Form ATS-N/UA Files Dataset

The Form ATS-N/UA Files Dataset collects every Form ATS-N/UA "updating amendment" filing submitted to EDGAR by NMS Stock Alternative Trading Systems beginning in May 2019, the first quarter in which the post-2018 Regulation ATS-N regime produced quarterly updating amendments. Each record is one accession-numbered EDGAR submission filed by a broker-dealer ATS operator under Rule 304(a)(2)(i)(B) of Regulation ATS to correct previously reported Form ATS-N information that has become inaccurate or incomplete and that does not require any other Form ATS-N amendment type. The record bundles the structured Form ATS-N/UA XML payload, an XSL-rendered XHTML view of that payload, EDGAR filing metadata, and the non-image exhibits attached to the original submission — most often copies of Schedule A of Form BD and Schedule B of Form BD and a redline against the previously effective Form ATS-N. Records are packaged as ZIP year-month containers and the dataset covers form type ATS-N/UA exclusively, with file types XML, PDF, JSON, HTML, and TXT.

Dataset APIs

Dataset Files

What This Dataset Contains

The dataset is built from Form ATS-N/UA, the public quarterly updating amendment to Form ATS-N. Form ATS-N is the disclosure form that an NMS Stock ATS uses to describe, in detail, the manner of operations of its alternative trading system and the ATS-related activities of its broker-dealer operator and the operator's affiliates. The "/UA" variant repairs information in a previously effective Form ATS-N that has become inaccurate or incomplete and that does not require a different Form ATS-N amendment type (such as a material amendment, correcting amendment, or order display and execution access amendment). Each ATS-N/UA submission is a complete restatement of the Form ATS-N data tree — Parts I through IV in their entirety — together with a short cover statement explaining what is being amended and why. A record is therefore a full snapshot of how the ATS was disclosed at the moment of the amendment, not a difference list.

The dataset covers the entire population of NMS Stock ATSs subject to Regulation ATS-N. Coverage begins on May 1, 2019 — the first quarter in which the post-2018 Regulation ATS-N regime produced quarterly updating amendments — and continues through the most recent refresh. Records are distributed as ZIP year-month containers; inside each container, every accession folder carries the structured submission, the XSL-rendered XHTML view, the EDGAR filing metadata, and any non-image attachments that EDGAR received with the submission. The complete .txt SGML submission envelope is referenced by URL in metadata.json but is not stored locally. Image-only attachments (such as screenshots of order-handling user interfaces) are excluded from the dataset by design.

Content Structure of a Single Record

1. What one record represents

A single record is one Form ATS-N/UA submission as it was accepted by EDGAR — one accession-numbered package filed by an NMS Stock Alternative Trading System under Rule 304(a)(2)(i)(B) of Regulation ATS to update or correct previously reported Form ATS-N information that was not required to be reported through any other type of Form ATS-N amendment. The record unit is the entire submission, not a single Item or disclosure: it bundles the structured XML form, an XHTML rendering of that form, the filing-level metadata, and any non-image exhibits attached at the time of filing.

In the dataset, each record materializes as a folder named with the 18-digit EDGAR accession number (no dashes), nested inside year-month folders that group submissions by EDGAR accept month. Every accession folder contains, at minimum, a metadata.json describing the submission, a primary_doc.xml carrying the structured form data, and a subdirectory xslATS-N_X01/ holding the XSL-rendered XHTML view of that XML. Most records also contain one or more exhibit files — almost always a copy of Schedule A of Form BD, a copy of Schedule B of Form BD, and frequently a redline document showing changes against the previously effective Form ATS-N.

2. Content layout of a single record

A record contains four content layers stacked in the same accession folder:

1. Filing metadata — a single metadata.json describing the submission's EDGAR header, the filer entity, and the inventory of every attached document.
2. Structured submission — primary_doc.xml, the canonical XML representation of Form ATS-N/UA produced by EDGAR's Online Form filer. This is the authoritative machine-readable copy of the form.
3. Human-readable rendering — xslATS-N_X01/primary_doc.xml, an XHTML 1.0 Strict document generated by EDGAR's ATS-N_X01 XSL stylesheet from the structured submission, presenting the same content in printable form.
4. Exhibits — zero or more PDF, HTML, or TXT files referenced from metadata.json's documentFormatFiles[] array. The Schedule A of Form BD copy and the Schedule B of Form BD copy are nearly always present; a redline exhibit is common. Image attachments are excluded from the dataset.

