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AM vs. PM Option Settlement: Control the Expiration Timeline

Identify the exact option series, its last trading time, AM or PM settlement inputs, official value, cash amount, and posting sequence.

Updated

For educational purposes only; not investment advice. Investing may result in loss.

Direct answer

AM settlement normally derives an option’s official exercise-settlement value from opening-session inputs on the expiration date. PM settlement normally derives it from closing-session inputs. These labels identify an observation convention, not a guaranteed clock time. They do not by themselves determine the last trading time, exercise style, cash or physical settlement, multiplier, value symbol, publication time, or broker posting time.

For a cash-settled position with official value S_settle, strike K, multiplier M, and contract quantity Q:

I_call = max(S_settle - K, 0) × M × Q

I_put = max(K - S_settle, 0) × M × Q

I is the gross cash credit to the long and gross cash debit to the short, before premiums, fees, tax, margin effects, or broker adjustments. Use the exchange-designated value for the exact series. A prior close, live index, related ETF, futures quote, option mark, or broker estimate is only a proxy.

Option type
Ready
Screen-based amount (not settlement)
$400
Official amount
$800
Settlement difference
$400

Cash settlement with a 100 multiplier. Only the official settlement value determines the contractual amount; the displayed level is a comparison only.

Separate the five clocks

  1. Last trading time: the final time the expiring series can be closed or rolled, including any product-specific curb or holiday schedule.
  2. Settlement observation: the contract-defined opening, closing, auction, or other prices used as inputs.
  3. Official value publication: the reporting authority calculates and publishes the exercise-settlement value, sometimes under a symbol different from the option root.
  4. Exercise processing: applicable exercise rules, broker cutoffs, and OCC processing determine which positions produce settlement obligations.
  5. Cash posting and reconciliation: the clearing and broker ledgers post debits or credits; corrections and account display can follow a different timetable.

For the current Cboe specifications, standard third-Friday SPX options are AM-settled and ordinarily stop trading on the preceding business day, while SPXW expirations are PM-settled and ordinarily trade until their expiration-day cutoff. This is a series-level distinction: seeing “SPX” in a platform is not enough. Verify the root, expiration, and product specification together.

An SPX special opening quotation (SOQ) uses each constituent’s official opening trade on its primary listing market. Constituents do not all open simultaneously. The SOQ is published only after the required openings are established, and a specified fallback applies when a constituent does not open. Consequently, the SOQ can differ from the prior close, the first displayed index level, the live index when the SOQ appears, and even that day’s displayed high-low range.

PM settlement usually uses expiration-day closing inputs, but it is still an official contract calculation. Closing auctions, trading halts, early closes, calculation rules, and the option’s own cutoff can separate the last tradable option price from the final settlement value.

AM or PM settlement is independent of:

  • exercise style: American, European, or another permitted schedule;
  • settlement method: cash, securities, or another deliverable;
  • listing cadence: standard monthly, weekly, daily, quarterly, or end-of-month;
  • contract scale: multiplier, adjusted deliverable, and quantity.

The close is not the settlement value

Assume one AM-settled index call and one put stop trading Thursday. The displayed index closes at 5,000. Friday’s constituent openings produce an official value of 4,930. Both options have strike 4,950, multiplier 100, and quantity 1:

Call: max(4,930 - 4,950, 0) × 100 × 1 = $0

Put: max(4,950 - 4,930, 0) × 100 × 1 = $2,000

At Thursday’s close, the call appeared 50 points in the money and the put appeared out of the money. Those readings did not determine settlement. The official Friday value reversed the apparent result after the options could no longer be traded.

For comparison, a hypothetical PM-settled series with the same strike, multiplier, and quantity but an official expiration close of 5,005 gives:

Call: max(5,005 - 4,950, 0) × 100 × 1 = $5,500

This does not make PM settlement safer or more profitable. It isolates the rule: the exact contract’s official observation determines intrinsic settlement. For a spread, calculate every leg from the same applicable official value, then net the cash; do not mix Thursday marks, Friday proxies, and official values.

Expiration control workflow

  1. Identify the series. Record option root, full symbol, underlying index, call or put, strike, expiration, quantity, and account.
  2. Lock the contract terms. Record exercise style, settlement method, AM or PM convention, multiplier, deliverable, official-value symbol, and calculation authority.
  3. Normalize the timeline. Put the last trading cutoff, observation session, expected publication, exercise cutoff, and expected cash posting in one timezone; adjust for holidays.
  4. Plan the untradeable interval. Stress overnight gaps, auction moves, staggered openings, halts, and proxy basis after the option can no longer be closed.
  5. Use the official value. Retrieve it from the exchange or designated reporting authority and retain the symbol, timestamp, and source; do not infer it from a chart.
  6. Calculate signed cash. Apply the formula to each leg and quantity, credit longs, debit shorts, and keep premium and fees separate from settlement.
  7. Reconcile the account. Match the official value, exercise or expiration record, gross leg amounts, net cash, fees, corrections, and residual positions to the broker ledger.

Principal risks

  • Series error: neighboring monthly, weekly, daily, mini, or end-of-month contracts can use different terms.
  • Untradeable gap: settlement inputs may form after the final opportunity to close the option.
  • Opening or closing dispersion: constituent auctions occur at different prices and, for openings, different times.
  • Proxy basis: an ETF, futures contract, or live index can diverge from the official calculation.
  • Symbol and data error: the option root, underlying display, and settlement-value symbol may differ.
  • Exceptional procedure: halts, missing openings, holidays, and exchange determinations can change inputs or timing.
  • Cash and margin pressure: a short debit, delayed posting, or broker liquidation can matter even when a spread has bounded contractual payoff.
  • Specification change: archived knowledge or a generic options chain can be stale; the current series document controls.

Common misconceptions

  • “AM means the previous close.” AM settlement generally uses specified opening inputs; any fallback is contract-specific.
  • “PM means the last price on my screen.” The official closing calculation, not an arbitrary quote, governs.
  • “The option remains tradable until the value is published.” Some AM-settled series stop the prior business day.
  • “A live index should equal the SOQ.” They use different, nonsynchronous price sets.
  • “European exercise implies AM settlement.” Exercise opportunity and settlement observation are separate fields.
  • “Cash settlement removes expiration risk.” It removes asset delivery, not price, timing, liquidity, cash, or operational risk.
  • “A defined-risk spread needs no reconciliation.” Each leg settles first under its contract; the account must reflect the correct net result.

Authoritative sources

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