have limited, known risk and usually a low probability of a large win. Sellers are the landlords, collecting that rent daily, with a high probability of small wins and the constant tail risk that a sharp move and their negative gamma combine into a large loss.

Neither side is inherently smarter. The greeks simply make the bargain explicit. A buyer who does not respect theta will bleed out on quiet days. A seller who does not respect gamma and vega will be fine for months and then surrender a year of gains in one violent session. On First Plan India you can paper trade both sides and watch these greeks move in real time, which is the safest way to feel the difference before any real money is involved.

• Option buyer: negative theta (time hurts you), positive gamma (moves help you accelerate), positive vega (rising volatility helps you), and a delta whose sign matches your view, positive for calls and negative for puts.
• Option seller: positive theta (time pays you), negative gamma (moves hurt you faster and faster), negative vega (rising volatility hurts you), and the opposite delta of the contract you sold.

Buyers rent time and hope for a storm. Sellers collect the rent and pray for calm.

Net Position Greeks: Reading a Whole Portfolio

The real power of the greeks appears when you stop looking at single options and start adding them up. Because the greeks are additive, you can sum the delta, gamma, theta and vega of every leg you hold to get a single net figure for your whole position. That net profile, not any individual premium, is what actually determines your risk.

Take a simple example on NIFTY at 23,000. You buy one 23,000 call (delta plus 0.50, theta minus ₹15, vega plus ₹8) and you sell one 23,200 call against it (delta minus 0.30, theta plus ₹10, vega minus ₹5). This is a bull call spread. Your net delta is plus 0.20, your net theta is minus ₹5, and your net vega is plus ₹3, all per unit. The sold leg has paid for part of your theta and trimmed your volatility exposure, which is the whole point of the spread.

Now picture a long straddle: buy the 23,000 call and the 23,000 put together. The deltas (plus 0.50 and minus 0.50) roughly cancel, leaving you close to delta neutral, with no strong directional bias. But your gamma is large and positive, your theta is large and negative, and your vega is large and positive. In plain terms, you do not care which way NIFTY goes, you just need it to move far and fast, or for volatility to spike, before theta drains you. Reading the net greeks tells you exactly what kind of bet you are making, even when the individual legs look confusing.

Net greeks also tell you how to adjust rather than simply exit. If your bull call spread has run up and your net delta has shrunk because the long call is now deep in the money, you might roll the position higher to refresh your delta. If a sold strangle has seen IV spike and your negative vega is hurting, you might buy a cheap wing to cap the damage. Each adjustment is really a decision to push one net greek back toward the exposure you want, and thinking in those terms keeps your management deliberate instead of panicked.

This is how professional desks think. They rarely ask is this call cheap. They ask what is my net delta, gamma, theta and vega, and is that the exposure I want for the next few days. Once you adopt this habit, position sizing and risk control become far clearer, because you are managing a handful of net numbers instead of a tangle of separate trades.

A Worked Example: Greeks of a NIFTY Call Across a Day

Let us walk a single trade through a day to see the greeks interact, because in real markets they never act alone. Assume NIFTY opens at 23,000 and you buy one lot of the 23,000 weekly call at a premium of ₹120. Your starting greeks are roughly: delta 0.50, gamma 0.0015 per point, theta minus ₹15, vega ₹8. The lot size is 65, so your premium outlay is ₹120 times 65, which is ₹7,800, plus charges.

By midday NIFTY has risen 80 points to 23,080. Delta of 0.50 alone suggests a gain of about 80 times 0.50, or ₹40 per unit. But gamma has been lifting your delta as the index rose, by about 80 times 0.0015, which is 0.12, so your delta is now closer to 0.62. Because the average delta across the move was higher than your starting 0.50, your realised gain is a little more, perhaps ₹45 per unit. Across the lot that is roughly ₹45 times 65, about ₹2,925 in your favour. This is positive gamma working for you: the move paid more than a static delta would predict.

Then the market goes quiet for two hours and implied volatility slips by one point as the morning nervousness fades. Vega of ₹8 means that one point IV drop costs you about ₹8 per unit, clawing back part of your gain. Meanwhile theta keeps grinding: a chunk of that minus ₹15 daily decay is charged across the day regardless of direction. Your net result is the sum of all four forces, not just the delta you first noticed.

