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How to Read a 424B5 Prospectus Supplement

How to read a 424B5 prospectus supplement in five minutes: the cover, offering summary, dilution table, plan of distribution and baby shelf paragraph, in order.

7 min readLast verified

What is a 424B5 prospectus supplement?

A 424B5 is a prospectus supplement filed under Rule 424(b)(5) of the Securities Act. For small-cap dilution research it is the most important single filing type, because it is the document a company files when it actually takes securities off its shelf registration and sells them.

The shelf says what the company may sell; the 424B5 says what it is selling now, how much, at what price and through whom.

They can run to 50 pages or more, but almost everything you need sits in five places: the cover page, the offering summary, the dilution section, the plan of distribution and, for smaller companies, a short paragraph about the baby shelf limit. Read those in order and you have the deal.

Minute one: the cover page

The cover page answers four questions in a few paragraphs:

  1. What is being sold. Common stock, pre-funded warrants, common warrants, preferred stock or units of several.
  2. How much. A number of shares at a fixed price for a registered direct or underwritten deal, or a maximum dollar amount for an ATM program.
  3. Who is selling it. The underwriter or placement agent, named near the bottom of the page.
  4. Which prospectus it supplements. The first lines say "To Prospectus dated..." and give the registration number of the underlying S-3.

Planet Green Holdings Corp.'s 424B5 of October 2, 2026 is a typical ATM cover. It read "Up to $22,539,922 of Common Stock," was marked "(To Prospectus dated April 13, 2026)," named Craft Capital Management LLC as sales agent under an ATM Sales Agreement, and stated that the company "may, but are not obligated to, offer and sell new shares." In four lines you know it is an ATM, its maximum size, the agent, and that nothing is committed.

Minute two: the offering summary

Under a heading like "The Offering," the supplement gives a table with:

  • shares offered;
  • shares outstanding before the offering, as of a stated date;
  • shares outstanding after the offering;
  • use of proceeds;
  • the exchange and ticker.

The before and after numbers are the quickest way to size dilution. Watch the footnote that follows: it usually lists what the "before" figure excludes, such as outstanding warrants, options, restricted stock units and convertible notes. That footnote is a compact inventory of warrant overhang and other potential dilution.

Minute three: the dilution section

Most supplements include a section titled "Dilution." It measures how much the new investor pays above the company's net tangible book value (assets minus liabilities, minus intangible assets) per share. The math is the same everywhere, so it is worth learning once.

Hypothetical Company X has net tangible book value of $10,000,000 and 20,000,000 shares outstanding. It sells 10,000,000 shares at $1.00 in a registered direct with $700,000 of fees and expenses.

LineValue
Net tangible book value before$10,000,000
Shares before20,000,000
NTBV per share before$0.500
Net proceeds ($10,000,000 − $700,000)$9,300,000
NTBV after$19,300,000
Shares after30,000,000
NTBV per share after$0.643
Increase per share to existing holders$0.143
Dilution per share to new investors ($1.00 − $0.643)$0.357

All figures are hypothetical.

The "increase to existing holders" line confuses people. It does not mean existing holders gained from the deal in market terms. It means the shares were sold above book value per share, so book value per share rose. If a company with negative net tangible book value sells shares, the table can show large dilution to new investors and still show book value per share improving. Treat the section as an accounting measure, not as a judgement on the deal. For an ATM, the table is illustrative, usually computed at an assumed price, because the actual sale prices are not known in advance.

Minute four: the plan of distribution

This section, sometimes titled "Underwriting," gives the fees and the mechanics:

  • the underwriting discount, placement agent fee or ATM commission (Planet Green's supplement disclosed a commission rate of 4.0% of the gross sales price);
  • expense reimbursements;
  • warrants issued to the agent, often a few percent of the shares sold;
  • any overallotment option;
  • lockups for the company and its insiders;
  • for ATMs, how the agent sells and that sales are "at the market" under Rule 415.

Minute five: the baby shelf paragraph and the rest

If the company's public float is under $75 million, the supplement usually includes a paragraph applying General Instruction I.B.6 of Form S-3: the public float, how it was computed, the one-third limit, and how much has been sold under I.B.6 in the prior 12 months. Planet Green's paragraph gave a public float of approximately $67,619,766 and a one-third limit of approximately $22,539,922, with $0 sold in the prior 12 calendar months.

With the time left, skim:

  • Use of proceeds. "General corporate purposes and working capital" is common. Specific uses, such as repaying a note, are worth noting.
  • Description of securities. For deals with warrants, the exercise price, term, cashless exercise rights and any price adjustment clauses.
  • Risk factors specific to the offering. These often mention the possibility of further offerings.

