IPO (Initial Public Offering)

Stock trading dictionary: meaning, example and how traders use it.

Last updated: October 17, 2026

Definition: An IPO (Initial Public Offering) is the first sale of a company's shares to the public, after which the stock lists and trades on an exchange such as the NYSE or Nasdaq, turning a privately held company into a public one.

How an IPO works

A company goes public to raise capital, give early investors and employees a way to sell, and gain a publicly traded currency for acquisitions. It hires investment banks as underwriters, which help prepare a registration statement (Form S-1) filed with the SEC. The prospectus describes the business, risks, financial statements, and how the money will be used.

  1. Preparation and filing: audits, legal review, and the SEC registration process.
  2. Roadshow: management presents to institutional investors, who indicate interest.
  3. Pricing: on the evening before trading, the underwriters and company set the offer price based on demand.
  4. Listing: shares begin trading on an exchange, and the market sets the price from then on.

Example of IPO math

Suppose a company sells 20 million new shares at $25, raising $500 million before fees. After the offering it has 200 million shares outstanding, implying a market capitalization of $5 billion. If demand is strong and the first trade prints at $32, the stock "pops" 28%. Investors who received allocations at $25 gain on paper, while the company received $25 per share; the gap is sometimes called money left on the table.

If the company earned $100 million, the offer price implies a P/E ratio of 50, a valuation that requires strong future growth to justify.

Lockups and early trading

Insiders usually agree to a lockup period, commonly 90 to 180 days, during which they cannot sell. When the lockup expires, a wave of potential supply can weigh on the price. New listings often show high volatility in their first weeks because there is no trading history, limited analyst coverage, and a small float. Formal analyst ratings from underwriting banks usually begin after a quiet period.

Individual investors often cannot get shares at the offer price, since allocations go mostly to institutions. Buying on the first day means paying the market price, which may be well above the offer.

IPO alternatives and risks

Companies can also go public through a direct listing, where existing shares begin trading without a traditional underwritten offering, or by merging with a special purpose acquisition company (SPAC). Each route has different costs and disclosure dynamics.

Risks include limited operating history, losses that may continue for years, dual-class share structures that limit voting power, and dilution from future share sales. Reading the prospectus, especially the risk factors and the income statement, is a key part of fundamental analysis before buying a new issue.

Frequently asked questions

How can I buy shares in an IPO?

Some brokers offer access to IPO allocations for eligible clients, but most individual investors buy shares once they begin trading on the exchange.

Why do IPO stocks often jump on the first day?

Underwriters often price the offering below expected demand to ensure it sells, so strong demand on listing day can push the price above the offer.

What is an IPO lockup period?

It is a period, commonly 90 to 180 days, during which insiders and early investors agree not to sell their shares after the offering.

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For information only, not investment advice. See the disclaimer.