Quadruple Witching 2026: Dates and What Actually Happens

The next quadruple witching session is Friday 18 September 2026. It is the quarterly expiry when stock index futures, index options, single-stock options and single-stock futures all settle in the same session — and, in the same closing print, index funds execute the S&P quarterly rebalance. Expect two to three times normal share volume and a violent closing auction. What it does not reliably deliver is direction: across the last four witching sessions the S&P 500 moved -1.5%, +0.5%, +0.9% and +1.1%, with the sign set by macro news each time, not by the expiry.

What quadruple witching actually is

Four classes of derivative expire together on the third Friday of March, June, September and December:

• Stock index futures — e.g. the E-mini S&P 500 quarterly contract.
• Stock index options — SPX, NDX and the rest of the index complex.
• Single-stock options — the standard monthly series on individual names.
• Single-stock futures — the fourth leg, which is why the day is called "quadruple".

Single-stock futures barely trade in the US any more, which is why most desks and most news wires now just say triple witching. The two terms describe the same session on the same date. If you searched for one and landed on the other, you have not missed anything.

The mechanical effect is concentration. Every expiring contract has to be settled, closed or rolled into the next quarter inside one session, and the bulk of that flow is not discretionary — it is market makers unwinding hedges as their gamma exposure evaporates at the bell. That is what produces the volatility spike and the outsized closing cross, and it is also why the move often looks meaningless the following Monday.

Quadruple witching dates: 2026 and 2027

The rule is fixed — third Friday of the quarter-end month — so the calendar is knowable years ahead. The only thing that shifts it is an exchange holiday.

Quarter	2026	2027
Q1	Friday 20 March	Friday 19 March
Q2	Thursday 18 June*	Friday 18 June
Q3	Friday 18 September	Friday 17 September
Q4	Friday 18 December	Friday 17 December

*Juneteenth fell on Friday 19 June 2026 and US equity markets were closed. The whole expiry was pulled forward to Thursday 18 June — a detail that caught out a lot of calendar tools, several of which still list 19 June. There is no such conflict in September: 18 September 2026 is a full trading day.

What the last four witching sessions actually did

This is the part that most explainers skip. Below are the S&P 500 closes for the four most recent witching sessions, taken from Associated Press end-of-day index reports.

Witching session	S&P 500 close	Day move
Fri 19 Sep 2025	6,664.36	+0.5%
Fri 19 Dec 2025	6,834.50	+0.9%
Fri 20 Mar 2026	6,506.48	-1.5%
Thu 18 Jun 2026	7,500.58	+1.1%

Three up, one down, and an average of roughly +0.25% — statistically indistinguishable from any other Friday. More useful than the average is the dispersion: the range from -1.5% to +1.1% is wide, and in every one of those four cases the driver was identifiable macro news, not the expiry. March 2026 fell because oil rallied and rate-cut hopes collapsed. June 2026 rose 1.1% into a reported $8.3 trillion of expiring notional because the Iran war had just ended and semiconductors ripped; the VIX fell 11% to 16.40 on the day.

Our read: treat witching as a liquidity and slippage event, not a signal. It changes how you should execute, not what you should own.

The S&P rebalance lands in the same closing print

The September index changes are announced in the first week of the month and take effect before the open on the Monday following the expiry — in June 2026 that was Marvell Technology and Flex joining the S&P 500 effective 22 June, the trading day after the 18 June witching. Passive funds tracking the index do not trickle into new constituents; they buy them at the rebalance print, which is precisely the closing auction on witching day.

That is why the last thirty minutes of a witching session can print volume larger than the preceding four hours, and why a stock being added to or dropped from an index can move several percent in the cross with no news attached. If you hold a name involved in an index change, that closing auction is a real risk event for your fill.

The setup into 18 September 2026

Markets are going into this one on the back foot. As of the close on Tuesday 1 September 2026:

• S&P 500 7,631.47, down 54.67 points (-0.7%) on the day, up 11.5% year to date.
• Nasdaq composite 26,099.77, -1.0%; Dow 52,766.88, -0.8%; Russell 2000 2,920.13, -1.2%.
• 10-year Treasury yield 4.79%, higher on the session after renewed US strikes on Iran.
• WTI crude closed above $90 for the first time in more than a month, with Brent up 4.6%.
• VIX 14.92 at the 31 August close (CBOE via FRED) — still low, and it rose on 1 September.

The combination that matters here is a low volatility index against a rising oil and rising yield backdrop. Cheap options plus a genuine macro shock is exactly the mix that turns a routine expiry into a disorderly one, because hedges that were bought cheaply get monetised all at once. That is a risk to size for, not a forecast — and if oil retraces and yields settle, 18 September will most likely pass as a high-volume, low-information Friday like most of them do.

For the wider year-end picture, our S&P 500 forecast for 2026 sets out the strategist targets and the valuation maths behind them. For how a single macro headline reshapes a session, see our breakdown of the August jobs-report session.

How to actually handle the day

• Check your options positions the week before. Anything you hold that expires on the 18th needs a decision — close, roll or accept assignment — made deliberately, not at 15:55 on the day.
• Use limit orders, especially into the close. Spreads widen and the auction imbalance can print far from the last trade. Market-on-close orders in a witching auction are how retail accounts get bad fills.
• Do not read the day's move as a trend. Judge direction on the following Monday and Tuesday, once expiry flow has cleared.
• Know whether your holdings are in an index change. The announcement lands roughly two weeks ahead; that is your warning.
• Mark the date. Our economic calendar flags the macro releases that will decide whether this expiry is quiet or not.

If you trade index products around these dates, our desk publishes levels and setups on the indices signals hub, and you can open a trading account if you need index CFD access. Nothing here is investment advice: derivatives expiries amplify both directions, and position sizing is the only reliable protection.

How this was produced

Dates were derived from the exchange rule (third Friday of March, June, September and December) and cross-checked against the 2026 US equity holiday calendar, which is what surfaced the Juneteenth conflict in June. Index closes and day moves come from Associated Press end-of-day reports for each session; the VIX level is the CBOE series published by the St. Louis Fed. The June 2026 rebalance effective date comes from S&P Dow Jones Indices' own announcement. Written by our options and derivatives desk and reviewed before publication.