What is a stock option?
A stock option is a contract giving the buyer the right, but not the obligation, to buy or sell 100 shares of a stock at a set price (the strike price) on or before a set date (the expiration date), in exchange for an upfront payment called the premium. A call option is the right to buy; a put option is the right to sell. The buyer pays the premium and gets the rights; the seller, called the writer, collects the premium and takes on the obligation.
Options are derivatives, meaning their value derives from something else, in this case the underlying stock. You can buy or sell an option without ever owning the stock, and most option buyers close their position by selling the contract back before expiration rather than exercising it. This lesson explains the mechanics; it does not recommend trading options, which carry a high risk of rapid, total loss of the premium paid.
Calls: the right to buy
A call option gives you the right to buy 100 shares at the strike price before expiration. Buyers of calls generally expect the stock to rise. As an illustration, suppose a stock trades at $50 and you buy a call with a $55 strike expiring in three months for a $2.00 premium, which costs $200 per contract. If the stock climbs to $65, your right to buy at $55 is valuable: the contract's intrinsic value is $10 per share, or $1,000, against your $200 cost. If the stock stays at or below $55, the right is worthless and you lose the $200 premium.
Calls are described by their relationship to the stock price. A call is in the money when the stock is above the strike, at the money when it is roughly equal, and out of the money when it is below. Only in-the-money options have intrinsic value at expiration; everything else about an option's price is time value, covered in a later section. Deeper in-the-money calls behave more like the stock itself, while far out-of-the-money calls are cheap lottery tickets that need a big move to pay off.
One practical note: most call buyers never exercise. If the contract has gained value, selling it back to the market (sell to close) usually captures more than exercising, because the sale price includes remaining time value that exercising would throw away. Exercise is the exception, not the norm, and brokers handle the mechanics when it happens.
Puts: the right to sell
A put option gives you the right to sell 100 shares at the strike price before expiration. Buyers of puts generally expect the stock to fall, or want insurance against a fall. As an illustration, with a stock at $50 you might buy a $45-strike put for a $1.50 premium ($150 per contract). If the stock drops to $35, your right to sell at $45 is worth $10 per share, or $1,000. If the stock stays above $45, the put expires worthless and the $150 is gone.
Puts have a second, defensive use: the protective put. An investor holding 100 shares can buy a put as insurance, capping downside while keeping upside. If the stock falls, the put gains value and offsets part of the loss; if the stock rises, the put expires worthless and the cost was the price of the insurance. Fund managers use this structure routinely, which is why puts are sometimes called portfolio insurance. The mirror image of the call terminology applies: a put is in the money when the stock is below the strike.
Puts also let traders express a bearish view without short selling the stock directly, since the buyer's loss is capped at the premium while a short seller's loss is theoretically unlimited. That asymmetry is exactly why beginners find buying puts attractive, and exactly why the premium can be an expensive way to be wrong about timing.
The two sides of every contract
Every option trade has a buyer and a seller, and their risk profiles are mirror images. The buyer pays the premium, gets the rights, and can lose at most the premium. The writer collects the premium, takes on the obligation, and faces the larger risk. Someone must be willing to take the other side of your trade, and that someone is being compensated for the risk you are shedding.
The writer owns the 100 shares. If assigned, they sell shares they already hold at the strike. Risk is capped but so is upside: the premium is income against a stock they own. This is the most conservative form of option selling.
The writer keeps enough cash to buy the 100 shares if assigned. The put premium is collected for the willingness to buy the stock at the strike. Brokers require the cash to be set aside, which limits the leverage.
The writer has neither the shares nor the cash. A naked call writer faces theoretically unlimited losses if the stock rockets; a naked put writer faces large losses if it collapses. Brokers require margin and experience for this, for good reason.
Traders combine bought and sold options to cap both risk and reward, for example buying one call and selling another at a higher strike. Spreads define the maximum loss upfront, which is why experienced traders prefer them to naked positions.
