Financial Derivatives
Don’t short, don’t borrow, don’t do what you don’t understand—stick to these three rules and it’s hard to die
📌 Concept Explanation
Financial derivatives (for Duan) = A class of tools with unlimited risk; avoiding them entirely is the best strategy.
You go to a casino—at worst a gambler loses their entire principal. But shorting is like borrowing the casino’s money to gamble—if you lose, not only is your principal gone, you owe a massive debt. Financial derivatives (especially shorting and leverage) are dangerous because: losses have no upper limit while gains do. This is completely opposite to the logic of value investing.
💡 Core Understanding
1. Shorting carries unlimited risk—one mistake can be fatal.
—Even if you’re correct, markets may only return to rationality after you’ve already gone bankrupt. The Volkswagen short case is typical: the judgment was correct, but market mania pushed it to the extreme.
2. Don’t short, don’t borrow, don’t do what you don’t understand—Buffett’s three commandments to Duan.
—These three are the core embodiment of Stop Doing List in the realm of investing.
3. Shorting is a zero-sum game; very few succeed at it long-term.
—Going long means sharing in enterprise growth; shorting means betting on enterprise failure. The former is positive-sum; the latter zero-sum—their long-term expected values differ completely.
4. For companies you don’t like, simply avoid them—no need to short.
—This is an extension of circle of competence principle: for things outside your circle, not doing anything is the optimal strategy.
❓ Selected Q&A
Q: Is it true that shorting carries unlimited risk and one error could be fatal?
A: It’s indeed very dangerous. Reasons not to short: when shorting, you face not only fundamentals but market mania too. Anyone can make mistakes, but shorting mistakes face unlimited risk—just look at the VW shorting case from recent years and you’ll understand.
Source: Duan Yongping Investment Q&A (Investment Logic Chapter), 2012-06-26
Q: Would you consider margin-selling Tencent shares?
A: I will never short any stock again. I don’t feel Tencent at 200 is ridiculously expensive. Shorting faces unlimited risk—I won’t do it.
Source: Duan Yongping Investment Q&A (Investment Logic Chapter)
Q: Where did the three rules—no shorting, no borrowing, no doing what you don’t understand—come from?
A: I asked Buffett what shouldn’t be done in investing. He told me: Don’t short, don’t borrow, and most importantly don’t do what you don’t understand. Over the years, I’ve lost hundreds of millions of dollars in investing—every loss came from violating Old Ba’s teachings, while big earnings were made where I truly understood.
Source: Duan Yongping Investment Q&A (Investment Logic Chapter), 2010-02-04
⚠️ Common Misconceptions
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❌ “Shorting is a good tool for hedging risk” — Correction: “Shorting is stupid!” (Source: Investment Logic Chapter, 2013-03-04). The best way to hedge risk is to buy only companies you truly understand, not hedge with derivatives.
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❌ “I judged this company as a scam, so shorting it is fine” — Correction: “Just avoid companies you don’t like—never ever short, because getting it wrong once will make you miserable for a long time or even a very long time.” (Source: Investment Logic Chapter) Even if you’re right, market mania could bankrupt you first.
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❌ “Using leverage to amplify returns is fine if your judgment is correct” — Correction: “No shorting, no margin, don’t do what you don’t understand. It’s never too late to understand this.” (Source: Investment Logic Chapter) Borrowing to invest forces you into wrong decisions precisely when you most need calmness.
💬 Original Quotes
“Don’t short, don’t borrow, and most importantly don’t do what you don’t understand. Over the years, I’ve lost hundreds of millions of dollars in investing—every loss came from violating Old Ba’s teachings.” (Source: Duan Yongping Investment Q&A (Investment Logic Chapter), 2010-02-04)
“Shorting is stupid!” (Source: Duan Yongping Investment Q&A (Investment Logic Chapter), 2013-03-04)
“Long-term, very few people succeed through shorting—best not to take such a difficult path.” (Source: Duan Yongping Investment Q&A (Investment Logic Chapter))
“Just avoid companies you don’t like—never ever short, because getting it wrong once will make you miserable for a long time or even a very long time.” (Source: Duan Yongping Investment Q&A (Investment Logic Chapter))
“Don’t short, don’t margin—and dying becomes quite difficult.” (Source: Duan Yongping Investment Q&A (Investment Logic Chapter), 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 · Error and Correction
Related Figures 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