Special Opening Quotation (SOQ): How AM-Settled Index Options Settle
Reviewed by Leon Moyer - Published October 9, 2026 - Last reviewed October 9, 2026
In this lesson
Explain how the special opening quotation is calculated, which index options settle to it, why it can differ from the prior close and the opening index value, and what holding an AM-settled position into it risks.
The special opening quotation (SOQ) is an index value calculated from the official opening trade price of every component stock on settlement day, and it is the number that decides what an AM-settled index option pays. For standard third-Friday S&P 500 Index (SPX) options, Cboe publishes that settlement value under the symbol SET.
SPX vs SPXW Options explains the difference between AM and PM settlement. This lesson covers how the SOQ is built, why it rarely matches a screen price, and the risk of holding into it.
What is the special opening quotation?
According to Cboe's guide to settlement of standard, AM-settled SPX options, the exercise settlement value for these options "is based on a special opening quotation (SOQ) of the S&P 500 Index that is calculated on their expiration days (typically the third Friday of the expiration month)." The same guide says the SOQ uses the opening trade price of each constituent stock in its primary market, and that the index provider, S&P, calculates it.
Each opening price is set on the stock's primary listing exchange, usually through an opening auction. Cboe says those auctions aim to open each stock "at the price that maximizes the quantity of shares transacted." If a stock does not open that day, its prior-day last trade is used, according to the guide.
The payout then follows the formula from Cash-Settled Options: intrinsic value at the SOQ times $100, paid in cash the business day after expiration.
From Thursday's last trade to the SOQ
Last trading day
Usually Thursday for AM-settled SPX
Friday open
Each stock opens in its own opening auction
SOQ (SET) set
Only after every stock has opened
Next business day
Settlement amount paid in cash
Why can the SOQ differ from the open and the prior close?
It is not the first index value of the day. The S&P 500 is updated continuously from the last trade in each stock. Stocks do not all open at the same moment, so for a while the published index blends fresh trades with the prior day's closing prices. Cboe says the SOQ "is not calculated until all of the constituent stocks of the S&P 500 Index have opened for trading," so it is not tied to any time of day.
It is not a single traded price. It is a calculation from about 500 separate opening trades, some no longer current by the time the last stock opens. So it will usually differ from the index on screen when it is published, and Cboe notes it "may fall outside of the open, high, low or closing values" of the index that day.
Cboe's guide looked at 61 March quarterly expirations from March 2009 to March 2024. The SOQ's difference from the index open ranged from -0.98% to +1.00%, and the median difference from the prior day's close was 0.16%. Usually small, but not always.
Which index options settle to an SOQ?
Only AM-settled ones, such as standard SPX and RUT.
Cboe's SPX specifications and RUT specifications both define the settlement value from "the opening sales price in the primary market of each component security on the expiration date," and both say trading in the standard options ordinarily ends the business day before, usually a Thursday. The RUT specifications list RUTW as PM-settled, and for PM-settled end-of-month SPXW, Cboe's end-of-month SPX specifications use "the last (closing) reported sales price" of each component instead.
What is the risk of holding into the SOQ?
Trading in expiring standard SPX options ordinarily ends the business day before expiration, usually Thursday, and the SOQ comes from Friday's opening auctions. Overnight, the expiring contract cannot be traded, and whatever moves stocks before the open goes straight into the settlement value.
Worked example
Example: a short SPX put settled at an SOQ well below Thursday's close
All index levels are hypothetical. A month before expiration, with the S&P 500 at 6,000, you sell one AM-settled SPX 5,900 put for 52.40, collecting 52.40 x $100 = $5,240. That is the free profit calculator's model value at 15% implied volatility, rounded to the 0.10 tick.
On Thursday, the last trading day, the index closes at 6,000 again. The put is 100 points out of the money, and the same model values it at about 0.25, so buying it back would have cost about $25. You hold it instead.
- If the SOQ is 6,030: the put finishes out of the money. You owe nothing and keep the $5,240.
