Option Series
What Is an Option Series?
A specific set of option contracts that share the exact same underlying asset, expiration date, strike price, and option type (Call or Put).
An Option Series represents a single, specific trading instrument. While the "Option Class" refers to all calls or all puts on a stock, the "Option Series" drills down to the exact contract. When you place a trade, you are buying or selling a specific series. For example, "Microsoft (MSFT) Calls" is a class. But "MSFT Call, Expiring June 18th, Strike $250" is a series. All contracts within a series are identical. If you buy one contract of that series and your friend sells one contract of that same series, you are trading the exact same standardized product. This fungibility is what allows the Options Clearing Corporation (OCC) to net positions and settle trades efficiently.
Key Takeaways
- An option series is the most granular level of identification for an option.
- It refers to the single line item you see in an option chain (e.g., AAPL Jan 150 Call).
- All contracts in a series are fungible (identical and interchangeable).
- Multiple series make up an "Option Class."
- New series are listed by exchanges based on demand and price movement of the underlying.
The Four Identifiers
To define a series, you need four pieces of data:
- 1. Underlying Asset: The ticker symbol (e.g., TSLA).
- 2. Expiration Date: The day the contract ends (e.g., Jan 21, 2026).
- 3. Strike Price: The price at which the deal is struck (e.g., $900).
- 4. Type: Call or Put.
How Option Series Are Created
Option series don't appear by magic. They are listed by exchanges (like CBOE or ISE) in accordance with OCC rules. * Standard Cycles: Exchanges list series for specific expiration months (Cycles) years in advance (LEAPS) or weeks in advance (Weeklys). * Strike Listings: As a stock price moves up, exchanges add new higher strike prices. If it drops, they add lower strikes. This ensures there are always "At-The-Money," "In-The-Money," and "Out-of-The-Money" options available to trade. * Demand: If there is huge interest in a specific stock, exchanges may list "Weekly" series to capture the trading volume, creating thousands of new series for a single ticker.
Option Class vs. Option Series
Hierarchy of the Option Chain.
| Level | Scope | Example | Quantity |
|---|---|---|---|
| Underlying | The Asset | AAPL | 1 |
| Class | The Type | AAPL Calls | 2 (Calls & Puts) |
| Series | The Contract | AAPL 150 Call Jan 21 | Hundreds |
Real-World Example: Reading the Tape
A trader sees a large block trade on the tape: "10,000 contracts of AMD 120 Call 15OCT25 traded at $5.50." This is a specific Series. The liquidity (Open Interest) is specific to this series. The Volume is specific to this series. The Greeks (Delta, Theta) are specific to this series. The trader knows that liquidity in this series might be high, but liquidity in the "AMD 115 Call 15OCT25" series might be low. You cannot assume liquidity transfers between series.
Common Beginner Mistakes
Trading errors related to series:
- Fat-finger errors: Selecting the wrong series (e.g., buying the $150 strike when you meant $155).
- Liquidity Traps: Trading an illiquid series (wide bid-ask spread) when a liquid one (e.g., monthly expiration) is available nearby.
- Confusing Weeklys and Monthlys: They are different series even if the strike is the same.
FAQs
The exchanges. However, they follow rules set by the Listing Procedures Plan. Market makers or brokerage firms can also request the exchange to add specific strikes if there is customer demand.
It ceases to exist. It is removed from the option chain. All open positions are either exercised, assigned, or expire worthless. The ticker symbol for that specific series is retired.
This is the "Penny Pilot Program." For highly liquid series (like SPY or AAPL), regulators allow trading in $0.01 increments to tighten spreads. Less liquid series trade in $0.05 or $0.10 increments.
Look at the "Open Interest" and the width of the "Bid-Ask Spread." High Open Interest and tight spreads indicate a liquid series.
Yes. If an underlying stock is delisted or undergoes a major corporate action, the option series may be adjusted or delisted (set to "closing only" transactions).
The Bottom Line
The Option Series is the atom of the options market. It is the fundamental unit that is bought, sold, cleared, and settled. While strategists think in terms of "Volatility" or "Direction," the actual execution always comes down to selecting the correct series. Choosing the right series—balancing liquidity, time, and strike—is often just as important as choosing the right direction.
More in Options Trading
At a Glance
Key Takeaways
- An option series is the most granular level of identification for an option.
- It refers to the single line item you see in an option chain (e.g., AAPL Jan 150 Call).
- All contracts in a series are fungible (identical and interchangeable).
- Multiple series make up an "Option Class."