Form ATS-N-C Files Dataset

The Form ATS-N-C Files Dataset is the public archive of cessation-of-operations notices filed on EDGAR by registered broker-dealers that operate NMS Stock Alternative Trading Systems. Each record corresponds to a single Form ATS-N-C accession — a one-time advance notice required under Rule 304(a)(3) of Regulation ATS, filed at least ten business days before an NMS Stock ATS will stop operating, at which point the operator's Form ATS-N becomes ineffective. The dataset begins with the earliest live filings on EDGAR in April 2019, when the SEC's 2018 Regulation ATS amendments (Release No. 34-83663) made the Form ATS-N family operative, and continues through the present. Records are distributed as monthly ZIP containers carrying the structured EDGAR XML primary document, the XSL-rendered XHTML presentation, and a JSON metadata sidecar that flattens the EDGAR submission header. The dataset is the authoritative public census of equity ATS shutdowns under the post-April 2019 Rule 304 regime.

Dataset APIs

Dataset Files

What This Dataset Contains

The dataset captures every Form ATS-N-C filing accepted by EDGAR from April 2019 onward. Form ATS-N-C is the short-form notice of cessation prescribed by Rule 304(a)(3) of Regulation ATS — the terminal counterpart to Form ATS-N (the initial operation report) and Form ATS-N/A (material amendments) / Form ATS-N/UA (unmaterial amendments). An NMS Stock ATS operator must file Form ATS-N-C at least ten business days before it stops operating; once the cease date is reached, the operator's Form ATS-N is treated as ineffective and the ATS may no longer hold itself out under that name.

The form is structurally minimal because the substantive disclosures about the ATS — order types, subscriber categories, fees, conflicts of interest, affiliate activities — have already been published through the operator's prior Form ATS-N and any subsequent amendments. ATS-N-C exists to put the Commission and the public on notice that those prior disclosures are about to lapse, by stamping a definite cease-to-operate date onto the docket. EDGAR implements the form as a thin XML schema (root <edgarSubmission>, namespace http://www.sec.gov/edgar/atsncw) with all variable content carried inside <headerData> and a deliberately empty <formData> block. There are no narrative items, no exhibits, no financial statements, and no embedded signature blocks.

The dataset is distributed as monthly ZIP archives following a YYYY/YYYY-MM.zip -> YYYY-MM/<accession-no-dashes>/ layout. The file types found in the dataset are XML and JSON: the structured XML primary document, the JSON sidecar, and the XSL-rendered XHTML which EDGAR delivers under the .xml extension. Image files attached to the original EDGAR submission are excluded by the dataset builder; in practice this exclusion is moot for ATS-N-C because the underlying submissions do not carry image exhibits.

Content Structure of a Single Record

One record in the Form ATS-N-C Files Dataset corresponds to a single Form ATS-N-C filing as accepted by EDGAR, identified by its 18-character SEC accession number. Physically, the record is a per-accession folder distributed inside monthly ZIP archives. Logically, it packages the entire EDGAR submission for that accession (excluding image attachments) together with a metadata.json sidecar that flattens the EDGAR submission header into JSON. Each record therefore captures one cessation notice issued by an NMS Stock Alternative Trading System operator: the broker-dealer identity, the ATS identity, the operational contact, the submission flags, and the date on which the ATS will cease operating and at which its Form ATS-N becomes ineffective.

Each per-accession folder is flat and contains exactly three files:

1. metadata.json — JSON sidecar summarising the EDGAR submission header and document manifest.
2. primary_doc.xml — the canonical EDGAR XML carrying the structured form data.
3. xslATS-N-C_X01/primary_doc.xml — the XHTML rendering of the same submission, produced by EDGAR's ATS-N-C_X01 XSL stylesheet. Despite the .xml extension, this file's contents are XHTML 1.0 Strict.

