Options Basics

An option is a contract that gives its holder the right, but not the obligation, to buy or sell an underlying asset at a specified price under the contract’s exercise terms. The holder pays a premium to acquire this right. The seller receives the premium and accepts the corresponding obligation if the option is exercised and the seller is assigned. Unlike ownership of shares, an option has a finite term: its exercise right ends at expiration.

For standard U.S. stock and exchange-traded fund (ETF) options, the underlying asset consists of shares. A call provides a right to buy those shares, whereas a put provides a right to sell them. The contractual transaction price is the strike price, and using the right is called exercise. These terms distinguish the price of the option from the separate payment involved in buying or selling its underlying asset.

Contract terms and premium

An option series is identified by its underlying, option type, strike, expiration, and applicable exercise and settlement terms. Options on the same underlying can therefore represent quite different rights. A change in the market premium does not change the strike or extend the contract’s life.

In a hypothetical example, SPY trades at $750 and a $775 call with 45 days to expiration has a premium of $8.50 per share. One standard contract covers 100 shares, so its purchase price is $850. This payment acquires the right to buy 100 SPY shares at $775 each; it does not pay for those shares. The strike payment becomes due only if the purchase right is exercised.

The contract multiplier converts the quoted premium into a dollar amount for one contract. With a multiplier of 100, two identical calls cost $1,700 and cover 200 shares. Standard contract size should not be assumed for an adjusted option: a split, merger, or other corporate action can change the specified deliverable or other terms. The contract specifications determine what is exchanged.

Long and short positions

Buying a call or put to open a position establishes a long option. Selling either type to open establishes a short option. These descriptions identify ownership of the right or responsibility for the obligation; they do not, by themselves, indicate whether the position benefits from a rising or falling market.

When a holder exercises, assignment allocates the resulting obligation to a seller with an open short position in the same series. An assigned call seller must sell the specified shares at the strike, and an assigned put seller must buy them there. The obligation remains relevant even when the required transaction is unfavorable compared with the current market price. Assignment is allocated through clearing and broker procedures rather than by reconnecting the original buyer and seller.

Payoff and profit at expiration

A call has intrinsic value when the underlying is above its strike, because the right permits a purchase below market value. A put has intrinsic value when the underlying is below its strike, because it permits a sale above market value. An option with positive intrinsic value is in the money. At expiration, this strike-price advantage determines the option’s payoff.

For the $775 call purchased for $8.50 per share, the following outcomes separate the payoff from the buyer’s profit or loss. The profit and loss column includes the $850 entry premium but excludes trading costs.

At $780, the contract has a $500 payoff but has not recovered its $850 purchase cost. The expiration break-even is $783.50, where the payoff equals the premium paid. Being in the money is therefore a property of the contract, not a statement that its holder has made a profit.

Using $S_T$ for the final underlying price and $K$ for the strike, the per-share payoffs are:

The maximum function selects the greater of the price difference and zero. It expresses the holder’s ability to leave an unfavorable right unused. A zero payoff produces the largest loss on the option itself: the premium paid.

At the same entry premium, the short option’s result is the opposite of the long option’s result. The seller keeps the premium when the payoff is zero, but a growing obligation can exceed that premium substantially. In particular, an uncovered call has no finite maximum loss as the underlying price rises.

Trading before expiration

An unexpired option can have value beyond its current intrinsic value because future price changes may make its right more valuable. This additional component is extrinsic value, also called time value. The market premium can change with the underlying price, time remaining, implied volatility, and other valuation inputs.

A holder can sell to close rather than exercise. Selling the example call for $12 per share after purchasing it for $8.50 returns $1,200 and realizes a $350 profit on one contract. The short seller closes by buying to close the same series. A completed closing transaction removes the option exposure for the quantity traded; an order that has not filled does not do so.

Exercise and settlement

Exercising the example call purchases 100 SPY shares at $775 each, requiring a $77,500 payment separate from the premium. The assigned seller delivers the shares and receives the strike payment. This is physical settlement. The call’s payoff measures the economic benefit of the strike purchase, rather than a separate cash payment of intrinsic value. Many index options instead use cash settlement, under which the exercise value is paid in money.

Standard U.S. stock and ETF options are American-style, allowing exercise before expiration as well as at expiration. European-style options permit exercise only at expiration, although they can still be traded during their listed trading periods. Selling an option can recover remaining time value; exercise uses the right immediately and does not pay that additional value.

Qualifying in-the-money options left open at expiration may be exercised under the broker’s procedures without a new instruction from the holder. A resulting share position has separate funding requirements and continues to gain or lose value after the option ends. The premium-based loss limit of a purchased option does not extend to shares retained after exercise.