Form S-3MEF Files Dataset

The Form S-3MEF Files dataset is a complete EDGAR archive of every Rule 462(b) "More Effective Filing" registration statement that upsizes an already-effective Form S-3 by up to twenty percent of the prior maximum aggregate offering price. Each record is one EDGAR submission, identified by its 18-digit SEC accession number, packaged as an accession-numbered folder that bundles a canonical metadata.json descriptor with every primary document attached to the submission except binary image exhibits. The filer is the same legal registrant as on the underlying Form S-3 — typically a domestic Exchange Act reporting issuer in the middle of a follow-on, convertible, or shelf takedown that needs to register additional securities of the same class at or near pricing. Form S-3MEF becomes effective the instant EDGAR accepts it, with no staff review and no separate effectiveness order. The dataset covers all S-3MEF filings submitted to EDGAR from June 1, 1995 to the present and is distributed as monthly ZIP containers holding TXT, JSON, HTML, and PDF files.

Dataset APIs

Dataset Files

What This Dataset Contains

The dataset captures every Form S-3MEF registration statement accepted by EDGAR, organized one record per accession number. Form S-3MEF is a short-form "upsizing" registration statement filed under Rule 462(b) of the Securities Act of 1933. It does not stand on its own as a substantive disclosure document; it is a thin wrapper that incorporates by reference a previously filed and already-effective Form S-3 (the "Prior Registration Statement," cited by its 333-prefixed Securities Act file number). Its purpose is mechanical: to register an additional dollar amount of the same class of securities — capped at 20% of the maximum aggregate offering price registered on the prior S-3 — without preparing a new prospectus.

Because the form is automatically effective on filing, its content footprint is minimal: a facing page, an explanatory note that ties the new registration to the prior one by file number, the statutorily required exhibits (legality opinion, auditor consent, filing-fee table), the signature page, and any Rule 430A pricing information that had been omitted from the earlier registration. The substantive disclosure — risk factors, business description, plan of distribution, financial statements — lives in the prior S-3 and is pulled into the S-3MEF only by reference.

The dataset is distributed as a tree of monthly ZIP containers. The earliest sample dates from June 1, 1995, and refreshes track new EDGAR submissions through the present. Available file types in records include TXT, JSON, HTML, and PDF, although in practice modern S-3MEF records consist almost exclusively of HTML exhibits plus the JSON descriptor.

Content Structure of a Single Record

What one record represents

A single record in the Form S-3MEF Files dataset is one complete EDGAR submission of a Form S-3MEF registration statement, identified by its 18-digit SEC accession number. The record unit is a per-accession folder that bundles a single canonical metadata.json descriptor together with every primary document attached to that EDGAR submission, with the exception of binary image exhibits. Each record therefore corresponds one-to-one with a discrete Rule 462(b) "More Effective Filing" event — the moment an issuer expanded an already-effective Form S-3 registration by up to twenty percent of the prior maximum aggregate offering price, with the new registration statement becoming effective immediately upon filing.

Container layout and record packaging

The dataset is distributed as a tree of monthly ZIP containers organized as <dataset>/<YYYY>/<YYYY-MM>.zip. Each monthly archive contains zero or more accession-numbered subfolders, each of which is one record. Folder names are the SEC accession number with the two dash separators removed, producing an 18-digit string of the form <filer-or-agent-CIK><YY><sequence> (for example, accession 0001654954-25-011644 becomes folder 000165495425011644). Form S-3MEF is a low-volume form type, so most monthly archives hold only a handful of records.

Inside an accession folder, file naming follows the registrant's own EDGAR submission conventions rather than a normalized scheme. A typical pattern uses a short ticker- or company-stem prefix followed by a document-type suffix (for example, uamy_s3mef.htm, uamy_ex51.htm, uamy_ex231.htm, uamy_ex107.htm). The stable, machine-friendly mapping from filename to document role is supplied by metadata.json rather than by the filename itself, through the sequence, type, and description fields on each documentFormatFiles entry.

The metadata.json descriptor

Every record carries a metadata.json written at the root of the accession folder. It is the canonical, structured view of the filing and the only file in the record that is guaranteed to exist regardless of what the registrant attached. Its top-level fields include:

