Form 424B

Form 424B is the EDGAR label for a prospectus filed under Rule 424(b) of the Securities Act of 1933: the final version of a prospectus, or a supplement to one, used after a registration statement has become effective. It is where the actual terms of an offering, including the price, the number of shares or principal amount, and the underwriters, are formally put on the record.

A registration statement such as an S-1 or S-3 makes an offering legally possible. The 424B shows what was actually sold and on what terms.

Full guide: S-1 Filing Explained: How to Analyze an IPO Prospectus

Rule 424(b) requires a company to file each form of prospectus it uses after effectiveness, but only when it contains substantive changes from or additions to a prospectus already filed. The rule sorts these filings into numbered paragraphs, and the cover of each must identify the paragraph it is filed under, which is why EDGAR shows variants such as 424B1, 424B2, 424B3, 424B4, 424B5, and 424B7. Each paragraph carries its own deadline. A prospectus that fills in pricing information omitted under Rule 430A, or a supplement for a shelf takedown under Rule 415, is generally due by the second business day after the earlier of pricing or first use. A prospectus reflecting other substantive changes is due by the fifth business day after first use. A prospectus naming selling shareholders omitted under Rule 430B is due within two business days of the sale or first use, and a prospectus filed late is made under Rule 424(b)(8) as soon as practicable after the failure is discovered.

Rule 424(a) is the pre-effective counterpart, covering changed forms of a prospectus sent out before the registration statement goes effective.

For investors, 424B filings are the most reliable record of dilution from a shelf. Each supplement on a Form S-3 shelf shows how many new shares or notes were sold, at what price, and how the company plans to use the proceeds, turning a registered capacity into an actual issuance.