SomerQuant Daily — Options Flow + Dark Pool, 15 September 2026

SomerQuant Daily · Tuesday, 15 September 2026 · EOD options flow & dark-pool research · SomerQuant

15 September 2026 — EOD read. The $100M-and-larger dark-pool board more than doubled overnight, printing $39.81 billion across 127 prints in 85 names against $18.52 billion in 44 names yesterday, and that is the largest and broadest session in the five we have on record. Underneath it the tape was quietly heavy: SPY opened at its high of 760.35 and closed 0.46% lower at 757.39, QQQ gave up 0.65%, and market-wide net options premium sat below zero for 74 of 79 five-minute readings. With the Federal Reserve decision due tomorrow at 2:00 PM ET, the size showed up in index vehicles and sector baskets rather than in single-name conviction.

SPY opened at 760.13 on the first five-minute bar and never traded higher. The opening fifteen minutes framed a range of 758.73 to 760.34, the session high of 760.35 printed inside that first bar at 9:30 ET, and the low of 756.15 came at 10:50 ET before a long afternoon drift that closed the day at 757.39. Fourteen SPY dark-pool prints cleared the regular session, and every one of them carried a contingent condition, the largest at $1.00 billion. All fourteen were stamped at 760.82, a price above the day’s high, so that level is where a derivative leg was marked rather than anywhere stock changed hands on the tape. Two premium shelves sit inside the day’s range, 760 at −$36.8M and 759 at −$17.0M, and three fall off the price scale: 750 at −$49.9M and 745 at −$19.7M below, 800 at +$31.4M above.

The tide opened at +$3M and spent its entire useful life below the line. It peaked at +$6M at 9:35 ET, crossed zero three times inside the first thirty-five minutes, and then never came back. The trough of −$256M landed at 3:10 PM ET, and the series finished at −$218M. Five of the 79 five-minute readings sat above zero against 74 below, which is the most one-sided tide we have printed since 10 September.

Monday’s radar — OI confirm

Verdict describes the open-interest update only, never the contract.

Seven of the nine contracts we froze on Monday came back as new open interest, one partially, and one not at all. The two cleanest were the ones that looked most mechanical at the time: MTDR March 2027 $70 calls turned 30,690 contracts of volume into 30,464 of fresh open interest, and PANW December 2027 $420 calls did the same with 1,642 of 1,652. The SPX December 7690 line confirmed on both legs at ratios of 0.88 and 0.86, which is what a genuine two-sided structure looks like the morning after. The SPY October $722 puts came in partial at 0.37 on a 35,425-contract base, and the CRWD December 2027 $230 calls saw open interest fall by 1,743, so that one was closing rather than opening business.

What happened

The session was decided in its first twenty minutes and then spent six hours confirming the verdict. SPY printed its high on the opening bar and drifted from there, losing 3.49 points to close at 757.39. QQQ was heavier at 0.65% lower, and the divergence that mattered was NVDA, which closed up 0.57% at 212.17 while the index it anchors fell. VIX finished in a 16.79 to 18.03 band.

The options tape was one-directional. Market-wide net call premium bled steadily through the afternoon to −$334M while net put premium turned positive in the last hour, and the combined tide reached −$256M at 3:10 PM ET. On SPY strikes, put premium led nine of the ten heaviest strikes across all expiries. The 750 strike carried the largest single imbalance at −$49.9M, and the only shelf where calls led was 800, a strike 5.6% above the close.

The dark pool was where the day got interesting. The $100M-and-larger universe printed $39.81 billion, up 114.9% from yesterday’s $18.52 billion, across 127 prints in 85 distinct names against 44 yesterday. ETFs took 62.9% of that notional across 70 prints. The three largest prints on the board were VOO at $1.78 billion, IVV at $1.71 billion and a second IVV at $1.52 billion, all of them stamped within fifteen minutes of the close at prices inside a few cents of their funds’ official marks. Eight IVV prints clustered at 758.83 for $6.38 billion between 16:00 and 16:14 ET.

Why it matters

A board that doubles while breadth nearly doubles alongside it is a different animal from a board that doubles on one enormous single-name print. Eighty-five names is the widest participation in our five-session record, and the money went overwhelmingly into vehicles that express the whole index or a whole sector: VOO, IVV, SPY, XLY, XLI, IHI, ITB, IGV and a long tail of Vanguard and iShares sector funds. That is the signature of positioning being reshaped at the portfolio level rather than views being taken on companies.

The timing is not incidental. The Federal Reserve decides tomorrow afternoon, and the options tape spent the session paying up for downside while the dark pool moved index exposure in size. Put premium led every SPY strike inside 1% of the close. The one call-led shelf sat 5.6% higher, which is the shape of a book that wants protection near the money and is willing to be long only well out of it.

Our own regime read moved with it. We published Bull · early on 14 September at an MPI of 63. Today the composite reads 60 and the regime scores as Neutral. That flip is frozen and scored mechanically in the Accountability Ledger like every other line we publish.

