The Series B Clock

All figures from our own reconstruction of SEC Form D filings, 2014–2026. Cohort-level results use

Series A vintages 2014–2019, which have 78+ months of observation.

01

Of companies that raise an A-scale round, 30.3% ever raise a genuinely

larger follow-on. Under a looser definition it is 39%; under a stricter one, 23%. Crunchbase puts the

2020–21 cohort at 36%; Carta, which sees full cap tables, puts it higher at 40–50%. Our level is

conservative — the timing is what matters here.

02

• Nothing happens before month 9. The quarterly hazard peaks at 3.7% in the
• quarter ending month 21 , then decays monotonically. Half of all eventual Series B raisers

have closed by month 24.

03

• Contrary to the standard narrative, median time-to-B among companies who make it within
• three years has barely moved: 18.5 → 18.3 → 17.2 months across the 2014-17, 2018-20 and

2021-23 eras. What collapsed is how many make it, not how long it takes those who do.

06

• Among companies still B-less at month 24, those who had taken a smaller interim round
• went on to raise a real B 25.8% of the time versus 15.8% for those who

had not — a 1.6× lift. Either way, the eventual round lands around month 40, deep in the tail.

So what

The urgency is real, but it is not where founders feel it. The pressure point is not month 24 when cash

runs low — it is month 9 to 12, when the metrics that will be diligenced are already being

generated. By the time the runway is visibly short, the outcome is largely set.

The Clock

Conditional probability that a company still without a Series B at month m will ever raise one.

Kaplan–Meier estimate, Series A vintages 2014–2019 (n = 3,093).

• Month 0
• Round just closed
• 30.3 %
• chance of ever raising a Series B
• 0 12 24 36 48 60
• 0% of day-one odds gone
• 0% of the cohort already raised
• — chance of closing this quarter
• The Shape

Share of still-waiting companies that close a Series B in each quarter · Series A vintages 2014–2019

The window opens at month 9, peaks in the quarter ending month 21, and falls below

half its peak at month 36. After month 48 the hazard is statistical noise.

• Cumulative graduation (purple) against conditional probability of ever graduating (lime)
• The two curves cross at roughly month 27 — the moment when a company has a better

chance of being already funded than of ever being funded.

Four Gates

Each gate is a point where the conditional odds step down and never recover.

Month 12

Only 3.9% of the cohort has raised. Nothing looks wrong. But the metrics that will be

diligenced in the next six months are being generated right now.

• 27.4% odds remaining · 9% of day-one odds gone
• Month 24

Typical Series A runway is exhausted. Half of everyone who will ever raise a B has

already done it. Odds have fallen below the point where the average outcome is a raise.

• 17.1% odds remaining · 44% of day-one odds gone
• Month 36

The hazard has fallen below half its peak. 72% of all eventual graduates are already

through. This is the point of no return in the data.

• 10.2% odds remaining · 66% of day-one odds gone
• Month 48

• Conditional odds of ever graduating, by how strictly a Series B is defined
• The absolute level moves with the definition; the decay pattern does not. Half-life

of the odds is 27 months under both the loose and base definitions, 30 months under the strictest.

The Vintage Effect

Cumulative share of each Series A vintage that had raised a Series B by 12, 24 and 36 months.

Kaplan–Meier cumulative incidence · bars omitted where the vintage is not yet old enough to observe

The 2022 vintage is the worst on record: 5.3% at 24 months, against 24.5% for 2020.

2023 recovered to 11.2% and the 2025 vintage is running at 4.7% by month 12 — the best 12-month rate since 2020.

So what

A 2022 Series A company was roughly four times less likely to reach a Series B in two years

than a 2020 one, at the same quality of execution. When you plan a raise, you are partly betting on a

market you do not control — which is an argument for getting to the window early rather than

optimising into it.

The Other 69%

Half of all Series A companies raise something again. Only 30%

raise something bigger . The gap between those two curves — about 24 points — is the bridge

economy: flat rounds, insider extensions, and structured paper that keeps the lights on without

resetting the story.

• Of the 2,133 companies in our mature cohorts that never
• graduated, 1,389 (65%) never filed another financing of any kind. The remaining 744 raised

only smaller or flat rounds — a median of one.

• Cumulative share of the 2014–2019 Series A cohort
• 65 %
• Of non-graduates go dark
• never file again, at any size
• 25.8 %
• Bridged & still made it
• of those B-less at month 24
• 15.8 %
• No bridge, still made it
• same starting position
• $27 M
• Median graduating round
• vs $9.5M median Series A
• The bridge lift is real but partly selection:
• a company that can raise a bridge already has insiders willing to fund it. Read it as

"insider conviction is the single best observable predictor," not "take a bridge and your odds improve."