• formType — the literal form type, "S-3MEF".
• accessionNo — the dashed accession number (e.g. "0001654954-25-011644").
• filedAt — the EDGAR acceptance timestamp as an ISO-8601 datetime with offset.
• effectivenessDate — for S-3MEF this is identical to the filing date because Rule 462(b) makes the registration effective on receipt.
• description — the free-text EDGAR human description, typically "Form S-3MEF - Registration adding securities to prior Form S-3 registration [Rule 462(b)]".
• linkToFilingDetails — direct URL to the primary S-3MEF document on sec.gov/Archives/edgar/....
• linkToTxt — URL to the complete SGML submission text file.
• linkToHtml — URL to the EDGAR -index.htm page for the accession.
• linkToXbrl — URL to a standalone XBRL instance when one exists; blank for the typical S-3MEF, which carries XBRL only inside the Inline XBRL fee exhibit.
• id — internal hash identifier for the record.
• documentFormatFiles[] — the inventory of every primary document in the EDGAR submission, with sequence, size, documentUrl, description, and type for each. type values seen on S-3MEF submissions include S-3MEF, EX-5.1, EX-23.1 (and additional EX-23.x entries when more than one accounting firm consents), EX-FILING FEES, and GRAPHIC. The final entry, with a blank type and a URL ending in .txt, represents the complete SGML submission file.
• dataFiles[] — companion XBRL/XML artifacts, most commonly the extracted XBRL instance document for the filing-fee exhibit (type: "XML", description: "EXTRACTED XBRL INSTANCE DOCUMENT").
• entities[] — the parties on the filing, almost always a single Filer entity. Per-entity fields cover companyName (with role suffix such as "(Filer)"), cik, irsNo, fileNo (the new 333- file number assigned to the S-3MEF itself, distinct from the prior S-3's file number that appears inside the document body), filmNo, stateOfIncorporation, fiscalYearEnd, act ("33" for the Securities Act of 1933), sic (industry code with description), tickers[], and an entity-level type.
• seriesAndClassesContractsInformation[] — typically empty for S-3MEF; populated only when the registrant is a fund-style issuer with separate series/classes.

The SGML document envelope and primary documents

Each non-Inline-XBRL document referenced from documentFormatFiles is stored on disk as an .htm file whose payload follows the EDGAR SGML submission envelope. A small set of header tags identifies the document, followed by the HTML payload between <TEXT> and </TEXT>:

          1
          <DOCUMENT>
        

          2
          <TYPE>S-3MEF
        

          3
          <SEQUENCE>1
        

          4
          <FILENAME>uamy_s3mef.htm
        

          5
          <DESCRIPTION>S-3MEF
        

          6
          <TEXT>
        

          7
          <html>... full HTML of the registration statement ...</html>
        

          8
          </TEXT>
        

          9
          </DOCUMENT>
        

The header keys (TYPE, SEQUENCE, FILENAME, DESCRIPTION) align one-to-one with the corresponding documentFormatFiles entry in metadata.json, so the mapping between metadata and on-disk content is unambiguous even when filenames are idiosyncratic.

Primary S-3MEF document (<stem>_s3mef.htm)

The HTML body of the registration statement is short and largely formulaic. It opens with the EDGAR cover-page block — the title FORM S-3 / REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933, the registrant's exact legal name, state of incorporation, IRS Employer Identification Number, principal executive office address, telephone number, and the name and address of the agent for service. A check-box section flags the Rule 462(b) status and quotes the prior registration statement's file number in the form (File No. 333-XXXXXX). A second checkbox cluster identifies the registrant as a Large Accelerated Filer, Accelerated Filer, Non-Accelerated Filer, Smaller Reporting Company, or Emerging Growth Company.

Following the cover page, the document contains an "EXPLANATORY NOTE AND INCORPORATION BY REFERENCE" paragraph that performs the substantive work of the form: it invokes Rule 462(b), states the additional dollar amount being registered, identifies the prior registration statement by 333- file number, and confirms that the additional amount represents no more than twenty percent of the maximum aggregate offering price remaining available under the prior registration. The document then incorporates the prior registration statement by reference rather than restating any of its disclosure.

Next is an "EXHIBIT INDEX" table that enumerates the attached exhibits — typically Exhibit 5.1 (legal opinion), Exhibit 23.1 (auditor consent), additional EX-23.x consents when more than one accounting firm is involved, and Exhibit 107 (filing-fee table) — with hyperlinks to the local exhibit filenames. The document ends with the signature page: the registrant's signature block, the printed name and title of the principal signing officer (typically the CEO), the principal financial officer (typically the CFO), and director signatures rendered with /s/ script-style attestations and dates. When pricing information was omitted from the prior S-3 in reliance on Rule 430A, the S-3MEF body may also contain a Rule 430A pricing supplement disclosing the offering price and underwriting terms.

Legality opinion (<stem>_ex51.htm, type EX-5.1)

A short letter from outside or in-house counsel addressed to the registrant's board, on firm letterhead, dated as of the filing date. It describes the securities being registered, recites counsel's review of the registrant's organizational documents and the prior S-3 registration statement, and delivers the standard "validly issued, fully paid and non-assessable" opinion required by Item 601(b)(5) of Regulation S-K. The HTML often includes <img> references to firm-logo and signature graphics, but the underlying image binaries are not part of the dataset record (see the excluded content notes below).

Auditor consent (<stem>_ex231.htm, type EX-23.1)

A brief consent letter on the audit firm's letterhead in which the independent registered public accounting firm consents to the incorporation by reference of its audit report on the registrant's financial statements into the new registration statement. The letter names the registrant, identifies the audit report by date and the periods covered, and is signed and dated by the audit firm. When more than one auditor is implicated (for example after a change of accountants), additional EX-23.x consents appear with the same structure. As with the legality opinion, embedded logo and signature images are referenced from the HTML but not included as binaries in the record.

