By The Oracle · For education, not financial advice.
Last checked: 2026-11-08. Exchanges change hours and listings from time to time, so check the exchange’s product page or your broker before relying on any detail.
SPX and SPY options both follow the S&P 500, and both have a contract expiring every trading day, so both are popular for 0DTE trading. They are built differently. SPX options settle in cash, can be exercised only at expiration, and are about ten times the size of a SPY option. SPY options settle in shares, can be exercised on any trading day, and trade 15 minutes longer on expiration day, until 4:15 p.m. ET. Those differences decide what happens at the close, how much one contract controls, and when you can trade. Every source is listed at the end.
The two products, and a third
- SPX is an option on the S&P 500 Index itself, listed by Cboe. Nobody can own an index, so it pays cash. Same-day contracts use the symbol SPXW.
- SPY is an option on the SPDR S&P 500 ETF, a fund whose shares trade like a stock. Each contract covers 100 shares.
- XSP, the Mini-SPX, is an index option like SPX at one tenth of the size.
Side by side
| Feature | SPX (SPXW) | XSP | SPY |
|---|---|---|---|
| Settles in | Cash | Cash | Shares of the ETF |
| Exercise style | European | European | American |
| One contract, about | $650,000 | $65,000 | $65,000 |
| Expirations | Every weekday | Every weekday | Every weekday |
| Same-day contract stops | 4:00 p.m. ET | 4:00 p.m. ET | 4:15 p.m. ET |
| Early trading | Overnight, from 8:15 p.m. ET | Overnight, from 8:15 p.m. ET | From 7:30 a.m. ET on Cboe’s C1 exchange |
| Tax treatment | May differ (Section 1256) | May differ (Section 1256) | Standard |
Contract sizes are Cboe’s own approximation, with the S&P 500 at 6,500. Holidays can move or remove an expiration.
Settlement: cash or shares
Settlement is what happens to an option still open when it expires. The strike is the price written into the option. An option worth something if used now is in the money; one worth nothing is out of the money.
- SPX and XSP pay cash. The holder of an in-the-money option receives the difference between the settlement value and the strike, times $100, on the next business day. The seller pays it. Same-day SPXW contracts take their settlement value from the closing prices of the index stocks.
- SPY turns into shares. An in-the-money call becomes 100 shares bought at the strike, per contract; a put, 100 shares sold. If you sold the option, you can be assigned: made to take the other side.
One SPXW 6,500 call · pays (6,510 − 6,500) × $100 = $1,000 in cash. Nothing else happens.
One SPY 650 call · becomes 100 SPY shares bought at $650, a $65,000 position, unless it was sold before the close.
Ten SPY 650 calls · 1,000 shares, a $650,000 position.
A small account may not be able to pay for that. FINRA notes that a broker may close a share-settled option before the close if you lack the cash or shares to settle it. What happens at the bell, minute by minute, is in when do 0DTE options expire.
Exercise style: European or American
- European-style options, such as SPX and XSP, can be exercised only at expiration. If you sell one, you cannot be assigned early.
- American-style options, such as SPY, can be exercised on any trading day before expiration, whether they are in, at or out of the money. Early exercise of in-the-money calls becomes more likely as the ETF’s ex-dividend date nears: the cut-off for receiving its next dividend.
The difference matters most to sellers. Cboe points out a second one: an American-style option can even be exercised after the close when it finished out of the money. A cash-settled European option cannot.
Contract size
Both products use a multiplier of 100: the quoted price times 100 gives dollars. What differs is the price of the thing underneath.
- One SPX contract covers the index level times $100. With the index at 6,500, that is about $650,000 of exposure, by Cboe’s comparison.
- One SPY or XSP contract covers about $65,000, one tenth as much.
- The cost follows the same rule. An option quoted at 5.00 costs $500 per contract; one quoted at 0.50 costs $50.
For a beginner, size often matters most. One SPX contract behaves roughly like ten SPY contracts, so one position can be large before you notice. Cboe quotes SPX options in price steps of 0.05 ($5 per contract) under 3.00, and 0.10 ($10) above. A common habit is to decide the dollar loss first and size from there; risk management shows how.