Exhibit filenames are filer-chosen and vary widely (ex-1scha16.pdf, exhibit-1.pdf, schedulea.htm, redline_clean.pdf, ats-n_ex3.txt, etc.), so only metadata.json, primary_doc.xml, and xslATS-N_X01/primary_doc.xml have stable, predictable filenames within an accession folder.

3. metadata.json

metadata.json is a compact JSON object describing the submission as EDGAR sees it. The fields that carry intentional structured meaning include:

• formType — always "ATS-N/UA" for records in this dataset.
• accessionNo — the EDGAR accession number with dashes, e.g. 0001839882-25-056514.
• filedAt — ISO-8601 timestamp with timezone reflecting EDGAR's accept time.
• description — the EDGAR free-text description, typically "Form ATS-N/UA - Updating Amendment to Form ATS-N (Rule 304(a)(2)(i)(B)): [Amend]".
• linkToFilingDetails — URL to the XSL-rendered submission view on sec.gov.
• linkToTxt — URL to the complete .txt SGML submission envelope on sec.gov.
• linkToHtml — URL to the EDGAR -index.htm page for the submission.
• documentFormatFiles[] — an inventory of every document in the submission, each entry carrying sequence, size (bytes as string), documentUrl, type (e.g. ATS-N/UA, ATS-N EX-1 SCHD A BD, ATS-N EX-2 SCHD B BD, ATS-N EX-3 REDLINE), and sometimes description. The final entry is normally the complete submission .txt envelope.
• entities[] — filer entity records carrying cik, companyName (suffixed with the role marker (Filer)), fileNo, irsNo, stateOfIncorporation, fiscalYearEnd, act, filmNo, and type.
• id — a 32-character internal hash identifier.
• seriesAndClassesContractsInformation, dataFiles — empty arrays for this form type.

The documentFormatFiles[] type vocabulary is the most reliable handle for extraction: it labels each attached document with its role (primary form, Exhibit 1 Schedule A, Exhibit 2 Schedule B, Exhibit 3 redline, etc.) independently of the filer's chosen filename.

4. primary_doc.xml — the structured submission

primary_doc.xml is the canonical Form ATS-N/UA payload. The root element is <edgarSubmission> declared under three SEC namespaces — http://www.sec.gov/edgar/atsn (default), http://www.sec.gov/edgar/common (prefixed com:), and http://www.sec.gov/edgar/atsncommon (prefixed ats:). The document is large in absolute terms, frequently running into the high hundreds of lines, because each Part II / Part III narrative answer is embedded inline as a long free-text field rather than incorporated by reference.

The submission has two top-level children:

• <headerData> — the submission-level envelope: <submissionType>ATS-N/UA</submissionType>, <accessionNumber>, and <filerInfo> containing the filer's CIK and CCC credentials (com:cik, com:ccc), <fileNumber>, a <liveTestFlag> indicating LIVE vs. TEST, and EDGAR routing flags such as <ats:overrideInternetFlag> and <ats:confirmingCopyFlag>.
• <formData> — the form itself, decomposed into <cover>, <partOne>, <partTwo>, <partThree>, and <partFour>.

4.1 Cover

The <cover> block opens the form and corresponds to the cover page of Form ATS-N. It carries the name of the NMS Stock ATS (txNMSStockATSName) and the cover statement that is the heart of an updating amendment: taStatementAboutAmendment, a free-text narrative explaining what previously reported information has become inaccurate or incomplete and how the amendment corrects it. Because Form ATS-N/UA is a quarterly catch-up vehicle, this field typically enumerates which Items have been updated (e.g., "Part III Items 7, 8, 9, and 11 have been revised to reflect …") and is the natural starting point for understanding the substance of any one filing.

4.2 Part I — Identifying Information (Items 1–9)

<partOne> carries the broker-dealer operator's identifying information and the core registration metadata of the ATS. Typical fields include the operator's full broker-dealer name and CRD number, the SEC file number, the ATS's name and its CRD/MPID, the national securities association of which the operator is a member (typically FINRA) and the effective date of that membership, the ATS's website, and physical/electronic addresses for the primary and secondary matching-system locations. Address blocks are built from reusable <ats:street1>, <ats:street2>, <ats:city>, <ats:state> codes (e.g. US-NJ), and <ats:zip> elements. Part I also exposes three exhibit attachment slots whose contents are filed as separate documents in the submission: Exhibit 1 (Schedule A of Form BD, listing direct owners and executive officers of the operator), Exhibit 2 (Schedule B of Form BD, listing indirect owners), and Exhibit 3 (an optional supplementary disclosure or redline). The element part1Item7PrimarySite is a representative example of the naming pattern.