The folder name is the accession number with the two dashes removed (for example, accession 0001323893-25-000003 becomes 000132389325000003). Folders are grouped by EDGAR filing month (YYYY-MM/), and monthly groups are zipped into YYYY/YYYY-MM.zip containers that constitute the dataset distribution. No PDFs, image files, additional exhibits, or R*.htm financial-report fragments appear in an ATS-N-C accession folder, because the underlying EDGAR submission carries only the primary document.

metadata.json

The sidecar is a single JSON object describing the submission at the EDGAR-header level. The meaningful fields for ATS-N-C are:

• formType — fixed string "ATS-N-C".
• accessionNo — dashed accession number (NNNNNNNNNN-NN-NNNNNN).
• filedAt — ISO-8601 timestamp with timezone offset, recording the EDGAR acceptance moment.
• description — free-text label, typically "Form ATS-N-C - Notice of Cessation of Operations of NMS Stock ATS (Rule 304(a)(3))".
• linkToFilingDetails — URL to the rendered (XSL-transformed) primary document on SEC.gov.
• linkToTxt — URL to the full submission text file on SEC.gov.
• linkToHtml — URL to the EDGAR submission index page (-index.htm).
• linkToXbrl — empty string; ATS-N-C carries no XBRL.
• documentFormatFiles — array of submission documents with sequence, size, documentUrl, description, and type. For ATS-N-C this array typically lists the XSL-rendered primary document, the raw primary XML, and the complete-submission .txt envelope.
• entities — array of filer entities. Each entry carries cik, companyName (with role marker, e.g. "... (Filer)"), type (ATS-N-C), act (34, the Exchange Act under which Regulation ATS is promulgated), fileNo (the broker-dealer's 013-XXXXX SRO file number), filmNo (EDGAR film identifier), fiscalYearEnd in MMDD form, and stateOfIncorporation.
• seriesAndClassesContractsInformation — empty array; the construct does not apply to ATS notices.
• dataFiles — empty array; no data exhibits accompany ATS-N-C.
• id — opaque 32-character hex identifier assigned by the dataset builder.

The sidecar is the most convenient point of entry for indexing and joins because it surfaces the operator's CIK, the broker-dealer SRO file number, the rendered-document URL, and the filing timestamp without parsing the XML.

primary_doc.xml

The structured EDGAR document. Its root is <edgarSubmission> in namespace http://www.sec.gov/edgar/atsncw, with auxiliary namespaces http://www.sec.gov/edgar/common (prefix com:) and http://www.sec.gov/edgar/atsncommon (prefix ats:). The document has two children: <headerData> (populated) and <formData> (intentionally empty).

<headerData> carries:

• submissionType — fixed string ATS-N-C.
• filerInfo/liveTestFlag — LIVE for production filings, TEST for EDGAR validation submissions.
• filerInfo/filer/filerCredentials/com:cik — the 10-digit zero-padded Central Index Key of the broker-dealer operator.
• filerInfo/filer/filerCredentials/com:ccc — the EDGAR access code, redacted to XXXXXXXX in publicly disseminated copies.
• filerInfo/filer/MPID — the four-letter Market Participant Identifier (FINRA-assigned) of the ATS.
• filerInfo/filer/NMSStockATSName — the display name of the ATS as registered with FINRA and the Commission.
• filerInfo/contact/ats:contactName, ats:contactPhoneNumber, ats:contactEmailAddress — the operational contact for the filing.
• filerInfo/flags/ats:overrideInternetFlag — boolean indicating an internet-hardship override of the standard EDGAR posting requirement.
• filerInfo/flags/ats:confirmingCopyFlag — boolean marking the filing as a confirming copy of a prior submission.
• dateCeaseToOperate — the substantive payload of the form: an MM/DD/YYYY date on which the ATS will cease operating, after which the operator's Form ATS-N is rendered ineffective.

