SomerQuant Weekly: Week of September 14–18, 2026

SomerQuant Weekly · Week of 14 – 18 September 2026 · Options flow & dark-pool research · SomerQuant

Week of 14 to 18 September 2026. The week’s read. The index finished almost exactly where it started and took a detour to get there. SPY closed the week at 761.69 against 764.29 a week earlier, a give-back of 0.34%, after three consecutive lower closes carried it to 754.05 on Wednesday and an overnight gap carried most of it back on Thursday. The regime classifier moved out of the Bull family and read Neutral on all five sessions, and the quarterly expiration on Friday put $117.73B through our $100M-and-above dark-pool board, more than the other four sessions of the week combined.

The MPI column is taken from the published MPI history file, stamped to each session. The 16 September edition published no MPI reading for its own session because the composite had not yet stamped one when that late edition went out; the 56 shown here is the value the history file now carries for that date.

The week’s radar: scorecard

Confirmation means the flow showed up as new open interest. It is not a measure of price outcome or profit.

The largest confirmed open-interest build of the week was the VIX 21 October $24 calls, flagged on Thursday: 50,859 contracts traded and open interest rose 45,209, a ratio of 0.89. The MTDR March 2027 $70 calls flagged on Monday were the cleanest conversion by proportion, turning 30,690 contracts of volume into 30,464 of fresh open interest at 0.99.

The misses are named as plainly as the confirmations. The clearest was the SPX 19 March 2027 $8,000 calls flagged on Thursday: 1,323 contracts traded and 31 stayed, a ratio of 0.02. The SMH October $545 puts flagged on Tuesday added 1,903 of open interest on 20,222 contracts of volume, a ratio of 0.09, and the AMZN November $290 calls flagged the same session saw open interest fall by 1,988, which is the shape of a position being closed rather than a build. Two of Thursday’s three non-confirmations, the IWM 18 September $315 puts and the QQQ 18 September $745 puts, were contracts expiring the next day, so closing activity is the expected outcome there rather than a failure of the screen.

One link in the chain is missing and stays missing. The contracts flagged on Wednesday 16 September were never checked, because the 17 September edition published without an open-interest confirmation section while the desk was dark during the move from AZTMM.com to SomerQuant. Those nine contracts are not counted in the 27 above, and they are not scored retrospectively. The scorecard covers three of the week’s four flagging sessions.

What happened this week

Monday set the tone and semiconductors set Monday. NVDA closed at 210.96, down 3.36% from Friday, SPY gave back 0.45% to 760.88 and QQQ lost 0.80%. Market-wide net call-minus-put premium sat below zero for 64 of the session’s 79 five-minute readings and finished at −$72.1M. The dark pool was the quietest session on our record at $18.52B across 74 prints, and ETF share fell to 46.8%, the only reading of the week below half until Friday. The MPI read 60 and the regime label moved to Neutral.

Tuesday inverted the dark pool and kept the tape heavy. The $100M-and-larger board more than doubled to $39.81B across 127 prints in 85 names, the broadest session we had logged at that point. SPY opened at its session high of 760.35 and closed 0.46% lower at 757.39, and net premium sat below zero for 74 of 79 readings before finishing at −$218M. With a Federal Reserve decision due the following afternoon, the size showed up in index vehicles and sector baskets rather than in single names. MPI 59.

Wednesday was the week’s reversal and its low. SPY opened at 759.50, worked up to 761.67 by 11:45, then lost twelve handles into a 749.60 low at 15:25 and closed at 754.05. The options tape kept the same clock: net premium peaked at +$191M in the 11:45 bar, crossed zero once at 14:55 and fell to a −$169M trough at 15:25. The board came to $28.82B and was 84.3% ETF, the most index-weighted session of the five. MPI 56, the week’s low reading.

Thursday gave the whole week back overnight and then did nothing. SPY opened at 763.15, 1.21% above Wednesday’s close, and finished at 762.60, a whisker below its own open, having traded a 3.61 point cash range. The one unusual thing on the tape was in SPY options, where call premium ran $4.27B against $908.7M of puts on the session before the fund went ex-dividend. The board was $27.59B, 65.5% ETF. MPI 62.

