Financial Derivatives
Don’t short, don’t borrow, don’t do what you don’t understand—keep these three rules and it’s hard to get wiped out.
📌 Concept Analysis
Financial derivatives (from Duan Yongping’s perspective) = A class of tools with unlimited risk; the best strategy is to avoid them entirely.
You go to a casino—a gambler can at most lose their principal. But shorting is like borrowing money from the casino to gamble—if you lose, not only do you lose your principal, you’re also in massive debt. The danger of financial derivatives (especially shorting and leverage) lies in: losses have no upper limit while gains have an upper limit. This is completely opposite to value investing logic.
💡 Core Understanding
1. Shorting has unlimited risk—one mistake can be fatal.
Even if your judgment is correct, the market may only return to rationality after you’ve gone bankrupt. The Volkswagen short-selling case is a classic example: judgment was right, but market mania pushed it to the extreme.
2. Don’t short, don’t borrow, don’t do what you don’t understand—these are the three precepts Buffett gave Duan Yongping.
These three rules represent Stop Doing List’s core embodiment in the investment realm.
3. Shorting is a zero-sum game—very few people succeed long-term through shorting.
Going long means sharing in a company’s growth fruits; shorting means betting on a company’s failure. The former is a positive-sum game, the latter zero-sum—their long-term expected values are completely different.
4. For companies you dislike, simply avoiding them suffices—no need to short them.
This extends the circle of competence principle: for things outside your circle of competence, not doing anything is the best strategy.
❓ Selected Q&A
Q: Is it true that shorting has unlimited risk—one mistake can be fatal?
A: It’s indeed very dangerous. Reasons not to short: when shorting, you face not only fundamentals but also market mania. Anyone can make mistakes, but mistakes while shorting can expose you to infinite risk—just look at the case of shorting VW from a few years ago to understand.
Source: Duan Yongping Investment Q&A (Investment Logic), 2012-06-26
Q: Would you consider margin selling Tencent shares?
A: I will never short any stock again. I don’t think Tencent at 200 yuan is outrageously expensive. Shorting faces infinite risk—I won’t do it.
Source: Duan Yongping Investment Q&A (Investment Logic)
Q: Where did these three rules come from: don’t short, don’t borrow, don’t do what you don’t understand?
A: I asked Buffett what things shouldn’t be done in investing, and he told me: don’t short, don’t borrow, most importantly don’t do what you don’t understand. Over these years, I’ve lost hundreds of millions of dollars in investing, and every loss came from violating old Buffett’s teachings. The big money I made was all earned in areas I truly understood.
Source: Duan Yongping Investment Q&A (Investment Logic), 2010-02-04
⚠️ Common Misconceptions
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❌ “Shorting is a good tool for hedging risk” — Correct view: “Shorting is stupid!” (Source: Investment Logic, 2013-03-04). The best way to hedge risk is to buy companies you truly understand, not use derivatives to hedge.
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❌ “I’ve determined this company is a scam, so shorting it should be fine” — Correct view: “Just avoid companies you dislike—never ever short them because one wrong call will make you miserable for a long time, perhaps a very long time.” (Source: Investment Logic) Even if judgment is correct, market mania could bankrupt you first.
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❌ “Using leverage to amplify returns is fine as long as I’m right” — Correct view: “Don’t short, don’t margin, don’t do what you don’t understand. It’s never too late to understand this.” (Source: Investment Logic) Borrowing to invest forces you into wrong decisions precisely when you most need to stay calm.