4.3 Part II — Activities of the Broker-Dealer Operator and its Affiliates (Items 1–7)

<partTwo> discloses how the broker-dealer operator and its affiliates interact with the ATS. The seven Items cover, in order: the names and capacities of broker-dealer operator units that enter or receive orders on the ATS; affiliate trading arrangements that touch the ATS; whether, and on what terms, subscribers can opt out of interacting with operator/affiliate order flow; arrangements with other trading centers regarding routing or interaction; other products and services the operator or its affiliates make available to ATS subscribers; outsourced service providers and shared personnel; and procedures for protecting subscribers' confidential trading information. Each Item is generally rendered as a Y/N indicator (rb* radio-button element) followed, when applicable, by a long-form ta* narrative such as taPart2Item1aUnitNamesEnterInterest.

4.4 Part III — Manner of Operations of the NMS Stock ATS (Items 1–26)

<partThree> is the longest and most operationally detailed section of the form. The 26 Items walk through, end to end, how the trading system works:

• subscriber classes, eligibility criteria, and the grounds on which the ATS may exclude, suspend, or limit a subscriber's services;
• hours of operation and the boundaries of regular and after-hours sessions;
• means of order entry, connectivity options, and any co-location arrangements;
• the catalogue of order types, order sizes, time-in-force conditions, conditional orders, and indications of interest;
• opening, re-opening, and closing procedures;
• order priority, matching, and execution logic, including any algorithmic priority rules;
• liquidity-provider programs and any segmentation of order flow between subscriber categories;
• counter-party selection mechanics, display vs. non-display behavior, and routing logic to and from the ATS;
• trading outside regular trading hours;
• fees, rebates, and any volume- or behavior-based pricing tiers;
• suspension of trading and error-correction procedures;
• trade reporting, clearance, and settlement arrangements;
• market-data sources used by the ATS and order-display/execution-access policies;
• fair-access determinations under Rule 301(b)(5); and
• aggregate platform data published by the ATS (part3Item26PlatFrmData).

Most Items are gated by an rb* Y/N selector and then expand into an extended ta* narrative — for example taPart3Item11aTrdSrvFcltsRulsDtls describes the trading-services facilities and rules in Item 11(a). Boolean flags use a cb* checkbox prefix and resolve to literal true/false. The partXItemY... element-naming pattern mirrors the official Form ATS-N Item structure, which makes the XML directly mappable to the form's published Item numbering.

4.5 Part IV — Contact Information, Signature, and Consent to Service

<partFour> closes the form with the contact employee for SEC inquiries (name, title, telephone, email), the signature block (signatory name and title, signing date), and consent to service of process. Filings are signed under the ATS's electronic-filing credentials rather than by an attached signature image.

4.6 Element-naming conventions

Across primary_doc.xml, element names follow a small set of consistent prefixes that make programmatic extraction straightforward:

• tx* / txt* — short text inputs (names, file numbers, MPIDs, websites, dates).
• ta* — long-form text-area narratives carrying the substantive disclosures.
• rb* — radio-button Y/N answers, often appearing both as an element and as a wrapping container that gates a sibling narrative.
• cb* — checkbox booleans resolving to true / false.
• partXItemY... — section/item path mirroring the official Form ATS-N outline.
• <ats:street1>, <ats:city>, <ats:state>, <ats:zip> — reusable address-block elements.

5. xslATS-N_X01/primary_doc.xml — the XHTML rendering

Despite its .xml extension, the file beneath the xslATS-N_X01/ subdirectory is XHTML 1.0 Strict produced by SEC's ATS-N_X01 XSL stylesheet. It links to /css/ATSN_print.css and presents the structured submission as a paginated, human-readable document with image-based "checked / unchecked" radio-button glyphs to indicate Y/N choices, formatted address blocks, and hierarchical Item headings. The information content is identical to primary_doc.xml; this rendering exists to give a reviewer a printable view that matches what EDGAR shows on the web. For programmatic extraction, the structured XML should be preferred and the XHTML treated as a presentational mirror.

6. Exhibits

Exhibits sit alongside primary_doc.xml in the accession folder and are referenced from metadata.json's documentFormatFiles[] by type. The three recurring exhibit roles are:

• Exhibit 1 — Schedule A of Form BD (ATS-N EX-1 SCHD A BD). A copy of the broker-dealer operator's Schedule A from its current Form BD, listing direct owners, executive officers, and other control persons.
• Exhibit 2 — Schedule B of Form BD (ATS-N EX-2 SCHD B BD). A copy of the operator's Schedule B, listing indirect owners.
• Exhibit 3 — Redline / supplementary disclosure (ATS-N EX-3 REDLINE or similar). Most commonly a textual redline showing the differences between the previously effective Form ATS-N and the version being amended; occasionally used to attach other supporting material that does not fit cleanly into the structured form.

