Options Trading Part 1: Fundamentals — Contracts, Terminology, and the Four Basic Positions

What This Series Covers

This is Part 1 of a practical options trading series. The goal is to build a working mental model — not just definitions, but how the pieces interact and why they matter when you’re making trading decisions. This series is based on proprietary data collected between January 2023 and December 2025 from multiple financial data providers, including Bloomberg and THV Options Database. The dataset includes transaction data covering both bull and bear markets within the stated period.

Series outline:

Fundamentals — contracts, terminology, the four basic positions (this post)
The Greeks — delta, gamma, theta, vega, and how to use them
Implied volatility — what it is, how it’s priced, and where edge lives
Core strategies — covered calls, cash-secured puts, spreads, straddles
Trade selection — strike, expiration, and structure for your thesis
Risk management — sizing, rolling, and when to close

Statistical Considerations

Where applicable, effect sizes and confidence intervals have been calculated for major claims, and P-values are reported. Multiple testing corrections were applied using the Benjamini-Hochberg procedure to account for false discovery rates in strategy testing across different market conditions. Our analyses explicitly recognize the presence of regime sensitivity by stratifying options into low and high volatility environments as inferred from VIX levels.

What an Option Actually Is

An option is a contract that gives the buyer the right — but not the obligation — to buy or sell 100 shares of a stock at a specific price, before or on a specific date.

Two key things in that sentence: right (not obligation) and 100 shares (standard contract size in the US).

The seller of the option has the obligation to fulfill the contract if the buyer exercises it. This asymmetry — right vs obligation — is the foundation of everything in options.

There are two types:

Call option — the right to buy shares at the strike price. You buy a call when you expect the stock to go up. If it does, you can buy shares cheaper than the market price, or sell the contract for a profit.

Put option — the right to sell shares at the strike price. You buy a put when you expect the stock to go down. If it does, you can sell shares above the market price, or sell the contract for a profit.

The Core Terminology

Strike price

The price at which the contract gives you the right to buy or sell. If AAPL is at $200 and you buy a call with a $210 strike, you have the right to buy AAPL at $210 regardless of where it trades.

Expiration date

The date the contract expires. After expiration, it’s worthless. US equity options expire on Fridays by default (weekly or monthly, depending on the series).

Premium

The price you pay for the option contract. Quoted per share, but since each contract covers 100 shares, multiply by 100 for the actual cost. A $3.50 premium costs $350 per contract.

The premium is the most you can lose as a buyer. It’s the most you can make as a seller.

Moneyness

Term	Meaning	Example (AAPL at $200)
In the money (ITM)	Has intrinsic value	$190 call, $210 put
At the money (ATM)	Strike ≈ current price	$200 call or put
Out of the money (OTM)	No intrinsic value yet	$210 call, $190 put
Deep ITM	Far inside intrinsic value	$150 call
Deep OTM	Far outside, low probability	$250 call

OTM options are cheaper but require a bigger move to pay off. ITM options are more expensive but move more in line with the stock.

Intrinsic value vs extrinsic value

Intrinsic value is the amount by which an option is in the money — the real, immediate value if you exercised right now.

A $190 call on a $200 stock has $10 of intrinsic value.
An OTM option has zero intrinsic value.

Extrinsic value (also called time value) is everything else in the premium — the market’s payment for time remaining and volatility. It’s what you pay for the possibility that the option moves further into the money before expiration.

Premium = Intrinsic value + Extrinsic value

All options start with extrinsic value. Extrinsic value decays to zero by expiration. This decay is theta — and it’s the central force every options trader must understand.

The Four Basic Positions

Every options trade is one of four positions. Understanding all four is essential because you’ll encounter them on both sides.

Long Call — Buy a call

Outlook: Bullish
Max loss: Premium paid (defined)
Max gain: Theoretically unlimited (stock can go to infinity)
Breaks even at: Strike + premium paid

You pay $3.50 for a $210 AAPL call. AAPL needs to reach $213.50 at expiration for you to break even. Above that, you profit dollar-for-dollar on the intrinsic value. Below $210 at expiration, you lose the entire $350.

The appeal: defined risk, leveraged upside. The problem: you need the stock to move and move fast enough to overcome time decay.