What to watch into Wednesday’s session

• 757.39 is today’s close and 756.15 was the low. A close below that low would mark the first break of this week’s floor.
• 760.35 was the session high and the open. Reclaiming it undoes the whole of today’s drift.
• The 750 SPY strike carries −$49.9M of net premium across all expiries, the heaviest shelf on the board.
• 800 is the only strike among the ten where calls lead, at +$31.4M, and it sits 5.6% above the close.
• Whether the $100M+ board holds above $20 billion, or whether today’s $39.81 billion was a one-session rebalance.
• The Federal Reserve decision at 2:00 PM ET, against a tide that has now finished below zero on consecutive sessions.

Names on our radar

Every row below is frozen at publication and scored mechanically in the Accountability Ledger at +5 and +21 sessions — misses stay on the page. Options prints are checked against the next morning’s open-interest update in the following session’s post.

Positioning into Wednesday

The gauge reads light and one-sided. Across the flagged-events screen and the complete $100M+ dark-pool universe, leveraged long vehicles carried $0, volatility vehicles carried $0, and inverse vehicles carried $1.08M, all of it in SQQQ October $40 calls. Zero is information here: nobody reached for leverage in either direction ahead of the decision. The hedging that did happen went through index options and through the dark pool in index funds, not through the leveraged complex.

The boards — data appendix

Today’s $39.81 billion is 114.9% above yesterday’s $18.52 billion and 9.9% above the previous high of the record, 10 September’s $36.23 billion. Print count at 127 and breadth at 85 names both exceed anything in the five sessions we have archived, and the ETF share of 62.9% sits between 14 September’s 46.8% and 10 September’s 72.6%. The pattern across the week is that the two heaviest boards were also the two most ETF-weighted, which is consistent with index-level activity rather than name-level activity driving the extremes.

The heaviest shelf on the board is 750, one percent below the close, carrying $58.28M of put premium against $8.40M of calls for a net of −$49.88M. The nearest shelf on the other side is 800, 5.6% above the close, where $34.28M of call premium leads $2.85M of puts for a net of +$31.43M. Between them every strike from 730 to 760 is put-led, including the four sitting within half a percent of where SPY actually closed.

Relative size is each print’s share count divided by that name’s 30-day average daily volume.

The two screens disagree on which print was the day’s most unusual, and the disagreement is the point. The boards universe is a $100M notional screen, and on it LNG’s $135.6M print is the only name here that qualifies at all. The relative-size tape is a $10M screen measured against each name’s own 30-day average volume, and on that measure PSTL’s $17.4M print is 2.69 times an ordinary day for the stock while LNG’s $135.6M is a quarter of one. The tile and the headline unusual-by-size figure use the relative-size screen; the $39.81 billion board total uses the $100M screen.

The universe below is every off-exchange print of $100 million or more executed on 15 September 2026, paginated to completion and deduplicated on tracking identifier, premium and size, with canceled prints dropped. It totals 127 prints, $39.81 billion and 85 distinct names. Trailing baselines are not computed in the cloud publisher, so none are shown.

Cluster watch, the three heaviest price levels carrying two or more prints:

The SPY prints at 760.82 are the contingent block drawn hollow on the session map, and they are counted once here rather than narrated again as standalone prints.

Notable data points

1. Market-wide put/call premium ratio closed at 0.81, with $22.23B of call premium against $17.09B of put premium.
2. SPY put premium of $803.7M led call premium of $707.9M, while QQQ put premium of $835.6M led calls of $687.0M.
3. NVDA closed up 0.57% at 212.17 and carried $1.36B of dark-pool prints, all of it at 212.17 after the close.
4. Four IWM prints of exactly 501,316 shares at 287.1386 cleared at four separate times between 11:06 and 14:16 ET, each for $143.9M.
5. INTC printed four times on the $100M+ board at 97.14 for a combined $838.9M.
6. MU carried three prints at 927.60 totalling $2.04B, fifteen days ahead of its 30 September earnings date.
7. SPY implied-volatility rank finished at 18.2, up from 15.7 yesterday.
8. The tide crossed zero three times, all of them inside the first thirty-five minutes of the session.

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. Volume-over-OI activity is unconfirmed as new positioning until the next morning’s open-interest update; confirmations are published in the following session’s post. 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. Option premium by strike is aggregated across all expiries. The session map is drawn from 5-minute bars; the opening range is the first fifteen minutes; dark-pool prints marked contingent carry the vendor’s contingent or derivative-priced sale condition. Board baselines are trailing-session averages computed from our own archived pulls; derived indicators are computed by SomerQuant from licensed market data.

The flagged-events screen shows the 50 most recent flagged events above $1M of premium, so the options lines discussed here are stated within that depth rather than as the day’s complete tape. The vendor returned a VIX close of 17 against a session high of 18.03 and a low of 16.79. An integer close alongside decimal extremes is truncated and unusable for a percentage, so the session range is printed instead of a move. The MPI composite and regime carry an as-of date of 14 September, one session behind the price data in this edition, and the strip is labelled accordingly. To stay inside the payload budget, three figures shipped in a single width rather than the usual wide and narrow pair: the session map, the strike ladder and the five-session strip.

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

AZTMM HLDGS LLC is not a registered broker-dealer, investment adviser, or FINRA member. All content is retrospective research published for general circulation, not personalized advice, not trade signals. Options involve substantial risk, including losses that may exceed the initial investment. Full disclaimer.

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