Filing-fee table (<stem>_ex107.htm, type EX-FILING FEES)

The Exhibit 107 filing-fee exhibit is the only structured-data component of a typical S-3MEF record. Unlike the other exhibits, it is delivered as an Inline XBRL document — XHTML carrying XBRL tags — and is not wrapped in the SGML <DOCUMENT> envelope. Its root XHTML element declares the Inline XBRL namespace xmlns:ix="http://www.xbrl.org/2013/inlineXBRL" together with the SEC filing-fee taxonomy namespace xmlns:ffd="http://xbrl.sec.gov/ffd/<YYYYqQ>" (the year-quarter version varies by filing date) and the xmlns:dei namespace for entity identifiers.

The visible HTML renders the standard SEC filing-fee schedule with sections for "Newly Registered Securities," "Fees Previously Paid," "Carry Forward Securities," "Total Offering Amounts," "Total Fees Previously Paid," "Total Fee Offsets," and "Net Fee Due." Behind each visible value, an ix:nonNumeric or ix:nonFraction tag carries the structured fact. Common ffd: tags include ffd:FormTp, ffd:SubmissnTp, ffd:OfferingSctyTp, ffd:Rule457oFlg, ffd:MaxAggtOfferingPric, ffd:FeeRate, ffd:FeeAmt, and ffd:NetFeeAmt; the dei: block carries dei:EntityCentralIndexKey and dei:EntityRegistrantName. The SEC additionally publishes an "EXTRACTED XBRL INSTANCE DOCUMENT" companion XML for this exhibit, referenced from the dataFiles[] array in metadata.json.

Included content

A record reliably includes the metadata.json descriptor and one HTML file for each entry in documentFormatFiles whose type is S-3MEF or any EX- prefix. This means the registration statement itself, the legality opinion, the auditor consent (or consents), and the Inline XBRL filing-fee exhibit are all materialized on disk in the accession folder. The complete SGML submission text file referenced by the trailing blank-typed entry in documentFormatFiles is identified in metadata via linkToTxt. The file-types found in the dataset are TXT, JSON, HTML, and PDF, although in practice modern S-3MEF records consist almost exclusively of HTML exhibits plus the JSON descriptor.

Excluded or separate content

By the dataset's design, image exhibits — GRAPHIC-typed entries in documentFormatFiles, typically .jpg files holding firm logos, signature images, and similar binary artifacts referenced from the HTML exhibits — are listed in metadata.json but are not written into the record folder. As a result, <img src="...jpg"> references inside the legality opinion and auditor consent will not resolve to local files; the existence and file-level metadata of those images are still recoverable from documentFormatFiles. The substantive disclosure of the offering — risk factors, business description, plan of distribution, financial statements, and the prospectus narrative — is not in the S-3MEF at all; it lives in the Prior Registration Statement (the earlier Form S-3 identified by 333- file number) and is incorporated only by reference. Amendments to S-3MEF filings are filed under the form type S-3MEF/A and are not part of this dataset, whose formTypes is restricted to the bare S-3MEF.

Format evolution over time

Form S-3MEF has been accepted on EDGAR since June 1995, and the on-disk presentation of records has tracked the broader EDGAR format evolution.

• The earliest filings (mid-1990s through the late 1990s) were submitted as plain ASCII text inside the SGML <DOCUMENT> envelope. The registration statement and exhibits appear as flat text with form-feed page breaks, monospaced tables, and no styling. The fee table is rendered as an ASCII table directly in the body of the registration statement rather than as a separate Exhibit 107.
• HTML-formatted submissions began appearing in the early 2000s and gradually became the norm, with <TEXT> payloads switching from ASCII to inline HTML and exhibits delivered as separate .htm files.
• A material structural change took effect with the SEC's 2021 final rule on filing-fee disclosure (Release No. 33-10997). Beginning with phase-in compliance dates in 2022, registrants were required to present filing-fee information in a separately tagged Exhibit 107 using the SEC's filing-fee taxonomy in Inline XBRL, with the ffd: namespace identifying tagged facts. Records filed before this transition do not have an EX-FILING FEES entry in documentFormatFiles; records filed after it consistently do, and the exhibit is the dataset's principal source of structured financial facts for an S-3MEF filing.
• PDF documents occasionally appear among documentFormatFiles entries when registrants submit auxiliary materials in PDF form, though for S-3MEF this is uncommon — the form's exhibits are nearly always HTML or Inline XBRL.

The overall content of the form — facing page, Rule 462(b) explanatory note, exhibit index, legality opinion, auditor consent, signature page — has been remarkably stable across the dataset's full historical span. The most material substantive change is the Exhibit 107 transition from a free-form table inside the body to a separately filed Inline XBRL exhibit.

Interpretation and extraction notes

Several characteristics of the form and of the dataset packaging warrant attention for downstream use.