When you place an option order, you choose among four actions: buy to open, sell to close, sell to open, and buy to close. Most retail volume is buy to open followed by sell to close. Exercise and assignment are handled through your broker and the Options Clearing Corporation, which guarantees every listed contract, so counterparty risk sits with the clearinghouse, not with the stranger on the other side of your trade.
Why options lose value as expiration nears
An option's price has two components: intrinsic value and time value (sometimes called extrinsic value). Intrinsic value is what the option would be worth if exercised right now: for a call, the stock price minus the strike when positive, otherwise zero. Time value is everything else, the market's price for the chance that the stock moves favorably before expiration. Time value always decays, and it decays faster as expiration approaches.
This decay has a name, theta, one of the option Greeks. As an illustration, an out-of-the-money call worth $1.00 with 30 days left might lose a few cents per day early on, then bleed faster in the final week. The stock can stay perfectly flat and the option still loses money every day. This is the structural headwind every option buyer faces: you must be right about direction, magnitude, and timing, because the clock charges rent.
Volatility feeds time value. When a stock is expected to swing wildly, perhaps around earnings, options cost more because the chance of a big favorable move is higher. After the event passes, volatility collapses and option prices drop even if the stock barely moved, a phenomenon traders call volatility crush. Checking an events calendar for scheduled catalysts is part of understanding why an option is priced the way it is.
The risks beginners underestimate
Options offer leverage: a small premium controls 100 shares' worth of exposure. Leverage magnifies percentage gains and percentage losses alike, and the most common beginner outcome is the entire premium going to zero at expiration. Unlike a stock, which can recover after a bad year, an expired option is gone permanently. There is no waiting it out.
Assignment is the second surprise. Writers can be assigned at any time before expiration on American-style options, which is most U.S. equity options. A put writer can wake up owning 100 shares bought at the strike; a call writer can be forced to deliver shares. Dividends add a wrinkle: holders of in-the-money calls sometimes exercise just before the ex-dividend date to capture the payout, since option holders get no dividends themselves.
The summary without the sales pitch: buying options caps your loss at the premium but stacks direction, magnitude, and timing against you while the clock drains value daily. Selling options collects steady premiums until a violent move produces an outsized loss. Neither side is free money; the premium exists because the risk is real. Anyone new to options should paper-trade first, keep position sizes small enough that a total loss is survivable, and treat every strategy article, including this one, as education rather than a recommendation.
Questions about options
What does one stock option contract control?
One standard U.S. equity option contract controls 100 shares of the underlying stock. A $2.00 premium means $200 per contract before commissions and fees. Always multiply the quoted premium by 100 to get the real cash outlay.
What is the difference between American and European options?
American-style options can be exercised at any time before expiration; European-style options can only be exercised at expiration. Most U.S. stock options are American-style, while many index options are European-style. The label refers to exercise rules, not where the option trades.
Can I lose more than I paid when buying options?
No. An option buyer's maximum loss is the premium paid, because you can simply let a losing option expire. Option writers face larger and sometimes theoretically unlimited losses, which is why selling options requires margin and experience.
What is assignment in options trading?
Assignment is when an option seller is forced to honor the contract because the buyer exercised it. A call writer may have to sell 100 shares at the strike price; a put writer may have to buy 100 shares at the strike price. Assignment can happen any time before expiration for American-style options.
Why do most options expire worthless?
An option only has value at expiration if it is in the money. Time value decays every day, so an option that never gets in the money bleeds to zero. That is the normal outcome buyers pay for: limited-risk exposure to a move that may not happen.
Do option holders receive dividends?
No. Only actual shareholders of record receive dividends. Holding a call option gives you no dividend rights, though an upcoming dividend can affect option prices and sometimes prompts early exercise of deep in-the-money calls.
StockEyes provides informational research organization and transparent calculations, not personalized investment advice, valuation conclusions, trade instructions, or predictions. Options involve a high risk of rapid and total loss of premium and are not suitable for all investors. Consult a qualified professional before trading derivatives.