Last Modified: August 18, 2026
Table of Contents
An initial public offering is the process by which a privately held company first sells shares of its stock to the general public on a national securities exchange, transitioning from private ownership with a limited group of shareholders to public ownership with shares freely tradeable by any investor through a standard brokerage account.
The IPO is one of the most significant events in the lifecycle of a company, representing a fundamental change in its ownership structure, governance obligations, disclosure requirements, and access to capital. It is simultaneously a capital-raising transaction, a liquidity event for existing shareholders, and a branding exercise that dramatically raises the public profile of the company and its leadership.
The decision to go public involves complex trade-offs between the benefits of public market access and the substantial burdens that come with it. The primary benefit is access to the deepest and most liquid pool of capital in the world, allowing the company to raise large amounts of equity capital from a broad investor base to fund growth, retire debt, or make acquisitions.
The IPO also provides liquidity for founders, early employees, and venture capital and private equity investors who have held illiquid private stakes and can now sell into the public market. However the IPO also subjects the company to ongoing SEC reporting requirements, quarterly earnings disclosure and analyst scrutiny, the governance obligations of a publicly listed company, and the short-term performance pressures that come with continuous market pricing of the company's shares.
For investment professionals, understanding the IPO process is important for multiple reasons. IPOs represent significant primary market events that affect the prices of related securities, create new investment opportunities, and generate corporate finance fees that are important revenue sources for investment banks. The evaluation of IPO investment opportunities for client portfolios requires understanding of the IPO pricing process, the dynamics of first-day trading, the lock-up restrictions on existing shareholders, and the historical evidence on IPO performance relative to existing public market alternatives.
The IPO process is a complex and carefully sequenced series of legal, financial, and marketing activities that typically takes six to twelve months from the initial decision to go public to the first day of trading.
The selection of underwriters is one of the first and most consequential decisions in the IPO process. The issuing company selects one or more investment banks to serve as underwriters of the offering, with the lead underwriter or bookrunner taking primary responsibility for managing the IPO process and building the order book of investor demand.
The selection criteria include the bank's distribution capabilities and relationships with institutional investors, its research coverage and analyst quality in the relevant sector, its track record in comparable IPOs, and the credibility its reputation lends to the offering. For large IPOs, a syndicate of multiple banks is typically assembled, with the lead underwriter managing the process and co-managers assisting with distribution.
The due diligence and registration process involves the preparation of the registration statement filed with the SEC, the primary disclosure document for the IPO that describes the company's business, financial results, risk factors, use of proceeds, management team, and the terms of the offering.
The registration statement must include audited financial statements for typically three fiscal years prepared in accordance with US GAAP, risk factor disclosures covering all material risks to the business and the investment, and management discussion and analysis of the company's financial condition and results of operations. The SEC reviews the registration statement and may issue comment letters requesting additional disclosure or clarification before declaring the registration effective.
The preliminary prospectus, often called the red herring because of the red ink disclaimer on its cover noting that it is not a final prospectus and the offering price has not yet been determined, is distributed to potential investors during the marketing phase of the IPO. The red herring provides the full disclosure of the company but omits the final offering price and the number of shares to be sold, which are determined at the conclusion of the marketing process.
The roadshow is the intensive two to three week marketing campaign during which the company's senior management, accompanied by the lead underwriter, makes presentations to institutional investors in major financial centres across the United States and often internationally.
The roadshow is the primary opportunity for the management team to present the company's investment thesis directly to the institutional investors who will be the largest buyers in the IPO, to answer detailed questions about the business and financial model, and to generate the investor interest that will support a successful offering.
The bookbuilding process runs concurrently with the roadshow, as the underwriters collect indications of interest from institutional investors, recording the price levels at which different investors are willing to purchase shares and the quantities they are interested in acquiring. The bookbuilding process is not a formal auction but rather a structured process of information gathering that allows the underwriters to assess the level of demand across a range of potential offering prices and to determine the appropriate offering price and allocation of shares.