<formData> is present in the schema for parity with Form ATS-N but contains no children. There are no Part-I-through-Part-IV item answers, no exhibits, and no narrative blocks. All variable content for the filing therefore lives within <headerData>, with dateCeaseToOperate as the only field unique to the cessation event itself.

xslATS-N-C_X01/primary_doc.xml

This is the printable presentation produced by the ATS-N-C_X01 XSL stylesheet on EDGAR. The file is XHTML 1.0 Strict (it opens with the corresponding DOCTYPE) and is laid out as a multi-panel form titled "Form ATS-N Filer Information" with the subhead "ATS-N-C: Notice of Cessation (Rule 304(a)(3))". The rendered panels include:

• A masthead with the SEC notice block and OMB approval information.
• A "Filer Information" table displaying CIK, masked CCC, MPID, NMS Stock ATS name, and the cease-to-operate date.
• A LIVE/TEST radio-button block, an internet-hardship-exemption checkbox, the operational contact name/phone/email, and a notification-preference selection.
• A "Part IV: Contact Information, Signature Block, and Consent to Service" section. ATS-N-C does not require Part IV content, so the rendered template emits empty placeholders for mailing address, signer name, signer title, and signature date.

The stylesheet references CSS at /css/ATSN_print.css and image assets at /Images/radio-checked.jpg, /Images/radio-unchecked.jpg, /Images/box-checked.jpg, and /Images/box-unchecked.jpg, all hosted on sec.gov. Those external assets are not bundled into the record; the rendered XHTML expects them to resolve against the SEC web origin when displayed in a browser.

Included content

Each record packages the full machine-readable submission for one ATS-N-C accession: the structured XML primary document, the XHTML rendering generated by EDGAR's stylesheet, and the JSON sidecar that flattens header metadata. Together, the XML and JSON layers cover every field the Commission collects for this form: filer credentials (CIK, masked CCC), ATS identification (MPID, ATS display name), broker-dealer identifiers (SRO file number, film number, state of incorporation, fiscal year end, company name), operational contact details, submission flags (LIVE/TEST, internet override, confirming copy), the cease-to-operate date, and direct links back to the canonical SEC.gov copies of the rendered document, the raw submission text, and the EDGAR index page.

Excluded or separate content

Image files attached to the original EDGAR submission are excluded by the dataset builder; in practice this exclusion is moot for ATS-N-C because the underlying submissions do not carry image exhibits. The CCC value in filerCredentials/com:ccc is redacted in the public EDGAR copy and therefore appears as XXXXXXXX in the dataset; no operational secret is exposed. The CSS and image assets referenced by the XSL-rendered XHTML are not bundled — they remain hosted on sec.gov. The full-submission .txt envelope and the EDGAR submission index page are referenced by URL inside metadata.json rather than mirrored as files.

The substantive disclosures about the ATS's operations (order types, subscriber rules, fee structure, affiliate conduct, conflict mitigation, and related matters) are not contained in an ATS-N-C record. Those disclosures live in the operator's prior Form ATS-N and any subsequent Form ATS-N/A or Form ATS-N/UA amendments and must be retrieved separately if they are needed alongside the cessation notice.

Changes in required content or structure over time

Form ATS-N-C is a creature of the SEC's Regulation ATS amendments adopted in July 2018 (Release No. 34-83663) and made operative in 2019. Before those amendments, NMS Stock ATSs filed the older Form ATS (and its amendments) as confidential submissions; there was no public, structured cessation notice. The 2018 rulemaking introduced the Form ATS-N family — Form ATS-N for initial operation reports, Form ATS-N/A for material amendments, Form ATS-N/UA for unmaterial amendments, and Form ATS-N-C for cessation — and required them to be filed publicly through EDGAR using a defined XML schema. The dataset accordingly begins with the form's earliest live filings in April 2019 and contains every Form ATS-N-C accession from that point forward.

Because the form was launched in its current XML form, its structure has remained essentially stable since inception: the <edgarSubmission> root, the <headerData> / <formData> split, and the cease-to-operate date as the single substantive field have been constant. The ATS-N-C_X01 XSL stylesheet likewise dates from the initial release and continues to render filings using the same multi-panel layout. Minor, non-breaking variations across records reflect filer behaviour (use of the internet-hardship override, presence or absence of a contact email, exact MPID assignment) rather than schema evolution.

