Series A Due Diligence Is Where Most Investors Leave Money on the Table
The questions that separate real traction from a good story, and the AI prompts that surface the difference.
Last week we published AI-Powered Due Diligence: The VC Prompt Library for Pre-Seed & Seed Analysis 💡.
That guide focused on evaluating companies when data is scarce and the signal mostly comes from founders, early users, and market timing.
Series A is the opposite problem.
By this stage, companies finally have numbers.
Revenue is growing.
Customers exist.
The slide deck looks credible.
The founder can point to logos, retention charts, and early traction.
And yet many Series A investments that later struggle looked exactly like that at the time.
The real question at Series A is not simply “is this growing?”
It is “is this real?”
Real product-market fit versus early adopters who have not churned yet.
A repeatable sales motion versus a founder who personally closes every deal.
Unit economics that improve with scale versus metrics that look healthy only because the sample size is still small.
This is why Series A is difficult.
You are evaluating a business that has enough data to look convincing, but not enough history to prove durability.
Getting that judgment right requires more than a strong pitch meeting.
It requires a disciplined way to test whether early traction represents something that can actually scale.
Below are some of the core areas where serious Series A diligence should focus.
1. Product-market fit: identify the real segment
PMF at Series A is rarely universal.
It usually exists inside a specific customer segment.
The key diligence question is simple:
Which customers cannot realistically replace this product?
Instead of relying on survey metrics like NPS, investors should look at behavioral signals:
retention curves by cohort
expansion revenue within cohorts
usage intensity among the most engaged customers
concentration of revenue by segment
The goal is to identify whether one segment shows consistent retention and expansion.
If it does, the next question becomes whether that segment is large enough to support a venture-scale company.
2. Unit economics: trends matter more than snapshots
Series A decks often highlight LTV:CAC ratios.
But a single ratio tells you very little.
The useful signal is how the ratio evolves across cohorts.
For example:
Is CAC rising or falling as the company scales acquisition?
Do later cohorts retain better or worse than earlier ones?
Does payback improve as the team builds a real sales process?
Six cohorts tell you more than a single aggregate metric.
3. Go-to-market: remove the founder test
One of the simplest but most revealing diligence questions is this:
Can the company sell the product without the founder in the room?
Early traction often comes from founder-led sales.
That is normal.
The problem appears when the company cannot replicate those results with new hires.
Signs of a scalable GTM motion include:
consistent conversion rates across sales reps
documented sales playbooks
predictable pipeline generation
similar close rates across comparable customer segments
If every important deal requires the founder’s involvement, the company may not yet have a repeatable sales engine.
4. Financial projections: forward logic vs valuation math
Series A financial models should be built forward from observed performance.
That means projections based on:
conversion rates
sales capacity per rep
historical growth velocity
retention trends
When projections instead appear reverse-engineered from a valuation target, the model is not analysis.
It is storytelling.
The 22nd Century Frontier - VC Due Diligence Prompt Playbook: Guide 02 | Series A
We built 11 prompts that guide Series A diligence systematically.
Each prompt specifies the role, inputs, expected output, benchmark, and how it connects to the next step, ready to run on real company data.
What’s inside:
✅ 11 prompts calibrated for Series A stage
✅ PMF segment mapping framework
✅ Unit economics cohort analysis prompt
✅ GTM scalability and repeatability assessment
✅ Financial model credibility audit
✅ Exit scenario modelling with current market multiples
✅ Final investment memo synthesis prompt
Next week: Guide 03 - Series B+ Edition drops.
The most quantitatively rigorous guide in the set.
Download the full Series A Guide Below 👇
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