Option Premium
Explained
Premium is the price of an option — what you pay as a buyer, what you collect as a seller. Understanding what drives it separates informed traders from those who are simply guessing.
What exactly is option premium?
When you buy an option — a call or a put — you pay the seller a price called the premium. It is quoted per unit of the underlying, and the actual cash exchanged is premium × lot size. For NIFTY (lot size 75), a premium of ₹120 means you pay 120 × 75 = ₹9,000 for one lot.
For the seller, this premium is income received upfront. For the buyer, it is the maximum amount they can lose on the trade. Premium is not a deposit — it is the price of the rights the contract grants.
Premium is not static. It moves every second the market is open, driven by five forces: the underlying's spot price, the strike price chosen, time to expiry, implied volatility, and risk-free interest rates. Understanding each of these is the key to reading whether an option is cheap or expensive.
The two components: intrinsic value and time value
Every option premium can be split into two parts:
- Intrinsic value — the amount by which the option is already profitable if exercised right now. For a call: max(0, spot − strike). For a put: max(0, strike − spot). An option that is out-of-the-money or at-the-money has zero intrinsic value. See glossary: intrinsic value.
- Time value (extrinsic value) — everything in the premium above intrinsic value. It is the price of possibility: the chance that the underlying will move further in the buyer's favour before expiry. At expiry, time value is exactly zero — the option is worth only what it is intrinsically worth at that moment. See glossary: time value.
Premium = Intrinsic Value + Time Value. For an at-the-money option, intrinsic value is zero, so premium equals pure time value. This is why ATM options are the most sensitive to volatility and to the passage of time.
The five drivers of premium
Option pricing models (Black-Scholes is the most widely referenced, though actual market prices reflect supply and demand) identify five inputs that determine premium:
- Spot price vs strike price (moneyness) — as the underlying moves closer to and through the strike, premium increases for the in-the-money side and falls for the out-of-the-money side. The sensitivity here is captured by delta. See ITM, ATM, OTM Explained.
- Time to expiry — more time = more premium, all else equal. A NIFTY call expiring in 30 days will carry more time value than the same call expiring in 3 days. The rate of time value erosion is measured by theta.
- Implied volatility (IV) — the single most impactful driver after moneyness. Higher IV inflates all option premiums because a wider expected price range means a better chance of the option finishing in-the-money. The sensitivity of premium to IV is measured by vega. See What is Implied Volatility?
- Interest rates — higher rates marginally increase call premiums and decrease put premiums, all else equal. For short-dated weekly options, the effect of interest rates (measured by rho) is minimal.
- Dividends — for individual stock options, an upcoming ex-dividend date reduces call premium and increases put premium, since the stock price is expected to fall by the dividend amount on the ex-date. This is less relevant for index options.
Time decay: the invisible cost of holding options
Theta — daily time decay — is often called the options buyer's silent enemy and the options seller's best friend. Every day that passes without a favourable move in the underlying, the option loses some of its time value. This loss is not linear: it accelerates as expiry approaches.
For NIFTY weekly options, the last two trading days before Thursday expiry can see dramatic theta. An ATM option that was worth ₹100 on Monday might fall to ₹40–₹60 by Wednesday even if NIFTY barely moves, simply from time erosion.
This is why buyers of weekly options need a strong, timely directional move to profit, while sellers of weekly options specifically target this time decay window. See Options Terminology for how theta fits into the broader Greek framework.
How implied volatility inflates or deflates premium
Imagine India VIX (the market's volatility gauge) jumping from 13 to 20 before a major economic announcement. All NIFTY option premiums will expand — even for strikes that have not moved relative to spot. A NIFTY ATM call that was ₹100 on a calm day could be ₹160 on a high-IV day, with no change in the underlying's price.
This matters profoundly for buyers: if you buy an option when IV is high and the underlying moves in your favour but IV then collapses (an IV crush), you might still lose money because the premium deflation outweighs your delta gain. This is why experienced traders always check IV levels before buying options. See IV Crush Events.