Friday was the quarterly expiration and the board swallowed the week. Our $100M-and-above dark-pool universe came to $117.73B across 379 prints in 128 names, almost all of it clearing in the closing cross, and the largest single print was $9.36B of SPCX at 152.71, the exact closing price. ETF share collapsed to 25.3% because the single-stock rebalance notional dwarfed the trackers. The index itself barely moved: SPY finished at 761.69 against 762.60, down 0.12%, on a day it went ex-dividend $1.888834, so the fund was fractionally higher on a total-return basis while the quote showed red. MPI 63.

Why it matters

Three of the five sessions closed lower and the week still ended within a third of a percent of where it began, because the one session that rose did all of its rising while the cash market was shut. That is the shape of a tape where the risk is being repriced overnight and worked off slowly during the day, and it is visible in the options ladder as well as the price. On Monday, Tuesday, Wednesday and Friday the heaviest SPY strike shelves carried more put premium than call premium, nine of ten on Monday and nine of ten on Friday. Thursday was the exception, and on Thursday every one of the ten heaviest shelves sat below spot and carried more call premium, which is what an ex-dividend day does to a call ladder rather than what a change of view does.

The dark-pool board tells a second story about where size went. Excluding Friday’s expiration, the four ordinary sessions ran between 46.8% and 84.3% ETF, and the two heaviest of those four were also among the most ETF-weighted. Index machinery, not name-level accumulation, carried the notional through a week in which the regime classifier read Neutral on every session.

What to watch next week

The levels the week leaves behind are Friday’s low of 757.97 and its high of 762.00, with Wednesday’s 749.60 low and Thursday’s 763.57 high framing the wider week. On Friday’s premium ladder the heaviest shelf below spot was the 745 strike at −$19.7M net, 2.2% below the close, and the only shelf of the ten carrying more call premium than put premium was 720 at +$12.0M net.

On dates, two items carried through from the week’s own tape. A 25 September SPXW line and a 25 September MU put line both appeared on Friday’s flagged-events screen, so that weekly expiry is already carrying size. MU earnings are dated 30 September, which falls the week after next rather than next week. No wider economic or earnings calendar is published in this edition, because the run that produced it could not verify one from a licensed source.

Themes on our radar

The five sessions put $232.5B through the $100M-and-above screen. Splitting each session by its published ETF share gives $105.9B in ETF wrappers against $126.6B in single names, or 45.5% ETF across the week. That single-name majority is entirely a Friday effect: on the four sessions before the expiration the board ran 46.8%, 62.9%, 84.3% and 65.5% ETF.

The table below was assembled from the five daily editions and then screened again across the whole week, from 09:30 on 14 September to 16:00 on 18 September, keeping flow lines of $1M premium or more and ranking them by premium. The screen agreed with four of the five themes the dailies had produced. It corrected one detail and added one theme, both noted in the rows.

Source: Unusual Whales (licensed, 15-minute delayed); week of 14 to 18 September 2026, screened Saturday 19 September 2026; delayed.

Unusual by size

This table is screened independently of the daily editions: off-exchange common-stock prints of $10M or more during regular hours across the five sessions, each print worth at least 10% of that name’s 30-day average volume, keeping the five largest by that multiple and one row per name.

Source: Unusual Whales (licensed, 15-minute delayed); week of 14 to 18 September 2026, screened Saturday 19 September 2026; delayed.

The largest of the five was NHIC on Friday, where 3,000,000 shares printed against an 831,379-share 30-day average, or 3.61 times a normal day’s volume in that name. Only one of the five clears the $100M screen behind the week’s boards: OTIS, at $116.41M on Friday. The other four range from $30.33M to $67.62M and could not clear it, which is a screen difference rather than a disagreement, and where the two are quoted together the headline board figures use the $100M screen. One number moved between screens: NHIC reads 3.61 times here against the 5.10 times published in Friday’s daily edition, because the weekly screen carries an 831,379-share 30-day average for that print where the daily carried 587,755. The weekly figure is the one used above.

Insider buying

Eight open-market purchases of $1M or more were disclosed on Form 4 during the week of 14 to 18 September, and the six largest by value are below. The largest was 525,000 shares of PMTS at $21.50, or $11.29M, reported by a 10% owner. Form 4 is filed after the trade rather than with it, which is why this section belongs to the weekly and not to a daily edition: the lag across these six rows runs from same day to three days, and two of the six report trades that happened on the Friday before the week began.

