What an option actually is

An option is a contract that gives you the right — but not the obligation — to buy or sell a specific stock at a set price on or before a certain date. You pay a fee upfront, called the premium, for that right. The person on the other side of the contract collects that premium and agrees to sell you the stock (if you buy a call option) or buy it from you (if you buy a put option) at the agreed price, called the strike price.

Options are traded on exchanges like the Chicago Board Options Exchange (CBOE). Unlike buying a stock outright, you do not own the underlying company — you own a contract with an expiration date. That date matters because your right to buy or sell expires, and after that date the contract is worthless.

The two main types are call options (the right to buy) and put options (the right to sell). A call option makes money if the stock price rises above the strike price plus the premium you paid. A put option makes money if the stock price falls below the strike price minus the premium you paid.

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 own the option contract, and that premium is money you lose if the stock does not move in your favor.
  • Options expire on a specific date, and after that date the contract has no value and cannot be exercised.
  • The strike price is the price at which you can buy (call) or sell (put) the stock if you choose to exercise the option.
  • Most options traders close their position by selling the contract back before expiration rather than actually buying or selling the stock.

Call options: the right to buy

When you buy a call option, you are paying for the right to buy 100 shares of a stock at the strike price anytime before the expiration date. If you buy a call option on Apple stock with a strike price of $150 and pay a $5 premium per share, you have paid $500 total ($5 × 100 shares) for the right to buy 100 Apple shares at $150 each.

If Apple stock rises to $160 before expiration, your option is now worth at least $10 per share ($160 market price minus $150 strike price), so the contract itself is worth $1,000 or more. You can sell that contract back to another trader for a profit, or you can exercise it and actually buy the 100 shares at $150 and immediately sell them at $160. Most traders close the position by selling the contract rather than taking ownership of the stock.

If Apple stock stays at $150 or falls, your option loses value. If it stays at $150, the option is worthless at expiration because there is no advantage to buying at $150 when you can buy on the open market at $150. You lose the $500 premium you paid. If it falls to $140, the option is still worthless — you would never exercise the right to buy at $150 when the market price is $140.

Put options: the right to sell

When you buy a put option, you are paying for the right to sell 100 shares of a stock at the strike price anytime before expiration. If you buy a put option on Apple stock with a strike price of $150 and pay a $5 premium per share, you have paid $500 for the right to sell 100 Apple shares at $150 each.

If Apple stock falls to $140 before expiration, your put option is now worth at least $10 per share ($150 strike price minus $140 market price). You can sell the contract back for a profit, or you can exercise it by buying 100 shares at $140 on the open market and selling them to the option seller at $150, pocketing the $10 difference per share. Again, most traders close the position by selling the contract.

If Apple stock rises or stays flat, the put option loses value. If it rises to $160, the option is worthless because there is no reason to sell at $150 when the market price is $160. You lose the $500 premium you paid.

Expiration dates and time decay

Every option has an expiration date, usually the third Friday of the month for standard monthly options. After that date, the contract ceases to exist and cannot be exercised. If you own an option that is out of the money (meaning it would lose money if exercised), it will expire worthless and you lose your entire premium.

Options lose value as the expiration date approaches, a process called time decay. Even if the stock price does not move, an option contract becomes less valuable each day because there is less time for the stock to move in your favor. This works against option buyers and in favor of option sellers. A call option worth $5 per share with 60 days until expiration might be worth only $2 per share with 10 days until expiration, even if the stock price has not changed.

You can close your position anytime before expiration by selling the contract back on the exchange. You do not have to hold it until the expiration date.

How the premium is set

The premium — the price you pay for an option contract — is determined by supply and demand on the options exchange, but several factors influence what traders are willing to pay. The distance between the current stock price and the strike price matters: an option that is closer to being profitable (in the money) costs more than one that is far from profitable (out of the money).

The time until expiration also matters. An option with 60 days until expiration is worth more than the same option with 10 days until expiration, because there is more time for the stock to move in your favor. Volatility — how much the stock price swings up and down — also affects the premium. A stock that moves 5% per day is riskier and more likely to reach a profitable price, so options on volatile stocks cost more than options on stable stocks.

You do not negotiate the premium; you accept the market price or you do not trade. Different strike prices on the same stock have different premiums, and different expiration dates have different premiums. Traders choose the combination that matches their outlook and risk tolerance.

Buying versus selling options

When you buy an option, you pay the premium upfront and your maximum loss is that premium. Your profit potential is theoretically unlimited (for calls) or large (for puts). You need the stock to move significantly in your favor to make money, because the stock has to move enough to cover the premium you paid plus generate a profit.

When you sell an option (also called writing an option), you collect the premium upfront and that is your maximum profit. Your loss potential can be large or unlimited depending on the type of option. Selling a call option on a stock you do not own (a naked call) has theoretically unlimited loss potential if the stock price rises sharply. Selling a put option means you are agreeing to buy the stock at the strike price if the option is exercised, so your loss is limited to the strike price minus the premium you collected.

Most beginning traders buy options rather than sell them, because the risk is defined and limited to the premium paid. Selling options requires more capital and carries larger potential losses.

What happens at expiration

If you own an option that is in the money (profitable) at expiration, most brokers will automatically exercise it for you — they will buy the stock (for a call) or sell the stock (for a put) at the strike price. If you own a call option on Apple with a strike price of $150 and Apple closes at $160 on expiration day, your broker will buy 100 shares at $150 and you will own them. You can then sell them immediately or hold them.

If you own an option that is out of the money (unprofitable) at expiration, it expires worthless and you lose your premium. If you own a call with a strike price of $150 and Apple closes at $140, the option has no value and disappears.

If you do not want automatic exercise — for example, because you do not have the cash to buy 100 shares — you must close the position by selling the option contract before expiration. Most traders do this anyway, because selling the contract lets you lock in a profit or cut a loss without taking ownership of the stock.

Frequently Asked Questions

Can I lose more money than I paid for the option?

If you buy an option, no — your maximum loss is the premium you paid. If you sell an option, yes — your loss can be much larger than the premium you collected. Selling a naked call (a call option on a stock you do not own) has unlimited loss potential if the stock price rises sharply.

Do I have to own the stock to buy a call option?

No. Buying a call option is a bet that the stock price will rise; you do not need to own the stock. If the option is profitable at expiration and your broker exercises it, you will own the stock briefly, but you can sell it immediately.

What does "in the money" mean?

A call option is in the money when the stock price is above the strike price. A put option is in the money when the stock price is below the strike price. In the money means the option would be profitable if exercised right now, though you still need to account for the premium you paid.

Can I sell an option I bought before expiration?

Yes. You can close your position anytime during market hours by selling the contract back on the exchange. Most traders do this rather than holding until expiration, because it lets you lock in a profit or cut a loss without waiting for expiration day.

What if the stock splits after I buy an option?

The option contract adjusts automatically. If you own a call option on a stock that splits 2-for-1, your strike price is halved and your contract now covers 200 shares instead of 100. The total value of your position remains the same, but the per-share numbers change.