Option Series

An option series is a specific listed option contract line. It identifies contracts that share the same underlying asset, option type, strike price, expiration date, and other contract terms.

In practical terms, an option series is one row in an option chain. The broader option class might be all options on a stock or index, while the series is the exact call or put a trader can buy, sell, close, exercise, or be assigned on.

The series is where the trade becomes specific. Changing the strike, expiration, option type, multiplier, or deliverable creates a different contract line with different risk.

What Defines A Series

An option series is usually defined by:

• the underlying asset or index
• whether the contract is a call or put
• the expiration date
• the strike price
• the contract multiplier
• the settlement style and exercise style
• any adjusted deliverable after corporate actions

Example: a December $100 call on a stock is not the same series as a December $105 call, a January $100 call, or a December $100 put. Each has a different payoff, price, liquidity profile, and risk.

Option Class Versus Option Series

This distinction matters because most trade decisions are made at the series level, not at the class level.

Why It Matters

Choosing the wrong option series can change the entire trade. A different strike changes moneyness and payoff. A different expiration changes time decay and event exposure. A different settlement or deliverable can change assignment, tax, or operational handling.

Series selection affects:

• premium and bid-ask spread
• probability of finishing in the money
• delta, gamma, theta, and vega exposure
• exercise and assignment risk
• liquidity and open interest
• whether the contract is standard or adjusted

For audit, risk, and reconciliation work, the exact series identifier matters more than a plain-language strategy label.

Worked Example

Assume a trader says they bought an XYZ $100 call. That is incomplete. A risk review needs the expiration date, option root, multiplier, premium, settlement terms, and whether the deliverable is still standard.

The December $100 call and the January $100 call can respond very differently to the same stock move because the January series has more time value. If a corporate action adjusts the deliverable, even the same strike and expiration can require separate treatment.

Authority Sources

Use public sources to check standardized option terms:

• OCC Characteristics and Risks of Standardized Options explains standardized option characteristics, risks, exercise, assignment, and adjustments.
• OCC weekly and quarterly options reports show how weekly and quarterly series are added or delisted.
• FINRA’s options overview explains option rights, premiums, expiration, and the importance of contract terms.

For live trading or reconciliation, use the broker confirmation, OCC memo if the deliverable changed, exchange product details, and the current option chain.

Common Confusion

Do not confuse an option series with an option strategy. A strategy may use several series, such as a vertical spread using two strikes with the same expiration.

Do not confuse a standard series with an adjusted series. Corporate actions can change deliverables, multipliers, or settlement treatment.

Do not assume liquidity at the class level applies to every series. A highly traded underlying can still have illiquid far-dated or far-out-of-the-money contracts.

Related Terms

• Option Cycle: The listing schedule that affects available expirations.
• Option Chain: A table of available option series for an underlying.
• Option Class: The broader group of options on a particular underlying.
• Strike Price: The exercise price that distinguishes one series from another.
• Expiration Date of Options: The expiration date attached to a specific series.
• Option Premium: The traded market price of the series.

Review Checklist

• Confirm the option root, underlying, call/put type, strike, expiration, multiplier, and premium.
• Check whether the series is standard, weekly, quarterly, LEAPS, or adjusted.
• Compare bid-ask spread, volume, and open interest before trading.
• Verify whether the deliverable or settlement terms changed because of a corporate action.
• Use the exact series identifier in risk reports, trade tickets, and reconciliation notes.

FAQs