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L.3 · BEGINNER · 3 MIN

The Greeks: Delta and Theta

The Greeks are sensitivity measures that tell you how an option’s price will change in response to different market conditions. Delta and Theta are the two most important for beginners.

Quiz · 5 questions ↓
§ 01
AAPL — Current Price, Today's Change. Open AAPL on the Ledge to see current values.
§ 02
GreekMeasuresRangeKey Insight
Delta (Δ)Price change per $1 stock move0 to 1 (calls), −1 to 0 (puts)Also approximates probability of expiring ITM
Theta (Θ)Daily time decayAlways negative for buyersAccelerates as expiration approaches
§ 03
Expected Option Move = Delta × Stock Move
§ 04

A delta of 0.50 means two things: the option moves ~$0.50 per $1 stock move, AND there’s roughly a 50% chance it expires in-the-money. Deep ITM options have delta near 1.0; far OTM options have delta near 0.

§ 05
Look at an options chain and compare the delta of ITM, ATM, and OTM options. Notice how delta increases as the option moves deeper in-the-money.
§ 06
You own a call with delta 0.70 and theta −0.08. The stock doesn’t move for a week. What happens to your position?
§ 07

Option buyers fight theta every day. Option sellers collect theta every day. This asymmetry is why ~80% of options expire worthless and why understanding time decay is essential before buying any option.

§ 08
You buy a deep-out-of-the-money call (AAPL $250 when AAPL is at $200) expiring in 5 days. Delta is 0.05. AAPL moves +$5 over the 5 days. What happens to the option's value?
Five questions · AI feedback

Sit with the ideas.

You own a call option with delta 0.40 and theta -$0.05. The stock rises $2 and one day passes. Approximately what happens to your option's value?

Why:
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