STX

Implied volatility · 30-day constant maturity

Term structure · constant maturity

31 consecutive sessions in contango (the normal upward slope).

Skew · risk reversal

Skew has been collected since 2026-07-30 only: the vendor serves no earlier history, so each percentile here is taken over all of it - the few weeks of readings there are, which the n beside it counts.

Next earnings: 2026-10-27 time unknown, stated by the vendor's estimate, first moves the 2026-10-27 session, no expected move served. As the vendor's calendar stood on 2026-09-22, not on the page's date.

DTE counts calendar days from 2026-09-21, the page's date and the earliest an entry could be made - not from the 2026-09-18 book the expiries and IVs come from, which would overstate it by 3 days; an expiry first listed after 2026-09-18 is not in the book and not here. A premarket report moves its own session and a postmarket one the next; one with no stated time is placed at the earlier of the two - or at the later, once the earlier is already in the 2026-09-21 close - so an expiry can be called spanning when it might not be, never the reverse. "spans +N": the expiry settles N calendar days after that session, and the line under it says whether the 28-DTE exit comes before it ("inside the exit": that date is already behind 2026-09-21, so it protects nothing); "clear N": it settles N days before it. Thesis = DTE − 28 (the hard exit is 21), cut to the last session before a report that comes first. Every expiry in the band is listed, and one that is not a third Friday is marked weekly — §1 of the trading rules admits no weeklies and no 0DTE, so those rows are context, not candidates; the mark is the calendar test on the date alone, and a monthly pulled back to a Thursday by a holiday carries it too. ATM IV is the vendor's at the 2026-09-18 close, on the out-of-the-money side of the listed strike nearest book spot: a display selection, not a statistic, read at that one strike, so "no IV at X" is about X and not about its neighbours. The expected move is the vendor's, for the report the expiry spans. Every row links to that expiry on the strike axis below.

Chain · one strike axis

Book as of 2026-09-18: 1 session behind 2026-09-21: no STX chain statistics (net_gex) dated after 2026-09-18 are knowable as of 2026-09-21, and no ticker has newer ones. The strikes drawn below are 2026-09-18's rows as stored now; the levels and statistics are the readings dated 2026-09-18, computed from those rows when the readings were derived, and a fetch of 2026-09-18 after that can revise rows. Open interest is what entered 2026-09-18 (OCC's settlement of 2026-09-17), valued at the 2026-09-18 close.

book spot $858.79 (unadjusted close, 2026-09-18) · call wall $900.00 (+4.80% from book spot) · put wall $800.00 (-6.85% from book spot) · max pain $800.00 (-6.85% from book spot, 2026-10-16 monthly)

Each level is stored as a distance from the book's own spot, so each is drawn at $858.79 × (1 + that distance) - the 2026-09-18 unadjusted close, the price the chain was taken at. That is why two prices appear on this page. STX headlines $877.33, its newest unadjusted close, on 2026-09-21; the book was taken at $858.79 on 2026-09-18, because the book trails the page by the one session counted above. Both are closes, both are dated, and neither is adjusted. Recomputing a wall on the newer close would put it at a level this book never had, so none of these is: they are the 2026-09-18 book's levels, on the 2026-09-18 close.

Dashed: 7 DTE or less, where the vendor's gamma is noisy. "mp": the monthly max pain describes.

Tradability of the 2026-10-16 expiry: 25 calendar days from 2026-09-21 (28 from the book date), outside the owner's 35–65 DTE entry window. Spreads are the NBBO stored with the 2026-09-18 chain snapshot - not a live quote, and not DESIGN J's quote at a trade (per-trade quotes are not collected) - as a percent of mid; a zero or missing bid, or a crossed quote, is drawn as × for no two-sided quote. The owner's floors are marked and filter nothing: spread 10% of mid, OI 500, and the strike nearest 0.20 delta on each side - call 1020 (Δ 0.19), put 750 (Δ -0.20).