Shelf registrations, S-3, baby shelf and S-1
Form D and Reg D: Rule 506(b) vs 506(c) Explained
Form D and Regulation D explained: Rule 506(b) vs 506(c) private placements, the 15-day filing deadline, what a Form D shows and why public companies file one.
What is Form D?
Most securities sold in the US must be registered with the SEC or fit an exemption. Regulation D is the most widely used set of exemptions for private sales, and Form D is the short notice a company files after it starts selling under one of them.
Form D is filed by startups and private funds, but also by public small caps that raise money in private placements. For a public company, a Form D is often a quiet confirmation that a PIPE (compared with a registered direct) or other private sale has begun, sometimes alongside an 8-K and later a resale registration.
Rule 506(b) vs 506(c)
Rule 506 is the Regulation D exemption with no dollar cap, and it is where nearly all of the money goes. It comes in two versions:
| Rule 506(b) | Rule 506(c) | |
|---|---|---|
| General solicitation or advertising | Not allowed | Allowed |
| Accredited purchasers | Unlimited | Unlimited |
| Non-accredited purchasers | Up to 35, who must be financially sophisticated | None |
| Verification of accredited status | Reasonable belief, often self-certification | Issuer must take reasonable steps to verify |
| Disclosure to non-accredited purchasers | Required information under Rule 502(b) | Not applicable |
| Form D box checked | 506(b) | 506(c) |
The trade-off is simple: 506(c) lets a company advertise the offering publicly, and in exchange every purchaser must be accredited and the company must verify it. In March 2025, SEC staff stated that a high minimum investment (at least $200,000 for a natural person or $1,000,000 for an entity), together with written representations, can be a reasonable verification step.
Two smaller exemptions also sit in Regulation D. Rule 504 allows up to $10 million in 12 months but is not available to Exchange Act reporting companies. Rule 506 offerings are also "covered securities", which preempts state registration, though states can still require a notice filing and a fee.
The Form D 15-day filing deadline
Under Rule 503, Form D is due within 15 calendar days after the first sale of securities in the offering. The first sale is the date the first purchaser is irrevocably contractually committed to invest, which can be before any money changes hands. If the 15th day falls on a Saturday, Sunday or federal holiday, the deadline moves to the next business day.
Amendments (D/A) are required annually for an offering still open on the anniversary of the last filing, to correct a material mistake, or to reflect certain changes, such as an increase in the offering size of more than 10%.
What Form D discloses
Form D is structured data, not a narrative. The fields worth reading:
- Exemption claimed (506(b), 506(c), 504).
- Type of securities: equity, debt, options or warrants, pooled fund interests.
- Total offering amount, total amount sold, and total remaining. "Indefinite" is allowed for the offering amount.
- Number of purchasers who have invested, and how many are not accredited.
- Sales compensation: names of brokers or placement agents and commissions paid (see reading counterparty disclosures).
- Use of proceeds paid to related persons, such as executives and directors.
- Revenue range, which the company may decline to disclose.
- Related persons: executive officers, directors and promoters.
A worked reading. Hypothetical Company X files a Form D showing:
| Field | Value |
|---|---|
| Total offering amount | $5,000,000 |
| Total amount sold | $3,200,000 |
| Total remaining to be sold | $1,800,000 |
| Sales commissions | $224,000 |
| Commission as a share of amount sold | 7.0% |
All figures are hypothetical.
The arithmetic tells you the round is 64% filled ($3,200,000 ÷ $5,000,000) and that the agent is paid 7% ($224,000 ÷ $3,200,000). What Form D does not tell you is the price per share or the number of shares. For that, you need the company's other filings.
Why public companies file Form D
A listed small cap raising money privately usually relies on Rule 506(b). The paper trail often looks like this:
- 8-K announcing a securities purchase agreement, with the agreement attached. If the unregistered shares exceed 1% of the class outstanding (5% for a smaller reporting company), Item 3.02 requires disclosure. Warrants sold alongside are often concurrent private placement warrants.
- Form D within 15 days of the first sale.
- Resale S-1 (how S-1s work) or S-3, if the investors received registration rights, so they can sell the shares publicly.
Until a resale registration is effective, privately placed shares are restricted. Holders can generally sell under Rule 144 only after a holding period of six months for a reporting company (one year for a non-reporting one), subject to other conditions.
A deal marketed to investors privately but sold off an effective shelf is a different structure: a registered direct uses a prospectus supplement, not Regulation D, and typically has no Form D.
What Form D does not tell you
- Price and share count. Not included.
- Deal terms. Warrant coverage, conversion features and resets live in the agreements filed with the 8-K, not on Form D.
- Whether it closed in full. "Amount sold" is as of filing. Later amendments, or the next 10-Q, show the final figure.
How to check a company on Signal8
- Filter the live SEC filings feed by form type to see Form D and D/A filings as they arrive.
