Definition

An initial public offering (IPO) is the first sale of a company's shares to public investors, after which the shares trade on a stock exchange and the company becomes subject to public reporting obligations.

Source: US Securities and Exchange Commission, Investor Bulletin on Investing in an IPO.

An IPO does two things at once. It raises primary capital — new shares sold, proceeds to the company’s balance sheet. And it creates liquidity for existing holders: founders, employees with vested equity, and venture investors who have held illiquid positions for years.

The valuation attached to the offering is a negotiated estimate of the present value of cash flows that have not occurred yet. It is not measured, discovered, or verified. That is the structural reason founders and underwriters disagree about it, and the reason a founder’s stated number is a bargaining position rather than a fact.

How the Offer Price Is Set

1. The company files a registration statement. Form S-1 (or F-1 for foreign issuers) discloses financials, risk factors, use of proceeds, and ownership. Companies above a revenue threshold may file confidentially first and make the filing public later.

2. Underwriters build a book. The lead investment banks canvass institutional investors — asset managers, pension funds, hedge funds, sovereign funds — for indications of interest at various price levels. This produces a demand curve, and the range published in the prospectus is derived from it.

3. The offer price is set the night before trading. The company and underwriters choose a price from the book. It is typically set below the level at which the book would fully clear, deliberately.

4. Shares are allocated at the offer price. The underwriters distribute to institutional accounts and favoured clients. Retail access to the offer price is limited, and where brokerage platforms offer it, allocations are small and rationed.

5. Trading opens at a price set by the exchange’s opening auction. This is where the public transacts, and it reflects broad demand rather than the allocated book.

Steps four and five contain the mechanism that matters. The offer price and the opening print are different numbers, and the difference is a transfer from the issuing company to the allocated buyers.

The Underpricing Data

US IPOs have averaged a 19.0% first-day return — offer price to first-day close — over the period from 1980 through 2025, per Jay Ritter’s dataset at the University of Florida. Recent years have run above that average: 29.3% in 2025, against 15.3% in 2024.

Underpricing is the issuer’s cost. A company that prices at $30 and closes its first day at $39 sold shares $9 below what the market immediately paid. On a 50 million share offering, that is $450 million that went to allocated buyers instead of onto the company’s balance sheet.

Two competing explanations, both partially supported: underwriters underprice to compensate institutional buyers for revealing honest demand during book building, and underpricing manages the winner’s curse, in which uninformed buyers receive full allocations only in deals informed buyers avoided.

The long-run record is the other half. Ritter’s 1991 study found that investors buying at the first-day closing price and holding three years underperformed a matched sample of comparable firms by approximately 29%. The pop and the drift are two faces of the same structure: the offer price is set low, the opening price overshoots, and the subsequent path reflects the correction.

StageWho transactsAt what price
Book buildingInstitutions indicate interestPrice range in prospectus
Pricing (night before)Company and underwriters setOffer price
AllocationInstitutions, favoured clientsOffer price
Opening auctionGeneral publicOpening print, historically above offer
Day one closeGeneral publicAveraged 19.0% above offer, 1980–2025
Lock-up expiry (~90–180 days)Insiders become eligible to sellMarket price, supply increases

How to Evaluate an IPO in Practice

1. Read the use of proceeds section. Primary proceeds funding capacity, research, or debt repayment differ from an offering that is largely secondary — existing holders selling. The S-1 states the split explicitly.

2. Compare the offer price to the opening print before deciding. The gap quantifies how much demand exceeded the priced supply. Buying at the opening print means paying that gap.

3. Locate the lock-up expiration date. Insiders are typically restricted from selling for 90 to 180 days. The expiry adds supply on a known date, and the date is disclosed in the prospectus.

4. Check share class structure. Dual-class structures common in technology listings give founders voting control disproportionate to economic ownership. The ratio is disclosed and determines whether public holders have any governance influence.

5. Read the risk factors as a list of what management is worried about. Risk factor sections are drafted by counsel to limit liability, which means they are unusually candid about what could go wrong. They are the most information-dense section of the filing.

6. Wait for reported quarters before applying valuation models. A discounted cash flow requires cash flow history as a public reporter. The first two or three quarterly reports establish whether the growth described in the prospectus survives contact with public disclosure.

Common Mistakes and Misconceptions

“A founder’s stated valuation is what the company is worth.” It is an anchoring position stated publicly before any transaction. Sam Altman’s characterisation of any OpenAI IPO below $1 trillion as a “nonstarter” sets a negotiating floor; whether a book clears there is determined by institutional demand, not by the statement.

“A big first-day pop means the IPO succeeded.” A large pop means the offering was underpriced — the issuer left money on the table. It is a good outcome for allocated buyers and a costly one for the company. It says nothing about whether the business will perform.

“I can buy at the IPO price.” Retail access to offer-price allocations is limited and rationed. Most retail orders execute at the opening print or later, after the first-day gap has been captured by allocated accounts.