• The S-3MEF's substantive content is determined almost entirely by what the prior S-3 says. Reading an S-3MEF in isolation will reveal the dollar amount and class of additional securities being registered and the prior file number, but the offering's economic terms and risk profile must be reconstructed from the referenced earlier registration statement.
• Two distinct 333- file numbers are relevant to each record. The new file number assigned to the S-3MEF itself appears as fileNo on the filer entity in metadata.json. The prior S-3's file number — the pointer needed to recover the substantive disclosure — appears only inside the body of the S-3MEF document, typically in the cover-page checkbox area and in the explanatory-note paragraph, and is not surfaced as a top-level metadata field.
• The Inline XBRL fee exhibit is the most reliable machine-readable source of the offering's headline numbers (maximum aggregate offering price, fee rate, fee amount, net fee due). For pre-2022 filings, those figures must be parsed out of the registration-statement body table.
• Because filename conventions inside an accession folder are registrant-driven rather than normalized, automated extraction should rely on the documentFormatFiles[] array in metadata.json (matched by type and sequence) rather than on filename regular expressions.
• Because S-3MEF is automatically effective upon filing, filedAt and effectivenessDate in metadata.json are functionally identical for every record. This is informative when reconciling against EDGAR effectiveness data and against the parent S-3's own effectiveness timing, but it means the dataset offers no independent effectiveness signal beyond the filing timestamp itself.
• The 20% cap under Rule 462(b) is asserted in the explanatory note rather than enforced through structured metadata; verifying that a particular S-3MEF stays within the cap requires reading the prior S-3's registered amount and comparing it to the ffd:MaxAggtOfferingPric carried by Exhibit 107.

Who Files or Publishes This Dataset, and When

Who files the record

Each record is an abbreviated registration statement filed by an issuer that already has an effective Form S-3 and wants to register additional securities of the same class, for the same offering, under Rule 462(b) of the Securities Act of 1933. The filer is the same legal registrant as on the underlying S-3. Co-registrants on the prior S-3 (typically guarantor subsidiaries of registered debt) sign the S-3MEF in the same capacity. The "MEF" suffix stands for "Money, Effective on Filing": the form upsizes the dollar amount registered on an effective S-3 and becomes effective the instant it is accepted by EDGAR, with no staff review and no separate effectiveness order.

Filing population

Only issuers eligible to use Form S-3 may file an S-3MEF. That means domestic Exchange Act reporting issuers that meet the registrant requirements of General Instruction I.A to Form S-3 and one of the transaction requirements in General Instruction I.B (primary offerings subject to the public-float test or the limited-class exception, secondary offerings, or registered investment-grade non-convertible securities, among others). The typical filer is an issuer in the middle of a registered takedown (a follow-on equity offering, a convertible note offering, or a debt offering) that has seen demand exceed the maximum aggregate offering price registered on the original S-3 and wants to upsize without preparing a new registration statement.

The form is not available to:

• Issuers that do not qualify for Form S-3 (an S-1 issuer uses Form S-1MEF for the equivalent Rule 462(b) upsize).
• Foreign private issuers registering on Form F-3 (they use Form F-3MEF).
• Investment companies registered under the Investment Company Act of 1940 (which use the N-series forms).
• Any issuer trying to register a different class of securities than the prior S-3 covered, or to register more than 20% of the maximum aggregate offering price set forth on the prior S-3.

Triggering event

The S-3MEF is event-driven, not periodic. The trigger is the issuer's decision, while a Form S-3 is effective and an offering is live, to register additional securities of the same class for the same offering. In practice this is last-minute investor demand during marketing or pricing of a takedown: the underwriters and issuer agree on a deal size that exceeds the dollar amount already registered, and the issuer files an S-3MEF to cover the incremental amount before sales are confirmed. Because effectiveness is automatic upon filing, the S-3MEF is typically transmitted to EDGAR very close to pricing, often the same day and sometimes within minutes of launch or pricing. No SEC declaration of effectiveness is required and no waiting period applies.

Rule 462(b) conditions

Form S-3MEF is the EDGAR vehicle for a Rule 462(b) registration. Rule 462(b) permits an abbreviated, immediately effective registration of additional securities of the same class for the same offering, provided all of the following are met:

• The new registration statement is filed before any confirmations of sale are sent for the additional securities.
• It registers additional securities in an amount and at a price that together represent no more than 20% of the maximum aggregate offering price for each class set forth in the filing fee table (formerly the "Calculation of Registration Fee" table, now Exhibit 107 under Rule 457) of the earlier registration statement.
• It is for the same offering as the earlier registration statement and identifies that earlier registration statement by SEC file number on the cover page.
• The required filing fee under Rule 457 has been paid in connection with the new registration statement.
• The cover page states that the registration statement is being filed pursuant to Rule 462(b).

Substantive disclosure is satisfied by incorporating the contents of the earlier effective Form S-3 by reference. Beyond the facing page and incorporation statement, an S-3MEF generally includes any pricing information omitted from the earlier registration statement in reliance on Rule 430A, a new Exhibit 5 legality opinion covering the additional securities, a new Exhibit 23 auditor consent (and any other required consents), the Exhibit 107 filing fee table reflecting the additional securities and the fee paid under Rule 457, and the required signatures (or reliance on powers of attorney already on file).

The 20% cap is measured against the maximum aggregate offering price registered on the prior S-3, not against the unsold portion, and it is a per-offering ceiling. Successive S-3MEFs against the same base S-3 cannot collectively exceed it.

