Pro Investor Academy
Intermediate
5 min read

Building an Investment Thesis

A thesis states what you believe, why, and what would prove you wrong.

What you'll learn

  • Write the four parts of an investment thesis
  • Set the condition that would prove you wrong first
  • Revisit a thesis on results, not price moves

Optional supplemental lesson. It doesn't count toward the certificate. Suggested after Lesson 6.1: Fundamental Analysis.

Back to Lesson 6.1

The four parts

A usable thesis fits on one page.

  • What the business does and how it makes money
  • Why you believe it can be durably stronger in five to ten years
  • What evidence supports that, and where the evidence is missing
  • What specific developments would tell you the thesis is wrong

Write the falsification condition first

Without a pre-written condition for being wrong, any decline becomes a buying opportunity and any rise becomes confirmation. The falsification condition is the part that makes the thesis honest.

Revisit on results, not on price

Review a thesis when the company reports, not when the price moves. Price movement is not evidence about the business.

Why this matters

A written thesis lets you check later whether you were right for the right reasons.

Terms used in this lesson

Select a term to read its definition.

  • Investment thesis

    A written explanation of why you own something, what evidence supports it and what would show it is wrong.

    View in the glossary
  • Falsification

    The pre-written condition that would tell you your investment reasoning was wrong.

    View in the glossary
  • Due diligence

    The research done before a decision: reading filings, checking facts and understanding the risks.

    View in the glossary
See the full glossary

Key takeaways

  • A thesis states what you believe, why, and what would prove you wrong.
  • Writing the falsification condition first keeps you honest.
  • Review against business results, not daily prices.
Written by
Pro Investor Academy Research Team
Content type
Educational article
Published
2026-09-13
Last reviewed
2026-09-13

Sources

This lesson is general educational guidance and does not cite an external source.

Where Reliable Information Comes FromEvidence Levels and Missing Data

Educational content only. This lesson is not investment, tax or legal advice and does not recommend buying or selling any specific investment. All investing involves the risk of loss.