By the close NIFTY sits at 23,090, only 10 points above midday. The higher delta keeps your position slightly more profitable on that last leg, but theta has eaten further into the premium and the small IV drop still stings. The lesson is not the exact rupee figure, it is the structure: your profit and loss is delta plus gamma, minus theta, plus or minus vega, every single day. Traders who track only delta are repeatedly surprised. Traders who read all four greeks are rarely caught off guard.

Greeks on BANKNIFTY and Single Stocks Like Reliance and HDFC Bank

The greeks behave identically across instruments, but the rupee impact scales with lot size and price, so it pays to see them on more than NIFTY. BANKNIFTY, the banking index on the NSE, trades at a higher level and moves in larger point swings, and its lot size is 30 (lot sizes are revised periodically by the exchange, so confirm the current NSE circular). A BANKNIFTY at the money option with a delta of 0.50, when the index moves 200 points, hands you about 200 times 0.50 times 30, which is ₹3,000 per lot from delta alone. Because BANKNIFTY routinely moves several hundred points in a session, its gamma and theta in rupee terms feel larger and faster than NIFTY. One expiry difference matters too: BANKNIFTY now trades monthly only, expiring on the last Tuesday, after its weekly expiries were discontinued in November 2024, whereas NIFTY still offers weekly options every Tuesday plus a monthly contract on the last Tuesday, and on the NSE weekly options now exist only for NIFTY.

Single stock options behave the same way but with two India specific wrinkles. First, stock options on names like Reliance and HDFC Bank are physically settled under the current SEBI framework, not cash settled like index options. If you let an in the money Reliance option run into expiry, you can be assigned actual delivery of shares, which means a large obligation and extra margin. Since Indian equities now settle on a T+1 basis, delivered shares hit the account quickly, so most retail traders square off stock options before expiry rather than risk physical settlement.

Second, single stocks often have lower liquidity and wider spreads than NIFTY and BANKNIFTY, which makes their implied volatility jumpier and their vega exposure trickier to manage around results season. An HDFC Bank option going into its quarterly results can see IV inflate sharply beforehand and crush afterwards, exactly the vega trap described earlier. Index options, being cash settled and deeply liquid, are where most beginners are gently steered to learn the greeks first. The same greeks govern options on the BSE, such as on the SENSEX, exactly as they do on the NSE, before anyone graduates to the rougher waters of stock options.

Common Greek Mistakes Indian Retail Traders Make

Knowing the greeks and respecting them are different things. The mistakes below are the ones the greeks expose most often, drawn from how the maths actually plays out rather than from any single trader story.

Notice that every one of these mistakes is really a failure to read one greek. The cheap option trap is theta plus low delta. The right but losing trade is vega. The blown up seller is gamma. The surprised buyer is gamma again. The confused multi leg trader is net greeks. There is no separate body of knowledge to learn here: master the four greeks and these errors stop happening to you.

There is also a cost dimension worth flagging. In India, charges nibble at every option trade. Securities Transaction Tax (STT) applies on the sell side of options, and a steeper STT applies if an in the money option is left to expire and gets exercised, which is one more reason to square off rather than carry to settlement. On top of that, an 18 percent GST is levied on brokerage and exchange transaction charges, within the broader market framework regulated by SEBI. These are not greeks, but they sit alongside theta as a steady drag, and a strategy that looks profitable on the greeks alone can turn marginal once costs are counted.

• Buying cheap far out of the money weekly options and holding them, ignoring that low delta plus heavy theta means the premium usually melts before the big move arrives.
• Being right on direction but losing money because of an IV crush, the vega trap, especially around the Budget, RBI policy and company results.
• Selling options for the easy theta while ignoring negative gamma, then giving back months of profit in one sharp expiry day move.
• Treating delta as fixed and being shocked when gamma accelerates gains or losses near the money and near expiry.
• Looking at single leg premiums instead of the net delta, gamma, theta and vega of the whole position.