The pricing of the IPO occurs at the conclusion of the roadshow, typically in the evening before the first day of trading. The underwriters and the company's management review the order book and determine the offering price based on the level and quality of investor demand, the valuation implied by the proposed price relative to comparable public companies, and the desire to ensure that the stock performs well on the first day of trading to maintain investor confidence and the underwriter's reputation for well-priced offerings. The company and the underwriters then execute the underwriting agreement in which the underwriters commit to purchase the shares from the company at the agreed offering price, assuming the price risk of distributing those shares to investors.
The greenshoe option, formally called the overallotment option, gives the underwriters the right to purchase up to an additional fifteen percent of the originally offered shares at the offering price within thirty days of the IPO.
This option allows the underwriters to stabilise the stock price in the secondary market by purchasing shares if the stock trades below the offering price in the days following the IPO, using the proceeds from the overallotment to fund these stabilising purchases.
If the stock performs well and trades above the offering price, the underwriters exercise the greenshoe option to purchase additional shares from the company at the offering price rather than buying in the market at higher prices, providing the company with additional capital and the underwriters with additional fee income.
The pricing of IPOs and their subsequent first-day trading performance have been extensively studied by academic researchers and represent one of the most consistently documented anomalies in financial markets.
IPO underpricing refers to the tendency of IPO shares to trade above their offering price on the first day of trading, generating positive first-day returns for investors who receive allocations at the offering price. Academic research has documented average first-day returns of approximately fifteen to twenty percent for US IPOs over long historical periods, though the average masks enormous variation with some IPOs generating triple-digit first-day returns while others trade below their offering price on the first day.
The existence of consistent IPO underpricing is puzzling from the perspective of efficient market theory, because it implies that the underwriters are systematically pricing IPOs below the price the market will subsequently establish, leaving money on the table for the company that could have been raised through a higher offering price. Several explanations have been proposed for this phenomenon.
The winner's curse theory suggests that underpricing is necessary to compensate less informed investors for the risk of being allocated shares in poor-quality IPOs while missing out on the most desirable ones. The information extraction theory suggests that underpricing compensates institutional investors for truthfully revealing their demand information during bookbuilding, allowing the underwriter to price the IPO more accurately.
The signalling theory suggests that high-quality companies underprice their IPOs to signal quality to the market, knowing they can recoup the cost through subsequent seasoned offerings at higher prices.
The flip side of average first-day gains is that investors who purchase IPO shares in the aftermarket on the first day of trading at prices above the offering price capture none of the first-day return and may actually be buying at inflated prices if the initial enthusiasm subsequently fades. Long-run IPO performance, measured over the three to five years following the offering date, has consistently been found to be inferior to comparable non-IPO stocks of similar size and industry in academic research, suggesting that the initial enthusiasm that drives first-day price appreciation often reflects overoptimism about the company's prospects that is subsequently corrected as the company reports actual results against its IPO projections.
One of the most important structural features of IPOs for investors and analysts to understand is the lock-up period, the contractual restriction on the ability of pre-IPO shareholders including founders, executives, early employees, and venture capital and private equity investors to sell their shares following the IPO.
Lock-up periods typically last one hundred and eighty days from the date of the IPO, during which the locked-up shareholders are contractually prohibited from selling their shares regardless of the market price. The lock-up period is designed to reassure public market investors that the insiders who know the company best are not immediately flipping their shares into the public market, which would signal negative information about the company's prospects and potentially suppress the stock price in the period immediately following the IPO.
The expiration of the lock-up period is a closely watched event in the equity markets because it represents the first opportunity for large quantities of insider shares to enter the public market. Historical analysis shows that IPO stocks tend to underperform in the weeks surrounding the lock-up expiration as the market anticipates and then absorbs the potential selling pressure from newly freed insiders.
The magnitude of this lock-up expiration effect depends on the proportion of total shares outstanding that are subject to lock-up, the financial condition of the locked-up shareholders and their need or desire for liquidity, and the company's recent fundamental performance.
Secondary offerings following the IPO allow the company to sell additional newly issued shares to raise additional capital, or allow existing shareholders to sell their shares through a registered offering on the company's registration statement. Secondary offerings typically provide the first organised opportunity for venture capital and private equity investors to achieve meaningful liquidity for their holdings, and the announcement of a large secondary offering can be a negative signal if it is interpreted as suggesting that informed insiders view the current market price as attractive for selling.