Changes in data format over time

Form ATS-N-C did not transit the ASCII or HTML eras of EDGAR. From its first acceptance in 2019, it has been an XML-only form rendered through a fixed XSL stylesheet to XHTML for human reading. There is no XBRL or iXBRL component to the form, and the financial-reporting tagging regime does not apply to Regulation ATS notices. The dataset's distribution format (monthly ZIP archives carrying a JSON sidecar plus the raw XML primary document plus the XSL-rendered XHTML) has likewise been consistent across the form's life.

Interpretation notes

Several nuances matter for downstream consumption.

• <formData> is structurally present but always empty for ATS-N-C; extraction code should not treat its emptiness as a parsing error.
• dateCeaseToOperate uses American MM/DD/YYYY formatting inside the XML, not ISO-8601. The only ISO-8601 timestamp in the record is metadata.json:filedAt, which records the EDGAR acceptance time and is not interchangeable with the cessation date. Consumers must parse and normalise the MM/DD/YYYY string explicitly.
• The rendered XHTML in xslATS-N-C_X01/primary_doc.xml shares its filename with the raw XML and is differentiated only by its enclosing subfolder. Care is needed when unpacking records into a flat directory to avoid collapsing the two primary_doc.xml files.
• The rendered XHTML emits an empty Part IV signature panel inherited from the Form ATS-N template. This is presentation-template overflow rather than missing data: Part IV is not required for an ATS-N-C notice and the XML schema carries no Part IV elements.
• The relationship between an ATS-N-C record and the operator's prior disclosures is by reference only. Pairing a cessation notice with the substantive Form ATS-N narrative requires joining on the broker-dealer's CIK, MPID, or SRO file number across the relevant dataset families.
• The entities array in metadata.json typically contains a single filer entity for ATS-N-C, but multi-entity edge cases (for example, when an affiliated broker-dealer is co-listed) should be handled by iterating over the array rather than assuming a singleton.
• The CCC redaction means the XML cannot be replayed back to EDGAR as a live submission; the dataset record is an archival artefact, not a round-trippable form package.

Who Files or Publishes This Dataset, and When

Each record is a single Form ATS-N-C submission filed on EDGAR by a registered broker-dealer that operates an NMS Stock alternative trading system. The legal filer is the broker-dealer operator, not the ATS as a separate entity and not its subscribers or counterparties. The filing announces that the venue will stop operating on a specified future date.

The reporting population is narrow. A filer must be:

• a broker-dealer registered under Section 15 of the Exchange Act,
• operating an ATS within the meaning of Rule 300(a) of Regulation ATS,
• where the ATS trades NMS stocks (Rule 600 of Regulation NMS, generally exchange-listed equities and certain ETFs),
• with a Form ATS-N previously declared effective by the Commission,
• and a decision to wind the venue down.

In practice these filers are the broker-dealer parents of equity dark pools, single-dealer platforms, and other off-exchange NMS equity venues. The ATS is typically a facility operated within the broker-dealer, so the broker-dealer entity is the filer of record on EDGAR and the ATS is identified by name inside the filing.

Triggering event and timing

Form ATS-N-C is event-driven, not periodic. The trigger is the operator's decision to cease operations of an NMS Stock ATS with an effective Form ATS-N. There is one filing per cessation, no materiality threshold, and no recurring schedule.

Rule 304(a) of Regulation ATS requires the operator to file Form ATS-N-C at least 10 business days before the designated cessation date. The 10-business-day clock runs backward from the intended cessation date; operators may file earlier but not later. On the cessation date, the operator's Form ATS-N becomes ineffective by operation of Rule 304, and the venue can no longer rely on the Rule 3a1-1 exemption from exchange registration under Section 5 of the Exchange Act.

A typical filing identifies the broker-dealer operator, the name of the ATS, the designated cessation date, and a short reference to operations previously disclosed on the venue's Form ATS-N. The form is a one-time advance notice with no quarterly or annual follow-up; material changes to a pending cessation are handled through an amended Form ATS-N-C.

