Options trading is a contract that gives you the right—but not the obligation—to buy or sell a stock at a set price by a certain date

An option is a contract between two people: one who owns it and one who sold it. The owner pays money upfront (called the premium) for the right to buy or sell 100 shares of a specific stock at a locked-in price (called the strike price) on or before an expiration date. The seller keeps that premium whether or not the owner ever uses the right.

You do not have to exercise the option. If the stock price moves against you, you can let the contract expire worthless and lose only the premium you paid. If the price moves in your favor, you can exercise the option, sell it to someone else, or let it expire. This flexibility—the ability to profit from price movement without owning the stock—is what makes options different from buying shares outright.

Options exist on thousands of stocks and exchange-traded funds (ETFs). Each contract covers 100 shares, so if you buy one contract, you control 100 shares' worth of price movement. The contracts are standardized and trade on exchanges like the Chicago Board Options Exchange (CBOE), which means you can buy and sell them quickly during market hours.

Key Takeaways

  • An option is a contract giving you the right to buy or sell a stock at a set price by a set date, and you pay a premium upfront for that right.
  • Call options let you profit if a stock price rises; put options let you profit if a stock price falls.
  • You can close an option position by selling the contract back to the market before expiration, rather than exercising it.
  • Options are leveraged—a small premium payment controls a large amount of stock value, which means you can lose your entire premium quickly if the price moves against you.
  • Most options expire worthless, and most options traders lose money because they underestimate how much the stock price must move to make a profit.

Calls and puts: the two types of options

A call option gives you the right to buy a stock at the strike price. You buy a call when you think the stock price will rise. If the stock rises above the strike price plus the premium you paid, you make money. If it stays below that level, you lose the premium.

A put option gives you the right to sell a stock at the strike price. You buy a put when you think the stock price will fall. If the stock falls below the strike price minus the premium you paid, you make money. If it stays above that level, you lose the premium.

Each option has a seller on the other side. The seller of a call (called a call writer) collects the premium but takes on the obligation to sell the stock at the strike price if the buyer exercises. The seller of a put (called a put writer) collects the premium but takes on the obligation to buy the stock at the strike price if the buyer exercises. Sellers face larger potential losses because they do not control whether the option gets exercised.

How the premium is set and what affects it

The premium—the price you pay for the option contract—is not set by the company or an exchange. It is set by supply and demand in the options market, just like a stock price. Buyers and sellers place orders, and the price where they meet becomes the market price for that option.

Several factors move the premium up or down. Time to expiration matters: an option with three months left is worth more than the same option with one week left, because there is more time for the stock to move in your favor. How far the strike price is from the current stock price matters: an option that is already in the money (profitable if exercised today) costs more than one that is out of the money. How much the stock price swings—called volatility—matters: a stock that moves 5 percent a day has options worth more than a stock that moves 1 percent a day, because bigger swings mean bigger profit potential.

Interest rates and dividends also affect the premium, but less dramatically. The point is that you are not just betting on whether the stock goes up or down; you are also betting on how fast it moves and how much time is left. This is why two traders can buy the same call option and have completely different outcomes depending on when they bought it and when they sold it.

Expiration dates and what happens when they arrive

Every option has an expiration date. For stock options, this is usually the third Friday of the month. Some brokers offer weekly options that expire every Friday. On the expiration date, the option contract ceases to exist.

If you own a call and the stock is above the strike price at expiration, the option is in the money. Most brokers will automatically exercise it for you, meaning you will own 100 shares at the strike price. If the stock is below the strike price, the option is out of the money and expires worthless. You lose the premium you paid.

If you own a put and the stock is below the strike price at expiration, it is in the money and will be automatically exercised, meaning you will be forced to sell 100 shares at the strike price. If the stock is above the strike price, the put expires worthless.

You do not have to hold an option until expiration. You can sell it back to the market at any time during market hours. Most options traders close their positions before expiration rather than exercise them, because selling the contract is often simpler than taking ownership of shares.

Leverage: why small money can control large stock positions

Options are leveraged instruments. A single option contract controls 100 shares of stock. If a stock trades at $50 per share, those 100 shares are worth $5,000. But you might pay only $200 for a call option on those shares. That $200 premium gives you control over $5,000 worth of stock movement.

This leverage cuts both ways. If the stock rises to $55, your option might be worth $700, giving you a 250 percent return on your $200 investment. But if the stock falls to $45, your option might be worth $0, giving you a 100 percent loss on your $200 investment. You can lose your entire premium quickly, and you cannot lose more than you paid (unless you are the seller).

This is why options are riskier than owning stock outright. With stock, if you buy 100 shares at $50 and the price falls to $45, you have lost $500 but you still own the shares and can hold them until the price recovers. With an option, if the price falls and expiration arrives, your contract is worthless and your money is gone.

Why most options expire worthless

The odds are stacked against the option buyer. For a call to make money, the stock must rise above the strike price plus the premium paid. For a put to make money, the stock must fall below the strike price minus the premium paid. The stock has to move far enough and fast enough to overcome the cost of the premium.

Studies of options markets show that most options expire worthless. This does not mean most traders lose money—some close their positions early at a profit—but it does mean that holding an option until expiration is a losing bet for most buyers. The premium you pay is essentially the market's estimate of how likely the option is to finish in the money. If you are paying that premium, you are betting against the market's consensus.

Sellers, on the other hand, profit when options expire worthless, because they keep the premium. This is why selling options is sometimes called a "high probability" strategy—most options do expire worthless, so the seller wins most of the time. But when the seller loses, the loss can be very large, which is why selling options requires more capital and carries more risk than buying.

How options are used in practice

Some traders use options to speculate on price direction: they buy calls if they think a stock will rise or buy puts if they think it will fall. This is the simplest use case and the one most new traders attempt.

Other traders use options to hedge existing stock positions. If you own 100 shares of a stock you believe in long-term but are worried about a short-term drop, you can buy a put option. The put acts like insurance: if the stock falls, the put gains value and offsets your loss. You pay the premium as the insurance cost.

Still others use options to generate income. A trader who owns a stock can sell a call option on it, collecting the premium. If the stock stays below the strike price, the call expires worthless and the trader keeps the premium as profit. This is called covered call writing.

Advanced traders combine multiple options into strategies like spreads (buying one option and selling another to reduce cost and risk) or straddles (betting that a stock will move a lot in either direction). These strategies are designed to profit from specific market conditions or to reduce the cost of taking a position.

Frequently Asked Questions

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

If you are buying options, no—your maximum loss is the premium you paid. If you are selling options, yes—your loss can be much larger than the premium you collected, because you are obligated to buy or sell the stock at the strike price regardless of where it trades.

What happens if I do not sell or exercise my option before expiration?

If your option is in the money at expiration, most brokers automatically exercise it, meaning you will own or be obligated to sell 100 shares at the strike price. If it is out of the money, it expires worthless and you lose the premium. Check your broker's policy, as some require you to act manually.

How do I know what strike price to choose?

Strike prices closer to the current stock price cost more but have a higher chance of finishing in the money. Strike prices far from the current price cost less but require a larger stock move to profit. Your choice depends on how much you want to risk and how much movement you expect.

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

No. You can buy a call on any stock without owning it. If you exercise the call, you will be required to buy 100 shares at the strike price. Most traders close the position before expiration instead of exercising.

Why does the option price change even if the stock price does not move?

Options lose value as expiration approaches, even if the stock price stays flat. This is called time decay. Additionally, changes in volatility or interest rates can shift the premium. An option can lose money even if your prediction about the stock direction is correct, if the stock does not move fast enough.