Option Greeks Explained
The Greeks — delta, gamma, theta, vega, and rho — are the five numbers that explain exactly why an option's price moves. Master them and you stop guessing: you know how your trade reacts to price, time, and volatility before you place it. Here's each Greek in plain English, with examples and links to deeper guides.
The Greeks at a glance
| Greek | Measures sensitivity to… | What it tells you |
|---|---|---|
| Delta | $1 move in the stock | Directional exposure + rough probability ITM |
| Gamma | Change in delta | How fast your exposure shifts |
| Theta | Passage of time | Daily time decay (− for buyers, + for sellers) |
| Vega | 1% change in implied volatility | Your exposure to volatility |
| Rho | 1% change in interest rates | Rate sensitivity (matters for LEAPS) |
Delta — directional exposure
Delta is how much the option moves per $1 move in the stock. A 0.50 delta call gains roughly $0.50 when the stock rises $1. It doubles as a rough probability of finishing in the money and as a share-equivalent (0.50 delta ≈ 50 shares of exposure). Most income sellers anchor strike selection on delta.
Deep dive: what is delta in options and how to use delta to pick a strike.
Gamma — how fast delta changes
Gamma is the delta of delta. High gamma means your directional exposure changes quickly as the stock moves — explosive when you're right, brutal when you're wrong. It peaks for at-the-money options near expiration, which is why short-dated ATM trades feel so jumpy.
Deep dive: gamma risk explained and negative gamma positions.
Theta — time decay
Theta is the daily value an option loses just from time passing. A −0.05 theta means about $5 per contract lost per day. Decay accelerates in the final 30 days. Theta is the enemy of buyers and the engine of premium-selling strategies like covered calls and cash-secured puts.
Deep dive: what theta means and the theta decay curve.
Vega — volatility sensitivity
Vega is how much the option price changes per 1-point move in implied volatility. It's why options inflate before earnings and crater after (IV crush). Long options are long vega; selling premium is short vega. Knowing your vega tells you whether a volatility spike helps or hurts you.
Deep dive: what is vega. See also implied vs historical volatility.
Rho — interest rate sensitivity
Rho measures price change per 1% change in interest rates. It's the quietest Greek for most retail traders because rates move slowly, but it matters for long-dated LEAPS where small rate changes compound.
Deep dive: what is rho in options.
Related strategies & tools
Option Greeks FAQ
What are the option Greeks?
The option Greeks are five risk measures that describe how an option's price reacts to different forces: delta (price moves in the underlying), gamma (the rate delta itself changes), theta (time decay), vega (changes in implied volatility), and rho (changes in interest rates). Together they tell you exactly what's driving your option's value and how it will behave as conditions change.
What is delta in options?
Delta measures how much an option's price changes for a $1 move in the underlying stock. A 0.50 delta call gains about $0.50 per $1 the stock rises. Delta also roughly approximates the probability the option finishes in the money, and tells you the directional exposure (a 0.50 delta call behaves like 50 shares).
What is gamma in options?
Gamma measures how fast delta changes as the stock moves. High gamma means your delta — and therefore your directional exposure — shifts quickly, which is great when you're right and painful when you're wrong. Gamma is highest for at-the-money options near expiration, which is why short-dated ATM positions feel so volatile.
What is theta in options?
Theta measures time decay — how much value an option loses each day, all else equal. A theta of −0.05 means the option loses about $5 per contract per day. Theta works against option buyers and for option sellers, and it accelerates as expiration approaches, especially in the final 30 days.
What is vega in options?
Vega measures how much an option's price changes for a 1-point change in implied volatility. A vega of 0.10 means the option gains $10 per contract for each 1% rise in IV. Vega is why options get expensive before earnings (IV rises) and collapse afterward (IV crush). Long options are long vega; short options are short vega.
What is rho in options?
Rho measures sensitivity to interest rates — how much an option's price changes for a 1% change in rates. It's the least important Greek for most retail traders because rates move slowly, but it matters for long-dated options (LEAPS) where small rate changes compound over time.
Which option Greek is most important?
For most traders, delta and theta matter most day to day — delta is your directional bet and theta is your time-decay tailwind or headwind. Vega becomes critical around earnings and volatility events. Gamma matters most for short-dated trades and anyone running delta-neutral strategies. Rho is usually negligible except for LEAPS.
How do I use the Greeks to pick a strike?
Delta is the usual starting point: covered call and cash-secured put sellers often target 0.20–0.35 delta strikes for a balance of premium and assignment probability, while directional buyers pick higher-delta strikes for more share-like exposure. Then sanity-check theta (decay you're paying or collecting) and vega (your volatility exposure) before placing the trade.
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