How Options Pricing Works
Every option premium has three components: intrinsic value, time value, and implied volatility. Understanding how each contributes — and how they interact with theta decay — is the difference between knowing you can buy an option and knowing whether it is actually worth buying.
Intrinsic Value and Time Value
Every option premium can be decomposed into exactly two components: intrinsic value and time value. Understanding this decomposition is the foundation of options pricing, because it tells you what you are actually paying for when you buy an option contract.
Intrinsic value is the immediate exercise value — the amount of money you would receive if you exercised the option right now. For a call, it is the stock price minus the strike price (if positive; zero if negative). For a put, it is the strike price minus the stock price (if positive; zero otherwise). Only in-the-money options have intrinsic value. An out-of-the-money option has zero intrinsic value by definition — exercising it would make no economic sense.
Time value is everything else in the premium beyond intrinsic value. It represents the market's assessment of how much the option might be worth in the future — the probability-weighted expectation that the option will become more in-the-money before expiry. An at-the-money Apple call might cost $5 even though it has zero intrinsic value (because it is exactly at the money). That entire $5 is time value: you are paying for the chance that Apple will rise above the strike before expiry. Time value is highest for at-the-money options, decreases as options move deeper in-the-money or further out-of-the-money, and always decays to zero at expiry.
Example: Stock at $150, call option with $145 strike priced at $9.
Intrinsic value = $150 − $145 = $5
Time value = $9 − $5 = $4
You are paying $4 for the possibility that the stock moves above $145 even further before expiry. If you are paying more time value than the stock is likely to move, the option is overpriced — this is the insight that volatility analysis provides.
A critical implication of this decomposition: if you buy a deep in-the-money option, you are mostly paying intrinsic value. An AAPL call with a $100 strike when the stock trades at $185 costs roughly $85 in intrinsic value plus a small amount of time value. This behaves much more like owning shares than a typical option — if Apple rises $5, the call rises approximately $5 too. Conversely, if you buy a far out-of-the-money option, you are paying pure time value: if the stock does not move substantially, this time value erodes to nothing. Neither extreme is inherently wrong — they serve different purposes — but understanding what you are buying prevents surprises when the market moves against you.
The Black-Scholes model (1973), developed by economists Fischer Black and Myron Scholes (and Robert Merton, who expanded it), formalised the mathematical relationship between these components. The model uses five inputs — current stock price, strike price, time to expiry, risk-free rate, and volatility — to calculate a theoretical "fair value" for an option. While the original model has known limitations (it assumes constant volatility and log-normal stock returns, neither of which perfectly describes reality), it remains the conceptual foundation for all options pricing and the risk-management framework that modern options desks use. Myron Scholes and Robert Merton received the Nobel Prize in Economics in 1997 for this work; Fischer Black died in 1995 before the prize was awarded.
Apple stock is trading at $185. You hold a call option with a $180 strike price. The option is priced at $9. How much of that $9 is intrinsic value and how much is time value?
Theta Decay: Time Working Against Buyers
Theta is the Greek letter used to measure the rate at which an option loses time value per day from the passage of time alone, all else being equal. A theta of −$0.05 means the option loses $0.05 per share (or $5 per contract) each day purely from time passing. Theta is always negative for option buyers (time decay erodes their premium) and positive for option sellers (they benefit from the decay of the premium they received).
The critical characteristic of theta is that it is not linear — it accelerates as expiry approaches. This non-linearity follows a convex curve: an option with 90 days to expiry loses time value slowly day by day; the same option with 7 days remaining loses proportionally far more each day. The practical consequence is stark: if you buy an out-of-the-money option and the stock does not move for 3 weeks, you have not lost a predictable fraction of your premium — you have lost a disproportionately large fraction because theta has been accelerating the entire time.
The diagram above shows a typical time value decay curve for an at-the-money option. Notice how the curve is relatively flat in the 60–90 day range, then begins steepening around 30 days, and accelerates sharply in the final 2 weeks. The "rapid decay" zone in the last 14 days is where theta reaches its peak — an ATM option with 7 days remaining might lose 20–30% of its remaining value in a single day of flat trading. This is why experienced traders avoid buying very short-dated options unless they have a specific catalyst (earnings, FDA decision, merger announcement) expected within that window.
Options sellers — those who write calls or puts and receive the premium — are naturally long theta: they want the option to decay. This is the fundamental business model of many professional options strategies. A covered call writer selling a 30-day ATM call against their stock position collects the time value premium upfront and profits if the stock stays flat or moves modestly — the time decay works in their favour every single day. A cash-secured put seller selling a put on a stock they want to buy at a lower price collects premium that decays toward zero if the stock stays above the strike.
A common intermediate options strategy specifically designed to capitalise on theta decay is the iron condor: selling both an out-of-the-money call and an out-of-the-money put, while buying further OTM options for protection. The trade profits if the stock remains within a range — the entire premium collected from selling both options decays to zero as long as the stock doesn't move too far. This strategy is "short volatility" and "long theta": it benefits from stability and time passage. The iron condor was popularised by tastytrade (formerly tastyworks) and has become one of the most common retail premium-selling strategies.
Implied Volatility: The Hidden Price Driver
Implied volatility (IV) is arguably the most important pricing variable in options after the direction of the stock move. It is the market's forward-looking estimate of how much the stock will move — expressed as an annualised percentage — derived by working backwards from the current market price of an option. If you see two identical options (same strike, same expiry, same stock price) priced at $2 and $6, the difference is entirely explained by implied volatility: the $6 option is on a more volatile stock or during a period of higher market uncertainty.
The CBOE Volatility Index (VIX), launched in 1993, measures the implied volatility of 30-day S&P 500 options. A VIX reading of 20 means the market is pricing in approximately 20% annualised volatility for the S&P 500 over the next 30 days — roughly ±1.25% per day. VIX typically trades between 12 and 25 in calm markets; it has spiked above 40 during major crises (the 2008 financial crisis, the March 2020 COVID crash — where it hit 82.69 on March 16, 2020, its highest ever reading). These spikes reflect genuine market fear and uncertainty, which dramatically increases the cost of options.
The most consequential practical implication of implied volatility for retail traders is the "IV crush" phenomenon. Before high-uncertainty events — quarterly earnings announcements, FDA drug approval decisions, major central bank meetings — implied volatility rises substantially as the market prices in the possibility of a large move. After the event, regardless of the outcome, uncertainty resolves and IV collapses back to its baseline. This IV collapse destroys time value rapidly, which can make options lose money even when the underlying move is directionally correct.
This is why simply buying options before earnings is a poor strategy without understanding IV. The "right" level of implied volatility — whether it is cheap or expensive relative to how much the stock typically moves — is captured by comparing IV to historical volatility (HV). If a stock typically moves ±5% per quarter on earnings but the options are pricing in ±12% (high IV), the options are expensive and selling them (collecting the inflated premium) may be statistically superior to buying them. Conversely, when IV is below historical volatility, options are cheap and buying may be advantageous.
Professional options traders often think of their position not primarily in terms of direction (will the stock go up or down?) but in terms of volatility (will the stock move more or less than what is priced in?). This is what it means to "trade vol" rather than trade direction. A delta-neutral straddle — buying both a call and a put at the same strike — profits if the stock makes a large move in either direction and loses if the stock stays flat. The entire bet is on whether realised volatility will exceed implied volatility. Most retail traders never reach this level of sophisticated vol analysis, but understanding that implied volatility inflates and deflates independently of the stock price is essential to avoid the most common options mistakes.
The VIX index (CBOE Volatility Index) spikes from 15 to 35 during a market selloff. What happens to the price of SPY put options with 30 days to expiry?