Data & methodology

Qualifying Seed means each company’s earliest reported Seed round of at least $1M and less than $4M. Earlier smaller or undisclosed Seeds are allowed. Investor names are optional: missing names do not establish that a round was unfunded. Amounts are recorded US dollars, not inflation-adjusted. This reported-round definition differs from the standardised Seed classification used in The startup journey in Europe.

Download every company, qualifying Seed and outcome (CSV) · Selection review and sources · Independent count reconciliation.

The explorer’s slider selects qualifying Seed years. It counts all recorded outcomes through the September 2026 snapshot. Older cohorts have had more time to convert. The two handles select any inclusive Seed-year range from 2005 to 2019. Rates divide total outcomes by total Seeds.

The cohort lines count outcomes by whole-year anniversaries of each company’s qualifying Seed, measured in elapsed months and including the anniversary month. Year 6 gives every company 72 months to convert. Denominators stay fixed, including closed and acquired companies. The 2005–2009, 2010–2014 and 2015–2019 cohorts end at Years 16, 11 and 6, the last whole ages observable for every company in each cohort. Later outcomes remain in the explorer. For example, Calastone reached $1B 17 years after its 2008 Seed, so it is outside the Year 16 endpoint.

Missing milestone months are supplemented by dated, non-estimated $1B+ valuations in the recorded unicorn year, or a cited announcement. Unknown dates remain intervals. A point is omitted when its count depends on a missing month: Kodiak Sciences at Year 10 of Bay Area 2005–2009, and Nurix at Year 8 of Bay Area 2010–2014. Date audit and sources.

Unicorn outcomes use Dealroom’s verified historical $1B valuation or exit flag, retaining companies whose value later fell. Decacorns require a recorded, non-estimated $10B+ valuation in that population. Private, public-market and exit values qualify. Complete valuation histories cover 192 eligible historical unicorns. These are observed recorded outcomes; no sampling confidence intervals are shown.

The identity review consolidated 22 duplicate company profiles, removed 5 misattributed Seed records, and quarantined 4 Seed records across the conflicting Sphere and Arc identities pending reliable attribution. Same-name companies and acquired companies sharing a website remain separate where their identities differ. Every decision is in the downloadable review. Missing investor names and unverified Seed-record flags alone do not exclude an otherwise qualifying round; those fields remain in the company download.

The analysis covers 4,047 eligible recorded companies. Companies tagged Outside Tech in the captured scan and companies already unicorns before Seed are excluded. London uses current HQ city boundaries; Bay Area uses current HQ region 165. Relocation, unequal boundaries, missing Seed amounts, historical reporting coverage and changes in the real value of the funding band limit comparisons. The 2005–2009 London cohort contains 28 recorded Seeds. This audit checks selection and arithmetic; it does not establish complete historical coverage or future conversion probabilities.

All recorded outcomes to September 2026, grouped by qualifying Seed year
HQ	Seed cohort	Unicorns / Seeds	Unicorn rate	Decacorns / Seeds
London	2005–2009	3 / 28	10.7%	0 / 28 · 0.0%
London	2010–2014	8 / 185	4.3%	2 / 185 · 1.1%
London	2015–2019	20 / 816	2.5%	1 / 816 · 0.1%
Bay Area	2005–2009	12 / 118	10.2%	3 / 118 · 2.5%
Bay Area	2010–2014	75 / 1144	6.6%	20 / 1144 · 1.7%
Bay Area	2015–2019	74 / 1756	4.2%	5 / 1756 · 0.3%

Seed and unicorn snapshot: 20 September 2026. Complete original scans: 38,369 European Seed transactions, 64,056 US Seed transactions, 15,431 Bay Area Seed transactions and 4,030 verified unicorn records. Earlier years were scanned before selecting cohorts. All 4,078 candidate company profiles were checked on 22 September; historical unicorn flags matched. Valuation and date receipts identify their individual capture dates.

Annual counts and rates · Cohort curves and counts. CSV and image downloads preserve each chart’s definition.

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