What an options contract is and why people trade them

An options contract gives you the right—but not the obligation—to buy or sell a specific stock at a set price by a certain date. You pay a smaller upfront cost (called the premium) for this right, rather than paying the full price of the stock itself. This is why options attract traders: you can control a larger position with less money down, which means your gains can be bigger—but so can your losses.

The two basic types are calls and puts. A call gives you the right to buy a stock at a set price. A put gives you the right to sell a stock at a set price. Every options contract covers 100 shares of the underlying stock, even though you only pay for the premium.

People trade options for different reasons. Some use them to bet on whether a stock price will go up or down. Others use them to hedge—to protect gains they already have in a stock they own. Still others sell options to collect the premium as income. The mechanics are the same; the strategy changes.

Key Takeaways

  • An options contract gives you the right to buy (call) or sell (put) 100 shares of a stock at a fixed price by a set date, and you pay a premium upfront for that right.
  • The price you can buy or sell at is called the strike price; the date the contract expires is the expiration date, usually a Friday several weeks or months out.
  • If you buy a call and the stock price rises above the strike price plus the premium you paid, you make money; if it falls below that, you lose the premium.
  • Options expire worthless if the stock price never moves the way you bet, meaning you can lose your entire premium investment on a single trade.
  • Selling options (writing) is riskier than buying them because your potential loss is much larger, even though the premium you collect upfront is smaller.

The strike price and expiration date: the two numbers that matter

Every options contract has two fixed numbers: the strike price and the expiration date. The strike price is the price at which you can buy (for a call) or sell (for a put) the stock. The expiration date is when the contract ends and becomes worthless if you have not exercised it.

Expiration dates are almost always on a Friday, and they range from one week out to several months. The longer the time until expiration, the more expensive the premium, because there is more time for the stock price to move in your favor. A call option expiring in one week costs less than the same call expiring in three months, even if the strike price is identical.

The strike price you choose determines your breakeven point. If you buy a call with a $50 strike price and pay a $2 premium, the stock has to rise above $52 for you to make money. If you buy a put with a $50 strike price and pay a $2 premium, the stock has to fall below $48 for you to profit. The further the strike price is from the current stock price, the cheaper the premium—but the less likely you are to make money.

How buying a call works: betting the stock price will rise

You buy a call when you think a stock price will go up. Let's say Apple stock is trading at $150. You buy one call contract with a $155 strike price expiring in four weeks, paying a $3 premium per share. Since each contract covers 100 shares, you pay $300 total.

If Apple rises to $160 before expiration, your call is now worth at least $5 per share (the $160 stock price minus the $155 strike price). You can sell the contract for $500 or more, netting a $200 profit on your $300 investment. If Apple falls to $145, your call expires worthless because there is no reason to buy at $155 when you can buy on the open market at $145. You lose the entire $300 premium.

The maximum you can lose on a call you buy is the premium you paid. The maximum you can gain is theoretically unlimited, because a stock price can rise indefinitely. This asymmetry—limited downside, unlimited upside—is why buying calls appeals to traders betting on a strong move up.

How buying a put works: betting the stock price will fall

You buy a put when you think a stock price will fall. Using the same Apple example: Apple is at $150, and you buy one put contract with a $145 strike price expiring in four weeks, paying a $2 premium per share. You pay $200 total.

If Apple falls to $140 before expiration, your put is now worth at least $5 per share (the $145 strike price minus the $140 stock price). You can sell the contract for $500 or more, netting a $300 profit on your $200 investment. If Apple rises to $155, your put expires worthless because there is no reason to sell at $145 when the market price is $155. You lose the $200 premium.

Puts are often used as insurance. If you own 100 shares of Apple at $150, you can buy a put with a $145 strike to protect yourself if the price crashes. If it does, your put gains value and offsets your loss on the shares. If it does not, you lose the premium but keep your shares.

Selling options: collecting premium but risking larger losses

When you sell (or write) an options contract, you collect the premium upfront but take on the obligation to buy or sell the stock if the buyer exercises the contract. Selling is riskier than buying because your potential loss is much larger.