- A public company's filings tab, for example AAPL's, puts any Form D next to the 8-K that announced the deal.
- Alerts can notify you of new filings for names you follow.
FAQ
When is a Form D due?
Form D is due within 15 calendar days after the first sale in the offering, which is the date the first purchaser becomes irrevocably committed to invest. If the 15th day falls on a weekend or federal holiday, the deadline moves to the next business day. Amendments are due annually while the offering continues, and when certain information changes.
What is the difference between Rule 506(b) and Rule 506(c)?
Rule 506(b) prohibits general solicitation and allows up to 35 sophisticated non-accredited purchasers alongside unlimited accredited ones. Rule 506(c) allows general solicitation and advertising, but every purchaser must be accredited and the issuer must take reasonable steps to verify that status.
Do public companies file Form D?
Yes. A public company that sells unregistered securities in a private placement under Regulation D files Form D like any other issuer. It usually also discloses the deal on Form 8-K, and if investors received registration rights, it later files a resale registration statement so they can sell the shares publicly.
Does Form D show the price per share?
No. Form D reports the total offering amount, the amount sold, the number of purchasers, commissions and related persons, but not the price per security or the number of shares. Those terms appear in the purchase agreement, usually filed as an exhibit to an 8-K or a later periodic report.
See it on DilutionScan
Companies DilutionScan covers, with the instruments read from their SEC filings. Open one to see each instrument and the filing it came from.
- GNSGenius Group Limited8 warrant series, 1 convertible, 1 ATM program, 3 shelf registrations and 2 completed offerings on file
- SMXSMX (Security Matters) Public Limited Company Ordinary Shares10 warrant series, 8 convertibles, 2 equity lines, 4 shelf registrations, 4 S-1 registrations and 2 completed offerings on file
- MLGOMicroAlgo, Inc. Ordinary Shares2 warrant series, 5 convertibles and 2 shelf registrations on file
- HOLOMicroCloud Hologram Inc. Ordinary Shares2 warrant series, 1 convertible, 3 shelf registrations and 2 completed offerings on file
Terms in this guide
- PIPE (private investment in public equity)
- A PIPE (private investment in public equity) is a private sale of unregistered shares, warrants or convertibles by a public company to selected investors, usually followed by a resale registration.
- Placement agent
- A placement agent is a broker-dealer hired to find investors for a company's offering on a best-efforts basis, paid a cash fee and often warrants, without committing to buy the securities.
- Rule 144
- Rule 144 is the SEC safe harbor that lets holders publicly resell restricted or control securities without registration once conditions such as a holding period are met.
- S-1 resale registration
- An S-1 resale registration registers shares already issued or issuable to named investors so they can sell them publicly; the company itself usually receives no proceeds from those sales.
- Form 8-K
- A Form 8-K is the SEC current report a public company files, generally within four business days, to disclose material events such as agreements, offerings, executive changes and listing notices.
- Registered direct offering
- A registered direct offering is a sale of new shares to a small group of investors, arranged by a placement agent off an effective shelf, so the shares are freely tradeable at closing.
Related guides
- Registered Direct vs PIPE vs Underwritten OfferingRegistered direct vs PIPE vs underwritten offering: how each sells a block of shares at a fixed price, how each is registered and disclosed, and what fees cost.
- Form S-1 Explained: IPO vs Resale RegistrationForm S-1 explained: IPO vs resale S-1 registrations, how an S-1 moves through S-1/A amendments to effectiveness, and what the 424B4 and 424B3 prospectuses mean.
- 8-K Item Codes Explained: Items 1.01 to 9.018-K item codes explained: what Items 1.01, 2.03, 3.01, 3.02, 5.02 and 9.01 mean, the four-business-day rule, and the item combinations that flag a financing.
- What Is Stock Dilution? How New Shares Affect YouStock dilution explained with worked numbers: what happens to your ownership when a company issues new shares, and where to spot it coming in SEC filings.
- Baby Shelf Rule Explained: S-3 I.B.6 vs Form S-1The baby shelf rule explained: how Form S-1 and S-3 differ, who can use a shelf, and how I.B.6 caps sales at one-third of public float per 12 months.
- S-3 vs S-8: Capital-Raising Shelf or Employee Stock Plan RegistrationForm S-3 registers securities a company can sell to raise cash; Form S-8 registers shares for employee equity plans. Who can file each and what each means.
Check any ticker for dilution
DilutionScan reads each covered company's SEC filings and lists its warrants, convertibles, ATM programs, shelves and S-1s on one page, with a dilution rating and cash runway.
This guide is from the Signal8 Academy, the research team behind DilutionScan. Educational content only. DilutionScan and Signal8 are not broker-dealers or investment advisers, and nothing here is a recommendation to buy or sell any security.