Deep Dive · Lesson 3
Strike Price and
Expiration Date
Big Idea
Every option has two very important details: the strike price and the expiration date.
- Strike price = the set price (the price at which the option buyer has the right to buy or sell)
- Expiration date = the deadline (when the option contract ends)
These two details help determine whether an option is useful, valuable, or worthless.
Why These Two Terms Matter
An option is not open-ended. The contract has specific terms: what asset, call or put, strike price, expiration date, premium. Without the strike price and expiration date, the option would be incomplete — they are part of the contract's skeleton.
Strike Price
What Is the Strike Price?
For a call, the strike price is the price at which the buyer has the right to buy the underlying asset. For a put, the strike price is the price at which the buyer has the right to sell.
Call Example
Acme shares trade at $50. You buy a call with a strike price of $55. If Acme later rises to $70, the right to buy at $55 is valuable — because the market price is $70.
Put Example
Acme shares trade at $50. You buy a put with a strike price of $45. If Acme later falls to $30, the right to sell at $45 is valuable — because the market price is only $30.
Important: The strike price is not a prediction. It is a contract term — a fixed reference point written into the option contract.
Expiration Date
What Is the Expiration Date?
The expiration date is the deadline for the option contract. After this date, the option no longer exists. If the option has no value at expiration, it expires worthless and the buyer loses the premium paid.
Expiration Example
You hold a call on Acme with the right to buy at $50, expiring July 19. If Acme rises above $50 before expiration, the option may be useful. If Acme stays below $50, the option may expire worthless. The clock is always ticking.
How They Work Together
Strike Price and Expiration Work Together
Same Strike, Different Expiration
Two options can share the same strike price but have very different expirations — and therefore different premiums.
| Option | Strike | Expiration | Time |
|---|---|---|---|
| Option A | $55 | This Friday | Very little time |
| Option B | $55 | 6 months from now | Much more time — usually costs more |
More time usually means a higher premium. Option B has more time for the stock to move in a favorable direction.
Same Expiration, Different Strike Prices
Three call options on Acme (trading at $50) all expire on the same date but have different strike prices — and therefore different premiums.
| Option | Strike | Expiration |
|---|---|---|
| Call A | $45 | Same date |
| Call B | $50 | Same date |
| Call C | $55 | Same date |
Different strikes lead to different premiums, even when the expiration date is the same.
Simple Ways to Think About It
Calls and Puts Relative to the Strike
Call
You want the stock to rise above the strike.
$50 strike call: useful if stock at $60, not useful if stock at $40.
Put
You want the stock to fall below the strike.
$50 strike put: useful if stock at $40, not useful if stock at $60.
Interactive Checks
Check 1 of 5
Acme shares are trading at $50. You buy a call option with a strike price of $55.
What does the $55 strike price mean?
Check 2 of 5
Acme shares are trading at $50. You buy a put option with a strike price of $45.
What does the $45 strike price mean?
Check 3 of 5
You buy an option expiring July 19.
What does the expiration date mean?
Check 4 of 5
You hold a call option with a $50 strike. At expiration, the stock is at $40.
Is the right to buy at $50 useful?
Check 5 of 5
You hold a put option with a $50 strike. At expiration, the stock is at $40.
Is the right to sell at $50 useful?
Common Beginner Mistakes
- ❌ Thinking the strike price is a prediction. The strike price is a contract term, not a forecast of where the stock will go.
- ❌ Forgetting the expiration date. Even if your idea is right, the option can expire before the move happens. Timing matters.
- ❌ Looking only at the strike price. The expiration date, premium, stock price, volatility, and time remaining all matter too. An option is a small machine with several gears.
Quick Memory Tool
- Strike price = the set price
- Expiration date = the deadline
- For calls, the strike price is the price where the buyer can buy.
- For puts, the strike price is the price where the buyer can sell.
- The expiration date tells you how long the option lasts.
- "A good options learner always asks two questions: At what price? By what date?"
Next Lesson
Premium and intrinsic value — The premium is what the option costs. Intrinsic value helps explain whether the option already has real value.