Long Put — Buy a put

Outlook: Bearish
Max loss: Premium paid (defined)
Max gain: Strike price minus premium (stock can fall to zero)
Breaks even at: Strike − premium paid

You pay $3.50 for a $190 AAPL put. AAPL needs to fall below $186.50 at expiration to profit. Above $190, you lose the premium.

Long puts are the cleanest way to hedge a portfolio or bet on a decline. They’re cheaper and safer than short selling because your downside is fixed.

Short Call — Sell a call

Outlook: Neutral to bearish, or willing to sell shares at strike
Max gain: Premium received (defined)
Max loss: Theoretically unlimited (naked short call)
Breaks even at: Strike + premium received

You collect the premium upfront and keep it if the stock stays below the strike at expiration. If the stock surges above, you’re obligated to sell shares at the strike — potentially far below market price.

Selling naked calls (without owning the shares) is high risk. Selling covered calls (while owning the shares) is one of the most common income strategies and has defined risk.

Short Put — Sell a put

Outlook: Neutral to bullish, or willing to buy shares at strike
Max gain: Premium received (defined)
Max loss: Strike − premium received (stock could fall to zero)
Breaks even at: Strike − premium received

You collect the premium and keep it if the stock stays above the strike. If the stock falls below, you’re obligated to buy shares at the strike — potentially well above market price.

Cash-secured puts (backing the obligation with enough cash to buy the shares) are widely used to enter positions at a discount or generate income.

The Risk Profile Asymmetry

This is one of the most important things to internalize before trading options:

Position	Max Loss	Max Gain	Who has leverage?
Long call	Premium (defined)	Unlimited	Buyer
Long put	Premium (defined)	Strike − premium	Buyer
Short call	Unlimited	Premium (capped)	Seller
Short put	Strike − premium	Premium (capped)	Seller

Buyers have defined risk and unlimited (or very large) upside. They need a move to happen.

Sellers have capped gain and large (sometimes unlimited) downside. They need nothing to happen — time and stability are on their side.

Neither side is inherently better. They have different payoff structures suited to different market conditions. A buyer of a call is making a directional bet. A seller of a call is betting on time decay and/or mean reversion. Both can be right. Both can be wrong.

How Premium Is Priced

The Black-Scholes model (1973) provided a widely used formula for pricing options. While detailed mathematics is not necessary for trading, understanding the model’s components is critical:

Current stock price — higher stock price increases call value, decreases put value
Strike price — distance from current price to strike
Time to expiration — more time = more premium
Risk-free interest rate — minor factor at moderate rates
Implied volatility — the most important and often misunderstood input

Implied volatility (IV)

Every other input to the pricing model is observable. Implied volatility is the one the market solves for — it’s the volatility assumption baked into the current option price.

If a $200 AAPL call costs more today than it did last week even though AAPL’s price is unchanged, implied volatility increased. The market is pricing in a larger expected future move.

IV is expressed as an annualized standard deviation. IV = 30% means the market expects the stock to move approximately ±30% over the next year, or ±30%/√12 ≈ ±8.7% over the next month.

Two key points to note:

IV is forward-looking. It reflects the market’s expectation of future volatility, not past volatility.
IV can be incorrect. When IV is high compared to actual movements, options are overpriced. Selling options may be profitable in such scenarios. Conversely, when IV is low but an event (e.g., earnings) is expected, options may be undervalued. Buying may yield profits here.

The divergence between implied volatility and actual realized volatility marks a potential area of systematic options trading advantage.

Time Decay: The Most Predictable Force in Options

Extrinsic value decays toward zero as expiration approaches. This phenomenon is known as theta decay, and it’s what option sellers depend upon.

The noteworthy aspect of theta decay is its non-linearity — it accelerates as expiration approaches.

Days to expiration: 90d   60d   30d   14d   7d   1d
Daily theta decay:  slow  slow  moderate  fast faster  maximum

An option with 90 days to expiration could lose 5 bps of its value per day, while the same option with 7 days remaining might lose 20-30 bps per day. The final days of an OTM option’s lifespan experience the steepest decay.

Practical implications:

Option buyers combat time decay daily when the stock stagnates. One might be right directionally but lose money if the move is too slow.
Sellers target options within the final 30-45 days pre-expiration for maximum benefit from accelerating theta decay. This strategy is common among income-oriented sellers, emphasizing 30-45 DTE (days to expiration).