Timing constraints

There is no calendar deadline. The two binding timing rules are:

• The S-3MEF must be filed before confirmations are sent for the additional securities. In practice this means before pricing of the upsized takedown, or at the latest before the underwriters confirm sales of the incremental amount.
• The earlier S-3 must still be effective when the S-3MEF is filed. Once the underlying S-3 has been withdrawn, deregistered, or otherwise lapsed, Rule 462(b) is unavailable.

Effectiveness of the S-3MEF is automatic upon EDGAR acceptance, and counsel typically dates the Exhibit 5 opinion as of that moment.

Important distinctions

• Versus a post-effective amendment. A post-effective amendment to an S-3 is broader (correcting disclosure, adding selling stockholders, adding offerings) and may require staff review and a separate declaration of effectiveness. The S-3MEF is narrower: same class, same offering, up to 20%, immediate effectiveness under Rule 462(b).
• Relationship to the base S-3. The S-3MEF does not replace the prior S-3. The prior S-3 remains operative; the S-3MEF is an incremental registration that piggybacks on it through incorporation by reference and is identified by the prior file number.
• Other form families. S-1 issuers use Form S-1MEF for the same mechanic. Foreign private issuers on Form F-3 use Form F-3MEF.
• WKSIs on automatic shelf registrations. Well-known seasoned issuers filing on Form S-3ASR can register additional classes or amounts by post-effective amendment that becomes effective immediately upon filing under Rule 462(e), so they often have no need for the S-3MEF path. The S-3MEF is most common among S-3 filers that are not WKSIs, or where Rule 462(b) is the chosen path for a specific takedown.
• Co-registrants. Guarantor subsidiaries that signed the prior S-3 must also sign the S-3MEF. The principal filer is the parent registrant, but each co-registrant's securities (such as guarantees) are covered on the same incorporated basis.
• Amendments. An S-3MEF can be amended; amendments appear as form type S-3MEF/A and are used for exhibit, signature, or fee-table corrections. They do not extend or reset the 20% cap.

Coverage

The dataset covers all Form S-3MEF filings submitted to EDGAR from June 1, 1995 to the present. Rule 462(b) in its modern form was adopted by the SEC in 1996, and the abbreviated, immediate-effectiveness mechanic was designed for the EDGAR era, so the electronic record is essentially coextensive with the form's full operational history. Filing volume tracks the level of S-3 follow-on and shelf takedown activity in each market cycle.

How This Dataset Differs From Similar Datasets or Filings

Form S-3MEF occupies a narrow procedural niche: a Rule 462(b) upsizing registration that piggybacks on an already-effective Form S-3 to add up to 20% more securities, effective immediately on filing. The most useful comparisons are to its parent registration, its 462(b) siblings, the WKSI alternative, and the prospectus and fee filings that travel with it.

Form S-3 (parent registration)

The parent S-3 carries the substantive disclosure — prospectus, plan of distribution, risk factors, incorporated Exchange Act reports, expert consents. The S-3MEF carries almost none of that; it identifies the parent by file number, incorporates it by reference, and registers the additional securities. Use S-3 to study what is being offered; use S-3MEF only to detect that an upsizing occurred and to link it to a parent file number. The two are complements, never substitutes.

Form S-3/A (amendments to S-3)

Easy to confuse because both modify a prior S-3, but the legal track is different. An S-3/A is an amendment to the original registration and can revise disclosure, add securities, or cure deficiencies; it generally requires a fresh effectiveness determination. An S-3MEF is not an amendment — it is a new registration under Rule 462(b), capped at 20% of the parent's registered dollar amount, limited to securities of the same class, and effective on filing. S-3/A is for substantive revision; S-3MEF is for same-day pricing-driven upsizing.

Form S-1MEF

The 462(b) sibling for issuers using Form S-1 instead of S-3. Identical mechanic — 20% ceiling, immediate effectiveness, minimal document set. The split is filer eligibility: S-3MEF requires the seasoned-issuer reporting and float tests of S-3, while S-1MEF is used by issuers who do not qualify for short-form registration, including IPO issuers. S-1MEF clusters around IPO pricing days; S-3MEF clusters around follow-ons, secondaries, and shelf takedowns.

Form F-3MEF

The foreign-private-issuer counterpart, layered on Form F-3. Same Rule 462(b) mechanic and 20% ceiling. The distinction is filer population and the underlying disclosure regime — F-3 incorporates 20-F and 6-K reports rather than Form 10-K and 10-Q. A complete view of 462(b) upsizings requires S-1MEF, S-3MEF, and F-3MEF together.

Form S-3ASR and Rule 462(e) post-effective amendments

For well-known seasoned issuers (WKSIs), the upsizing problem is solved differently. An automatic shelf on Form S-3ASR can be expanded through a Rule 462(e) post-effective amendment that is itself effective on filing, with no 20% cap. S-3MEF and 462(e) PEAs address the same business need — upsizing a shelf at or near pricing — but for different issuer tiers: S-3MEF for seasoned non-WKSIs (or WKSIs who did not elect automatic shelf registrations treatment); 462(e) PEAs for WKSIs. Studies of upsizing frequency must cover both populations.