Putting the Greeks to Work in Your Trading

The greeks are not an exam to pass, they are a lens for every decision a trade requires: what to buy or sell, which strike, which expiry, and when to get out. Start with your view. If you expect a fast, large move, you want positive gamma and you accept negative theta, so you lean toward buying at the money options. If you expect a calm, range bound market, you want positive theta and you accept negative gamma, so you lean toward selling, ideally with defined risk through spreads.

Then match the greek to the time you have. A genuine multi week thesis belongs in monthly options, where theta is gentler and vega has room to work. A sharp intraday or one day expiry view belongs in weeklies, where you are explicitly trading enormous gamma and rapid theta. Mismatching the two, like buying a weekly option for a view that needs a month to play out, is one of the most common and avoidable losses in the market.

Finally, manage the position by its net greeks, not its premium. Decide in advance how much delta exposure you are comfortable carrying, picture how gamma will change it on a move, respect what theta costs you each day you hold, and stay alert to vega around any scheduled event. When a trade no longer has the greek profile you wanted, that is your signal to adjust or exit, regardless of whether the premium is up or down.

A final discipline ties the greeks to position sizing. Because gamma and vega can enlarge a loss faster than the raw premium suggests, size the trade on the worst plausible move, not the comfortable one. Ask how many rupees a sharp 2 percent gap in NIFTY would cost you given your net delta and gamma, and whether your account can absorb it without forcing a panicked exit. The greeks give you the numbers to answer that question before the market asks it of you, which is the whole point of learning them.

The honest closing thought: the greeks describe risk, they do not remove it. They will not tell you which way NIFTY is headed tomorrow. What they will do is let you size, structure and time a trade with open eyes, so that your wins and losses come from your market view and not from a force you did not understand. Practise reading them on First Plan India with virtual money until the four numbers feel as natural as the price itself. This is education, not financial advice, and the goal is simple: to make you a more informed and more deliberate trader.

Frequently asked questions

What are the option greeks in simple terms?

Option greeks are numbers that measure how an option price reacts to change. Delta tracks the move with the underlying, gamma tracks how fast delta changes, theta tracks the value lost each day, and vega tracks sensitivity to implied volatility. Together they explain why a premium moves the way it does.

Which option greek is most important for beginners?

Delta and theta are the two to learn first. Delta tells you your directional exposure and roughly how much you make or lose for a given move, while theta tells you how much time decay costs you every day. Most beginner losses in weekly options come from underestimating theta, so respecting it early saves real money.

Why did my option lose money even though the stock moved in my favour?

The usual reason is vega, the volatility greek. If implied volatility falls after an event like results or an RBI policy, the premium can drop even though the underlying moved your way. This is called an IV crush. Theta, the daily time decay, can also offset a small favourable move.

What is the difference between delta and gamma?

Delta is how much the option price moves for a one point move in the underlying, like speed. Gamma is how much that delta itself changes for a one point move, like acceleration. Gamma is highest for at the money options and near expiry, which is when delta can change very quickly.

How does theta work for option buyers versus sellers in India?

For buyers, theta is negative, so the option loses time value every day, and that decay accelerates into the weekly or monthly expiry. For sellers, theta is positive, so they collect that decaying value daily. This is why option selling is sometimes described as earning rent, though sellers carry the larger gamma risk.

Do option greeks change as expiry approaches?

Yes, sharply. Gamma and theta both spike for at the money options near expiry, so delta swings violently and time value drains fast, which creates the well known expiry day gamma risk. Vega does the opposite and shrinks, because there is less time left for volatility to matter.

Does rho matter for Indian options traders?

Rho, the sensitivity to interest rates, is the least important greek for most Indian retail traders. The weekly and monthly contracts that dominate volume are too short dated for interest rate moves to meaningfully change the premium. It matters more for long dated options, which are uncommon in the Indian retail market.

How do I read the greeks of a multi leg position?

Because greeks are additive, you sum the delta, gamma, theta and vega of every leg to get one net figure for the whole position. For example, a bull call spread reduces your net theta and vega compared with a single long call. Managing those net numbers, rather than each premium separately, is how you control the real risk.