Regulatory anchor and dataset coverage

Form ATS-N-C sits inside the Form ATS-N regime adopted in Release No. 34-83663 (Regulation of NMS Stock Alternative Trading Systems, July 18, 2018), which became effective in early 2019. The regime rests on Section 5 of the Exchange Act, the Rule 3a1-1 exemption, and Rules 300 through 304 of Regulation ATS. The earliest filings on EDGAR date to April 2019, matching the dataset's start at 2019-04-01; there is no pre-EDGAR analogue.

Important distinctions

• Form ATS-N is the initial effective public disclosure for an NMS Stock ATS; Form ATS-N/UA covers material amendments during the venue's life; Form ATS-N-C is the one-time cessation notice that ends the Form ATS-N's effectiveness.
• A pre-effective NMS Stock ATS that abandons its application withdraws its pending Form ATS-N rather than filing Form ATS-N-C.
• Non-NMS ATSs (corporate debt, municipal, government, and other non-NMS securities) remain under the legacy framework: Form ATS for initial operation and amendments, Form ATS-R for quarterly volume, and a cessation amendment on Form ATS rather than Form ATS-N-C.
• Cessation under Rule 304 is distinct from broker-dealer withdrawal on Form BDW. Form ATS-N-C ends the venue's authority to operate as an NMS Stock ATS but does not affect the broker-dealer's overall registration; affiliates, parents, and subscribers of the broker-dealer are not filers.

How This Dataset Differs From Similar Datasets or Filings

Three constraints define the scope of Form ATS-N-C and shape every useful comparison: it covers (1) NMS Stock ATSs only, (2) the cessation event only, and (3) the post-April 2019 public Rule 304 regime only. The forms below sit closest to those boundaries.

Form ATS-N (initial NMS Stock ATS public disclosure)

ATS-N is the opening bookend; ATS-N-C is the closing one. ATS-N carries the full operational profile of the venue (order types, subscribers, fees, segmentation, conflicts, matching logic), while ATS-N-C carries almost no operational content beyond operator identity, ATS name, and effective cessation date. Every operating NMS Stock ATS has an ATS-N on file; only ceasing ATSs file ATS-N-C. To reconstruct what a shut-down venue actually did, join ATS-N-C to the most recent effective ATS-N for the same operator and ATS name.

Form ATS-N/UA and Form ATS-N/MA (amendments)

ATS-N/UA (updating) and ATS-N/MA (material) amendments keep the public ATS-N current during operation. They share filer population and the Rule 304 framework with ATS-N-C but are recurring mid-life updates with substantive operational content; ATS-N-C is a one-time terminal notice with none. A full lifecycle requires ATS-N (initial) plus ATS-N/UA and ATS-N/MA (mid-life) plus ATS-N-C (terminal), keyed on operator and ATS name.

Form ATS and Form ATS-A (non-NMS ATS filings)

Form ATS (initial) and Form ATS-A (amendment) are the confidential filings used by ATSs that trade non-NMS securities such as corporate bonds, municipals, and Treasuries. Same regulatory family and similar filer type, but disjoint asset-class scope and not publicly disseminated through EDGAR. A non-NMS ATS that shuts down files under Rule 301(b)(2), not Rule 304, and never appears in this dataset.

Form ATS-R (quarterly transaction reports)

ATS-R is a confidential quarterly volume and transaction report filed by all ATSs under Rule 301(b)(9). It is periodic, quantitative, and tabular; ATS-N-C is event-driven, narrative-light, and free of any transaction data. The two are complementary: ATS-R characterizes activity over time, ATS-N-C marks the terminal date. ATS-R is not generally available as filing text the way ATS-N-C is.

