S-1MEF registration statements under Rule 462(b)
S-1MEF: a short registration statement filed under Rule 462(b) to add securities to an effective Form S-1, usually to upsize an IPO at pricing.
curl -H "Authorization: Bearer $SECFEED_KEY" \ "https://secfeedapi.com/v1/filings?query=formType:%22S-1MEF%22&size=2"
import os, requests
r = requests.get(
"https://secfeedapi.com/v1/filings",
params={'query': 'formType:"S-1MEF"', 'size': '2'},
headers={"Authorization": f"Bearer {os.environ['SECFEED_KEY']}"},
)
print(r.json())What is S-1MEF?
Rule 462(b) lets an issuer register additional securities of the same class, up to 20 percent of the maximum aggregate offering price of the effective registration statement, by filing a short new registration statement that incorporates the earlier one by reference. When the earlier statement is a Form S-1, EDGAR tags the new one S-1MEF.
An S-1MEF on the night of pricing is a strong sign that an IPO was upsized. Pair it with the 424B4 final prospectus for the actual terms.
Issuers with an effective Form S-1 that want to register a limited amount of additional securities.
Before the sale of the additional securities; effective on filing.
Filings per year
Every S-1MEF filing on EDGAR, counted from the SecFeed index. Updated daily.
What is inside
| Section | Contents |
|---|---|
| Facing page | Reference to the earlier S-1 file number. |
| Fee table | Fees for the added securities. |
| Incorporation by reference | The earlier S-1 content. |
| Opinions and consents | Legal opinion and auditor consent. |
Get S-1MEF data with SecFeed
Search the filings with formType:"S-1MEF", read any document as text or PDF, and use these APIs for structured data:
IPO and follow-on registration statements and final prospectuses with offering terms: shares, price, proceeds, ticker, exchange and underwriters.
Filing Search APISearch every SEC EDGAR filing since 1993 with Lucene-style queries over ticker, CIK, form type, filing date, company, SIC and 8-K items.
Text Search APISearch every word of every EDGAR filing and exhibit since 2001. Exact phrases, form type, CIK and date filters, results as JSON.
Latest S-1MEF filings
| Company | Form | Filed | |
|---|---|---|---|
| Retension Pharmaceuticals, Inc. | S-1MEF | 2026-10-08 | EDGAR ↗ |
| ADARx Pharmaceuticals, Inc. | S-1MEF | 2026-09-24 | EDGAR ↗ |
| Electra Therapeutics, Inc. | S-1MEF | 2026-09-17 | EDGAR ↗ |
| Alliance Laundry Holdings Inc. | S-1MEF | 2026-08-18 | EDGAR ↗ |
| Latigo Biotherapeutics, Inc. | S-1MEF | 2026-08-06 | EDGAR ↗ |
| BlossomHill Therapeutics, Inc. | S-1MEF | 2026-08-06 | EDGAR ↗ |
| Braveheart Bio, Inc. | S-1MEF | 2026-08-05 | EDGAR ↗ |
| Churchill Capital Corp XIII | S-1MEF | 2026-07-30 | EDGAR ↗ |
Use cases
- Detect IPO upsizes at pricing
- Measure demand by comparing initial and final offering size
Related forms
Every Form S-1 registration statement and amendment since 1994: IPOs, follow on offerings and resale registrations, with offering terms as JSON.
424B4Priced IPO prospectusEvery 424B4 final prospectus since 1994: the priced IPO and offering prospectus with shares sold, price per share, proceeds and underwriters.
S-3MEFS-3 upsize (Rule 462(b))S-3MEF: a Rule 462(b) registration statement adding up to 20 percent more securities to an effective Form S-3, typically at pricing of a follow-on.
FAQ
What does MEF stand for?
It refers to the Rule 462(b) short form registration that becomes effective on filing.
How much can an S-1MEF add?
Up to 20 percent of the maximum aggregate offering price in the effective registration statement.
Every S-1MEF filing, one API call away
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