Conversely, selling options when IV is high collects richer premiums — and if IV falls after the event, the bought-back option is cheaper, locking in a gain even without a favourable direction move. Track live IV on TradePulse's IV dashboard.
A worked NIFTY example
Suppose NIFTY spot is 22,500 (hypothetical). Consider two call options:
- 22,400 call (ITM by 100 points) — intrinsic value = ₹100. If premium is ₹150, time value = ₹50. Total: 150 × 75 = ₹11,250 for one lot.
- 22,600 call (OTM by 100 points) — intrinsic value = ₹0. If premium is ₹70, entire ₹70 is time value. Total: 70 × 75 = ₹5,250 for one lot.
The ITM call costs more but carries intrinsic value — it is already partly "earned." The OTM call is cheaper but loses its entire premium if NIFTY stays below 22,600 at expiry. Neither is objectively "better" — the choice depends on your view, risk tolerance, and how much time you have. This is why strike selection is a discipline of its own.
Now suppose IV spikes 3% the next morning. The OTM call's vega might be ₹8, so its premium rises by 3 × ₹8 = ₹24, making it worth roughly ₹94 — a 34% gain in premium without NIFTY moving at all.
What option sellers must understand about premium
When you sell an option, you receive the premium immediately. Your P&L as a seller is the mirror image of the buyer's: you profit as long as the option's value stays below what you sold it for. You benefit from theta (time passing) and from IV falling. You are hurt by a large move in the underlying or a sharp rise in IV.
The asymmetry is important: as a seller, your maximum gain is the premium collected. Your loss, in theory, is much larger — especially for naked call or put selling. This is why margin requirements for option sellers are substantial and calculated via SEBI's SPAN framework. Never think of the premium you collected as "guaranteed income" until the option expires. See Options Selling Risks.
Common mistakes around premium
- Buying a cheap OTM option thinking the low rupee cost means low risk — the probability of profit may be very low and theta destroys it quickly.
- Ignoring IV when buying — paying ₹150 for an option when fair value at normal IV is ₹80 means you need a much bigger move to break even.
- Not accounting for the bid-ask spread — the quoted premium might be ₹90 bid / ₹95 ask; you pay ₹95 and can only exit at ₹90, a built-in ₹375 loss per lot on entry and exit.
- Assuming premium equals maximum profit for sellers — the actual risk is the difference between the strike and the underlying's eventual move, which can far exceed premium received.
Frequently asked questions
What is option premium?
Option premium is the price paid by the buyer to the seller for the rights conveyed by the options contract. It is quoted per unit of the underlying; the actual cash outlay is premium multiplied by lot size. Premium is made up of intrinsic value (the amount the option is already in-the-money) and time value (the remainder, reflecting probability and time to expiry).
Why does an option lose value over time even if the underlying does not move?
Options have an expiry date. Each passing day reduces the time available for the underlying to move in the buyer's favour, so the probability of that happening falls. This reduction in time value is called theta decay. It accelerates as expiry approaches, becoming most severe in the last few days before expiry.
How does implied volatility affect option premium?
Implied volatility (IV) represents the market's expectation of future price movement. Higher IV makes options more valuable because there is a greater chance of a large favourable move. When IV rises, all option premiums expand; when IV falls (IV crush), premiums shrink — which is why buying options before high-IV events can be expensive even if you are directionally correct.
What is the difference between an option's premium and its intrinsic value?
Intrinsic value is the amount an option is in-the-money right now. At-the-money and out-of-the-money options have zero intrinsic value. Premium is always equal to or greater than intrinsic value; the difference is time value. At expiry, time value falls to zero and premium equals intrinsic value alone.
Track live premiums and IV on TradePulse
See real-time NIFTY and Bank Nifty option premiums, implied volatility, and Greeks — with AI commentary explaining what is driving them.