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Options Basics: Understanding Calls and Puts
A plain-English guide to stock options — what they are, how they work, and how they are priced
Published 2026-04-13 · Back to Learning Hub
What Are Stock Options?
A stock option is a contract that gives its holder the right — but not the obligation — to transact shares of an underlying stock at a predetermined price before or on a specific date. That distinction between a right and an obligation is foundational: unlike owning stock outright, an option holder is never forced to complete the transaction. If the trade would not be profitable, the holder simply lets the contract expire.
There are exactly two types of stock options: call options and put options. A call gives the holder the right to purchase shares at the strike price. A put gives the holder the right to dispose of shares at the strike price. Every options contract in the US equity market covers exactly 100 sharesof the underlying stock — so when you see a premium quoted at "$5.00," the actual cost of one contract is $500 (100 × $5.00).
Options on US equities are traded on regulated exchanges, with the Chicago Board Options Exchange (CBOE) — now operating under the Cboe Global Markets brand — being the largest and most historically significant. The CBOE introduced listed options trading in 1973, transforming what had been an over-the-counter, largely unregulated market into a transparent, standardized exchange. Today, options also trade on NYSE American (formerly AMEX), Nasdaq PHLX, and several other venues.
Options exist on individual stocks, exchange-traded funds (ETFs), broad market indexes (such as the S&P 500 via SPX), and other assets. This article focuses on equity options — options on individual stocks — as those are typically where new options traders begin. For a foundation in equity ownership itself, see our article on what a stock is.
Call Options Explained
A call option gives the holder the right to purchase 100 shares of the underlying stock at the strike price, at any time before (American-style) or on (European-style) the expiration date. Call options become more valuable as the underlying stock rises in price, because the right to purchase at a fixed, lower strike price becomes increasingly attractive.
The cost of acquiring that right is the premium, paid upfront to the option writer (the party on the other side of the trade). The premium is the maximum amount a call buyer can lose — if the stock never rises above the strike price, the option expires worthless and the full premium is forfeited.
Hypothetical Example: Purchasing a Call Option
- Underlying stock: Hypothetical Company A
- Current stock price: $145.00
- Strike price: $150.00
- Premium paid: $5.00 per share → $500 per contract (100 shares)
- Expiration: 60 days from purchase
Scenario A — Stock rises to $170.00 at expiration:
- Intrinsic value at expiration: $170.00 − $150.00 = $20.00 per share
- Gross profit per share: $20.00 − $5.00 (premium paid) = $15.00
- Total profit on one contract: $15.00 × 100 = $1,500
- Return on premium: $1,500 ÷ $500 = +300%
- Compare to owning 100 shares outright from $145: profit = $2,500 on $14,500 invested = +17.2%
Scenario B — Stock stays at $145.00 at expiration (below strike):
- Option expires worthless (out-of-the-money)
- Loss: the full $500 premium paid — a −100% loss on the options position
Break-even at expiration: Strike price + Premium = $150.00 + $5.00 = $155.00
This example illustrates both the power of leverage and the asymmetric risk of options. The percentage gain from the call option vastly exceeds the percentage gain from owning stock — but only if the stock moves far enough in the right direction within the time frame. Options expire; stocks do not. A stockholder who purchased at $145 and saw the stock stay flat would lose nothing in that scenario, while the call option holder would lose the entire $500 premium.
Put Options Explained
A put option gives the holder the right to dispose of (deliver) 100 shares of the underlying stock at the strike price before or on expiration. Put options increase in value as the underlying stock declines, because the right to dispose of shares at a fixed, higher strike price becomes more valuable when the market price falls below that level.
Investors purchase puts for two primary reasons: to speculate that a stock will decline in price, or to hedge an existing stock position against potential losses. A put held alongside owned shares functions somewhat like an insurance policy — if the stock falls sharply, gains on the put partially offset losses on the shares.
Hypothetical Example: Purchasing a Put Option
- Underlying stock: Hypothetical Company B
- Current stock price: $155.00
- Strike price: $150.00
- Premium paid: $4.00 per share → $400 per contract
- Expiration: 45 days from purchase
Scenario A — Stock falls to $130.00 at expiration:
- Intrinsic value at expiration: $150.00 − $130.00 = $20.00 per share
- Gross profit per share: $20.00 − $4.00 (premium paid) = $16.00
- Total profit on one contract: $16.00 × 100 = $1,600
- Return on premium: $1,600 ÷ $400 = +400%
Scenario B — Stock rises to $165.00 at expiration (above strike):
- Option expires worthless (out-of-the-money)
- Loss: the full $400 premium — a −100% loss on the options position
Break-even at expiration: Strike price − Premium = $150.00 − $4.00 = $146.00
Note that put options have a natural floor on their value: a stock cannot fall below zero, so the maximum intrinsic value of a put at expiration is equal to the strike price (if the stock reached $0). This means put profits are very large but finite, whereas call profits are theoretically unlimited (stocks have no ceiling). In practice, both are subject to the premium paid and the time constraint imposed by the expiration date.
