Lesson film
Watch this lesson as a short film
Four dials — delta, theta, vega, gamma — and which ones work for a seller.
What you'll learn
- Read delta as both direction and a rough probability of finishing ITM
- Explain theta, vega and gamma from the seller's point of view
- Know which Greeks help you and which to respect
The Greeks sound scary but they are just gauges on a dashboard. Each one tells you how an option's price reacts to one specific thing changing: the stock price, time, volatility, or the speed of change. You do not need calculus — you need intuition, and from the seller's seat it is surprisingly simple.
Delta — direction and a probability clue
Delta does double duty. First, it tells you roughly how much the option's price moves when the stock moves one dollar. Second — the part wheel traders love — its absolute value is a rough estimate of the probability the option finishes in-the-money. A put with a 0.25 delta has roughly a 25 percent chance of ending ITM, which means about a 75 percent chance you keep the premium free and clear.
Make a guess
You sell a put showing a delta of −0.22. Roughly what is the chance it expires worthless?
Theta — your daily paycheck
Theta is the time decay we met earlier: how much value the option sheds each day just from the calendar advancing. As a seller you are short the option, so positive decay is income. Theta is the Greek working hardest for you.
Vega — sensitivity to fear and calm
Vega measures how much the option's price moves when implied volatility changes. High volatility inflates premiums; calming volatility deflates them. As a seller you generally want to sell when volatility is high (rich premium) and benefit as it falls back — falling volatility shrinks the option you are short, which is good for you.
Gamma — how fast delta moves
Gamma is the accelerator. It tells you how quickly delta itself changes as the stock moves. Gamma is small when expiration is far away and grows sharply in the final days, especially near the strike. That is why a short option that is calm one week can suddenly swing wildly right before expiration — high gamma magnifies every move.
Fig. 1Interactive
Delta
Direction + prob
rough chance of finishing ITM
Theta
Your friend
daily decay you collect
Vega
Sell high vol
falling vol helps a seller
Gamma
Respect it
spikes near expiration
What would you do?
Your call
Your short SOFI 22 put has 4 days left. SOFI sits at 22.30, right on the strike. You sold it for 0.80 and it's now worth 0.25 — most of the premium is already yours.
Key takeaways
- Delta is both directional sensitivity and a rough probability of finishing ITM — a 0.30-delta put has about a 70 percent chance of expiring worthless.
- Theta (time decay) is the seller's daily income; vega means sellers prefer to sell when volatility is high.
- Gamma accelerates delta and spikes near expiration, which is when short positions can move fastest against you.
Checkpoint
Knowledge check
Answer to lock in what you just learned.
You sell a put with a delta of about 0.30. Roughly what is the chance it expires worthless (good for you)?
From a seller's point of view, which Greek is most directly your daily income?
Why do many wheel traders close or roll a short option before its final week?
Keep going
7 more chapters, from your first put to an expert playbook
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Educational content only — not financial advice. Options involve risk of loss and are not suitable for every investor.