How a US IPO Works: From S-1 Filing to the First Trade
How a US IPO works step by step: confidential S-1 filing, SEC review, roadshow and price range, pricing, the 424B4 final prospectus, first trade and lock-up.
Here is how a US IPO works, in short. The company files a registration statement (Form S-1, or F-1 for foreign companies) with the SEC, often confidentially at first. It answers the SEC's comments, then makes the filing public and markets the shares on a roadshow with a price range. Underwriters build a book of orders, the price is set the evening before trading, and the shares start trading on Nasdaq or the NYSE the next morning. The final prospectus, with the price, is filed under Rule 424(b).
Here is each step, what is filed with the SEC, and where to find the details.
A US IPO in eight steps
| Step | What happens | SEC filing |
|---|---|---|
| 1. Preparation | Company picks underwriters, prepares audited financials | — |
| 2. Confidential submission | Draft registration statement reviewed privately | DRS |
| 3. SEC review | SEC staff send comment letters; company amends | DRS amendments |
| 4. Public filing | Registration statement made public | S-1 / F-1 |
| 5. Launch and roadshow | Price range set; management meets investors | S-1/A with price range |
| 6. Effectiveness and pricing | SEC declares the registration effective; price set | Effectiveness notice |
| 7. First trade | Shares list and begin trading | 424B4 (final prospectus) |
| 8. After the IPO | Closing, over-allotment option, lock-up expiry | 8-K, 10-Q, 10-K |
1–3. Preparation, confidential filing and SEC review
The company chooses underwriters, the investment banks that manage the offering and buy the shares from the company to resell them. Lawyers and auditors prepare the registration statement, including audited financial statements.
Most companies first submit a draft registration statement (DRS) confidentially. The SEC's Division of Corporation Finance reviews it and sends comment letters. The company replies and amends the draft, often several times. The review usually takes a few months.
4. Public filing of the S-1
The company must file its registration statement publicly at least 15 days before the roadshow begins. The public S-1 shows the business, risk factors, use of proceeds, financial statements, management, and the principal and selling stockholders. To read one section by section, see what is an S-1 filing.
At this point the IPO appears on Eyepio's upcoming US IPOs list once a prospectus is processed.
5. Price range and roadshow
An amended S-1 adds the expected price range and the number of shares. This preliminary prospectus is sometimes called a "red herring". The underwriters and management then run a roadshow, presenting to institutional investors over about one to two weeks.
During the roadshow, underwriters collect indications of interest: how many shares each investor wants and at what price. This is book building. There is no lottery as in some other markets. Underwriters decide allocations, and individual investors usually get access through brokers that are part of the selling group.
6. Effectiveness and pricing
When the SEC has no further comments, the company asks for the registration statement to be declared effective. The same evening, the company and underwriters agree on the IPO price and the final number of shares, based on the book.
7. The final prospectus and first trade
The final prospectus, with the price, is filed under Rule 424(b), usually as a 424B4. It shows the price per share, the underwriting discount, the net proceeds and the final share count. Eyepio builds US IPO pages from these filings.
Trading begins the next morning on the chosen exchange. The first trade price is set by an opening auction run by the exchange, and it can be far from the IPO price. Browse issues by exchange: Nasdaq, NYSE and NYSE American.
8. After the IPO: closing, greenshoe and lock-up
- Closing: the company delivers shares and receives the money, typically one or two business days after pricing.
- Over-allotment (greenshoe) option: underwriters usually have 30 days to buy up to 15% more shares at the IPO price, used to support trading after the IPO.
- Lock-up: insiders and pre-IPO investors usually agree not to sell for a period, most often 180 days. The terms are in the prospectus's "Shares eligible for future sale" and "Underwriting" sections.
- Ongoing reporting: the company now files quarterly (10-Q) and annual (10-K) reports, and 8-Ks for major events.
Monthly IPO counts are on the US IPO calendar.
Other ways to go public
- Direct listing: existing shares list without a traditional underwritten offering.
- SPAC merger: a private company merges with a listed special purpose acquisition company.
- Regulation A+: a smaller, lighter offering regime with lower limits.
Eyepio covers traditional underwritten IPOs filed on Form S-1, F-1 or S-11, and leaves out SPACs.
Frequently asked questions
How long does a US IPO take?
From the first confidential submission to the first trade, usually several months. SEC review often takes three to four months, and the roadshow one to two weeks.
What is the difference between an S-1 and a 424B4?
The S-1 is the registration statement filed for SEC review, amended as the process goes on. The 424B4 is the final prospectus filed after pricing, with the IPO price and final share count.
How are IPO shares allocated in the US?
Through book building. Underwriters collect orders during the roadshow and decide allocations, mostly to institutional investors. Individuals usually get access through brokers in the selling group.
What is an IPO lock-up period?
An agreement by insiders and pre-IPO investors not to sell their shares for a set time after the IPO, most often 180 days. The terms are disclosed in the prospectus.
Where can I read a company's IPO filings?
On the SEC's EDGAR search, by company name or ticker. Every Eyepio US IPO page also links to the filing it was built from.
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