Form BDW (broker-dealer withdrawal)

BDW terminates a broker-dealer's registration entirely and is filed through CRD/IARD, not EDGAR. Because an NMS Stock ATS must be operated by a registered broker-dealer, a BDW by the operator forces an ATS cessation, but the reverse does not hold: an operator can shut a single ATS while continuing other broker-dealer business, filing ATS-N-C but no BDW. Joining BDW to ATS-N-C on operator CIK or CRD distinguishes full-operator exits from venue-only shutdowns.

Form 25 and Rule 19b-4 (registered exchange regime)

Form 25 delists a security from a national securities exchange; Rule 19b-4 governs SRO rule filings, including those used to wind down exchange operations. These cover the parallel venue lifecycle for registered exchanges, not ATSs, and involve a different legal regime, filer population, and content depth. Comprehensive coverage of equity trading-venue shutdowns requires ATS-N-C for the ATS side and Form 25 / 19b-4 for the exchange side; neither substitutes for the other.

Boundary summary

Within the intersection of NMS Stock ATSs, cessation events, and the public Rule 304 regime, the Form ATS-N-C dataset is the authoritative record of terminal-date and operator-identity information for equity ATS shutdowns. Outside that intersection, ATS-N-C must be paired with ATS-N and its amendments (operational context), ATS-R (activity history), ATS / ATS-A (non-NMS venues), BDW (full operator exit), and Form 25 / Rule 19b-4 (exchange-side cessations). The rarity of the event confirms the dataset's role as the closing record in a multi-form ATS lifecycle rather than a standalone analytical corpus.

Who Uses This Dataset

The ten-business-day advance-notice window is what gives the Form ATS-N-C dataset operational weight far beyond its small footprint: routing systems, compliance functions, examiners, and vendors all need to act inside that window. The user base is narrow but well defined, and the same four fields — cessation date, NMS Stock ATS name, broker-dealer operator identity (CIK and MPID), and contact block — drive most downstream workflows.

SOR and routing engineering teams

Smart-order-router engineers at broker-dealers and execution-services groups treat each filing as an action item. They key on the cessation date, NMS Stock ATS name, operator CIK, and operator MPID (when present) to deterministically match the venue against internal venue master data, then remove it from routing tables, decommission FIX sessions, and update child-order logic before the effective date.

Broker-dealer compliance and legal

Best-execution committees and in-house counsel use the cessation date, operator legal name, and contact block to evidence accurate knowledge of active venues. The dataset feeds Rule 606/607 disclosure updates, best-ex committee minutes, and surveillance checks confirming no internal system routed to the venue after cessation.

SEC and FINRA examiners

Examiners compare filing date against designated cessation date to verify the ten-business-day Rule 304 requirement, and use the operator CIK and ATS name to tie the notice to the operator's Form ATS-N record and FINRA ATS volume reports. The dataset supports examination scoping, deficiency letters, and post-cessation review of the operating broker-dealer.

Venue reference-data and analytics vendors

Vendors maintaining ATS directories, venue maps, and execution-quality dashboards treat ATS-N-C as the authoritative retirement trigger. They consume the structured metadata for the ATS name, operator CIK/MPID, and cessation date to update venue master files and historical coverage timelines used in client backtests.

Transaction-cost analysis providers

TCA teams propagate the cessation date and venue identifier into venue dimension tables so fills are not misattributed across the wind-down period. Clean venue panels protect slippage and price-improvement metrics in client reports covering quarters when a venue disappeared mid-period.

Institutional buy-side execution desks

Head traders and broker-relationship managers use the ATS name, operator identity, and cessation date to update approved-venue lists, confirm executing brokers removed the venue from their algos, and raise the cessation in the next broker review.

Market-structure researchers and microstructure data scientists

Researchers build a complete census of NMS Stock ATS exits from April 2019 onward. The cessation date, ATS name, and operator CIK serve as join keys against Form ATS-N filings and FINRA ATS volume statistics, supporting venue survival analysis, fragmentation indices, and feature engineering for routing and liquidity-prediction models.

