Audit Investment Thesis

---
name: audit-investment-thesis
description: Use when evaluating the strength and validity of an investment thesis before committing capital
source: Charlie Munger's "Poor Charlie's Almanack"; Howard Marks memos (Oaktree Capital); Seth Klarman "Margin of Safety"
tags: [finance, investing, thesis, due-diligence, mental-models, margin-of-safety]
verified: true
---

# Audit Investment Thesis

Stress-test an investment thesis using systematic mental models and adversarial questioning.

## Why This Is Best Practice

**Adopted by:** Berkshire Hathaway, Oaktree Capital, top-tier value investors; taught at Columbia Business School Value Investing Program
**Impact:** Howard Marks' memos document that second-level thinking and explicit thesis auditing reduce permanent capital loss; Munger's "checklist" method is credited with Berkshire's long-run outperformance.

**Why best:** A thesis audit forces inversion — asking "how could this be wrong?" before "why will this work?" Explicit pre-mortems catch errors of omission (what you didn't consider) that optimistic analysis routinely misses. Requiring a margin of safety quantifies the price of being wrong.

## Steps

1. **State the thesis in one paragraph** — A thesis you cannot summarize clearly is a thesis you do not understand; require a concise statement of the core variant view vs. consensus.
2. **Identify the key assumptions** — List 3–5 assumptions the thesis requires to be true; rank them by impact and fragility.
3. **Apply inversion (pre-mortem)** — Assume the investment loses 50% over 3 years; write down the most plausible path that leads there; this surfaces hidden risks.
4. **Check the base rate** — What percentage of similar investments have succeeded historically? Anchor expectations to base rates before adjusting for specific factors.
5. **Assess the moat** — Evaluate competitive advantage: cost advantage, switching costs, network effects, intangible assets (brands, patents); use Morningstar's five-source framework.
6. **Stress-test valuation and margin of safety** — Discount intrinsic value estimate by 25–30% to establish a safe entry price; the thesis is only actionable below this price.
7. **Identify the falsifying event** — Define in advance what data would prove the thesis wrong; this prevents sunk-cost rationalization later.
8. **Document and sign off** — Write up the audit findings; revisit at least quarterly or when a key assumption changes.

## Rules

- Never invest without an explicit margin of safety; price always matters.
- Always invert: "What would have to be true for this to fail?" before "What would have to be true for this to succeed?"
- Require that the thesis rests on no more than 3 critical assumptions; more complexity means more failure points.
- Distinguish between risk (known unknowns with probabilities) and uncertainty (unknown unknowns); price appropriately for both.
- Update the thesis when facts change; do not confuse stubbornness with conviction.

## Examples

**Thesis under audit:** "Company X will triple revenue in 3 years via AI-driven upsell." Key assumptions: (1) AI product achieves 40% attach rate, (2) net revenue retention stays >120%, (3) competitive moat holds. Inversion: attach rate stalls at 15% due to integration friction → revenue grows 60% not 3×. Margin of safety: intrinsic value $80/share → entry only below $56. Falsifying event: two consecutive quarters of NRR below 110%.

## Common Mistakes

- **Confirmation bias in research** — Seeking only supporting evidence; deliberately assign a team member to argue the bear case.
- **Anchoring to purchase price** — The market does not know or care what you paid; evaluate the thesis on current facts, not sunk cost.
- **Ignoring second-order effects** — The investment may be right but too crowded; consider what happens when consensus agrees with you.

---

> **Finance disclaimer:** This skill encodes professional best practices for educational purposes. It is not financial advice. Consult a licensed financial advisor before making investment decisions.