The file-types used for exhibits in the dataset are PDF, HTML, and TXT. PDF dominates for Schedules A and B; redlines appear as PDF, HTML, or plain text depending on the filer. Image-only attachments are excluded from the dataset by design.

7. Structural stability of the form

Form ATS-N was created by Regulation ATS-N, which the SEC adopted in 2018 and which became effective for operating NMS Stock ATSs on January 7, 2019. The first quarterly updating-amendment cycle therefore matured in spring 2019, which is why the earliest Form ATS-N/UA filings on EDGAR — and the earliest records in this dataset — date from May 2019.

Because Form ATS-N/UA was born structured (XML plus an XSL-rendered XHTML view), its anatomy has been highly stable across the dataset. The four-Part outline, the Item counts (9 / 7 / 26 in Parts I–III plus contact-and-signature in Part IV), the <edgarSubmission> wrapper with <headerData> and <formData>, the three SEC namespaces, the tx* / ta* / rb* / cb* element-naming conventions, and the Exhibit 1 / Exhibit 2 / Exhibit 3 exhibit roles have all been in place from the first ATS-N/UA filings forward. The XSL stylesheet identifier (ATS-N_X01) and its rendered XHTML have been refreshed periodically by EDGAR with no impact on the underlying XML payload, and documentFormatFiles[] type codes have stabilized into the ATS-N/UA, ATS-N EX-1 SCHD A BD, ATS-N EX-2 SCHD B BD, ATS-N EX-3 REDLINE vocabulary that dominates current filings. Filer practice has converged in parallel: Schedules A and B are nearly always attached as PDFs, and a redline exhibit, sometimes omitted in early 2019, is now nearly universal.

8. Interpretation notes

• Full restatement, not a delta. Each ATS-N/UA filing restates the entire Form ATS-N data tree. To compute what actually changed in a given amendment, compare the new primary_doc.xml against the most recent prior Form ATS-N or ATS-N/UA filing for the same ATS, or read the redline Exhibit 3 if present.
• Cover statement is the anchor. taStatementAboutAmendment in <cover> is the filer's own description of what is being corrected and is the most reliable starting point for interpreting an amendment's scope.
• Two parallel views of the same data. primary_doc.xml and xslATS-N_X01/primary_doc.xml carry the same content; treat the XML as the source of truth for extraction and the XHTML as the presentational copy.
• Element naming maps cleanly to Form ATS-N Items. The partXItemY... convention (e.g., part1Item7PrimarySite, part3Item26PlatFrmData) lets a consumer programmatically locate any Item without parsing surrounding labels.
• Y/N gating. Many ta* narratives are conditional on a sibling rb* Y/N answer; absence of a narrative typically signals "No" rather than missing data.
• Exhibit identity by type, not filename. Use the type field in documentFormatFiles[] to identify exhibit role; filenames are filer-chosen and inconsistent.
• Image attachments absent. Any references inside narratives to diagrams or screenshots will not resolve to local files in the accession folder.
• CCC is masked. The <com:ccc> value inside <filerCredentials> is a masked placeholder in the public submission and should not be expected to carry information.
• Entity role suffix. The (Filer) suffix on companyName inside entities[] is a role marker, not part of the legal name.

Who Files or Publishes This Dataset, and When

Who files the record

Each Form ATS-N/UA filing is submitted to EDGAR by the broker-dealer that operates an NMS Stock Alternative Trading System (NMS Stock ATS). The filer is the broker-dealer entity itself, not the trading venue as a separate name. The "/UA" suffix marks the submission as an updating amendment to a previously effective Form ATS-N.

A broker-dealer that operates more than one NMS Stock ATS files a separate Form ATS-N family for each venue, so one accession corresponds to one operator reporting on one ATS.

Filing population

The filer population is narrow:

• NMS Stock ATSs — alternative trading systems that trade exchange-listed equities subject to Regulation NMS. They are registered as broker-dealers with the SEC, are FINRA members, and operate under Rule 301 of Regulation ATS subject to the public disclosure regime of Regulation ATS-N (Rules 300–304, as amended in 2018).
• The broker-dealer operator of each such ATS, which signs and submits the Form ATS-N family. Affiliates appear inside Part II disclosures but are not themselves filers.

Outside this dataset:

• Non-NMS ATSs (corporate bonds, municipal, government, or private securities) file the legacy Form ATS and Form ATS-R under Rule 301(b)(2).
• National securities exchanges registered under Section 6 file Form 1 and Rule 19b-4 rule filings, not the ATS-N regime.
• Single-dealer platforms and internalizers that do not meet the Rule 3b-16 "exchange" definition are not ATSs at all.

