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AM vs. PM Option Settlement: The Expiration Timeline

For educational purposes only; not investment advice.

Direct answer

Section titled “Direct answer”

AM settlement generally determines an option’s final value from opening-session inputs on the expiration date. PM settlement generally uses closing-session inputs. Those labels describe the settlement observation convention; they do not, by themselves, specify the last trading time, exercise style, multiplier, final-value symbol, or when cash reaches the account.

For cash-settled options with official settlement value S_settle, strike K, and multiplier M:

Call settlement = max(S_settle - K, 0) × M

Put settlement = max(K - S_settle, 0) × M

Use the exchange-published official value for the exact series. Do not substitute the prior close, live index display, related ETF, futures price, or broker estimate.

Read the expiration timeline

Section titled “Read the expiration timeline”

A position can pass through four different moments:

  1. Last trading time: the final moment the option can be closed or rolled.
  2. Settlement observation: the opening, closing, auction, or other inputs specified by the contract.
  3. Official value publication: when the exchange or calculation agent releases the final settlement value.
  4. Account cash processing: when OCC and the broker post resulting debits or credits.

For some AM-settled index series, trading ends before the expiration morning whose component opening prices create a special opening quotation (SOQ). The holder can therefore retain overnight market and opening dispersion risk after the option itself can no longer be traded. Components need not all open simultaneously; the official calculation can differ materially from a continuously displayed index.

PM-settled series commonly use expiration-day closing inputs, but “PM” does not guarantee that the option trades until every underlying closing print is known. Closing auctions, halts, late openings, calculation rules, and series-specific cutoff times still matter.

AM/PM settlement is separate from:

  • cash versus physical settlement: whether value is paid in cash or an asset is delivered;
  • American versus European exercise: whether exercise is permitted before expiration;
  • monthly versus weekly naming: series frequency does not alone establish settlement convention.

Before expiration, verify the exchange product specification, series identifier, last trade date and time, settlement style, exercise style, final-value ticker, multiplier, calculation method, broker cutoff, and expected posting schedule.

The close is not the settlement value

Section titled “The close is not the settlement value”

Suppose an AM-settled index option stops trading Thursday. The displayed index closes at 5,000. On Friday morning, component opening prices produce an official SOQ of 4,930. Consider strike 4,950, multiplier 100:

4,950 Call settlement = max(4,930 - 4,950, 0) × 100 = $0

4,950 Put settlement = max(4,950 - 4,930, 0) × 100 = $2,000

At Thursday’s displayed close, the Call appeared 50 points ITM and the Put appeared OTM. Neither observation determines the actual cash settlement. The official Friday value reverses those apparent outcomes, and the position could not be closed after Thursday’s cutoff.

For comparison, a hypothetical PM-settled series with the same strike and official expiration close of 5,005 would settle the Call at:

max(5,005 - 4,950, 0) × 100 = $5,500

This is not evidence that PM settlement is safer or more profitable. It only demonstrates that the contract’s specified observation and official value determine payment.

For a vertical spread, calculate each leg from the same official settlement value and then net the cash. Do not cap or value a spread using different timestamps for its legs.

Settlement risks

Section titled “Settlement risks”
  • Last-trade mismatch: the option may stop trading before its settlement inputs are known.
  • Overnight gap: news and futures movement can occur after the final option trade.
  • Opening dispersion: component stocks can open at different times and prices.
  • Proxy basis risk: an ETF, futures contract, or live index can diverge from the official calculation.
  • Symbol confusion: the trading symbol and settlement-value symbol may differ.
  • Series confusion: related monthly, weekly, mini, or end-of-month series can use different terms.
  • Calculation risk: halts, missing openings, auctions, and exchange procedures affect inputs.
  • Multiplier error: index products do not all use the same cash multiplier.
  • Posting delay: economic settlement and visible account cash may occur at different times.
  • Spread assumption: a bounded expiration payoff still faces mark, liquidity, and account risk before settlement.
  • Specification changes: current exchange documents must be checked for the actual expiration.

Common misconceptions

Section titled “Common misconceptions”
  • “AM settlement uses the previous close.” It generally uses specified opening-session inputs.
  • “PM settlement equals the last screen price.” The official calculation and closing procedure govern.
  • “The option trades until settlement is known.” Some series stop trading earlier.
  • “The live index predicts the SOQ exactly.” Staggered component openings can create a different value.
  • “Cash settlement removes expiration risk.” It removes asset delivery, not price, timing, or cash risk.
  • “European exercise means AM settlement.” Exercise style and settlement time are independent terms.
  • “All index options settle the same way.” Product and series specifications differ.
  • “An ITM reading before cutoff guarantees payment.” Only the official settlement value determines final intrinsic value.
Section titled “Related topics”

Authoritative sources

Section titled “Authoritative sources”