Source: SEC Form 4 filings via Unusual Whales (licensed, 15-minute delayed); filings dated 14 to 18 September 2026, retrieved Saturday 19 September 2026. The DGICA and ECL prices are the average across two reported transactions in the same filing. The two filings that fall outside the six rows above are TFC at $1.02M and KRMN at $1.01M, both filed on 18 September. These are reported as filed and nothing is inferred from them.

Positioning into next week

The week ends with the classifier reading Neutral for the fifth consecutive session and the MPI at 63, its highest reading of the week and four points above Wednesday’s 56. The index closed 0.34% below the prior Friday, the options ladder is put-heavy again after Thursday’s ex-dividend distortion, and the largest confirmed open-interest build of the week was in October VIX calls struck far above the index rather than in anything directional on the index. Friday’s enormous board is a rebalance artefact and carries no directional read; the four sessions before it are the ones that describe the week.

Notable data points

1. SPY closed the week at 761.69 against 764.29 on 11 September, a change of −0.34%. QQQ closed at 721.45 against 714.88, a change of +0.92%.
2. The $100M-and-above dark-pool board totalled $232.5B across the five sessions, of which Friday’s quarterly expiration alone was $117.73B across 379 prints in 128 names.
3. Of the 27 flagged contracts that were checked, 19 confirmed, two were partial and six did not confirm, a rate of 70%.
4. The MPI traded a 56 to 63 range across the week and the regime label read Neutral on all five sessions.
5. SPY call premium reached $4.27B against $908.7M of puts on Thursday, the session before the fund went ex-dividend $1.888834.
6. The single largest dark-pool print of the week was $9.36B of SPCX at 152.71 on Friday, at the exact closing price.
7. Eight open-market insider purchases of $1M or more were disclosed on Form 4 during the week, the largest being 525,000 shares of PMTS at $21.50, or $11.29M.
8. The heaviest premium line the weekly flow screen returned outside SPX was the IWM 18 September $315 puts at $87.9M, all of it on the bid, on 17 September.

Method note

Flow and dark-pool data sourced from Unusual Whales. MPI score and regime classifier are our internal composite; daily synthesis is AI-assisted from those inputs. Open-interest confirmation compares a flagged contract’s prior-session volume with the change in open interest reported the following session, so every verdict carries a one-session lag and describes the open-interest update only, never the contract. Three sections of this edition come from a live vendor pull made on Saturday 19 September: the weekly flow-theme screen behind the Themes on our radar table, the insider open-market purchase table, and the relative-size tape in Unusual by size. The rest of the edition is drawn from the five SomerQuant Daily editions of 14 to 18 September as published, from the published MPI history file and from the 11 September edition for the prior Friday closes, and that is the proper source for those figures rather than a gap: the week-in-one-line closes and the session table, the MPI column and its regime labels, the open-interest confirm scorecard and the $100M dark-pool board totals are all daily-edition figures and are reported here as such. The ETF and single-name split in the composition figure is derived by multiplying each session’s published $100M+ notional by its published ETF share, not read from a separate feed. Relative size is a print’s share count divided by that name’s 30-day average volume as reported with the print, computed by SomerQuant; it is not any vendor’s relative-size or relative-strength score. The weekly screen and the daily editions carry different 30-day averages for the same NHIC print, so the multiple differs between the two, and the weekly figure is the one used. Insider purchases are open-market buys reported on SEC Form 4, excluding 10b5-1 plan sales and purchases; Form 4 is filed after the trade, so the traded and filed dates are both shown. The VIX cell carries the week’s range rather than a change because the vendor close is integer-truncated and sits below its own session low at both ends of the week. The contracts flagged on 16 September were never checked and are excluded from the scorecard.

This is research, not advice. Nothing here is a recommendation to buy, sell, or hold any security.

SomerQuant is a publication of AZTMM HLDGS LLC. This edition is impersonal market commentary and education, published on a fixed schedule to the general public. It is not tailored to any reader, it is not investment, legal or tax advice, and it does not offer or solicit any security or strategy. No trade signals. SomerQuant does not know your circumstances and cannot tell you what to do. Market data is sourced from licensed third-party providers and is delayed. AZTMM HLDGS LLC and its principal may hold positions, long or short, in instruments discussed, and may change them at any time without notice. No compensation has been or will be received from any issuer, broker or third party for the coverage of any security. Full terms, disclaimer and editorial policy at somerquant.com.

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