“Oversubscription means the price is too low.” Order books at popular offerings are routinely reported as several times oversubscribed, because indications of interest are non-binding and institutions inflate them to secure allocation. Oversubscription measures the demand curve at a moment, not durable valuation.

“A private company cannot be a public-market risk.” Private status only means shares are not exchange-traded. Once a company lists, the risk becomes immediate — and status changes. SpaceX and OpenAI were both routinely described as permanently private; SpaceX listed on June 12, 2026.

Example: SpaceX, June 2026

SpaceX priced its offering at $135 per share on June 11, 2026, offering 555.6 million shares. Including the underwriters’ overallotment exercise, the deal raised approximately $85.7 billion — a record for a public offering.

Trading opened June 12 at $150, roughly 11% above the offer price. The stock closed at $160.95, up about 19% from the offer, valuing the company near $2.1 trillion.

The three prices tell three different stories. Allocated institutional buyers acquired at $135. The public transacted from $150. The first-day close at $160.95 marked the peak of the demand imbalance.

By August 2, 2026, SPCX traded at $108.37 — roughly 33% below the first-day close, and about 20% below the offer price, for a market value near $1.43 trillion.

Nothing here required a business failure. Roughly seven weeks passed. A buyer at the offer price was down about 20%; a buyer at the first-day close was down about 33%. This is the underpricing-plus-drift pattern Ritter documented, compressed into weeks rather than years, and it is why the two entry points are not interchangeable.

The comparison to OpenAI follows directly. OpenAI filed for an IPO in early June 2026 with no committed timing — Altman stated that timing had not been decided, and reporting has suggested a listing may not occur until 2027. A stated trillion-dollar floor is a negotiating anchor set before any book is built. SpaceX’s sequence demonstrates that even a record-breaking, heavily oversubscribed listing produces prices that reprice substantially within two months.

Three Prices, Not One

Every IPO has an offer price, an opening print, and a settled price some months later. Headlines quote whichever is largest. Before acting on a listing, identify which of the three you would actually transact at, and what the historical gap between them has been.

How Cluenex Covers Newly Listed Companies

Cluenex analyzes the top 1,000+ US-listed stocks using financial statement data, discounted cash flow and owner earnings valuation, moat scoring, sentiment, earnings timing, and insider and congressional trading activity.

For a company that listed last week, most of those inputs do not yet exist in the form the models require. A DCF needs cash flow history as a public reporter. Moat scoring needs multi-period margin and returns data. Insider trading signals need Form 4 filings, which begin only after registration. Coverage of a new issuer therefore builds over the first several quarters rather than beginning at the opening bell.

The practical consequence is that the period when an IPO attracts the most attention is the period with the least analyzable data. That is a limitation of quantitative analysis, and it is also a reasonable description of why first-day buying has the record it has.

Frequently Asked Questions

  • What is an IPO? An initial public offering is the first sale of a company’s shares to public investors, after which the shares trade on an exchange and the company must file periodic reports with the SEC. It raises new capital for the issuer and creates liquidity for existing shareholders.

  • How is an IPO price determined? Underwriters canvass institutional investors for indications of interest across a price range, building a demand curve. The company and underwriters then set an offer price from that book, typically below full clearing level. The public transacts separately at the opening auction price the following morning.

  • Why do IPOs jump on the first day? Because the offer price is deliberately set below the level the broader market will pay. US IPOs averaged a 19.0% first-day return from 1980 through 2025, and 29.3% in 2025. The gap transfers value from the issuing company to allocated institutional buyers.

  • Can retail investors buy at the IPO offer price? Rarely, and in small amounts. Offer-price allocations go primarily to institutional accounts and underwriters’ favoured clients. Some brokerages offer limited retail participation, but most retail orders execute at the opening print or later.

  • Do IPOs underperform after listing? Jay Ritter’s 1991 study found that buyers at the first-day closing price underperformed matched comparable firms by roughly 29% over the following three years. The pattern is a tendency across large samples, not a rule about any individual listing.

  • What is a lock-up period? A contractual restriction, usually 90 to 180 days, preventing insiders and pre-IPO holders from selling. The expiration date is disclosed in the prospectus and adds share supply on a known date, which frequently pressures the price.

  • What happened with the SpaceX IPO? SpaceX priced at $135 on June 11, 2026, raised approximately $85.7 billion including the overallotment, opened at $150 and closed at $160.95 on June 12 for a market value near $2.1 trillion. By August 2, 2026 the stock traded at $108.37, about 33% below the first-day close.

  • Is a high IPO valuation a warning sign? Valuation level alone signals little; the entry price relative to that valuation is what determines return. The more useful questions are what growth and margin assumptions the price embeds, how much of the offering is primary versus secondary, and how much supply arrives at lock-up expiry.