The Greeks Explained: Delta, Gamma, Theta, Vega, Rho

Every option carries all five Greeks at once. What delta, gamma, theta, vega and rho measure, how they combine, and how to read them on a quote.

By Michael Hewitt, Founder & Editor-in-Chief. Updated September 29, 2026.

You are never exposed to just one Greek. A call bought on a bullish view is also a bet on how fast the stock rises, how soon, and whether implied volatility holds while you wait; any one of those can turn a correct read on direction into a loss. Your broker prints them beside the quote, and only their sum reaches your account.

You Are Never Exposed to Just One

Every option carries all five at once:

• Delta: price change for a $1 move in the stock.
• Gamma: change in delta for that same $1 move.
• Theta: value lost per day to the passage of time.
• Vega: price change for a 1-point move in implied volatility.
• Rho: price change for a 1-point move in interest rates.

Delta: Directional Exposure

Delta ranges from 0 to +1 for calls and 0 to -1 for puts.

• ATM call ≈ 0.50 delta, so it moves $0.50 for every $1 in the stock.
• Deep ITM call → 1.00 delta, so it behaves like 100 shares of stock.
• Deep OTM call → 0.00 delta, so it barely moves when the stock moves.
• Put deltas are negative: ATM put ≈ -0.50.
• Delta also approximates probability of finishing ITM: a 0.30 delta call has roughly a 30% chance of expiring in-the-money.

Gamma: The Rate of Change of Delta

Gamma is highest at-the-money and collapses for deep ITM or OTM options. On at-the-money options it also climbs as expiration nears, which is why 0DTE and weekly options behave so violently.

• Gamma is always positive for long options, always negative for short options.
• Short-dated ATM options have the highest gamma. A 1% move in the stock can flip the option from 40 delta to 60 delta overnight.
• High gamma = large P&L swings, which is good if you're right about direction and painful if you're wrong.
• Long options benefit from convexity: gains accelerate in your favor, losses decelerate.
• Short options suffer negative gamma: losses accelerate against you, which is why selling 0DTE without a stop is catastrophic in tail events.

Theta: Time Decay

Theta is quoted per share per day. It is the rent you pay for controlling 100 shares with a small outlay.

• ATM 30-day option: theta might be -$0.05 per share per day = -$5 per contract per day.
• Theta accelerates as expiration approaches: last week can be -$0.20+ per day.
• Weekends count: Friday's theta decay includes Saturday and Sunday priced in.
• Long options = negative theta (paying time premium). Short options = positive theta (collecting).
• Theta is highest for ATM options because they have the most extrinsic value to decay.

Vega: Volatility Exposure

Options expand and contract with IV, often independently of the stock moving.

• Long ATM 30-day option: vega ≈ $0.10 per 1% IV change per share = $10 per contract per 1% move.
• Vega is highest for ATM and longer-dated options and near zero for deep ITM or OTM options.
• Long options = positive vega (benefit from IV expansion). Short options = negative vega (profit from IV crush).
• Pre-earnings: IV tends to climb into the announcement, lifting option prices.
• Post-earnings IV crush: with vega at $0.10, a 20-point IV drop takes about $2.00 a share ($200 a contract) out of the option before the stock's move counts.

Rho: Interest Rate Sensitivity

Rho matters for LEAPS (1-3 year options) and when rates are changing rapidly.

• Long calls = positive rho. Higher rates slightly raise call prices (cost of carry).
• Long puts = negative rho. Higher rates slightly lower put prices.
• You can usually ignore rho on options under 90 days.

Key Takeaways

• Every option carries all five Greeks at once, so a trade can be right on direction and still lose to theta or vega.
• Delta is directional exposure; gamma, how fast delta changes, peaks on short-dated at-the-money options.
• Short-dated calls bleed theta daily, and IV crush after earnings can erase a correct directional bet.
• Positive-theta strategies (covered calls, credit spreads, iron condors) win from sideways markets; long options need a fast move.