Competing ATS operators

Strategy and product teams at active NMS Stock ATSs monitor cessations for competitive intelligence, sales targeting of displaced subscribers, and reads on dark-pool consolidation. They focus on the cessation date, ATS name, and operator identity.

Specific Use Cases

The dataset is small but operationally pointed: each record carries a definite cease-to-operate date for an NMS Stock ATS, filed at least ten business days in advance. The use cases below show the workflows that actually consume those records.

Decommissioning ATS destinations in smart-order routers

Routing engineering teams poll the dataset for new accessions, parse dateCeaseToOperate from primary_doc.xml, and match the NMSStockATSName and operator CIK against the venue master. The match drives FIX session decommissioning, removal from routing tables, and disabling of child-order logic for the venue, all scheduled to complete before the cessation date.

Building a Rule 304 ten-day-notice compliance check

Examiners and internal compliance teams compare metadata.json:filedAt against dateCeaseToOperate to verify that the ten-business-day advance-notice requirement under Rule 304(a)(3) was met. Filings that fall short surface as exceptions and feed examination scoping, deficiency-letter drafting, and best-execution committee minutes.

Reconstructing full ATS lifecycles by joining to Form ATS-N

Researchers and reference-data vendors join ATS-N-C records to the operator's prior Form ATS-N and ATS-N/UA / ATS-N/MA filings on operator CIK, MPID, and ATS display name to produce a per-venue lifecycle table: launch date, material amendments, last effective disclosure, and terminal date. The cessation date from ATS-N-C closes the timeline that the ATS-N family opens.

Maintaining venue panels for transaction-cost analysis

TCA providers propagate NMSStockATSName, operator CIK, and dateCeaseToOperate into venue dimension tables so that fills booked during a wind-down quarter are not misattributed to a still-active venue. The clean venue panel preserves slippage, fill-rate, and price-improvement metrics across the period in which a venue disappeared mid-quarter.

Distinguishing venue-only shutdowns from full broker-dealer exits

Compliance and counterparty-risk teams join ATS-N-C records to Form BDW filings on operator CIK and SRO file number (013-XXXXX from metadata.json:entities[].fileNo). An ATS-N-C with no matching BDW indicates the broker-dealer is closing one venue while continuing other business; an ATS-N-C paired with a BDW signals a complete operator exit and triggers broader counterparty review.

Census of NMS Stock ATS exits for market-structure research

Microstructure researchers treat the dataset as the authoritative public census of equity ATS shutdowns from April 2019 onward. Extracting dateCeaseToOperate, ATS name, and operator CIK from every accession yields a survival-analysis panel used for fragmentation indices, dark-pool consolidation studies, and features in liquidity-prediction or routing models.

Competitive intelligence and displaced-subscriber outreach

Strategy and sales teams at active NMS Stock ATSs and execution-services brokers monitor new ATS-N-C filings for the operator identity, ATS name, and cessation date, then target displaced subscribers of the closing venue with onboarding outreach scheduled against the announced cease date.

Dataset Access

The dataset is accessible through three endpoints: a JSON index for metadata discovery, a full archive download, and per-container downloads for incremental access.

Dataset Index JSON API: https://api.sec-api.io/datasets/form-atsnc-files.json

This endpoint returns the dataset metadata and the list of available container files. It includes the dataset name, description, last updated timestamp, earliest sample date, total record count, total size, form types covered, container format, and file types included. Each entry under containers[] provides a download URL, key, size, record count, and updated timestamp for an individual container. Poll this endpoint to monitor which containers were modified during the most recent refresh and decide which to download. This endpoint does not require an API key.

