IPO investing explained: what an initial public offering means for investors
An initial public offering (IPO) is the process by which a private company offers shares to the public on a stock exchange for the first time. For investors, an IPO creates the opportunity to buy equity in a company at the point of transition from private to public ownership—but the conditions of that transition introduce specific risks that long-established public companies do not carry.
What an IPO is
When a company goes public, it issues new shares (a primary offering) or existing shareholders sell their holdings (a secondary offering) to public investors through a stock exchange listing. Investment banks manage the process: they conduct due diligence, set the initial offering price in consultation with the company, and coordinate with institutional investors during a bookbuilding phase before the IPO date.
The IPO price is the price at which shares are first offered to the public. On the first trading day, the market price can differ substantially from the IPO price in either direction. Strong demand produces a "pop"—a sharp opening-day price increase; weak demand or overpricing produces a decline. The first-day price is not a reliable signal of long-term performance.
How IPOs work for retail investors
Retail investors rarely receive allocation in the primary offering at the IPO price. Most IPO shares are allocated to institutional investors during the bookbuilding phase. Retail investors typically buy on the secondary market after trading has opened.
This distinction matters for return expectations. The widely documented IPO pop applies to investors who receive primary allocation at the IPO price—not to those who buy at the opening market price. Ritter (1991), The Long-Run Performance of Initial Public Offerings, Journal of Finance, documented that IPOs underperform comparable seasoned stocks by a cumulative average of 15–20% over the three years following the offering. The combination of selective institutional allocation at the IPO price and long-run underperformance means that retail investors who buy on the secondary market are typically not capturing the upside that headline IPO returns appear to offer.
Lock-up periods and insider selling
Following an IPO, existing shareholders—founders, employees, and pre-IPO investors—are typically restricted from selling their shares for a lock-up period of 90 to 180 days. When the lock-up expires, these holders may sell, which can create selling pressure on the share price. The lock-up expiry is a well-defined event risk for IPO investors and is publicly disclosed in the prospectus.
Limitations
IPOs carry limited historical data at the time of listing. A company that has been public for two months has no public track record against which to assess momentum, drawdown behaviour, or how it responds to market stress. Standard backtesting—which relies on long price histories—is not applicable. Volatility tends to be elevated in the weeks after listing as the market establishes a trading range.
Companies are not obligated to go public at the optimal time for investors. Many IPOs occur when private market valuations are high and existing owners want to monetise holdings—timing that may not coincide with attractive entry prices for public market buyers.
IPOs in pfolio
IPO stocks carry the Stock asset type and Equity asset class in pfolio. Because pfolio's analysis relies on historical price series for momentum signals, volatility estimation, and backtesting, recently listed stocks with short price histories may have insufficient data for reliable signal generation. Investors should note the limited data when interpreting metrics for recent IPOs. The current universe of stocks available is visible on the Assets page.
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