Key Options Terminology
Options come with a vocabulary of their own. The following terms appear constantly in options analysis, broker platforms, and financial media. A firm grasp of these concepts is a prerequisite for understanding any options strategy. Additional definitions are available in our financial glossary.
- Strike Price (Exercise Price)
- The fixed price at which the option holder has the right to purchase (call) or dispose of (put) the underlying shares. The strike price does not change over the life of the contract, regardless of where the stock trades.
- Premium
- The price paid by the option buyer to the option writer for the rights conveyed by the contract. Quoted per share; multiply by 100 for the total contract cost. The premium is the buyer's maximum loss and the writer's maximum gain (on a long options trade).
- Expiration Date
- The date after which the option ceases to exist. Standard US equity options expire on the third Friday of each month for monthly contracts. Weekly expirations (Weeklys) are also widely available. After expiration, unexercised options have no value.
- In-the-Money (ITM)
- A call option is in-the-money when the stock price is above the strike price (exercising would allow purchasing shares below market value). A put option is in-the-money when the stock price is below the strike price. ITM options have intrinsic value.
- At-the-Money (ATM)
- When the stock price is approximately equal to the strike price, the option is at-the-money. ATM options have no intrinsic value but typically carry the highest amount of time value (extrinsic value).
- Out-of-the-Money (OTM)
- A call is out-of-the-money when the stock price is below the strike; a put is OTM when the stock price is above the strike. OTM options have no intrinsic value — their entire premium consists of time value and volatility expectations. OTM options expire worthless if the stock does not move enough before expiration.
- Intrinsic Value
- The immediate exercise value of an option. For a call: max(Stock Price − Strike Price, 0). For a put: max(Strike Price − Stock Price, 0). Intrinsic value is always zero or positive — it cannot be negative.
- Extrinsic Value (Time Value)
- The portion of an option's premium that exceeds its intrinsic value. Extrinsic value reflects the time remaining until expiration and the implied volatility of the underlying stock. All else equal, extrinsic value erodes as expiration approaches — a phenomenon called theta decay.
- Open Interest
- The total number of outstanding options contracts for a given strike and expiration that have not been closed, exercised, or expired. High open interest generally indicates a more liquid options series. It updates after each trading day.
- Volume
- The number of contracts traded for a given options series during the current trading session. Unlike open interest, volume resets to zero each day. High volume relative to open interest can indicate new positions are being opened or existing ones closed.
How Options Are Priced
An option's market price (its premium) can be decomposed into two components: intrinsic value (the immediate exercise value discussed above) and extrinsic value (everything else). For an at-the-money or out-of-the-money option, the entire premium is extrinsic value. For a deep in-the-money option, the premium is mostly intrinsic value with a small extrinsic component.
Six primary factors influence an option's theoretical value:
- Underlying stock price: As a stock rises, call premiums increase and put premiums decrease (and vice versa).
- Strike price:The relationship between the strike and the current stock price determines intrinsic value and the option's moneyness (ITM, ATM, or OTM).
- Time to expiration: More time = more premium, because there is greater probability that the stock will move favorably before the contract expires.
- Implied volatility: Higher expected price swings inflate option premiums for both calls and puts, since larger moves increase the probability of a profitable outcome.
- Interest rates: Higher risk-free interest rates (such as the US Treasury bill rate) modestly increase call premiums and decrease put premiums, through the cost-of-carry effect.
- Dividends: Expected dividends reduce call premiums and increase put premiums on dividend-paying stocks, since a dividend payment reduces the stock price on the ex-dividend date.
In 1973, economists Fischer Black, Myron Scholes, and Robert Merton published what became the most influential options pricing framework: the Black-Scholes model (also called Black-Scholes-Merton). The model provides a closed-form equation for the theoretical price of a European-style option given the five inputs above (implied volatility is solved for, rather than input directly). While modern practitioners often use more sophisticated models (particularly for American-style options and those with skewed volatility surfaces), Black-Scholes remains the conceptual foundation taught in finance curricula worldwide. Scholes and Merton received the Nobel Memorial Prize in Economic Sciences in 1997 for this work (Black had passed away in 1995).
The Greeks: Delta, Gamma, Theta, Vega
"The Greeks" are measures of how an option's price is expected to change in response to changes in underlying variables. They are essential tools for understanding options risk and are displayed on every modern options trading platform. Each Greek is named after a letter of the Greek alphabet.