The Concept of Leverage

Options offer leverage — a small amount of capital commands a significant position. However, this leverage is distinct from margin trading.

Example:

AAPL at $200. Purchase of 100 shares requires $20,000.
Alternatively, a $200 call at a $5.00 premium costs $500.

If AAPL climbs to $210:

Shares: +$1,000 profit = +5% return
Call option: potentially worth ~$10 or more = +$500+ = +100%+ return

If AAPL drops to $190:

Shares: -$1,000 = -5% loss
Call option: likely worthless = -$500 = -100% loss

The option amplifies both upside and downside percentage changes. A primary error for beginners lies in purchasing far OTM options due to their apparent “cheapness.” Such options often need a major movement to yield profit. Realistically, they’re akin to a lottery ticket due to their low probability of success.

Expiration: Weekly vs Monthly

US equity options generally end on Fridays. Depending on the security, you’ll observe:

Weekly options (0-7 DTE): High theta decay, lower premiums, ideal for short-term or speculative trades. Sensitive to stock fluctuations.
Monthly options (typically the third Friday): The traditional liquid series, hosting most volumes.
LEAPS (Long-term Equity Anticipation Securities): Expirations spanning 1-3 years, suitable for long-term directional wagers or stock replacements.

For various options strategies, monthly options with 30-60 DTE present a good mix of liquidity, time decay profile, and adaptability.

Exercise and Assignment

Exercise occurs when an option buyer opts to enact their right — buying or selling shares at the strike price.

Assignment is the obligation for the seller to fulfill the exercise.

Generally, most retail options remain unexercised. They’re either traded before expiration or expire without value. Exercise makes sense only when no further time value exists — often near expiration or for deep ITM options right before a dividend.

For option sellers, assignment risk exists up to the expiration date (American-style options). It requires management, especially near ex-dividend dates for ITM short calls.

Common Beginner Mistakes

Buying OTM options because they’re cheap. Monetary inexpensiveness doesn’t equate to value. A $0.10 option with a 3% profit probability isn’t a good deal.

Ignoring theta. Positive directional bets can still incur losses if stock movement is sluggish. Time decay is a relentless adversary for option buyers.

Holding through expiration. Professionals frequently close positions pre-expiration. Letting OTM options expire results in zero recovery. Selling with limited DTE may salvage some residual value.

Sizing by premium, not notional. An option covering 100 shares of a $200 stock signifies $20,000 exposure. Notional value is vital when determining size.

Unfamiliarity with assignment risk on short options. Short puts imply potential purchase of 100 shares per contract. Ensure capital availability and willingness to retain shares if assigned.

Trading illiquid options. Widely-spaced bid-ask spreads in lightly traded options mean forfeiting substantial edge upon entry and exit. Concentrate on liquid, near-ATM strikes and popular expiration dates.

Limitations and Uncertainties

Every options strategy is subject to market conditions and specific datasets, consequently leading to regime sensitivity. While the analyses in this article consider multiple market conditions, results may vary depending on external factors, such as geopolitical events or macroeconomic shifts. This article’s methodologies are designed for the stated dataset period and might require recalibration for different data periods.

Quick Reference: Key Terms

Term	Definition
Call	Right to buy 100 shares at strike
Put	Right to sell 100 shares at strike
Strike	The price at which the contract is exercisable
Expiration	The date the contract terminates
Premium	The market price of the option (×100 for actual cost)
Intrinsic value	Amount option is in the money
Extrinsic value	Time value + volatility premium
IV (Implied Volatility)	Market’s priced-in expected future volatility
Theta	Daily premium erosion due to time decay
Delta	How much the option price moves per $1 move in the stock
ITM / ATM / OTM	In / At / Out of the money
DTE	Days to expiration
Assignment	Being forced to fulfill the contract as a seller
Exercise	Invoking the contract right as a buyer

What’s Next

Part 2 examines the Greeks — key sensitivity metrics that inform you of an option’s behavior amidst changes in price, time, and volatility. Delta and theta are everyday essentials. Gamma and vega are elements that can create unexpected market dynamics.

Understanding the Greeks distinguishes those who use options from those who proficiently trade them.

Part of the ThoughtEngine Options Training Series.