The traditional underwritten IPO has faced competition in recent years from alternative structures that offer different trade-offs between cost, pricing efficiency, and the interests of different stakeholder groups.
The direct listing is an alternative to the traditional IPO in which the company does not sell newly issued shares to raise capital but instead allows existing shareholders to sell their shares directly into the public market on the first day of trading without the involvement of underwriters in a formal capital-raising transaction.
The direct listing was pioneered by Spotify in 2018 and subsequently used by Palantir, Asana, Coinbase, and other technology companies seeking to go public without the cost and dilution of a traditional IPO.
Direct listings are particularly attractive for companies that do not need to raise additional capital and want to avoid IPO underpricing by allowing the market to set the opening price through a transparent auction process on the first day of trading rather than through the private bookbuilding process used in traditional IPOs.
The Special Purpose Acquisition Company, universally known as a SPAC, is a blank-check company that raises capital through a traditional IPO with the stated intention of using those proceeds to acquire an existing private company within a specified timeframe, typically two years, thereby taking the target company public through a merger rather than through a conventional IPO.
The SPAC structure attracted enormous attention and capital during 2020 and 2021, when hundreds of SPACs raised hundreds of billions of dollars in aggregate, before largely falling out of favour as the poor long-run performance of many SPAC mergers and increased regulatory scrutiny of SPAC disclosures reduced investor enthusiasm for the structure.
The IPO process is extensively regulated by the Securities Act of 1933, which requires the registration of any public offering of securities with the SEC unless a specific exemption applies, and by the SEC rules implementing the registration requirements of the act.
The JOBS Act of 2012 introduced the Emerging Growth Company designation for companies with annual revenues below one billion dollars, providing them with several accommodations designed to reduce the cost and complexity of going public including the ability to file a confidential draft registration statement with the SEC before the public filing, reduced financial statement requirements, and a two-year phase-in of certain executive compensation disclosure requirements.
The confidential filing provision allows companies to test the waters with the SEC review process before making a public commitment to an IPO, reducing the reputational and business risk of filing a registration statement that must subsequently be withdrawn.
FINRA regulates the conduct of broker-dealers participating in IPO distributions, including rules governing the allocation of IPO shares to retail and institutional investors, the prohibition on certain practices including spinning, the allocation of hot IPO shares to corporate executives in exchange for investment banking business that was widespread in the late 1990s and was subsequently prohibited, and the requirements for disclosure of compensation arrangements between underwriters and selling group members.
IPOs are tested on the SIE and Series 7 examinations in the context of primary market transactions, the securities registration process, the role of underwriters, and the regulatory framework governing new issues. Candidates must understand the definition and purpose of an IPO, the roles of the issuing company and underwriters in the IPO process, the key documents including the registration statement and prospectus, the bookbuilding and pricing process, the greenshoe option and its stabilisation function, the lock-up period and its expiration effects, the phenomenon of IPO underpricing and long-run underperformance, and the alternative IPO structures including direct listings and SPACs.
The core points to retain are these: an IPO is the first sale of shares by a private company to the general public on a national securities exchange, governed by the Securities Act of 1933 requirement that the offering be registered with the SEC; the underwriter purchases shares from the company at the offering price and distributes them to investors, bearing the price risk of the distribution; the red herring prospectus is distributed during the roadshow and contains all material information except the final offering price; bookbuilding collects institutional investor demand information to inform the pricing decision,
The greenshoe option allows underwriters to purchase up to fifteen percent additional shares within thirty days to stabilise the aftermarket price; IPO underpricing, averaging approximately fifteen to twenty percent on the first day of trading, represents value left on the table by the issuing company; lock-up periods of typically one hundred and eighty days prevent insider selling following the IPO with expiration often associated with stock price weakness; long-run IPO performance has historically been below that of comparable non-IPO stocks in academic research; direct listings allow existing shareholders to sell without new capital raising avoiding underpricing; and SPACs are blank-check companies that raise IPO capital to acquire a private company and take it public through a merger.
