October's monthly SPX options expire on Friday, October 16. Five days later, on Wednesday, October 21, the October VIX futures and options settle. Most equity traders know the first date and ignore the second. They shouldn't: VIX expiration week is when a large stack of volatility hedges rolls off, and the way VIX settles creates a specific set of flows in SPX options on that Wednesday morning.
When VIX expires
Standard VIX futures and options do not expire on the third Friday. They settle on a Wednesday that falls 30 days before the next month's standard SPX expiration. Depending on the month, that Wednesday falls two days before that month's SPX OPEX or five days after it. This quarter has both:
- October 21 (30 days before the November 20 SPX expiration), five days after October's OPEX on the 16th
- November 18 (30 days before December 18), two days before November's OPEX on the 20th
- December 16 (30 days before the January 15, 2027 expiration), two days before December's OPEX on the 18th
These dates follow from the published rule; check Cboe's expiration calendar before trading, since holidays can shift them.
How the settlement number is made
VIX contracts do not settle to the VIX index you see quoted on screen. They settle to a Special Opening Quotation, or SOQ, published under the ticker VRO. The SOQ uses the same formula as VIX, but instead of live quotes it uses the opening prices of the SPX options series that go into the calculation on settlement morning.
That detail matters. On VIX expiration morning, anyone with a position that depends on the settlement value has a reason to trade the SPX options that feed the SOQ at the open. Because the calculation leans on out-of-the-money puts and calls across a strip of strikes, the opening auction in those series can be busy — and occasionally the SOQ prints noticeably away from where spot VIX traded just before or after. It is a known feature of the product, not a malfunction.
Trading in the expiring VIX options ends before the settlement process, so by Wednesday morning the positions are locked and only the settlement value is left to determine.
Why the week matters for the SPX map
VIX calls are one of the most common tail hedges in the market. Funds buy them; dealers who sell them hedge by holding long volatility elsewhere — long VIX futures, or long downside SPX options. As VIX expiration approaches, those hedges have less and less to protect. Once the contracts settle, the hedges can come off.
In SPX terms, unwinding long put hedges means selling puts or letting them lapse. Less put demand tends to soften implied vol, and softer vol works through vanna: dealers short puts see those puts lose delta, and the short hedges against them get bought back. That chain is the same one that drives the drift around SPX OPEX described in vanna and charm around OPEX. In months where VIX expiration follows SPX expiration by a few days, the two can stack.
The flip side is that once those hedges roll off, the market can be less protected than it was the week before. If a shock hits after VIX expiration, the positioning that would have cushioned it may already be gone.
The window between the two expirations
Put the dates together and October has a clear sequence:
- Friday, October 16: monthly SPX expiration. A large slice of index gamma rolls off.
- Monday, October 19 and Tuesday, October 20: the map is lighter, with less open interest pinning price. The next monthly cycle is still building.
- Wednesday, October 21: VIX settlement at the SOQ, with opening-auction activity in the SPX options that feed it.
Traders often say volatility is "freer" in this window. There is a mechanical case for it — less pinning gamma after OPEX, fewer volatility hedges after VIX expiry — but it is a tendency, not a rule, and plenty of months pass quietly. Use it as a reason to check the map more often, not as a trade by itself.
Reading implied vs realized in this window
VIX measures the 30-day implied volatility the SPX options market is pricing. Settlement week is a good time to compare that number with what the index is actually doing. If implied vol stays well above realized into and through VIX expiration, the premium is still there for whoever is selling it; if realized starts catching up with implied after the hedges roll off, that is a sign the cushion is thinning. Realized vs implied vol explains how to read that spread.
A hypothetical walk-through
Suppose that after the October 16 expiration, SPX sits at 5,980 with the gamma flip at 5,930 and the call and put walls now much smaller than the week before, because the monthly open interest has expired. VIX is at 17 and VIX futures expiring October 21 trade close to it.
- Monday and Tuesday: with the pinning gamma gone, the daily range widens even though price stays above the flip. Mean-reversion still works, but the walls are softer, so targets should be closer than they were last week.
- Wednesday open: the SPX options in the VIX strip trade actively at the open. The SOQ prints at, say, 17.6 while spot VIX trades 17.2 a few minutes later. Nothing about the index itself changed; the settlement simply reflected the opening auction.
- After settlement: if hedges come off and implied vol eases, the vanna support for SPX is a reasonable expectation. If instead implied vol rises after the hedges are gone, that is a warning that the market is now paying up for protection it no longer holds.
Checklist for VIX expiration week
- Know the date. It is a Wednesday, either two days before SPX monthly OPEX or five days after it.
- Check how much of the gamma map rolled off at Friday's SPX expiration.
- On Wednesday morning, expect active opening trade in SPX options and do not read much into the SOQ print versus spot VIX.
- Watch implied vol after settlement. Easing vol supports the vanna drift; rising vol with fewer hedges in place is a risk flag.
- Re-mark the gamma flip and walls as the next monthly cycle's open interest builds.
VIX expiration does not move the market by itself, but it changes who is hedged and how, and that changes how the next shock gets absorbed. If you are new to the dealer-positioning framework, what is gamma exposure is the place to start. To watch the gamma flip and walls rebuild through each cycle, see GEXRadar's plans.
For educational and informational purposes. Not financial advice; options and futures trading involves substantial risk of loss. All prices in this post are hypothetical. Confirm expiration dates with Cboe.