RESEARCH · ATS REGULATORY INTELLIGENCE · JULY 2026
The Rewrite
U.S. dark pools filed 108 ATS-N amendments in the first half of 2026. Read for what they actually change, they describe one program: pulling benchmark execution into the pool, widening who can connect, and stretching the trading day.
Every U.S. dark pool has to publish how it works on SEC Form ATS-N and file an amendment every time it changes. That record is public, structured, and current, which makes it the clearest window there is into what these venues are actually building. In the first half of 2026 they filed 108 amendments. We read them for substance, not scale, and the same four themes keep recurring: benchmark and VWAP order types moving inside the pool, wider and more direct access for subscribers, a longer trading day, and a new layer of surveillance and anti-gaming controls. This is a build-out, and the filings show its blueprint.
01The Amendment Tape
Of the 108 amendments, 36 were material, 11 correcting, and 5 filed at the SEC's direction; the rest were routine updates. There was one new registration and three exits in the window, but the overwhelming activity was existing venues changing how they already run. June was the busiest month at 27. JPMorgan was the most active operator with 15 amendments across JPB-X and JPM-X, followed by Liquidnet at 11 and OneChronos and LeveL at 10 apiece.
Tagging each filing by the parts of Form ATS-N it touches shows where the effort is concentrated. Three categories dominate and describe the same contest from three sides: how the venue matches (execution logic), what instructions it accepts (order types), and who is allowed in and how (subscriber access). Together they account for the large majority of the half's activity. Everything else, from compliance to fees to trading hours, sits well behind.
02The Order-Type Race
The single loudest theme of the half is benchmark execution moving inside the dark pool. Five venues added a VWAP or benchmark cross order type, each letting an institution work a schedule or a benchmark price without leaving the venue for a separate algo:
- UBS ATS added Trajectory Cross, a quantity-over-time order priced at UBS VWAP across the interval, for Class A Direct Subscribers using the UBS algo.
- Goldman SIGMA X2 added a Benchmark Cross order type, generated and routed by Goldman algorithms on behalf of indirect subscribers.
- Intelligent Cross stood up an entirely new IVWP book that accepts only VWAP orders and matches over fixed or floating intervals, alongside its existing midpoint and ASPEN events.
- JPB-X introduced an MDVWAP Price Match order type with its own tiering and conditional-order handling.
- Citi-ONE opened Trajectory Cross conditional orders to direct subscribers.
Running alongside it is a smaller wave of pegged liquidity. Moon ATS added midpoint and primary peg orders that track the consolidated quote, and Admiral added primary, market, and midpoint pegs. The purpose is the same in both clusters: give the buyside more ways to source a benchmark or a passive midpoint fill without signaling to the wider market. Execution logic and order types are not two separate battlegrounds. They are the same one, and it is where the venues are spending most of their effort.
03Access and the Longer Day
The second theme is connectivity: who can reach the pool, and through what pipe. Blue Ocean amended its rules so subscribers can extend sponsored access to their own underlying customers. IBKR let execution customers connect by direct FIX, bypassing the smart order router that was previously mandatory, and added a new order type for brokerage customers. Virtu MatchIt built out Hosted Sessions for affiliated flow, and JPM-X restructured its subscriber tiers and added a counterparty-selection procedure. The common thread is granularity: venues are giving subscribers finer control over how they connect and whom they face.
The third theme is time. The trading day is being stretched from both ends. IBKR EOS added extended-hours sessions on days the NYSE is closed, moving its order-acceptance window earlier to 5:30 PM ET and running through 3:50 AM. OneChronos opened an Early Trading Session from 7:00 to 9:30 AM with its full order-type set available. PureStream reworked its post-close matching round. And the overnight venues continued to build the session itself: Moon moved clearing from Apex to Instinet, the kind of back-office plumbing a maturing overnight book requires. With extended SIP hours going live December 6, these are the filings that lay the track ahead of the infrastructure.
04Guarding the Pool
The fourth theme is defensive. As the pools add order types and open access, several used the same filing cycle to tighten controls. Liquidnet added automated market surveillance that can impose intraday, symbol-level trading blocks on members whose activity breaks the rules. CBX introduced a custom FIX-tag key that prevents a subscriber's own orders from executing against each other. Citi-ONE stopped including direct-subscriber orders in the aggregated data feeds sent to its algos and smart order router. Admiral made NBBO price protection the default while retaining a one-percent collar when it is switched off.