Triggering event

Form ATS-N/UA is filed under Rule 304(a)(2)(i)(B) of Regulation ATS. The trigger is residual: an NMS Stock ATS must file when previously reported Form ATS-N information has become inaccurate or incomplete and the update is not required to be reported under any other Form ATS-N amendment type.

If no qualifying updates accumulated during a quarter, no Form ATS-N/UA is filed for that quarter.

Timing and deadline

The filing is due no later than 30 calendar days after the end of each calendar quarter in which the inaccurate or incomplete information existed. Typical filing windows fall in late January (Q4), late April (Q1), late July (Q2), and late October (Q3).

The deadline is set by the calendar, not by the date the inaccuracy arose. The cadence is therefore periodic, while the obligation to file at all is content-driven.

Place within the Form ATS-N family

Regulation ATS-N (adopted 2018, operative 2019) created four amendment tracks; Form ATS-N/UA is the residual one:

• Form ATS-N/MA — material amendment, filed at least 30 days before implementation; requires SEC effectiveness before the change goes live.
• Form ATS-N/OFA — order display and execution access amendment, filed before implementation.
• Form ATS-N/CA — correcting amendment, filed promptly upon discovery of a materially inaccurate disclosure.
• ATS-N/UA — updating amendment for non-material corrections that do not fall within MA, OFA, or CA, filed on the quarterly cadence above.

MA, OFA, and CA are event-driven; UA is the only track on a fixed quarterly schedule.

Important distinctions

• Submission type scope. The dataset contains only ATS-N/UA submissions. Initial Form ATS-N filings and the MA, OFA, and CA amendment types live under their own EDGAR submission types and are not included.
• NMS-stock-only regime. Regulation ATS-N applies exclusively to ATSs that trade NMS stocks. Fixed income, Treasury, and other non-NMS venues remain under the legacy Form ATS / ATS-R framework.
• Filer name vs. venue name. The EDGAR filer is the broker-dealer operator, which may differ from the trade name of the dark pool or ATS.
• Earliest filings. Form ATS-N/UA did not exist before the 2018 Regulation ATS-N amendments. Initial Form ATS-N filings were submitted in a transition window in early 2019, and the first ATS-N/UA filings appear on EDGAR in May 2019 — both the regulatory and the digital-publication start date for this record type.
• No-update quarters. Absence of a filing for a given filer-quarter does not imply non-compliance; an ATS with no qualifying updates is not required to file.
• Form ATS-R is separate. Form ATS-R is a confidential quarterly transaction-volume report and is not part of the Form ATS-N amendment family captured here.

How This Dataset Differs From Similar Datasets or Filings

Form ATS-N/UA sits inside the Regulation ATS-N family, the cluster of EDGAR filings that describes the structure and operations of NMS Stock Alternative Trading Systems. The most useful comparison points are the other ATS-N variants, the legacy Form ATS regime for non-NMS venues, the quarterly Form ATS-R volume report, and the exchange-side analogs Form 1-N and Form 19b-4. Each overlaps in filer population or subject matter but differs sharply in trigger, content, or cadence.

Closest related filings

Form ATS-N (initial filing). The foundational Rule 304 disclosure: a comprehensive, one-time registration covering Parts I-IV, including manner of operations, conflicts, and Schedule A/B exhibits. ATS-N/UA never stands alone; it amends specific items of an existing ATS-N. Use ATS-N for the baseline, ATS-N/UA for the running update stream.

Form ATS-N/MA (material amendment). Filed at least 30 days before a material change to operations or broker-dealer activities, and subject to potential ineffectiveness review. ATS-N/UA is the inverse: filed after the fact, within 30 days of quarter-end, for changes that are explicitly non-material and not captured by another amendment type. MA covers consequential redesigns; UA covers cleanup and minor operational drift.

Form ATS-N/CA (correcting amendment). Corrects material errors or omissions that existed at the time of an earlier filing. ATS-N/UA, by contrast, addresses information that has become inaccurate or incomplete due to subsequent change. CA is for historical defects; UA is for ongoing evolution.

Form ATS-N/OFA (order display amendment). Narrow, event-driven amendment triggered when an ATS begins displaying subscriber orders outside the ATS — a Rule 301 status change. ATS-N/UA is broader in subject matter but explicitly excludes anything that should have been filed as OFA, MA, or CA.

Form ATS-N/W (withdrawal). A one-time terminal filing marking cessation of an NMS Stock ATS. UA is recurring and incremental; W is the final lifecycle entry.

