📖Warren Buffett

When to Sell

🌿 Intermediate★★★★★

Adapt your investment thesis when fundamentals genuinely change — not from price swings.

💬

When the facts change, I change my mind. What do you do, sir?

— Berkshire Hathaway Annual Meeting (frequently cited)，2010

🏠 Everyday Analogy

Just as a doctor must immediately adjust the treatment plan upon discovering a previous misdiagnosis or a worsening condition, the same principle applies to investing. When a company's fundamentals undergo a fundamental change, or when a better investment opportunity emerges, clinging to the original holdings is like stubbornly sticking to the wrong prescription—it will only make the situation worse.

📖 Core Interpretation

Correct reasons for selling: 1. Permanent deterioration in fundamentals 2. Extreme overvaluation (rare) 3. Discovery of a better opportunity 4. Need for capital allocation to other purposes
💎 Key Insight：Selling should be driven by changes in business fundamentals, not by market volatility or emotional reactions. If the competitive moat erodes, management integrity falters, or the original investment thesis breaks, sell regardless of price. But if only the stock price has changed while the business remains strong, holding is usually the right move.

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❓ Why It Matters

Wrong Reasons to Sell: 1. Stock price decline (if fundamentals remain unchanged, it is a buying opportunity) 2. Stock price increase (a rise does not necessarily indicate overvaluation) 3. Market predictions 4. Emotional factors

🎯 How to Practice

Buffett prefers long-term holdings, but he will consider selling when a company's economic moat erodes or management loses integrity.

🎙️ Master's Voice

When the facts change, I change my mind. What do you do, sir?
Buffett sold his entire airline position in 2020 when COVID changed the fundamental economics of the industry. He didn't sell because prices dropped—he sold because the business prospects changed dramatically. He adapts to new information, not market noise.

⚔️ Practical Guide

✅ Decision Checklist

  • Have the business fundamentals actually changed?
  • Is this a permanent or temporary change?
  • Am I reacting to price or to business reality?
  • Does my thesis still hold with new information?

📋 Action Steps

  1. Distinguish between price and fundamental changes
  2. Update your thesis when facts change
  3. Be willing to admit when you're wrong
  4. Act decisively on genuine fundamental change

🚨 Warning Signs

  • Holding positions despite thesis destruction
  • Selling due to price drops, not fundamentals
  • Ignoring negative fundamental developments
  • Stubbornly clinging to original thesis

⚠️ Common Pitfalls

✕Sell when it rises? - The value of excellent companies also grows, so a price increase does not necessarily mean overvaluation.
✕Set Stop-Loss to Protect Profits – If Fundamentals Remain Unchanged, Stop-Loss May Trigger Selling at Lows

📚 Case Studies

1
Selling Airline Stocks (2020)
The pandemic has altered the fundamentals of the aviation industry.
✨ Outcome：Warren Buffett decisively sold all airline holdings.
2
Holding Coca-Cola for over 35 years (1988)
Fundamentals Remain Consistently Strong
✨ Outcome：Never Consider Selling

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