SPX vs SPY Options: Taxes, Settlement and Assignment Explained

By Charlie Nguyen · Published Nov 4, 2026 · Quotes as of Nov 3, 2026 close · 12 min read

SPX options and SPY options both track the S&P 500, but they are not the same contract. SPX is cash-settled, European-style and gets Section 1256 60/40 tax treatment. SPY settles in shares, can be assigned early and is taxed like a stock option. Here’s how settlement, assignment, taxes and contract size differ, and how to pick the right one for your trading.

SPX vs SPY at a glance

Sources: Cboe SPX specifications, Cboe S&P 500 options comparison, Cboe Rule 5.4 minimum increments, IRS Pub. 550. Notional = last close × 100.

Settlement: cash vs shares

SPX is cash-settled. At expiration an in-the-money SPX option pays the difference between the strike and the settlement value, times $100, in cash on the next business day. No shares change hands, so you never end up long or short the market by surprise.

SPY is physically settled. Each contract is 100 ETF shares. If your short SPY put is assigned you buy 100 shares per contract; a short call is assigned and you deliver (or go short) 100 shares. That’s fine for a cash-secured put you wanted filled (see cash-secured puts to buy the dip), but it’s extra risk for a spread trader.

European vs American exercise. SPX options can be exercised only at expiration, so a short SPX leg can’t be assigned early. SPY options are American-style: the holder can exercise any business day. Early exercise is most likely on deep in-the-money options with little time value left, and on in-the-money calls the day before SPY goes ex-dividend, when the dividend is worth more than the option’s remaining time value. If your short call in a call spread gets assigned that night, you are short shares and owe the dividend.

AM vs PM settlement and 0DTE

• SPX monthlies (AM-settled): stop trading the business day before expiration (usually Thursday). The settlement value, SET (traders often call it the SOQ), is calculated from the opening prices of the S&P 500 stocks on expiration morning. It can land well away from Thursday’s close, so you carry overnight gap risk with no way to trade out.
• SPXW Weeklys and end-of-month (PM-settled): trade until 4:00 pm ET on expiration day and settle off the close. Cboe lists SPXW expirations every Monday through Friday, which is what makes 0DTE SPX trading possible.
• SPY: PM-settled, but settlement means shares, and option holders have until 5:30 pm ET to make a final exercise decision (more below).

For short-dated credit spreads, most SPX traders use the PM-settled SPXW series. Check the root (SPX vs SPXW) before you hold into expiration week.

Taxes: Section 1256 and the 60/40 rule

The IRS treats options on a broad-based stock index like the S&P 500 as nonequity options, which are Section 1256 contracts (Pub. 550). Options on SPY, an ETF that trades like a stock, are equity options and don’t qualify. Here is what Section 1256 changes (Form 6781 and instructions):

• 60/40 split: 60% of your net gain or loss is long-term and 40% short-term, regardless of how long you held the position. A 0DTE trade gets the same split as a one-year hold.
• Mark-to-market at year end: any SPX option still open is treated as sold at fair market value on the last business day of the year. You pay tax on open gains (and can deduct open losses) now, and adjust your basis next year.
• Form 6781: Section 1256 results go on Form 6781, Part I, then flow to Schedule D.
• Carryback option: an individual with a net Section 1256 loss can elect (box D) to carry it back 3 years against Section 1256 gains in those years. Corporations, estates and trusts can’t.
• Wash sales: the Form 6781 instructions say the wash sale rules don’t apply to Section 1256 contracts marked to market. SPY options and SPY shares are subject to the wash sale rules.

Example of the blended max rate (an example, not your rate). For 2026 the top federal rate on ordinary income and short-term gains is 37% (IRS 2026 adjustments) and the top long-term capital gains rate is 20% (IRS Topic 409). A trader in the top bracket pays 37% on short-term SPY option gains, but 60% × 20% + 40% × 37% = 26.8% on SPX gains. On a hypothetical $10,000 gain:

Hypothetical example at the top federal brackets only. It ignores the 3.8% net investment income tax, state tax, losses and your actual bracket. Lower brackets see a different gap.

As an advantage player I think of the tax edge as an EV boost: the same pre-tax edge keeps more after tax, every trade, with no extra risk. Over hundreds of trades that adds up like a better rule set at the table.

Contract size, ticks and liquidity

Size. Both use a $100 multiplier, but SPX is about 10 times the price of SPY (SPX 7,568.92 vs SPY 754.35 at the Nov 3, 2026 close, a ratio of 10.03). One SPX contract controls about $756,892 of S&P 500 exposure; one SPY contract about $75,435. SPY is the better fit for small accounts and fine-tuning size; Cboe’s XSP (Mini-SPX) is a cash-settled 1/10th-size alternative.