Example response:

          1
          {
        

          2
            "datasetId": "1f13365b-9ae0-6a5a-8308-34e8d87a56f6",
        

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

          4
            "name": "Form ATS-N-C Files Dataset",
        

          5
            "updatedAt": "2026-04-16T08:47:18.075Z",
        

          6
            "earliestSampleDate": "2019-04-01",
        

          7
            "totalRecords": 42,
        

          8
            "totalSize": 82222,
        

          9
            "formTypes": ["ATS-N-C"],
        

          10
            "containerFormat": "ZIP",
        

          11
            "fileTypes": ["XML", "JSON"],
        

          12
            "containers": [
        

          13
              {
        

          14
                "downloadUrl": "https://api.sec-api.io/datasets/form-atsnc-files/2024/2024-06.zip",
        

          15
                "key": "2024/2024-06.zip",
        

          16
                "size": 12483,
        

          17
                "records": 3,
        

          18
                "updatedAt": "2024-06-18T14:22:11.000Z"
        

          19
              }
        

          20
            ]
        

          21
          }
        

Download Entire Dataset: https://api.sec-api.io/datasets/form-atsnc-files.zip?token=YOUR_API_KEY

Downloads the complete dataset as a single ZIP archive containing all Form ATS-N-C filings from April 2019 to the present. This endpoint requires an API key.

Download Single Container: https://api.sec-api.io/datasets/form-atsnc-files/2024/2024-06.zip?token=YOUR_API_KEY

Downloads one monthly container ZIP rather than the full archive. Containers are organized by year and month (e.g. 2024/2024-06.zip), and the exact paths available are listed in the JSON index under containers[]. This endpoint requires an API key.

Frequently Asked Questions

What form does this dataset cover?

The dataset covers Form ATS-N-C, the notice of cessation of operations of an NMS Stock Alternative Trading System filed under Rule 304(a)(3) of Regulation ATS. It is the terminal counterpart to Form ATS-N (initial operation report) and the Form ATS-N/A and Form ATS-N/UA amendments.

What does one record in this dataset represent?

One record corresponds to a single Form ATS-N-C filing as accepted by EDGAR, identified by its 18-character SEC accession number. Physically the record is a per-accession folder containing three files — metadata.json, primary_doc.xml, and xslATS-N-C_X01/primary_doc.xml — that together capture the broker-dealer operator's identity, the ATS identity, the operational contact, the submission flags, and the date on which the ATS will cease operating.

Who is required to file Form ATS-N-C?

The filer is a broker-dealer registered under Section 15 of the Exchange Act that operates an NMS Stock ATS with a Form ATS-N previously declared effective by the Commission. The broker-dealer entity is the filer of record on EDGAR; the ATS is identified by name inside the filing rather than as a separate filer.

When must Form ATS-N-C be filed?

Rule 304(a) of Regulation ATS requires the operator to file Form ATS-N-C at least ten business days before the designated cessation date. The clock runs backward from the intended cessation date — operators may file earlier but not later — and on the cessation date, the operator's Form ATS-N becomes ineffective.

What time period does the dataset cover?

The dataset begins with the earliest Form ATS-N-C filings on EDGAR in April 2019, when the SEC's 2018 Regulation ATS amendments (Release No. 34-83663) made the form operative, and contains every Form ATS-N-C accession from that point forward. There is no pre-EDGAR analogue because no public, structured cessation notice existed before the Form ATS-N regime.

What file formats are in each record?

Each per-accession folder contains exactly three files: a JSON metadata sidecar (metadata.json), the canonical EDGAR XML primary document (primary_doc.xml), and the XSL-rendered XHTML 1.0 Strict presentation produced by the ATS-N-C_X01 stylesheet (delivered under the .xml extension at xslATS-N-C_X01/primary_doc.xml). The dataset itself is distributed as monthly ZIP archives organized as YYYY/YYYY-MM.zip.

How does Form ATS-N-C differ from Form ATS-N and Form ATS?

Form ATS-N is the initial public operational disclosure for an NMS Stock ATS and Form ATS-N-C is the one-time terminal cessation notice that ends Form ATS-N's effectiveness; the two are bookends of the same lifecycle. Form ATS (and Form ATS-A) are the confidential filings used by ATSs that trade non-NMS securities such as corporate bonds and municipals, are not publicly disseminated through EDGAR, and use a separate cessation procedure under Rule 301(b)(2) — non-NMS ATS shutdowns never appear in this dataset.