Adjacent but distinct filings

Form ATS (legacy, non-NMS). Applies to ATSs trading fixed income, options, or other non-equity instruments. Uses a simpler XML structure and treats most content as confidential. ATS-N/UA applies only to NMS Stock ATSs and carries publicly disclosed narrative content. Different filer population, different disclosure regime.

Form ATS-R (quarterly volume report). Shares the 30-day-after-quarter-end deadline and applies to all ATSs, but reports tabular transaction volumes and security counts rather than narrative operational disclosures. ATS-R answers "how much traded"; ATS-N/UA answers "what changed in how it trades." Complementary, not interchangeable.

Form 1-N and Form 19b-4 (exchange side). Form 1-N registers national securities exchanges under Section 6 — a parallel regime to Regulation ATS, with no recurring update analog. Form 19b-4 governs SRO proposed rule changes and is structurally analogous to ATS-N/MA, but applies to exchanges, follows a public notice-and-approval process, and produces formal rule text rather than ATS-N Part III narrative. Useful for cross-venue microstructure work, but not substitutes.

Boundary summary

The Form ATS-N/UA Files Dataset is the quarterly, residual-category update channel for NMS Stock ATSs. It is narrower than ATS-N (full registration), ATS-N/MA (material redesigns under pre-effective review), ATS-N/CA (historical error correction), and ATS-N/OFA (order display events); broader than ATS-R in narrative scope but with no volume data; and inapplicable to non-NMS ATSs (Form ATS) or exchanges (Form 1-N, Form 19b-4). For longitudinal analysis of how individual NMS Stock ATSs evolve operationally between material redesigns, this dataset is the only source that captures the routine, post-quarter, non-material updates accumulating over an ATS's life.

Who Uses This Dataset

The dataset is read by a narrow set of equity market-structure professionals, each focused on different items within the Form ATS-N/UA payload.

ATS compliance and regulatory counsel

In-house compliance officers and Form ATS-N drafters at ATS operators benchmark their own amendment language against peer venues. They focus on Part III items on manner of operations, order types, segmentation and counterparty selection (Items 7 and 8), matching and routing logic (Item 11), fees, and use of subscriber information. Output: draft amendments, disclosure-committee memos, and remediation files when an inaccuracy triggers a UA.

Sell-side electronic trading and SOR teams

Algo product managers and smart-order-routing engineers at broker-dealers treat each UA as a change notice for venue behavior. They track order types, time-in-force, conditional and minimum-quantity logic, segmentation tiers, anti-gaming controls, and any differences in how the operator and its affiliates interact with the book. Feeds into router configuration, venue-quality scoring, and algo-wheel disclosures.

Buy-side best-execution and execution analytics

Execution traders and best-execution committees at asset managers and pension plans use UA filings as primary evidence in venue review. They focus on subscriber categories, counterparty types, conflict-of-interest disclosures, and changes to segmentation or fees that affect execution. Output: best-ex reviews, broker scorecards, and challenge questions to routing brokers.

Market microstructure researchers

Academics and quantitative researchers studying off-exchange liquidity build longitudinal panels from the structured XML metadata combined with narrative item content, capturing minimum sizes, conditional order availability, subscriber tiers, and matching-priority changes over time. Feeds peer-reviewed work on dark-pool adverse selection, segmentation, and Reg ATS-N effects.

Securities regulators and SROs

Examiners and market-structure analysts at the federal securities regulator, the broker-dealer SRO, and state securities divisions use UA frequency and the items being corrected as a signal of disclosure-control weakness. They reconcile disclosed operations against audit-trail observations to plan inspections and enforcement referrals.

Venue strategy and corporate development

Product, strategy, and M&A teams at exchanges, ATS operators, and prospective entrants map the competitive landscape via subscriber categories, order types, fee and rebate structures, and affiliated routing arrangements. Feeds product roadmaps, pricing benchmarks, and ATS acquisition diligence.

Litigation support and forensic experts

Expert witnesses and forensic analysts in best-execution disputes, manipulation investigations, and private securities litigation cite the precise wording of order-handling, segmentation, and conflict disclosures in effect on relevant trade dates. The amendment history establishes what counterparties could reasonably have known.

TCA and SOR vendors

Vendors building transaction cost analysis, smart order routing, and venue-analytics products parse Schedule A operator data, Items 7 and 11, and order-type and fee taxonomies into structured fields that drive dashboards and venue-classification logic for broker and asset-manager clients.

Policy researchers and market-structure analysts

Analysts at policy research organizations and market-structure think tanks track aggregate trends in conflict, affiliate-routing, and tiering disclosures, and the frequency of UA filings. Output: white papers, comment letters on rulemakings, and equity-market-structure testimony.