Ticks. SPY options quote in $0.01 at every price. SPX quotes in $0.05 under $3.00 and $0.10 above (Cboe). Per dollar of exposure the gap is smaller than it looks: a $0.05 SPX tick is $5 on one contract, while one penny on the 10 SPY contracts it takes to match is $10.

Bid-ask. In the ETFap liquidity snapshot (Oct 23, 2026 close, near-the-money options expiring Nov 20, 2026), the median SPX spread was $1.20 (0.92% of the option price) and SPY’s was $0.14 (1.06%). Ten SPY contracts to match one SPX would cross about $1.40 of spread vs $1.20 on SPX in that snapshot.

Commissions and fees. Most brokers charge per contract, and SPX carries extra exchange and index license fees per contract that SPY doesn’t. But one SPX contract replaces about 10 SPY contracts, so fees per dollar of exposure are usually lower on SPX. Check your broker’s and Cboe’s current fee schedule before comparing.

Capital efficiency for spreads. A 25-point SPX put spread risks up to $2,500 minus the credit with one ticket; the SPY equivalent is about 10 contracts of a $2.50-wide spread, 10 times the commissions and legs to manage, plus assignment risk on each.

Pin risk and after-hours risk

On SPY, expiration-day trouble comes from shares. In-the-money options are exercised automatically if they finish at least $0.01 in the money under the OCC’s exercise-by-exception procedure (OCC/OIC), but holders can still give contrary instructions until 5:30 pm ET (FINRA), and SPY keeps trading after the 4:00 pm close. If SPY closes near your short strike, you might be assigned or not, and news after the bell can move the shares before Monday’s open. With a spread, the short leg can be assigned while your long leg expires worthless: pin risk.

PM-settled SPXW settles in cash off the close. There are no shares to carry into the weekend, and after-hours moves don’t matter once settlement is set. (AM-settled SPX monthlies still carry the overnight gap risk described above.)

Example: one SPX put credit spread

To make it concrete, here is the SPX Desk’s model 7DTE put credit spread from the Nov 3, 2026 close. It’s an illustration of the mechanics, not a recommendation. The credit is $1.05, below the Desk’s $1.20 minimum, so the Desk’s own rules would skip it that day.

MODEL FIGURES. Cboe delayed SPXW quotes at the close (short 7355 put 7.10/7.40, long 7330 put 6.10/6.30), credit at the mids; SPX 7,568.92. POP = chance of any profit at expiration, POT = chance SPX touches the short strike before expiration, P50 = chance the spread can be bought back for half the credit; lognormal model at the short strike’s IV 16.1%, risk-free rate 4.03%, P50 from 40,000 simulated paths. See POP vs POT vs P50 and why strikes get touched more than you think. The 1-year IV rank badge above shows where SPX implied volatility sits today (IV rank explained).

Same trade on SPY: about 10 contracts of a $2.50-wide SPY put spread near SPY 733 (SPX 7355 ÷ 10.03), each short put assignable any day, with pin risk at expiration and short-term tax treatment on the gain. Check the strike against the Open Lines expected move calculator (why sellers work outside the expected move).

Which one fits which trader

• SPX fits credit spread and iron condor sellers, 0DTE and weekly traders, and larger accounts in taxable accounts. Cash settlement and European exercise take assignment variance off the table, and the 60/40 split is a built-in edge.
• SPY fits smaller accounts, traders who want shares (cash-secured puts, covered calls, the wheel), and anyone who needs 1/10th the size. In an IRA, where the tax edge doesn’t apply, SPY’s penny ticks can make it the cheaper trade.
• Advantage-play view: a good player removes every source of variance that doesn’t pay. Surprise assignment, weekend share risk and wash-sale headaches don’t add EV; on SPX they mostly disappear. Then size each trade so a bad streak can’t knock you out.

Sources: Cboe SPX product specifications (multiplier, ticks, exercise style, SET, trading hours); Cboe S&P 500 options comparison (AM/PM settlement, SPXW expirations, settlement type, 60/40); Cboe Rule 5.4 (SPY $0.01 increments); IRS Publication 550 (Section 1256, nonequity vs equity options); IRS Form 6781 and instructions (60/40, mark-to-market, wash sales, 3-year carryback); IRS Topic 409 and IRS 2026 inflation adjustments (20% and 37% top rates); OCC/OIC options exercise FAQ (exercise by exception, $0.01); FINRA (5:30 pm ET exercise cutoff). Prices: SPX and SPY closes and Cboe delayed option quotes; liquidity snapshot from Cboe delayed quotes.

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