What Moves the Odds

• Share raising a Series B within 60 months · 2014–2019 vintages
• An inverted U. The $8–18M band graduates best; both the under-funded and the

over-funded do materially worse.

Companies raising $18–30M at the A graduate at

25.5% — no better than those raising $5–8M, and seven points worse than the $8–18M band.

The mechanism is a bar you set for yourself. A larger

A means a higher post-money, which means the step-up required to clear a Series B mark is larger, which

means the same execution reads as a flat round. Big A rounds do not buy time; they buy a harder exam.

• Geography moves the number less than people assume:
• 29.2% in California and 31.0% in NY/MA against 25.5%

for the rest of the US — a real coastal edge, but worth about five points, not a category difference.

Working Backwards

If the median successful Series B closes around month 18–21, every upstream requirement has to land

much earlier than founders plan for.

Month 18–21

Series B closes. Median for companies that graduate within three years.

Month 13–16

Process starts. A Series B takes 4–6 months from first meeting to wire.

• Month 10–15
• The diligence window. Investors want two to three consecutive quarters of a

go-to-market motion that repeats.

• Month 6–9
• The engine has to be running. Pipeline, conversion, retention and attribution must

already be producing clean, consistent numbers — because these are the quarters that get shown.

• Month 0
• Series A closes. The measurement infrastructure needed at month 10 has to be built now;

you cannot retrofit four quarters of clean data.

The operator's version

The Series B is not won in the raise. It is won in the four quarters that get shown during the raise —

which means the go-to-market engine has to be instrumented and repeatable by month nine.

Everything after that is reporting.

Method & Limits

Source

Every quarterly Form D structured data set from 2014 Q1 to 2026 Q2, downloaded from

SEC EDGAR. Form D is the notice a company must file for a private securities offering, so nearly every

priced US venture round leaves one.

Universe

US-domiciled C-corporations filing an equity offering under a technology industry group.

Filings were collapsed into 32,717 financing events, with amendments and tranches inside 120 days merged

into a single round.

Definition

Form D does not carry round names. A "Series A" is a company's first equity event of

$5–30M that is at least a 1.5× step-up on anything prior; a "Series B" is a later event of at least

max($12M, 1.3× the A). Median detected A is $9.5M — squarely on the published Series A median.

Model

Companies are observed to 30 June 2026, so recent vintages are right-censored. All

cohort figures are censoring-aware and suppressed where a vintage is too young to observe the horizon.

Limit 1

Some rounds never file, or file under a different classification. Validation against

known ladders: Ramp's five rounds reconstruct exactly; Vanta's and Writer's earlier rounds are missing.

This biases the graduation level down and is why our 30.3% sits below Crunchbase's 36%. It does

not bias the timing , which is the finding.

Limit 2

Form D carries no sector detail below the industry group and no revenue, headcount or

shutdown data. We cannot separate B2B SaaS from AI-native, and "never raised again" is a proxy for

failure, not a measurement of it.

• Our estimate against the three most-cited external datasets
• Measure This study External benchmark Source

Series A → B, eventually 30.3% (23–39% by definition) ~36% of 2020–21 US Series A cohort Crunchbase News

• Series A → B by 24 months, 2018 vintage 14.6% 25% for the Q3 2018 vintage Carta
• Series A → B by 24 months, 2022 vintage 5.3% 9% for the Q3 2022 vintage Carta
• Median months A → B among graduates 23.5 28 median / 31 mean (2024) Crunchbase News
• Graduation by year 4, 2018–20 vintages 28.7–31.6% 40–50%+ Carta (10,755 startups)
• Our levels run consistently below Carta's because Carta sees complete cap tables while

Form D sees only filed offerings, and because our step-up test excludes labelled Series B rounds that were

flat or down. Directionally every series agrees, including the collapse of the 2021–22 vintages.

To go deeper

Three gaps a paid data source would close: (1) real round labels and sector tags — PitchBook

or Crunchbase Pro would let us split B2B SaaS from AI-native and use actual Series A/B designations rather

than size heuristics; (2) outcomes — acquisition, shutdown and going-concern status, so

"never raised again" becomes a measured outcome instead of a proxy; (3) performance at the A

— ARR, growth and headcount, which would turn this from a timing model into a model of what actually

earns the B.

LeanScale

LeanScale builds the go-to-market engine behind venture-backed companies — the pipeline, systems and

reporting that turn a Series A into a Series B.

Analysis by LeanScale, July 2026. Built on public SEC data. Not investment advice.

Figures are estimates from a size-based reconstruction of round sequences and should be read as

directional, not as a company-level record.

• SEC EDGAR Form D data sets, 2014 Q1 – 2026 Q2
• 615,718 filings · 18,997 companies · 6,957 Series A rounds
• Kaplan–Meier survival model, censored at 30 June 2026
• Benchmarked against Carta and Crunchbase News
• www.leanscale.team