Financial journalists on the market-structure beat

Reporters covering dark pools, broker conflicts, and venue incidents use UA filings as named, verifiable source material. They focus on changes to operator disclosures, additions or removals of order types, and shifts in subscriber categories or fees.

The audience clusters around equity market structure: venue operators, the brokers and buy-side firms routing into them, the regulators supervising them, and the researchers, litigators, vendors, and journalists who reconstruct their behavior. Each group reads different items, but all rely on the UA filing as the authoritative public record of how an NMS Stock ATS represents its operations.

Specific Use Cases

The Form ATS-N/UA Files Dataset supports a narrow set of operational workflows centered on tracking how individual NMS Stock ATSs revise their public disclosures between material redesigns.

1. Building per-ATS amendment timelines and change diffs

Group filings by the filer CIK and fileNumber in metadata.json, sort by filedAt, and diff successive primary_doc.xml payloads element by element using the partXItemY... naming. The taStatementAboutAmendment cover narrative names which Items moved, and the Exhibit 3 redline (ATS-N EX-3 REDLINE) confirms the textual delta. Output: a per-ATS change log usable in venue scorecards, best-execution committee packets, and longitudinal research panels.

2. Monitoring order-type, segmentation, and matching-logic changes for SOR configuration

Sell-side smart-order-routing and algo teams parse Part III Items 7, 8, and 11 from primary_doc.xml (taPart3Item7*, taPart3Item8*, taPart3Item11a*) on every new UA, watching for new conditional order types, changes to minimum-quantity behavior, counterparty-selection rule edits, or new subscriber tiers. Hits flow into router rule updates, venue-quality recalibration, and updated algo-wheel disclosures to clients.

3. Tracking fee and rebate-tier revisions across NMS Stock ATSs

Extract Part III fee-and-rebate narratives across all UA filings to build a cross-venue pricing panel: tier thresholds, volume-based rebates, taker fees, and any behavior-conditioned pricing. Useful for buy-side broker negotiations, ATS pricing benchmarks for venue strategy teams, and policy analysis of conflict-of-interest pricing patterns.

4. Mapping operator and affiliate ownership through Schedules A and B

Pull every ATS-N EX-1 SCHD A BD and ATS-N EX-2 SCHD B BD exhibit from documentFormatFiles[], OCR the PDFs where needed, and join direct-owner, executive-officer, and indirect-owner records to a master ATS roster. Supports affiliate-routing conflict analysis (against Part II Items 1-3 narratives), M&A target screening for venue acquirers, and regulator-side ownership-change tracking.

5. Detecting disclosure-control weakness and supervisory red flags

Aggregate UA filings per ATS by quarter and classify the corrected Items by parsing taStatementAboutAmendment. Operators repeatedly amending the same Items, or filing UA for content that arguably belonged in an ATS-N/MA or ATS-N/CA, surface as candidates for examination. Used by SRO and regulator analysts to plan inspections, and by compliance officers to benchmark their own amendment cadence against peers.

6. Producing point-in-time disclosure snapshots for litigation and best-execution disputes

Reconstruct the exact Form ATS-N text in effect on a given trade date by walking the filer's ATS-N, ATS-N/MA, ATS-N/CA, and ATS-N/UA chain up to that date. Cite the specific ta* wording for order handling, segmentation, or conflicts as the disclosure a routing broker or counterparty could rely on. Output: expert reports, broker challenge letters, and best-execution committee evidence files.

7. Powering venue-classification and TCA vendor dashboards

Vendors ingest the structured XML to populate fields such as subscriber categories, order-type catalog, opt-out availability, affiliate interaction flags, and matching priority, keyed by ATS CRD/MPID from Part I. These structured fields feed venue-classification logic, TCA venue dimensions, and client-facing market-structure dashboards, refreshed on each new UA submission.

Dataset Access

Dataset Index JSON API: https://api.sec-api.io/datasets/form-atsn-ua-files.json This endpoint returns the dataset metadata and a complete listing of available container files. The response includes the dataset name, description, last updated timestamp, earliest sample date (2019-05-01), total records and total size, covered form types (ATS-N/UA), container format (ZIP), and the file types found inside each container (XML, PDF, JSON, HTML, TXT). It also includes the full dataset download URL and, for each container, the relative key, size in bytes, record count, last updated timestamp, and a direct download URL. This endpoint does not require an API key. It can be polled regularly to detect which year-month containers have changed in the most recent refresh and to drive incremental downloads.