Delta (Δ)
Delta measures how much an option's price is expected to change for every $1.00 move in the underlying stock. A call option with a delta of 0.50 would theoretically gain $0.50 in value if the stock rose $1.00 (and lose $0.50 if the stock fell $1.00). Call deltas range from 0 to +1.00; put deltas range from −1.00 to 0. An at-the-money option typically has a delta of approximately ±0.50. Deep in-the-money options have deltas approaching ±1.00, behaving almost like owning or shorting the stock. Delta is also commonly used as an approximation of the probability that an option will expire in-the-money.
Gamma (Γ)
Gamma measures the rate of change of delta for each $1.00 move in the underlying stock — in other words, how quickly delta itself changes as the stock price moves. Gamma is highest for at-the-money options close to expiration. A high-gamma position means your delta (and therefore your directional exposure) can shift rapidly as the stock moves, creating both opportunity and risk. Gamma is always positive for long options (calls and puts) and always negative for short options. Long gamma positions benefit from large stock moves in either direction; short gamma positions are hurt by them.
Theta (Θ)
Theta measures the daily erosion of an option's price due to the passage of time, all else being equal. A theta of −0.05 means the option loses approximately $0.05 of value per day as it approaches expiration. Theta is negative for long options (time erodes their value) and positive for short options (time benefits the writer). Theta accelerates as expiration approaches — an option with 5 days to expiration decays much faster per day than one with 60 days to expiration. This time decay is arguably the single most important concept for new options traders to internalize: every day that passes without a favorable move in the underlying stock, the option loses value.
Vega (ν)
Vega measures how much an option's price is expected to change for each 1-percentage-point change in implied volatility. A vega of 0.10 means the option gains $0.10 if implied volatility rises by 1% and loses $0.10 if it falls by 1%. Vega is positive for long options and negative for short options. Implied volatility tends to spike during periods of market uncertainty (such as before earnings announcements) and can dramatically inflate or deflate option premiums independently of any move in the underlying stock. A trader who purchased a call option before an earnings report, only to see the stock move favorably but implied volatility collapse post-announcement, may find the option has lost value despite the directional move — a phenomenon known as a "volatility crush."
Long Calls and Long Puts: The Simplest Strategies
"Going long" an option means purchasing it — paying the premium upfront to acquire the rights the contract confers. Long calls and long puts are the most straightforward options strategies and are typically where beginning options traders start.
For a long call:
- Maximum loss: Premium paid (the entire cost of the contract)
- Maximum profit: Theoretically unlimited — profit grows with every dollar the stock rises above the break-even point
- Break-even at expiration: Strike price + Premium paid
- Profitable when: The stock rises substantially above the strike price before expiration
For a long put:
- Maximum loss: Premium paid
- Maximum profit: Substantial but finite — the stock cannot fall below zero, so maximum profit = (Strike price − Premium paid) × 100
- Break-even at expiration: Strike price − Premium paid
- Profitable when: The stock falls substantially below the strike price before expiration
The asymmetric risk/reward profile of long options — defined maximum loss, larger potential gain — is one reason they are often described as having an attractive theoretical structure. In practice, however, the majority of long options expire worthless, as the stock must move far enough, fast enough, in the right direction to overcome the premium paid and the ongoing drag of theta decay.
Use our options profit calculator to model these payoff profiles across different strike prices, premiums, and stock price outcomes.
Options vs. Stocks: A Risk Comparison
Stocks and options share an underlying asset but have fundamentally different risk profiles. Understanding the differences is essential before considering any options transaction.
| Factor | Stocks | Long Options (Calls/Puts) |
|---|---|---|
| Expiration | None — held indefinitely | Fixed expiration date; contract ceases to exist after |
| Maximum loss (long) | 100% if stock goes to $0 | 100% of premium paid (can happen even if stock holds value) |
| Leverage | 1:1 (no leverage without margin) | Substantial leverage — controls 100 shares for cost of premium |
| Time decay | Not applicable | Continuous — works against option holders every day |
| Dividends | Shareholder receives dividends | Option holders do not receive dividends |
| Complexity | Relatively straightforward | Multiple variables (strike, expiration, Greeks, IV) affect value simultaneously |
A critical data point from the CBOE: historically, a substantial majority of options — often cited at 60% or more — either expire worthless or are closed at a loss before expiration. This does not mean options are categorically poor instruments; it means that profiting from purchasing options requires not just a correct directional view but also correct timing and sufficient magnitude of move to overcome time decay and the premium paid.
