What an option contract actually is

An option is a contract that gives you the right—but not the obligation—to buy or sell a stock at a set price on or before a specific date. You pay a small upfront cost called a premium to own that right. The person on the other side of the contract collects that premium and takes on the obligation to buy or sell if you decide to exercise your right.

Think of it like paying for the right to make a decision later. If the stock moves in your favor, you use that right. If it doesn't, you walk away and lose only the premium you paid. The stock owner or seller you're contracting with has to follow through if you choose to exercise.

Options are standardized contracts. One contract always represents 100 shares of the underlying stock. If you buy one call option contract, you have the right to buy 100 shares at the strike price. The expiration date is set when you buy—typically anywhere from days to months away.

Key Takeaways

  • A call option gives you the right to buy a stock at a set price; a put option gives you the right to sell a stock at a set price.
  • You pay a premium upfront to buy an option, and that premium is the most you can lose if the trade goes against you.
  • The strike price is the set price at which you can buy (call) or sell (put) the stock if you exercise your right.
  • Options expire on a specific date, and after that date the contract is worthless if you haven't exercised it.
  • The person selling you the option collects the premium and must fulfill the contract if you exercise your right.

Calls: the right to buy at a set price

A call option gives you the right to buy 100 shares of a stock at a fixed price (the strike price) before the expiration date. You buy a call when you think the stock price will rise. If it does, you can buy the shares at the lower strike price and either sell them immediately for a profit or hold them.

Here's a concrete example: You buy one call option on XYZ stock with a strike price of $50 and an expiration date two months away. You pay $2 per share, or $200 total for the contract (100 shares × $2). If XYZ rises to $65 before expiration, you can exercise your right to buy 100 shares at $50 each. You immediately sell them at $65, pocketing $15 per share, or $1,500, minus the $200 premium you paid—a $1,300 gain.

If XYZ never rises above $50, or rises only to $52, you simply don't exercise. Your loss is limited to the $200 premium you paid. The call seller keeps that premium as profit.

Puts: the right to sell at a set price

A put option gives you the right to sell 100 shares of a stock at a fixed price (the strike price) before expiration. You buy a put when you think the stock price will fall. If it does, you can sell the shares at the higher strike price, locking in a profit even if you own the shares at a lower cost.

Example: You buy one put option on ABC stock with a strike price of $40 and expiration in one month. You pay $1 per share, or $100 total. If ABC drops to $30, you can exercise your right to sell 100 shares at $40 each. If you own the shares, you sell them at $40 instead of the current market price of $30, keeping an extra $10 per share. If you don't own the shares, you can buy them at $30 and immediately sell them at $40 for a $10 per share profit, minus your $100 premium.

If ABC stays above $40 or falls only slightly, you don't exercise. Your loss is capped at the $100 premium you paid.

Strike price and expiration: the two numbers that matter

The strike price is the fixed price at which you can buy (call) or sell (put) the stock. It doesn't change. If you buy a call with a $50 strike, that price stays $50 until expiration, even if the stock soars to $100.

The expiration date is the last day you can exercise your right. After that date, the contract is worthless. Most stock options expire on the third Friday of the month. Some expire weekly. Once you know the expiration date when you buy, it doesn't change.

These two numbers determine whether an option has value. A call is valuable when the stock price is above the strike price (you can buy low and sell high). A put is valuable when the stock price is below the strike price (you can sell high and buy low). The further the stock price moves in your favor, and the more time left until expiration, the more the option is worth.

Premium: what you pay and what you can lose

The premium is the price you pay to buy an option contract. It's quoted per share, so you multiply by 100 to get the total cost. If a call option has a premium of $3, you pay $300 for one contract.

The premium reflects the probability that the option will be profitable by expiration. An option with a strike price close to the current stock price costs more than one far away from it. An option expiring in six months costs more than one expiring in one week, because there's more time for the stock to move in your favor.

The premium is also the maximum you can lose. If you buy a call for $300 and the stock never rises above the strike price, you lose $300. You cannot lose more than that. The person who sold you the option keeps the $300 as profit.

In-the-money, out-of-the-money, and at-the-money

These terms describe the relationship between the current stock price and the strike price. A call is in-the-money when the stock price is above the strike price—it has intrinsic value right now. A call is out-of-the-money when the stock price is below the strike price—it has no intrinsic value, only time value. A call is at-the-money when the stock price equals the strike price.

For puts, it's reversed. A put is in-the-money when the stock price is below the strike price. A put is out-of-the-money when the stock price is above the strike price.

An in-the-money option is worth more because it has immediate value. An out-of-the-money option is cheaper but requires the stock to move further in your favor before you profit. Most traders buy out-of-the-money options because they cost less, but they also fail more often.

How the option seller's side works

When you buy an option, someone sells it to you. The seller (also called the writer) collects the premium upfront. If you never exercise, the seller keeps the premium as profit and the contract expires worthless.

If you do exercise, the seller must fulfill the contract. If you exercise a call, the seller must sell you 100 shares at the strike price, even if the stock is worth much more. If you exercise a put, the seller must buy 100 shares from you at the strike price, even if the stock is worth much less. The seller's profit or loss depends on whether they own the shares or have to buy them at market price.

Selling options is how some traders generate income from stocks they own or are willing to own. It's also riskier than buying options because the seller's loss can be large if the stock moves sharply against them.

Frequently Asked Questions

Do I have to exercise an option if it's profitable?

No. You can sell the option contract itself to another trader before expiration instead of exercising it. If the option has gained value, you pocket the difference between what you paid and what you sold it for. Most traders close options this way rather than exercising them.

What happens if I don't exercise before expiration?

The contract expires worthless and you lose the premium you paid. The right to buy or sell disappears. Some brokers will automatically exercise in-the-money options on your behalf, but you should check your broker's policy and set reminders before expiration dates.

Can I lose more than the premium I paid?

No, not if you only buy options. Your maximum loss is the premium. If you sell options, your loss can be much larger because you're on the hook if the stock moves sharply against you.

Why would someone sell an option if they might lose money?

Sellers collect the premium upfront, which is profit if the stock doesn't move far enough to make the option valuable. Many sellers own the stock already and use options to generate extra income. Others are betting the stock won't move much and are willing to take that risk for the premium.

How do I know what premium to expect?

Your broker's trading platform shows the current bid and ask prices for every option contract. The bid is what buyers will pay; the ask is what sellers want. The difference between them is the spread. Premiums change constantly as the stock price moves and expiration approaches.