424B prospectus filings (424B1, 424B2, 424B3, 424B5)

424B filings carry the priced prospectus supplement and almost always accompany an S-3MEF, because the upsizing usually happens at the moment a takedown is priced. The two filings cover the same offering but capture different artifacts: 424B holds pricing, deal economics, underwriters, and use of proceeds; S-3MEF holds the registration wrapper that legally authorizes the added securities. Pair the two for full deal-level analysis.

Filing Fee Exhibit (Exhibit 107)

Since the 2022 fee-disclosure rule, Exhibit 107 carries the structured fee table that once sat on the facing page. S-3MEF filings now include an Exhibit 107 reflecting the incremental 20% and the additional filing fee. An Exhibit 107 dataset gives a uniform cross-form fee table across S-1, S-3, F-3, and their MEF variants; the S-3MEF dataset gives the full S-3MEF submission. Use Exhibit 107 for fee analytics across forms; use S-3MEF when the registration mechanic itself is the object of study.

Boundary summary

The S-3MEF dataset is bounded to a single device: same-day, immediately-effective upsizings of an already-effective S-3 shelf, capped at 20%, by seasoned non-WKSI issuers. It is not a disclosure dataset (the parent S-3 holds disclosure), not a pricing dataset (424B holds pricing), and not a fee-table dataset (Exhibit 107 generalizes that). S-1MEF and F-3MEF extend the same Rule 462(b) mechanic to other issuer classes; S-3ASR with 462(e) PEAs replaces it entirely for WKSIs. None substitute for S-3MEF when the research question targets this specific issuer tier and registration pathway.

Who Uses This Dataset

Each S-3MEF record marks a real cash event, and a tight set of capital-markets, legal, research, and quant functions reads the same fields for very different reasons.

ECM bankers and syndicate desks

Coverage and syndicate professionals use S-3MEF as a confirmed signal that book demand exceeded the base deal. They join filer CIK, filing timestamp, and the referenced prior 333- file number to the marketed S-3 and 424B prospectus supplement, then pull EX-107 line items for additional share count, additional aggregate offering price, and fee paid. Outputs: follow-on league tables, "deals priced at the cap" post-mortems, and pitch comps for shelf takedowns.

Securities lawyers and ECM associates

Disclosure counsel and capital-markets associates use the dataset as a precedent library for drafting their own 462(b) wrapper between book-close and pricing. They lift facing-page and incorporation-by-reference language from peer filings, validate EX-107 fee-table structure (carry-forward, Rule 457 offsets, fee rate), and pattern-match EX-5 opinion templates and EX-23 consent formats with correct re-issuance dates. Output: a deal-ready S-3MEF that can clear without an SEC review cycle.

Compliance and capital-markets regulatory operations

Compliance officers test 462(b) eligibility on in-flight deals: same form type and class, predecessor S-3 effective, additional offering price within 20 percent, fee paid at filing. They reconcile EX-107 arithmetic against the parent S-3 fee table and check metadata.json timestamps for same-day sequencing with the pricing prospectus. Feeds pre-filing sign-off, deal-control logs, and Section 5 audit trails.

Equity research analysts

Sell-side and buy-side analysts treat an S-3MEF as a real-time dilution event. They extract additional shares and aggregate offering price from EX-107, link back to the parent prospectus supplement for use of proceeds and primary-vs-secondary mix, and key on accession number to chain to subsequent 424B and 8-K filings. Output: revised share-count, EPS dilution, and price-target updates.

Event-driven and risk-arb funds

Event desks use S-3MEF as both a backtest variable and an intraday signal on hot follow-ons, overnight blocks, and ATM upsizes. They measure upsize size relative to the base deal (EX-107 vs. prior S-3 fee table), filing timestamp relative to the parent 424B, and cap-hit flags. Feeds short-horizon trading signals and event-study screens, including the "priced at the 20 percent ceiling" feature.

Issuer IR, treasury, and corporate finance

IR and treasury staff quantify capital actually raised on top of the base takedown for board and cash-forecast reporting. They focus on EX-107 additional aggregate offering price net of underwriting discounts in the related 424B, cumulative shelf utilization across the parent S-3 and all 462(b) top-ups, and signing officers on the signature page for authorization checks. Peer S-3MEF records support upsize benchmarking.

Quant researchers and data engineering

Quants ingest S-3MEF into corporate-action and issuance pipelines because it is uniformly structured and timestamped. They consume metadata.json (accession, CIK, form type, acceptance and filing timestamps, document index), structured EX-107 fields (class, additional shares, max aggregate offering price, fee rate, registration fee), and the prior 333- file number as a join key to the parent S-3. The 1995-to-present history supports event-factor fitting and validation.

