The Fundamentals of Options

Core idea

An option's price has two parts — intrinsic and time

Every option's premium decomposes into exactly two components. Intrinsic value is what the option would be worth if exercised right now: for a call, max(stock − strike, 0); for a put, max(strike − stock, 0). Time value is everything else — the premium the market assigns to the possibility that the option will move further in-the-money before expiration.

At expiration, time value is zero by definition. Intrinsic value is all that remains. Everything you do as an options trader — choosing strikes, timing entries, deciding when to close — is a bet on how those two components will evolve.

Five Greek letters explain almost every price move

Option prices look chaotic until you learn the Greeks. Each Greek isolates one input's effect on the premium, holding everything else constant.

• Delta — how much the option moves per $1 move in the stock (0 to 1 for calls, 0 to −1 for puts). Also the rough probability of finishing in-the-money.
• Gamma — how much delta itself changes per $1 stock move. Largest for at-the-money options near expiration.
• Theta — daily decay in time value. Always negative for long options. Accelerates in the final 30 days.
• Vega — sensitivity to a one-percentage-point change in implied volatility. The same option costs more when the market expects bigger moves.
• Rho — sensitivity to interest rates. Usually small and ignorable for short-dated trades.

Two contract types, four primitive positions

The two contracts (call, put) combine with the two sides (long, short) to produce four primitives: long call, short call, long put, short put. Every strategy in Basic Options Strategies through 7 is a combination of these four positions across different strikes and expirations. Master how each one reacts to the Greeks and the rest of the book follows naturally.

Why it matters

Premium is not price — it's a snapshot of expectations

The premium quoted in an options chain is the market's current consensus on what the contract is worth, given the stock price, days to expiration, implied volatility, dividends, and interest rates. Two traders looking at the same $50 call may disagree about whether $2.30 is cheap or expensive — and the trader who is consistently more right makes money over time. Reading the chain without understanding what each Greek contributes to the $2.30 is trading blind.

Implied volatility is the biggest swing variable

After the stock moves itself, implied volatility (IV) is the second-largest driver of option prices. A long option bought during a calm market and held through an IV spike can gain value even without a stock move. The reverse — buying expensive options before earnings and holding through the "IV crush" that follows the announcement — is one of the most common ways beginners lose money on a "correct" directional call.

Time decay is the silent tax

Theta works against every long option holder, every day, weekends included. A $2.00 option with 30 days left and theta of $0.05 loses $5 per contract per day if nothing else changes. By expiration, an out-of-the-money option is mathematically guaranteed to go to zero. Sellers harvest this decay; buyers pay it. Knowing which side of theta you are on is non-negotiable.

Key takeaways

Mental model

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Practical application

Read the chain in this order

Open an options chain and look at four numbers before placing a trade: strike (in relation to current stock price), bid/ask spread (tighter = more liquid), volume and open interest (avoid contracts trading fewer than ~100 per day), and implied volatility (compare to the stock's historical IV — high IV means you'll pay more for long options and receive more for short ones).

Pick the right Greek for the right thesis

If your thesis is "stock will rise 10% in 30 days," delta matters most. If it's "stock will drift sideways and IV will collapse after earnings," vega and theta dominate. If it's "stock will move ±15% but I don't know which direction," gamma and vega matter and delta should be near zero (a straddle or strangle). Matching the Greek profile to the thesis is the entire job.

Treat OTM options as lottery tickets, not investments

Far out-of-the-money options have low delta, high gamma, and decay quickly. They can multiply many times over on a sharp move but most often expire worthless. Size positions assuming they will go to zero — because most will.

Example

Decomposing a real-looking premium

XYZ trades at $52. The 60-day $50 call is bid at $3.80, ask $4.00. Mid is $3.90.

• Intrinsic value: $52 − $50 = $2.00
• Time value: $3.90 − $2.00 = $1.90
• Delta: about 0.65 (the contract roughly tracks 65 cents per $1 of stock movement)
• Theta: about −$0.04 per day (the option bleeds ~$4 per contract daily if nothing else changes)
• Vega: about $0.08 (a one-point IV rise adds $8 per contract; a one-point fall removes it)

If you buy this contract for $400 ($4.00 ask × 100) and the stock rises $1 to $53 the next day, you would expect roughly: +$0.65 from delta − $0.04 from theta = +$0.61 per share, or +$61 per contract. The new option price is around $4.51. But if IV also drops 2 points (common when uncertainty resolves), you lose another 2 × $0.08 = $0.16, leaving the option near $4.35 — a $35 gain on a $1 favorable move. Without understanding the Greeks, the "$1 up but option barely moved" outcome feels like a broken market. It isn't — it's vega doing what vega does.

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