If you sell a call, you are betting the stock price will stay below the strike price. You collect the premium immediately, but if the stock soars above the strike price, the buyer will exercise and you have to sell them 100 shares at the strike price—even if the market price is much higher. If you do not own the shares, you have to buy them at the higher price and sell them at the lower strike price, locking in a loss. Your maximum loss is theoretically unlimited.

If you sell a put, you are betting the stock price will stay above the strike price. You collect the premium, but if the stock crashes below the strike price, the buyer will exercise and you have to buy 100 shares at the strike price—even if the market price is much lower. Your maximum loss is the strike price times 100 minus the premium you collected. For a $145 strike, that is $14,500 minus whatever premium you took in.

Selling options requires a larger account and more experience because the losses can be severe. Many brokers require you to have a certain account balance and to pass a test before they allow you to sell options.

What happens at expiration: exercise, assignment, or worthless

On expiration day, one of three things happens. If you own a call or put that is in the money (profitable), you can exercise it—use your right to buy or sell the stock at the strike price. Most traders sell the contract instead of exercising, because selling captures the remaining value without tying up cash in the stock.

If you sold a call or put that is in the money, the buyer may exercise it, and you will be assigned—forced to buy or sell the stock at the strike price. If you sold a call and get assigned, you have to deliver 100 shares at the strike price. If you sold a put and get assigned, you have to buy 100 shares at the strike price. Assignment happens automatically if the contract is in the money at expiration, unless you close the position before that date.

If a contract is out of the money (unprofitable), it expires worthless. A call expires worthless if the stock price is below the strike price. A put expires worthless if the stock price is above the strike price. The buyer loses the premium; the seller keeps it.

The Greeks: how options prices change

Options prices do not move one-to-one with the stock price. Instead, they move based on several factors, often called the Greeks. Understanding these helps explain why an options contract can lose value even when the stock moves in the direction you bet on.

Delta measures how much the option price moves when the stock price moves $1. A call with a delta of 0.50 gains $0.50 in value for every $1 the stock rises. Theta measures how much value the option loses each day as expiration approaches. This decay accelerates in the final week before expiration, which is why time works against buyers and for sellers. Vega measures how much the option price changes when the stock's volatility changes. Higher volatility makes options more expensive; lower volatility makes them cheaper.

These factors interact. A call you buy might gain delta value if the stock rises, but lose theta value as expiration approaches. The net result depends on how fast the stock moves and how much time is left. This is why options traders watch these metrics closely.

Frequently Asked Questions

Can I lose more money than I invested in an options contract?

If you buy options, no—your maximum loss is the premium you paid. If you sell options, yes—your loss can be much larger than the premium you collected, especially if you sell calls without owning the stock or sell puts without having cash to buy the shares. This is why selling requires more experience and account restrictions.

What happens if I do not close my options contract before expiration?

If your contract is in the money, most brokers will exercise it automatically on your behalf. If you bought a call, you will own 100 shares at the strike price. If you bought a put, you will sell 100 shares at the strike price. If the contract is out of the money, it simply expires worthless and disappears from your account.

How do I know what strike price and expiration date to choose?

Strike price depends on how far you think the stock will move and how much risk you want to take. Closer strike prices are more likely to profit but cost more. Distant strike prices are cheaper but need a bigger move to profit. Expiration date depends on your timeline. Longer expirations cost more but give the stock more time to move your way. Shorter expirations cost less but expire faster.

Why would I buy a put if I do not own the stock?

You might bet the stock will fall, or you might use puts as insurance on a stock you plan to buy later. Some traders also use puts in spreads—combinations of multiple options contracts designed to limit risk and reduce the cost of entry.

Do I need a special account to trade options?

Most brokers require you to open an options account and approve you for a certain level. Level 1 usually allows buying calls and puts only. Level 2 or higher allows selling covered calls (calls on stock you own). Level 3 and 4 allow selling naked calls and puts, which require larger accounts and more experience. The approval process involves questions about your trading experience and financial situation.