IPOs: How Companies Go Public

It is simultaneously a financing event (the company raises capital), a liquidity event (early owners gain a market for their stakes), and a transformation of legal life (quarterly reporting, public scrutiny, a share price flashing judgment every second). This article walks the machinery — who does what between the decision and the opening trade — and then the two documented phenomena every IPO discussion orbits: the first-day "pop" and the long-run performance record. Per the pillar rule: mechanics and history, no guidance on whether or how to participate in any offering.

The machinery: from decision to opening trade

The classic bookbuilt IPO runs a well-worn path. Why go public at all: to raise growth capital in size; to give founders, employees, and early investors a liquid market for stakes accumulated over years; to mint a public currency (listed shares) usable for acquisitions and compensation; and — less flattering, equally real — because venture backers' funds have clocks and need exits. The underwriters: the company hires investment banks to run the process — drafting the prospectus (in the US, the S-1 registration statement: the company's finances, risks, and story, filed publicly and legally liable for accuracy), managing the regulatory review, and orchestrating the sale. Underwriting is paid via the gross spread — the discount at which banks buy shares from the company before reselling to investors, historically clustering around 7% for mid-sized US deals (a remarkably sticky figure the academic literature has long puzzled over). Bookbuilding: management and bankers tour institutional investors (the roadshow), collect indications of interest at various prices, and "build the book" — discovering demand before any share trades. The banks then price the deal (final IPO price, set the evening before trading), allocate shares — overwhelmingly to institutions, which is why retail investors rarely obtain shares at the IPO price and mostly first buy in the open market — and stabilise early trading, aided by the greenshoe (over-allotment option): authority to sell up to ~15% extra shares, covered either by buying stock back (supporting a weak debut) or exercising the option (supplying a strong one). The share then opens on the secondary market, where an auction among public buyers and sellers — not the IPO price — sets the first trade, sometimes far above it.

The two documented phenomena: the pop, and the long run

The first-day pop: IPOs, on average and across decades of data (the standard reference being the long-running datasets maintained by academic researchers, most prominently Jay Ritter), open above their offer price — average first-day returns in US data have run in the double digits over long samples, spiking far higher in hot markets. Two readings coexist and both deserve reporting. The critical reading: a pop is money left on the table — shares the company sold at the offer price were demonstrably worth more hours later, a wealth transfer from the issuer to allocated investors, and a conflict worth understanding given who chooses the price (banks whose best clients receive the allocations). The sympathetic reading: deliberate underpricing compensates investors for taking price risk on an unknown asset, rewards the research effort bookbuilding extracts, and buys a successful debut whose signalling value the issuer shares in. The literature documents both mechanisms; the tension is permanent. The long run: the same academic record documents that IPOs as a class have, on average across long samples, underperformed comparable seasoned stocks in the years following listing — an average concealing enormous dispersion (the category contains historic winners and total losses in unusual concentration). This portal reports that record as documented history, not as a verdict on any offering: the finding describes a base rate, and base rates, as the disruption article showed for innovation generally, are the sober backdrop against which exceptional cases get all the attention. Around the event sit supporting mechanics worth naming: the quiet period restricting company promotion around the offering; the lock-up barring insiders from selling for a period after listing (typically ~180 days — consequential enough to get its own article); and the reality that an IPO's "price" means three different numbers (offer price, opening trade, first close) that commentary routinely conflates.