Litigation support and forensic accounting

Securities litigation analysts and forensic accountants consult S-3MEF when an offering is challenged or restated. They verify the predecessor 333- effectiveness date, reconcile EX-107 against the parent fee table and any earlier 462(b) wrappers for the same deal, cross-check signing parties on the signature page and EX-5 opinion against the contemporaneous officer and director roster, and use metadata.json timestamps to fix sequence with pricing and any 8-K. Supports expert reports and Section 11 / Section 12(a)(2) exposure analysis.

Each group reads the same record for a different decision: bankers and event funds for demand signal, lawyers and compliance for precedent and eligibility, research and IR for dilution and capital raised, quants for a clean structured event, and litigation reviewers for evidence that 462(b) was satisfied.

Specific Use Cases

The following workflows tie directly to fields and exhibits present in every S-3MEF record: metadata.json, the EX-107 Inline XBRL fee table, the EX-5 legality opinion, EX-23 auditor consents, the prior 333- file number cited inside the registration statement body, and the signature block.

1. Cap-hit detection on follow-on offerings

Event-driven analysts flag deals that priced at the Rule 462(b) ceiling. For each record, they parse ffd:MaxAggtOfferingPric from EX-107, recover the parent S-3 by the 333- file number cited in the explanatory note, and compare the upsize amount to 20 percent of the parent's registered maximum. Records where the ratio sits at or near 0.20 feed a "priced at the cap" feature used in short-horizon event studies and post-mortem syndicate reviews.

2. Real-time dilution feeds for equity research

Sell-side and buy-side analysts ingest filedAt from metadata.json together with ffd:MaxAggtOfferingPric and the offering security type from EX-107 the moment a record lands. Joined to the parent 424B prospectus supplement via the prior 333- file number, this produces a revised share count and incremental issuance dollar figure that drops directly into EPS dilution models and price-target updates.

3. 462(b) eligibility and fee-arithmetic reconciliation

Compliance and capital-markets operations teams reconcile EX-107 fee math against the parent S-3 fee table on every in-flight deal. They check ffd:FeeRate, ffd:FeeAmt, and ffd:NetFeeAmt against the predecessor's remaining capacity, confirm that formType is the bare S-3MEF (not S-3MEF/A), and verify that effectivenessDate equals filedAt as Rule 462(b) requires. The output is a pre-filing sign-off log and a Section 5 audit trail.

4. Precedent library for drafting the 462(b) wrapper

ECM associates and disclosure counsel build a searchable precedent set from the primary *_s3mef.htm document, EX-5 opinion, and EX-23 consent across peer filings. They extract the explanatory-note paragraph, exhibit-index structure, and signature-block formatting, and template-match EX-5 "validly issued, fully paid and non-assessable" language and EX-23 reissuance-date conventions. This compresses the drafting cycle between book-close and same-day pricing.

5. Auditor and counsel mapping across the seasoned-issuer universe

Market-structure researchers build issuer-to-firm maps by parsing the signing party on each EX-23 consent and the firm letterhead on each EX-5 opinion, keyed to the filer CIK in entities[]. Records with multiple EX-23.x entries surface auditor changes and successor-auditor situations. Output: panel data on audit-firm and law-firm league shares specifically among issuers running 462(b) upsizings.

6. Officer-authorization checks for litigation and forensic review

Litigation analysts cross-check the printed names and titles on the S-3MEF signature page and the EX-5 opinion's addressee block against the contemporaneous officer and director roster reported in the issuer's 10-K and proxy. Combined with filedAt from metadata.json and the predecessor 333- file number, this supports Section 11 and 12(a)(2) exposure analysis and expert reports on whether the 462(b) mechanic was properly invoked.

7. Cumulative shelf-utilization tracking for issuer IR and treasury

Treasury staff aggregate every S-3MEF tied to a single parent 333- file number to compute total dollars added on top of the base shelf. They sum ffd:MaxAggtOfferingPric across all 462(b) top-ups for the parent S-3 and reconcile to net proceeds disclosed in companion 424B filings. Feeds board-level cash-forecast reporting and peer benchmarking on shelf usage intensity.

8. Structured corporate-action ingestion for quant pipelines

Quant data engineers load the dataset as a uniform issuance-event stream. They key on accessionNo, filer cik, and filedAt from metadata.json, pull EX-107 facts (ffd:OfferingSctyTp, ffd:MaxAggtOfferingPric, ffd:FeeAmt) via the dataFiles[] extracted XBRL instance, and use the prior 333- file number parsed from the registration body as the join key to the parent S-3 record. The 1995-to-present history supports event-factor fitting and out-of-sample validation.

Dataset Access

The Form S-3MEF Files dataset is accessible through three endpoints: a metadata index, a full archive download, and per-container downloads. Containers are sharded by year and month under the path <dataset>/<YYYY>/<YYYY-MM>.zip, and every container is a ZIP archive holding the original filing files (TXT, JSON, HTML, PDF).

Dataset Index JSON API: https://api.sec-api.io/datasets/form-s3mef-files.json

This endpoint returns dataset-level metadata (name, description, earliest sample date, form types, container format, file types, totals) along with the full list of container files and their per-container size, record count, updated timestamp, and download URL. Use this endpoint to monitor which containers were modified in the most recent refresh and decide which ones to re-download. This endpoint does not require an API key.