- If the SOQ is 5,820: overnight news drags Friday's opening prices down 3%, far beyond the fraction-of-a-percent gaps typical in Cboe's data. The put's intrinsic value is 5,900 - 5,820 = 80 points, so you are assigned and debited 80 x $100 = $8,000 in cash. Net of the premium, you lose $2,760.
- Break-even: 5,900 - 52.40 = 5,847.60 at settlement.
The put's holder is credited the same $8,000. Once trading in the expiring option ended on Thursday, nothing done to the option itself could change the result.
Illustrative and hypothetical. The ticker and prices are invented for teaching, and the figures exclude commissions, fees, margin interest and taxes, which reduce real results. Past or hypothetical outcomes do not indicate future results.
One AM-settled SPX 5,900 put sold for 52.40, at settlement
Hover or tap the chart, or focus it and use the arrow keys, to read any price.
Open this trade in the free calculatorShow as table
An uncovered short index option held into an AM settlement carries overnight gap risk. After trading in it ends on the last trading day (usually Thursday), the expiring option itself can no longer be closed or adjusted. Other instruments can offset some of the exposure, with risks of their own; closing the option before its trading ends is the only way to remove it. A short put loses $100 per contract for every point the SOQ settles below the strike, less the premium collected, up to the strike x $100 minus the premium if the index went to zero: $584,760 for the 5,900 put above. A short call loses $100 per point above the strike, less the premium, with no upper limit.
The same short put, settled at Thursday's close versus the SOQ
Cash the seller pays at settlement
Result of the trade, net of premium
How do you find the settlement value after the fact?
Cboe posts past values on its Index Settlement Values page, and your broker shows the cash credited or debited for each settled contract in your account activity or statement.
For your records, the option's exit price is its intrinsic value at the SOQ (80.00 points in the example), not Thursday's close or an intraday index print. Record that with the expiration date as the exit date, plus the SOQ and the cash amount, which posts the next business day.
Check your understanding
Thursday's close is 6,000 and the SOQ is 5,820. What does one long AM-settled SPX 5,900 put pay?
Show answer
$8,000 in cash: (5,900 - 5,820) x $100, credited the business day after expiration. Thursday's close does not enter the calculation.
At 10:00 a.m. ET on expiration Friday the S&P 500 is trading at 5,860, and Cboe publishes a SET of 5,820. Which number settles your standard SPX option?
Show answer
The SET of 5,820. It is calculated from each stock's opening trade, so it can differ from any index value shown during the session.
Key takeaways
- The SOQ is an index value built from each component stock's official opening trade on settlement day.
- It settles AM-settled index options such as standard SPX (published as SET) and standard RUT (RLS); PM-settled series use the close.
- It has no fixed time and can differ from the prior close, the opening index print, and even the day's high or low.
- Trading in the expiring options usually ends Thursday, so any overnight move flows straight into the settlement amount.
- An option settled at the SOQ exits at its intrinsic value there; record the SOQ alongside it.
Common questions
What is the special opening quotation (SOQ)?
It is the value of an index calculated from the official opening trade price of every component stock on settlement day. It sets the exercise settlement value of AM-settled index options, such as standard third-Friday SPX options, which Cboe publishes under the symbol SET.
What time is the SPX SOQ calculated?
There is no fixed time. Cboe says the SOQ is not calculated until every S&P 500 stock has opened and its official opening price is set, so it is usually calculated after the index itself has started updating that morning.
Why is the SPX settlement value different from the opening price?
The index value shown at the open mixes new trades with the prior day's closing prices for stocks that have not opened yet. The SOQ uses each stock's opening trade (or, for a stock that does not open, its prior-day last trade), so the two can differ, and Cboe notes the SOQ can even fall outside the day's high or low.
Which options settle on the special opening quotation?
AM-settled index options. Cboe's specifications show standard third-Friday SPX options (settlement symbol SET) and standard RUT options (symbol RLS) settle on opening prices. PM-settled series, such as end-of-month SPXW and RUTW, use the close instead.
Where can I find the SPX settlement value after expiration?
Cboe posts past settlement values on its Index Settlement Values page, and your broker shows the cash credited or debited for each settled contract on your account activity or statement.