Trading hours
- SPX trades from 9:30 a.m. to 4:15 p.m. ET, with a late “curb” session until 5:00 p.m. It also trades overnight, from 8:15 p.m. to 9:25 a.m. ET. On expiration day, the same-day SPXW contract stops at 4:00 p.m., or 1:00 p.m. on a half day.
- SPY options trade from 9:30 a.m. to 4:15 p.m. ET, including on expiration day. Since October 19, 2026, Cboe’s C1 exchange also opens them at 7:30 a.m., along with QQQ, IWM, GLD, XLF and a list of large stocks.
Why the 15-minute gap? The stock market’s regular session ends at 4:00 p.m. A same-day SPX contract is settled from those closing prices, so Cboe stops it at 4:00; otherwise it would trade after its value was fixed. Share-settled options get extra time so traders can close positions rather than take or deliver shares, Cboe says.
AM and PM settlement
SPX has one more wrinkle. Same-day SPX contracts are PM-settled: their value comes from closing prices on expiration day. The traditional monthly SPX contract, which expires on the third Friday, is AM-settled. Its last trade is usually on the Thursday before. Its value then comes from the opening prices of the index stocks on Friday.
So an AM-settled contract is never a 0DTE trade: it has stopped trading before its value is known. On the third Friday, the same-day SPX contract is the PM-settled SPXW, which Cboe lists for that date too. SPY has no such split; its options are PM-settled.
Taxes, briefly
Cboe notes that index options such as SPX and XSP may get different tax treatment from ETF options such as SPY, under Section 1256 of the US tax code. Whether it applies depends on the trader and the strategy. This guide gives no tax advice; ask a tax professional.
What it means for a beginner
- At the close, SPX and XSP end in cash. SPY can end in a share position you did not plan for.
- If you sell, SPX and XSP cannot be assigned early. SPY can, on any trading day.
- Neither is safe. A same-day option can lose its whole value within hours.
The risks themselves are in 0DTE options for beginners, and the other daily tickers in the 0DTE options list. Heavy same-day strikes can matter late in the day; 0DTE options and dealer hedging explains why, and MomoEdge’s gamma exposure tool estimates those dealer levels strike by strike.
Sources
- Cboe, SPX index options fact sheet (checked 2026-11-08).
- Cboe, SPX options specifications (checked 2026-11-08).
- Cboe, Equity Options Extended Trading Hours FAQ, updated November 2, 2026 (checked 2026-11-08).
- Cboe, extended trading sessions, October 19, 2026 (checked 2026-11-08).
- SEC, Release 34-105196, April 10, 2026 (checked 2026-11-08).
- OCC’s Options Industry Council, options exercise, assignment and options basics (checked 2026-11-08).
- FINRA, Zeroing In on an Options Trading Strategy: 0DTE (checked 2026-11-08).
FAQ
Is SPX or SPY better for 0DTE trading?
Neither is better for everyone. SPX settles in cash, cannot be assigned early and is about ten times larger per contract. SPY settles in shares, is smaller per contract and trades until 4:15 p.m. ET on expiration day. XSP offers cash settlement at about SPY’s size.
Do SPX options settle in cash?
Yes. An in-the-money SPX option pays the difference between the settlement value and the strike, times $100, in cash on the next business day. No shares change hands.
What is the difference between SPX and SPXW?
SPX is the traditional monthly contract. It is AM-settled on the third Friday, and its last trade is usually on the Thursday before. SPXW covers the PM-settled contracts, including every same-day contract.
Can SPY options be assigned early?
Yes. SPY options are American-style, so the holder can exercise on any trading day before expiration. Early exercise of in-the-money calls becomes more likely as the ETF’s ex-dividend date nears.
How big is one SPX option compared with one SPY option?
About ten times bigger. Cboe’s comparison, with the S&P 500 at 6,500, puts one SPX contract at about $650,000 of exposure and one SPY or XSP contract at about $65,000.
Words used here
- 0DTE: zero days to expiration; an option on its last trading day.
- Strike: the price written into an option.
- Exercise / assignment: the holder using the option; the seller made to take the other side.
- Cash vs share settlement: an expiring option pays cash, or turns into shares.
- European vs American style: exercisable only at expiration, or on any trading day.
- Multiplier: what the quoted price is multiplied by; 100 here.
- AM vs PM settlement: value set from opening prices, or closing prices.
- Curb session: a short session after the regular close.