S-3MEF registration statements under 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.
curl -H "Authorization: Bearer $SECFEED_KEY" \ "https://secfeedapi.com/v1/filings?query=formType:%22S-3MEF%22&size=2"
import os, requests
r = requests.get(
"https://secfeedapi.com/v1/filings",
params={'query': 'formType:"S-3MEF"', 'size': '2'},
headers={"Authorization": f"Bearer {os.environ['SECFEED_KEY']}"},
)
print(r.json())What is S-3MEF?
S-3MEF is the Form S-3 version of the Rule 462(b) short form. It registers additional securities of the same class, up to 20 percent of the maximum aggregate offering price of the effective S-3, and is effective on filing.
It shows up when a follow-on or secondary offering off a non-automatic shelf is upsized.
Issuers with an effective, non-automatic Form S-3 needing a little more registered capacity.
Before the additional securities are sold; effective on filing.
Filings per year
Every S-3MEF filing on EDGAR, counted from the SecFeed index. Updated daily.
What is inside
| Section | Contents |
|---|---|
| Reference to earlier S-3 | File number incorporated by reference. |
| Fee table | Fees for the added amount. |
| Opinion and consents | Legal and auditor consents. |
Get S-3MEF data with SecFeed
Search the filings with formType:"S-3MEF", read any document as text or PDF, and use these APIs for structured data:
Latest S-3MEF filings
| Company | Form | Filed | |
|---|---|---|---|
| BranchOut Food Inc. | S-3MEF | 2026-08-27 | EDGAR ↗ |
| Silence Therapeutics plc | S-3MEF | 2026-08-11 | EDGAR ↗ |
| AMTECH SYSTEMS INC | S-3MEF | 2026-06-01 | EDGAR ↗ |
| Editas Medicine, Inc. | S-3MEF | 2026-05-26 | EDGAR ↗ |
| Aura Biosciences, Inc. | S-3MEF | 2026-05-04 | EDGAR ↗ |
| Altimmune, Inc. | S-3MEF | 2026-04-22 | EDGAR ↗ |
| Guardian Pharmacy Services, Inc. | S-3MEF | 2026-03-19 | EDGAR ↗ |
| Dianthus Therapeutics, Inc. /DE/ | S-3MEF | 2026-03-10 | EDGAR ↗ |
Use cases
- Detect upsized follow-on offerings
- Reconcile shelf capacity
Related forms
Every Form S-3 and automatic shelf S-3ASR since 1994: shelf registrations by seasoned issuers for future debt and equity offerings.
S-1MEFS-1 upsize (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.
424B5Shelf takedown prospectusEvery 424B5 prospectus supplement since 1994: debt and equity takedowns from shelf registrations, including at the market programs.
FAQ
When is an S-3MEF used?
To add up to 20 percent more securities to an effective S-3, usually when an offering is upsized at pricing.
Do WKSIs need S-3MEF?
Rarely, because automatic shelves on S-3ASR can add securities by post-effective amendment.
Every S-3MEF filing, one API call away
500 free calls a month. JSON, CSV, PDF and a Python SDK.