💬 Original Quotes
“Don’t short, don’t borrow, and most importantly don’t do what you don’t understand. Over these years, I’ve lost hundreds of millions of dollars in investing, and every loss came from violating old Buffett’s teachings.” (Source: Duan Yongping Investment Q&A (Investment Logic), 2010-02-04)
“Shorting is stupid!” (Source: Duan Yongping Investment Q&A (Investment Logic), 2013-03-04)
“Long-term, very few people succeed through shorting—it’s such a difficult road, better not taken.” (Source: Duan Yongping Investment Q&A (Investment Logic))
“Just avoid companies you dislike—never ever short them because one wrong call will make you miserable for a long time, perhaps a very long time.” (Source: Duan Yongping Investment Q&A (Investment Logic))
“Don’t short, don’t margin—and dying becomes much harder.” (Source: Duan Yongping Investment Q&A (Investment Logic), 2001)
🔗 Related Nodes
Upstream Concepts (prerequisites for understanding this concept): Stop Doing List · Circle of Competence · Value Investing
Downstream Concepts (conclusions derived from this): Concentrated Investing · Margin of Safety · Mistakes and Correction
Related People Buffett · Duan Yongping
金融衍生品
不做空、不借钱、不做不懂的东西——这三条守住，就很难死
📌 概念解析
金融衍生品（对段永平而言）= 一类有无限风险的工具，不碰是最好的策略。
你去赌场，赌客最多赔光本金，但做空就像你借了赌场的钱去赌——赔了不仅本金没了，还欠了一屁股债。金融衍生品（尤其是做空和杠杆）的危险在于：亏损没有上限，而盈利有上限。这和价值投资的逻辑完全相反。
💡 核心理解
1. 做空有无限风险，一次错误可能致命。
——即使你判断正确，市场也可能在你破产之前才回归理性。做空大众汽车的案例就是典型：判断对了，但被市场的疯狂逼到了极限。
2. 不做空、不借钱、不做不懂的东西，是巴菲特给段永平的三条戒律。
——这三条是Stop Doing List在投资领域的核心体现。
3. 做空是零和游戏，长期靠做空成功的人极少。
——做多是在分享企业成长的果实，做空是在赌企业的失败。前者是正和游戏，后者是零和游戏，两者的长期期望值完全不同。
4. 不喜欢的公司，避开就好，不需要做空。
——这是能力圈原则的延伸：不在能力圈内的事情，不做就是最好的策略。
❓ 精选问答
问：做空有无限风险，一次错误就可能致命，这个说法对吗？
答：确实是非常危险的。不该做空的理由：做空时不光要面对基本面，还要面对市场的疯狂。任何人都可能会犯错，但做空犯错可能会面对无限风险，看看前几年做空大众汽车的那个案例就明白了。
来源：段永平投资问答录(投资逻辑篇)，2012-06-26
问：您会考虑融券卖空腾讯的股份吗？
答：我以后不会做空任何股票。我不觉得腾讯到200块就贵的离谱，做空要面对无限风险，我不做。
来源：段永平投资问答录(投资逻辑篇)
问：不做空、不借钱、不做不懂的东西，这三条是怎么来的？
答：我问过巴菲特在投资中不可以做的事情是什么，他告诉我说：不做空，不借钱，最重要的是不要做不懂的东西。这些年，我在投资里亏掉的美金数以亿计，每一笔都是违背老巴教导的情况下亏的，而赚到的大钱也都是在自己真正懂的地方赚的。
来源：段永平投资问答录(投资逻辑篇)，2010-02-04
⚠️ 常见误区
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❌ “做空是对冲风险的好工具” — 正解：“做空是愚蠢的！“（来源：投资逻辑篇，2013-03-04）。对冲风险最好的方式是只买自己真正懂的公司，而不是用衍生品对冲。
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❌ “我判断这家公司是骗局，做空它没问题” — 正解：“不喜欢的公司避开就好了，千万不要去做空，因为看错一次会让你难受很久甚至很长时间。“（来源：投资逻辑篇）即使判断正确，市场的疯狂也可能让你先破产。
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❌ “用杠杆放大收益，只要判断对了就没问题” — 正解：“不做空、不margin，不做不懂的东西。什么时候明白都不晚。“（来源：投资逻辑篇）借钱投资会让你在最需要冷静的时候被迫做出错误决策。
💬 原文金句
“不做空，不借钱，最重要的是不要做不懂的东西。这些年，我在投资里亏掉的美金数以亿计，每一笔都是违背老巴教导的情况下亏的。“（来源：段永平投资问答录(投资逻辑篇)，2010-02-04）
“做空是愚蠢的！“（来源：段永平投资问答录(投资逻辑篇)，2013-03-04）
“长期而言，靠做空成功的人极少，这么难的路还是不走的好。“（来源：段永平投资问答录(投资逻辑篇)）
“不喜欢的公司避开就好了，千万不要去做空，因为看错一次会让你难受很久甚至很长时间。“（来源：段永平投资问答录(投资逻辑篇)）
“不做空、不margin，想死就变得较难了。“（来源：段永平投资问答录(投资逻辑篇)，2001年）
🔗 关联节点
上游概念（理解这个概念的前提）： Stop Doing List · 能力圈 · 价值投资