SITREP #006 · WEEKLY SITUATION REPORT · 17–23 AUG 2026

The Contraction Lasted Exactly One Week

Overnight ATS notional rebounded 59 percent to $25.7B. Memory took 33.9 percent of the tape, the highest share in the nine-week series. And the year's largest biotech re-rating, a 1,700x one-night jump in Moderna's overnight notional, still could not crack the tape's top nine single names.

Sapinover Intelligence · Sunday, August 23, 2026 · Overnight figures computed from the three-venue pipeline; BlueOcean components verified against the master parquet.

00BLUF

//The Stack

Five layers of market plumbing, and where each one stands this week. Click any layer for the detail.

01The Tape Came Back

Three-venue overnight activity totaled $30.49B for the week. Tuesday was the heaviest session at $8.22B and the back half faded, with Thursday and Friday under $5B each. One venue-level note: Moon ATS reported no activity for the Friday session, on its own public data as well as in our pipeline, so Friday's total reflects two venues. We have an open question in with the operator side; the other two venues printed normally all five nights.

The names underneath

Note the split inside memory itself: SanDisk's median timing differential ran -58.9 basis points against Micron's +58.0 in the same week, on the two heaviest symbols on the tape. The overnight session was consistently paying up for one memory name relative to its subsequent open and consistently underpricing the other. Nvidia, which reports Wednesday, ran a near-flat +6.3 basis points on $374M, the calmest large print in the table.

02A Gap That Ran Both Ways

Last week's edition flagged sessions where the overnight bid did not carry into the opening print. This week produced the sharper version: the two measures disagreed by double digits in both directions, in consecutive sessions.

Wednesday night, the session after the Moderna readout, only 40.4 percent of symbols traded above their prior close overnight, yet 68.3 percent opened above it. The overnight tape was 28 points more cautious than the morning turned out to be. Thursday night inverted: 71.6 percent bid overnight, 37.5 percent opened higher, a 34-point gap in the opposite direction and the widest in either direction across the two editions we have tracked it.

Two consecutive sessions, two double-digit disagreements, opposite signs. Whatever the overnight session was pricing this week, the opening auction repriced it, twice.

The honest read stays the same as last week, with more evidence: overnight positioning and opening price discovery are different mechanisms run by different participants, and in event weeks the handoff between them is loose. Friday, with the event flow spent, the two measures converged to within six points.

03The Event the Tape Absorbed

On Wednesday, August 19, Merck and Moderna announced that the Phase 3 INTerpath-001 trial of intismeran autogene plus KEYTRUDA met both survival endpoints in resected melanoma, the first late-stage success for an mRNA cancer vaccine. Moderna closed the session at $174.38 against $62.96 the day before, then gave roughly a quarter of it back on Thursday.

The overnight tape's response is the cleanest single-name event print in the series so far:

A name whose median overnight print all summer was $365K, and which had not cleared $5M on any single night, printed $237.0M on the session after the readout, then $46.0M the night after that. The spike is enormous in relative terms and modest in absolute ones: $237M ranks below every core memory and semiconductor name for the week. The overnight market repriced a $24B biotech overnight, and the tape's structure barely moved. That asymmetry, huge relative response inside a narrow absolute footprint, is what an institutionally concentrated session looks like from the inside.

04One Venue Filing

One Form ATS-N amendment landed in the window. On August 17, IntelligentCross filed a Material Amendment introducing functionality that lets a subscriber send orders to the ATS and have them forwarded to the IntelligentCross SOR without entering the ATS matching engine. Routing is opt-in only, and a subscriber can invoke it two ways: a per-order FIX tag designating a specific SOR strategy, or a session-level configuration keyed to order attributes such as type, time-in-force, display instructions or size.

The mechanics are narrow but the role change is not. An ATS offering itself as a front door to its operator's router, for orders that never touch its own book, sits somewhere between a venue and an access layer. The filing also discloses what order information the ATS passes to the SOR for opted-in subscribers, which is the detail a routing desk will want to read in full. Source: Form ATS-N/MA, accession 0001708826-26-000015, filed August 17, 2026.

For the two venue filings covered in depth last edition, PureStream's operator- classified Liquidity Maker pool and OneChronos's pre-market extension, the full analysis remains at Two Venues, Opposite Moves.

05What We Published

Five reports since SITREP #005, all on execution economics and measurement. Together they form a single argument: the public files measure less than they appear to, and what they do measure is worth reading closely.

06Forward Calendar

• Nvidia reports Wednesday, August 26, after the close. Consensus revenue sits near $92B. Nvidia ran the calmest large print on our tape this week, +6.3 basis points median on $374M. Whether that composure survives the print is the single best test of the overnight session's read on the AI cycle. Marvell follows Thursday.
• Core PCE prints Wednesday morning, Jackson Hole runs Thursday to Saturday. The Fed chair speaks Friday morning. An inflation print and a policy address bracketing the Nvidia report makes Wednesday to Friday the densest macro stretch since July.
• Does memory hold a third of the tape? 33.9 percent is the series high. One week is a print; two would start to look like the summer concentration reasserting itself at a higher level.
• Does Moon print Sunday night? Friday was the first session in the life of our pipeline where Moon itself reported zero activity on an otherwise healthy feed. Whether Sunday's session resumes normally is the first thing we will know Monday morning.

07Get SITREP

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SITREP is a weekly situation report on market structure, published Sundays. Overnight notional figures reflect Sapinover's three-venue pipeline and are not comparable to full-market consolidated volume. This analysis is for information only and is not investment advice, a recommendation, or a solicitation. For methodology see the support page.