The leverage inherent in options amplifies gains and losses in equal measure. An investor who risked $500 on a call option and watched the stock move favorably may earn multiples of that amount. The same investor, if the stock moves against them or simply stays flat, loses the entire $500 regardless of the stock's ultimate long-term trajectory. This distinguishes options from stock ownership in a fundamental way: a stockholder who holds through a temporary decline may eventually recover; an option holder whose contract expires worthless cannot recover that loss.
Where Americans Trade Options
Options on US equities are available through most major retail brokerage platforms. The trading experience, approval process, commission structure, and available tools vary considerably across platforms. A comprehensive comparison is available on our brokers page.
Major US brokerages offering options trading as of this writing include Fidelity, Charles Schwab (which acquired TD Ameritrade and its thinkorswim platform), Interactive Brokers, Robinhood, and Tastytrade (formerly Tastyworks, now part of IG Group). Each platform has strengths: thinkorswim/Schwab is widely regarded as feature-rich for active options traders; Tastytrade was purpose-built for options and futures; Interactive Brokers appeals to sophisticated traders seeking access to global markets and advanced order types; Fidelity and Schwab are broadly full-service platforms with strong research tools.
Options approval levels are a regulatory and brokerage requirement. Before trading options, account holders must apply for approval and typically answer questions about their investment experience, income, net worth, and risk tolerance. Brokers assign approval tiers (commonly Level 1 through Level 4 or similar) that determine which strategies are permitted. Purchasing (going long) calls and puts is typically a lower-level approval. Writing uncovered (naked) options requires the highest approval levels and is generally restricted to experienced traders meeting specific financial thresholds.
Commission structures have shifted significantly over the past decade. Most major brokers have moved to $0 per-trade commissions on stocks and ETFs. Options commissions, however, generally retain a per-contract fee, commonly in the range of $0.50 to $0.65 per contract, with no base commission at many platforms. On small trades (e.g., one or two contracts), per-contract fees represent a meaningful percentage of the premium paid and should be factored into break-even analysis.
Frequently Asked Questions
What happens when an option expires?
At expiration, an option is either exercised or it expires worthless. If a call option is in-the-money — meaning the underlying stock is trading above the strike price — it may be automatically exercised by the broker, resulting in a stock purchase at the strike price (for long calls) or an obligation to deliver shares (for short calls). If the option is out-of-the-money at expiration, it expires worthless and the holder loses the entire premium paid. Most brokers have automatic exercise thresholds (typically $0.01 or more in-the-money at expiration). Traders often close positions before expiration to avoid exercise and assignment complications.
Can I lose more than I invested with options?
If you purchase (go long) a call or put option, your maximum loss is limited to the premium you paid for the contract. You cannot lose more than that amount. However, if you write (go short) options without owning the underlying shares or without sufficient collateral, losses can substantially exceed the premium collected. Writing uncovered (naked) calls carries theoretically unlimited risk because there is no ceiling on how high a stock can trade. These advanced strategies are generally restricted to accounts with higher options approval levels. This article focuses on long options (purchasing calls and puts), where maximum loss equals the premium paid.
What is the difference between American and European options?
American-style options can be exercised by the holder on any trading day up to and including the expiration date. European-style options can only be exercised on the expiration date itself. Most equity options traded on US exchanges (including individual stock options) are American-style. Many index options — such as SPX options on the S&P 500 — are European-style. The distinction matters primarily if you intend to exercise early; in practice, most options traders close positions in the open market rather than exercising.
How much money do I need to start trading options?
Requirements vary by broker. To purchase (go long) a single call or put option on a US equity, you need enough cash to pay the premium. Since each contract controls 100 shares, a $3.00 premium means a $300 cost per contract, plus any commission. Some brokers require account minimums of $2,000 or more to enable options trading. Writing (short) options or complex multi-leg strategies typically require significantly more capital due to margin requirements. Prospective options traders should review their chosen broker's options approval requirements before opening a position.
What is implied volatility?
Implied volatility (IV) is the market's forward-looking estimate of how much a stock's price is expected to fluctuate, expressed as an annualized percentage. It is derived mathematically from an option's market price using a pricing model such as Black-Scholes — working backwards from the observed premium to solve for the volatility assumption embedded in that price. High implied volatility generally means options premiums are more expensive, while low implied volatility means premiums are relatively cheaper. Implied volatility tends to spike around earnings announcements, major economic releases, or periods of market uncertainty. It is a critical concept for options pricing and strategy selection.
Continue Learning
- Learning Hub — all educational articles on stocks, options, taxation, and retirement accounts
- What Is a Stock? — foundational reading on equity ownership before exploring options
- Options Profit Calculator — model call and put payoffs across stock price scenarios
- Financial Glossary — definitions for options terms and broader financial vocabulary
- Brokers Comparison — compare US brokerage platforms for options features and fees