424B5 vs 424B3 vs 424B4

The suffix is the paragraph of Securities Act Rule 424(b) (17 CFR 230.424) the prospectus is filed under, and each paragraph is defined by what the document adds to the registration statement.

FormRule 424(b) paragraphTypical useDue
424B4(b)(4): pricing information omitted under Rule 430A, plus other changesFinal prospectus for an IPO or a deal registered on its own Form S-12nd business day after pricing or first use
424B5(b)(5): shelf takedown information omitted under Rule 430B, plus other changesA primary offering off an effective shelf, such as an S-3: ATMs, registered directs, underwritten deals2nd business day after pricing or first use
424B3(b)(3): any other substantive change or addition to a filed prospectusUpdates to a resale prospectus, merger prospectuses, supplements adding new financial statements5th business day after first use

A 424B3 often registers no new sale by the company at all: a resale prospectus lets existing holders, such as investors from a private placement, sell their shares. A 424B2 covers shelf pricing information alone and is less common for small caps. Whatever the suffix, the cover page says what is being offered and by whom.

The five-minute checklist

QuestionWhere to look
What and how much?Cover page
At what price, and what discount to the last close?Cover page, offering summary
How many shares before and after?The Offering
What else could become shares?Footnote to The Offering
What does it cost the company?Plan of distribution
Any new warrants, and on what terms?Description of securities
How much shelf capacity is left?Baby shelf paragraph

How to check a company on Signal8

  • The live SEC filings feed lists 424B5 supplements as they are filed, so you can open one minutes after it hits EDGAR.
  • Each company's Dilution tab, for example AAPL's Dilution tab, is where Signal8 organises recent offerings, shelfs and ATMs it has extracted. Coverage focuses on small-cap issuers.
  • The dilution screener lets you compare companies on dilution-related data.
  • Some tools answer questions about a prospectus in plain language instead. Signal8 vs AskEdgar compares that approach with a structured, cited dilution snapshot.

FAQ

What is a 424B5 filing?

A 424B5 is a prospectus supplement filed under Rule 424(b)(5) of the Securities Act. Companies file one when they sell securities off an effective shelf registration, such as a Form S-3. It describes the specific offering: what is being sold, the amount, the price or pricing method, the underwriter or agent, the fees and the use of proceeds.

Does a 424B5 mean shares have already been sold?

Not necessarily. For an underwritten or registered direct offering, the supplement is filed around pricing and the deal usually closes within a few days. For an at-the-market program, it only sets up the ability to sell; the company may sell gradually, or not at all, and reports actual sales later.

What does dilution to new investors mean in a prospectus?

It is the difference between the price new investors pay per share and the company's pro forma net tangible book value per share after the offering. It is an accounting measure required in prospectuses, not a measure of market value, and it can look very different for companies with negative book value.

How is a 424B5 different from a 424B3 or 424B4?

Each is filed under a different paragraph of Rule 424(b). A 424B5 is the usual form for a primary takedown off a shelf, a 424B4 the final prospectus for an IPO or S-1 deal, and a 424B3 an update such as a resale prospectus. See the comparison table above.

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.

Terms in this guide

Form 424B5 prospectus supplement
A 424B5 is a prospectus supplement filed under SEC Rule 424(b)(5) to document a specific offering made off an effective shelf, stating the securities sold, the price and the use of proceeds.
Form S-3
Form S-3 is the short-form SEC registration statement eligible reporting companies use for shelf offerings, letting them incorporate existing filings by reference and sell securities quickly.
Shelf registration
A shelf registration is a registration statement, usually on Form S-3, that registers securities now so the company can sell them later in one or more offerings without a new registration each time.
At-the-market (ATM) offering
An at-the-market (ATM) offering is a program that lets a company sell newly issued shares into the open market at prevailing prices, a little at a time, through a sales agent.
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.
Baby shelf rule
The baby shelf rule (Form S-3 General Instruction I.B.6) caps companies with under $75 million of public float at selling one-third of that float in primary shelf offerings in any 12 months.
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.
Pre-funded warrant
A pre-funded warrant is a warrant sold for almost the full share price up front, leaving a nominal exercise price such as $0.0001, so a buyer can stay under ownership limits until it exercises.
Warrant overhang
Warrant overhang is the block of shares that could be created if a company's outstanding warrants are exercised, potential dilution not yet in the shares outstanding figure.

Sources

  • SEC accession 0001213900-26-106502 Planet Green Holdings Corp. 424B5, 2026-10-02, ATM prospectus supplement: cover page, I.B.6 public float paragraph, commission rate

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.

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