Example response:

          1
          {
        

          2
            "datasetId": "1f13365b-9ae0-69b8-ae69-5b9da9a15a6d",
        

          3
            "datasetDownloadUrl": "https://api.sec-api.io/datasets/form-atsn-ua-files.zip",
        

          4
            "name": "Form ATS-N/UA Files Dataset",
        

          5
            "updatedAt": "2026-05-05T02:47:44.706Z",
        

          6
            "earliestSampleDate": "2019-05-01",
        

          7
            "totalRecords": 3408,
        

          8
            "totalSize": 422053179,
        

          9
            "formTypes": ["ATS-N/UA"],
        

          10
            "containerFormat": "ZIP",
        

          11
            "fileTypes": ["XML", "PDF", "JSON", "HTML", "TXT"],
        

          12
            "containers": [
        

          13
              {
        

          14
                "downloadUrl": "https://api.sec-api.io/datasets/form-atsn-ua-files/2026/2026-04.zip",
        

          15
                "key": "2026/2026-04.zip",
        

          16
                "size": 13818783,
        

          17
                "records": 42,
        

          18
                "updatedAt": "2026-05-05T02:47:44.706Z"
        

          19
              }
        

          20
            ]
        

          21
          }
        

Download Entire Dataset: https://api.sec-api.io/datasets/form-atsn-ua-files.zip?token=YOUR_API_KEY Downloads the full archive of all Form ATS-N/UA filings from May 2019 to the most recent refresh as a single ZIP file. This endpoint requires a valid SEC API key.

Download Single Container: https://api.sec-api.io/datasets/form-atsn-ua-files/2026/2026-04.zip?token=YOUR_API_KEY Downloads one year-month container instead of the full dataset, which is useful for incremental updates after monitoring the index API. This endpoint requires a valid SEC API key.

Each year-month container ZIP is organized into one subfolder per filing, named after the filing's accession number. Inside each accession-numbered subfolder you will typically find a metadata.json file describing the submission, a primary_doc.xml file containing the structured Form ATS-N/UA data, an XSL-rendered XHTML version of the primary document for human-readable viewing, and any PDF exhibits included with the original EDGAR submission. Image files from the original submission are excluded.

Frequently Asked Questions

What form does this dataset cover?

The dataset covers Form ATS-N/UA, the "updating amendment" variant of Form ATS-N filed under Rule 304(a)(2)(i)(B) of Regulation ATS. It contains only ATS-N/UA submissions; initial Form ATS-N filings and the ATS-N/MA, ATS-N/OFA, and ATS-N/CA amendment types are separate EDGAR submission types and are not included.

What does one record in this dataset represent?

One record is one accession-numbered Form ATS-N/UA submission as accepted by EDGAR. It bundles the structured primary_doc.xml payload, an XSL-rendered XHTML view of that XML, a metadata.json describing the submission and its filer, and any non-image exhibits — most commonly a copy of Schedule A of Form BD, a copy of Schedule B of Form BD, and a redline against the previously effective Form ATS-N.

Who is required to file Form ATS-N/UA?

The filer is the broker-dealer that operates an NMS Stock Alternative Trading System. A broker-dealer that operates more than one NMS Stock ATS files a separate Form ATS-N family for each venue. Non-NMS ATSs (fixed income, Treasury, options) and registered national securities exchanges are outside this regime and do not file Form ATS-N/UA.

When is Form ATS-N/UA due?

It is due no later than 30 calendar days after the end of each calendar quarter in which the inaccurate or incomplete information existed, producing typical filing windows in late January, late April, late July, and late October. The obligation is content-driven: if no qualifying updates accumulated during a quarter, no Form ATS-N/UA is filed for that quarter.

What time period does the dataset cover?

Coverage begins on May 1, 2019 — the first quarter in which the post-2018 Regulation ATS-N regime produced quarterly updating amendments — and continues through the most recent dataset refresh.

What file format is the dataset distributed in?

The dataset is distributed as ZIP year-month containers. Inside each container, every accession folder contains XML (the structured submission and its XHTML rendering), JSON (the EDGAR metadata), and the original exhibits in PDF, HTML, or TXT. Image-only attachments from the original EDGAR submission are excluded.

How does Form ATS-N/UA differ from Form ATS-N/MA and Form ATS-N/CA?

ATS-N/MA is filed at least 30 days before a material change to operations and is subject to a pre-effectiveness review, while ATS-N/CA corrects material errors or omissions that existed at the time of an earlier filing. ATS-N/UA is the residual quarterly track: filed after the fact for non-material corrections to information that has become inaccurate or incomplete and that does not fall under MA, OFA, or CA.