Minimum order size moved in both directions, and the split is telling. CrossStream dropped its floor from a 100-share round lot to a single share, admitting odd lots. PureStream went the other way, raising its large-size floor tenfold from 100 to 1,000 shares. One venue is reaching for retail-scale fragmentation, the other is protecting an institutional block franchise. The same regulatory instrument, pointed at opposite ends of the market.
05The Venues
For context, here is the market these filings describe, ranked the standard way. FINRA reports ATS activity in both shares and dollars, and the conventional league table is by shares, so that is the primary sort below, with notional shown alongside. Intelligent Cross leads on both. UBS is a close second. The top five hold roughly half the tape, and with a Herfindahl index near 730 this is a fragmented market, not a concentrated one.
H1 2026 · Volume by Shares (standard), Notional Alongside
| # | Venue | Operator archetype | Shares | Notional | Notl. # |
|---|---|---|---|---|---|
| 1 | Intelligent Cross | Electronic | 15.7% | 14.6% | 1 |
| 2 | UBS ATS | Bank pool | 11.9% | 13.9% | 2 |
| 3 | LeveL | Agency | 7.8% | 8.0% | 4 |
| 4 | Goldman SIGMA X2 | Bank pool | 6.7% | 8.5% | 3 |
| 5 | Instinct X | Electronic | 5.7% | 6.1% | 5 |
| 6 | MS Trajectory Cross | Bank pool | 5.1% | 4.4% | 7 |
| 7 | MS Pool | Bank pool | 4.7% | 4.9% | 6 |
| 8 | OTC Link NQB | OTC / IDQS | 4.5% | 0.1% | 32 |
| 9 | BIDS ATS | Block | 4.2% | 3.8% | 9 |
| 10 | Blue Ocean / BOATS | Overnight | 3.9% | 1.8% | 17 |
| 11 | OneChronos | Auction | 3.7% | 4.4% | 8 |
| 12 | PureStream | Independent | 3.1% | 3.4% | 12 |
| 13 | IBKR ATS | Electronic | 2.9% | 3.4% | 11 |
| 14 | Virtu MatchIt | Electronic | 2.8% | 2.8% | 14 |
| 15 | JPM-X | Bank pool | 2.8% | 3.5% | 10 |
The two columns diverge in ways worth reading. OTC Link NQB ranks eighth by shares but thirty-second by dollars, the signature of a venue trading enormous counts of sub-dollar OTC names. Blue Ocean runs the same direction more mildly, tenth by shares against seventeenth by notional, the retail-priced, high-count profile of an overnight book. The reverse case sits just off the shares table entirely: Dealerweb is thirteenth by dollars but barely registers by shares, an interdealer venue moving a handful of very large, high-priced tickets. Where a venue's share rank outruns its dollar rank, you are usually looking at either penny names or the night session; where it lags, at institutional size.
##References & Method
Sources
- SEC EDGAR, Form ATS-N. All H1 2026 (Jan 1 to Jun 30) amendments. Operator totals were verified per filer against the SEC submissions API at data.sec.gov. Featured order-type names (UBS Trajectory Cross, Goldman Benchmark Cross, Intelligent Cross IVWP, Moon peg orders, Blue Ocean sponsored access, CrossStream odd-lot) were verified in the filing text itself.
- FINRA Rule 4552 ATS Transparency Data. Weekly shares and notional by ATS, 36 NMS-equity venues, 30 weeks from December 15 2025 to July 6 2026. The leaderboard is ranked by shares, the conventional ATS league-table measure, with notional and notional rank shown alongside.
Method notes
- “Amendment” counts all ATS-N amendment form types (UA, MA, CA, and SEC-ordered). “Material” counts ATS-N/MA only.
- Change categories are assigned per filing from the amended Form ATS-N items; a single filing usually touches several, so the category counts sum to more than 108.
- Amendment activity is a measure of what a venue is changing, not of execution quality or performance. This report reads the filings for substance and does not attribute volume gains or losses to them.
Sapinover builds intelligence on the overnight and extended-hours market. This analysis is for informational purposes only and is not investment advice or a solicitation.