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          curl https://api.sec-api.io/datasets/form-s3mef-files.json
        

Example response:

          1
          {
        

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            "datasetId": "1f13365b-9ae0-698a-8382-efce5cf42426",
        

          3
            "datasetDownloadUrl": "https://api.sec-api.io/datasets/form-s3mef-files.zip",
        

          4
            "name": "Form S-3MEF Files Dataset",
        

          5
            "updatedAt": "2026-05-05T02:49:21.789Z",
        

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            "earliestSampleDate": "1995-06-01",
        

          7
            "totalRecords": 4898,
        

          8
            "totalSize": 13948612,
        

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            "formTypes": ["S-3MEF"],
        

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            "containerFormat": "ZIP",
        

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

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            "containers": [
        

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              {
        

          14
                "downloadUrl": "https://api.sec-api.io/datasets/form-s3mef-files/2026/2026-05.zip",
        

          15
                "key": "2026/2026-05.zip",
        

          16
                "size": 412380,
        

          17
                "records": 6,
        

          18
                "updatedAt": "2026-05-05T02:49:21.789Z"
        

          19
              }
        

          20
            ]
        

          21
          }
        

Download Entire Dataset: https://api.sec-api.io/datasets/form-s3mef-files.zip?token=YOUR_API_KEY

Returns the entire dataset as a single ZIP archive containing every monthly container from the earliest sample date to the most recent refresh. This endpoint requires an API key.

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          curl -o form-s3mef-files.zip \
        

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            "https://api.sec-api.io/datasets/form-s3mef-files.zip?token=YOUR_API_KEY"
        

Download Single Container: https://api.sec-api.io/datasets/form-s3mef-files/2026/2026-03.zip?token=YOUR_API_KEY

Downloads a single monthly container ZIP, which is more efficient than refetching the full archive when only specific months have changed. Container paths follow the <YYYY>/<YYYY-MM>.zip convention. This endpoint requires an API key.

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          curl -o 2026-03.zip \
        

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            "https://api.sec-api.io/datasets/form-s3mef-files/2026/2026-03.zip?token=YOUR_API_KEY"
        

Frequently Asked Questions

What form does this dataset cover?

The dataset covers Form S-3MEF, a short-form "More Effective Filing" registration statement filed under Rule 462(b) of the Securities Act of 1933 to upsize an already-effective Form S-3 by up to 20% of the prior maximum aggregate offering price. The dataset's formTypes is restricted to the bare S-3MEF; amendments filed as S-3MEF/A are not included.

What does one record in this dataset represent?

One record is a complete EDGAR submission of a Form S-3MEF, identified by its 18-digit SEC accession number. The record is a per-accession folder bundling a metadata.json descriptor with every primary document attached to that EDGAR submission — the primary registration statement, the Exhibit 5 legality opinion, the Exhibit 23 auditor consent or consents, and the Inline XBRL Exhibit 107 filing-fee table — except binary image exhibits.

Who is required to file Form S-3MEF?

Any issuer eligible to use Form S-3 — domestic Exchange Act reporting issuers meeting the registrant and transaction requirements of General Instructions I.A and I.B — that wants to register additional securities of the same class for the same offering as an already-effective S-3, capped at 20% of the prior maximum aggregate offering price. S-1 issuers use Form S-1MEF for the equivalent upsize, foreign private issuers on Form F-3 use Form F-3MEF, and WKSIs on automatic shelf registrations typically use a Rule 462(e) post-effective amendment instead.

When is Form S-3MEF filed?

It is event-driven, not periodic. The filing is triggered by an issuer's decision during a live offering — usually at or near pricing of a follow-on, convertible, shelf takedown, or other registered offering — to register additional securities because demand exceeded the base deal. The S-3MEF must be filed before confirmations of sale are sent for the additional securities and while the prior S-3 is still effective; effectiveness is automatic on EDGAR acceptance, with no SEC review or waiting period.

What time period does the dataset cover?

The dataset covers all Form S-3MEF filings submitted to EDGAR from June 1, 1995 to the present. Rule 462(b) in its modern form was adopted by the SEC in 1996, so the electronic record is essentially coextensive with the form's full operational history.

What file format is the dataset distributed in?

The dataset is distributed as a tree of monthly ZIP containers organized as <dataset>/<YYYY>/<YYYY-MM>.zip. Each ZIP holds zero or more accession-numbered subfolders, each containing the original filing files — TXT, JSON, HTML, and PDF — with the canonical structured view in metadata.json and the structured fee data inside the Inline XBRL Exhibit 107.

How does Form S-3MEF differ from a Form S-3/A amendment?

An S-3/A is an amendment to the original S-3 registration that can revise disclosure, add securities, or cure deficiencies and generally requires a fresh effectiveness determination. An S-3MEF is not an amendment — it is a new registration statement under Rule 462(b), strictly capped at 20% of the parent's registered dollar amount, limited to securities of the same class for the same offering, and effective immediately on filing. S-3/A is for substantive revision; S-3MEF is for same-day, pricing-driven upsizing.