How to write an investment thesis

Published 2026-04-28 - Updated 2026-05-18

An investment thesis is a written argument for owning or watching a business, including the assumptions and evidence that would make you change your mind.

Short answer

Write the core claim, time horizon, assumptions, evidence to monitor, disconfirming signals, action rules, and review cadence.

Make the thesis falsifiable

A thesis should say what would make it weaker or broken, not only why the company is attractive.

Tie evidence to assumptions

Each metric, source, or chart should support or challenge a named assumption.

Define review cadence before acting

A thesis becomes useful when it tells you when to return and what to check.

Practical checklist

• Core thesis statement.
• Time horizon.
• Key assumptions.
• Evidence to monitor.
• Disconfirming conditions.
• Position sizing and action rules.
• Checkpoint cadence.

Example thesis skeleton

Fictional sample only: a mid-cap software business with improving free cash flow.

• Thesis: enterprise upsell can support free cash flow growth over three years.
• Assumptions: retention remains high, acquisition cost falls, churn stays stable.
• Break condition: two quarters of retention below the defined threshold.

Mistakes to avoid

• Writing a story with no trigger.
• Tracking too many metrics.
• Not connecting the thesis to decision rules.