📖Charlie Munger

Concentration vs Diversification

🌳 Advanced★★★★★

Excessive diversification is a sign of ignorance, not prudence.

💬

The idea of excessive diversification is madness.

— Berkshire Hathaway Annual Shareholders Meeting，2004

🏠 Everyday Analogy

Just as in choosing friends, it is better to form deep bonds with three or five close friends you truly understand than to have a hundred superficial acquaintances. The same principle applies to investment: rather than spreading your money across a pile of companies you don’t understand, it’s wiser to concentrate your investments in a few outstanding businesses you have thoroughly researched.

📖 Core Interpretation

Excessive diversification is an excuse for ignorance; true investment acumen calls for concentrated holdings.
💎 Key Insight：If you truly understand a business, why dilute your returns by holding 50 others? Munger calls excessive diversification "madness" because it ensures mediocre returns. A concentrated portfolio of 3-5 deeply understood businesses will outperform a scatter-shot approach over time. The prerequisite is genuine understanding — without it, broad diversification is the safer choice.

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❓ Why It Matters

While diversification reduces risk, it also diminishes returns. True security stems from understanding, not from spreading investments.

🎯 How to Practice

Concentrate your investments on a select few that you truly understand and have confidence in, but ensure that your understanding is genuine.

🎙️ Master's Voice

You must know the big ideas in the big disciplines and use them routinely.
Munger maintains a "latticework of mental models" from physics, biology, psychology, and economics. These models help him see patterns others miss.

⚔️ Practical Guide

✅ Decision Checklist

  • Do I have models from multiple fields?
  • Am I applying the right model?
  • Do I see patterns across situations?

📋 Action Steps

  1. Learn core ideas from 10+ disciplines
  2. Practice applying models to problems
  3. Build your mental model toolkit

🚨 Warning Signs

  • Only one way of thinking
  • Ignoring relevant models
  • Forcing problems into familiar frameworks

⚠️ Common Pitfalls

✕Concentrated investing requires genuine skill.
✕When lacking capability, diversification is actually safer.

📚 Case Studies

1
Washington Post Concentrated Bet (1973)
Munger and Buffett made a large, concentrated investment in The Washington Post when it traded far below intrinsic value.
✨ Outcome：The stake compounded massively over decades, demonstrating the power of focused bets in high‑quality businesses.
2
Tech Bubble Avoidance (2000)
During the dot‑com boom, Munger stayed concentrated in understandable, high‑quality businesses and refused to diversify into fashionable tech stocks.
✨ Outcome：Avoided catastrophic losses when the bubble burst, reinforcing his view that intelligent concentration beats diworsified speculation.

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