Investor playbook
Building a written thesis
📖 9 min read · 🎯 New funds + angels · Updated April 2026
An unwritten thesis is no thesis. The discipline of putting it on paper — and publishing it — is the single highest-leverage thing a new GP or active angel can do.
What a thesis actually is
Not your fund's marketing. Not "we invest in passionate founders". A thesis is a falsifiable bet on the world. Written well, it answers four questions:
- What's changing? The shift you're betting on (regulatory, technological, behavioural).
- Who wins from it? The class of company best positioned to capitalise.
- What does winning look like? The economic outcome — not "great companies" but "category leaders with $200M+ ARR by 2030".
- What gets us there? Your specific role — capital, intros, operating expertise — that increases the founder's odds.
The 5-section thesis document
1. Sectors
Specifically: vertical-aware, with a clear ranking. "Primary: cross-border fintech infrastructure. Secondary: vertical SaaS in regulated industries. Tertiary: AI infra plays where the founder has 5+ years of relevant operating experience." Not "FinTech, SaaS, AI".
2. Stages
What stages do you write at? "Pre-seed and seed. Average cheque $250K. Lead-capable to $750K. Reserve 60% of fund for follow-on." Be specific. Founders mis-target you when this is vague.
3. Geographies
Where can you actually be useful? "India + SE Asia primary; US founders only with India market exposure." Be honest about your limits.
4. Cheque sizing
Min, max, lead-capable amount, follow-on reserve %. Concrete numbers. If you can write a $1M cheque but can only commit at $500K, founders need to know.
5. Anti-thesis
The most-underwritten section. "We don't invest in: pure consumer apps without B2B economics, hardware that requires >$5M before market validation, regulated industries where the founder hasn't been an operator." Saying no clearly is a kindness.
Publish it. The act of publishing a thesis filters bad-fit deals out of your pipeline. The founders who pitch you become the ones who genuinely fit. This compounds: better deals → better outcomes → better deal flow.
Using the thesis as a filter
Inbound deal volume scales linearly with fund visibility. A written thesis converts that into pre-filtered flow. Every founder pitch should be triaged in <30 seconds:
- Sector match? Yes / no. If no — pass with a kind note pointing them to a better-fit fund.
- Stage match? Yes / no. If no — pass.
- Cheque size match? Yes / no. If no — pass or co-invest if a lead is in place.
- Anti-thesis trip? Yes / no. If yes — pass.
This 4-question filter handles 80% of inbound. The remaining 20% gets a real first meeting.
Worked example
Vertex Micro · Investment Thesis · 2026
We back capital-efficient B2B founders solving cross-border friction.
What's changing. Cross-border SMB payroll, payments, and treasury are being unbundled from correspondent banks by stablecoin and licensed neobank rails. The 42-corridor SE-Asia / MENA / IN belt has $1.8B/yr of friction; we expect the bulk extracted by 2028.
Sectors. Primary: cross-border FinTech infrastructure. Secondary: vertical SaaS for SMBs in cross-border industries (logistics, BPO, hiring). Tertiary: regulatory tech in this corridor.
Stages. Seed only. $250K – $1M. Lead-capable to $750K. 50% reserve for follow-on.
Geographies. IN, SG, US founders building for IN-SEA-MENA corridors.
Anti-thesis. Pure consumer fintech. Crypto-native protocols without licensed-rail strategy. Hardware. Founders without 5+ years of operating experience in the corridor.
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