Methodology
There is no single number of IPOs in a year. Depending on what you count, a recent year in the United States contains somewhere between roughly 90 and roughly 350 first listings, and every figure in that range is defensible. This page states which one we mean.
What we cover
We read filings from SEC EDGAR: registration statements on Form S-1 and F-1, their amendments, final prospectuses on Form 424B4, and withdrawals on Form RW. Coverage is US offerings registered with the SEC.
The form alone does not tell you what kind of offering it is. A single S-1 can be an initial public offering, a follow-on offering by a company already public, a resale registration for existing holders, a shelf registration, a spin-off, or a trust listing. We classify each filing into one of those categories, and we cover initial public offerings.
Our default universe
Traditional operating-company IPOs on US exchanges. When a page gives a figure without saying otherwise, that is the population.
These are tracked as separate categories and never merged into the same table:
| Category | Why it is separated |
|---|---|
| SPAC IPOs | A blank-check shell raising capital to find a target later is not an operating business coming to market |
| Regulation A offerings | Qualified rather than registered, frequently best-efforts rather than firm-commitment |
| Direct listings | A listing without an underwritten offering |
| Follow-on offerings | The company is already public |
| Resale registrations | No new capital and no new listing |
| Spin-offs, trusts, and fund listings | Not an operating company coming to market |
We do not claim our default is the only correct one. We claim that publishing which one we used is the correct practice — most disagreements between published IPO counts are a difference of definition presented as a difference of fact.
Conventions
Dating. A deal is dated to its pricing date, not its first trading day. Where the two fall in different years, the year is set by pricing.
Proceeds. Stated at pricing, excluding any later exercise of the over-allotment option, unless a figure is explicitly labelled as including it. This is not cosmetic: Saudi Aramco's 2019 offering raised about $25.6 billion at pricing and about $29.4 billion after the over-allotment was exercised, and Alibaba's 2014 listing about $21.8 billion and about $25 billion respectively. A table mixing the two bases is not comparable.
Return metric. Where a page says "first-day return" without qualification it means offer-to-close: (first-day closing price − offer price) / offer price. That is the standard convention in the academic literature, which makes the figure comparable to published research. It is not a return an ordinary investor earns unless they received an allocation at the offer price.
| Metric | Formula |
|---|---|
| Offer-to-open | (first trade − offer price) / offer price |
| Offer-to-close (our default) | (first-day close − offer price) / offer price |
| Open-to-close | (first-day close − first trade) / first trade |
Foreign issuers. Non-US issuers listing on a US exchange are included, and we distinguish US exchange from US-domiciled issuer rather than treating them as the same thing.
Superlatives. Any ranking states the measure and the comparison set. "Largest" without "by what, among what" is not a claim we publish.