Short Selling
Short selling is stupid! Put away short-selling thoughts early
📌 Concept Explanation
Short selling = borrowing stocks to sell, then buying them back after the price falls for profit; Duan Yongping explicitly opposes short selling, considering it speculative behavior with unlimited risk, and very few people succeed at it long-term.
You borrowed your neighbor’s car, thinking it would depreciate, so you sold it first planning to buy it back cheaper later and return it. But if this car’s price rose instead, you’d have to spend more money to buy it back—and theoretically there’s no upper limit on how high prices can go, nor on your losses. This is short selling logic: going long worst case you lose all principal (100% loss), shorting theoretically has unlimited loss.
💡 Core Understanding
1. Short selling has unlimited risk—one mistake can be fatal—this is the most essential danger of shorting.
Going long worst case you lose all capital (100% loss), but shorting theoretically has unlimited loss—stock prices can rise to any height. This asymmetric risk structure means even if you judge direction correctly with shorting, you might get “squeezed” due to timing errors and be forced out before prices finally fall.
2. Very few people succeed long-term through shorting—this path isn’t worth taking.
Duan quotes Buffett and Munger to support this: Buffett says “Charlie and I aren’t strangers to shorting—we both failed”; Munger says “we don’t like exchanging money for painful trading.” Even these two top investors failed at shorting—ordinary investors have even less reason to try.
3. Short selling is speculation, not value investing—even if judgment is correct, it’s still wrong.
When Duan shorted Baidu, his directional judgment wasn’t entirely wrong (Baidu did fall very low later because of that issue), but he still considered shorting itself wrong—because it’s speculation, not intrinsic value-based investment.
4. Old Warren’s three iron rules: no shorting, no borrowing, don’t do what you don’t understand.
These three iron rules are what Duan learned from Buffett and repeatedly emphasized as bottom-line principles after personally experiencing the painful lesson of shorting Baidu. The three rules interconnect: shorting often requires borrowing (leverage), and shorting targets are often companies you don’t truly understand.
📖 Case Analysis
Duan Yongping Shorting Baidu (2010): Personal lesson, lost $150-200 million
Duan once shorted Baidu—an operation he considers “extremely stupid.” His review: “Previous investment performance was very good, got a bit carried away, truly thought I was great. Started wanting to just play small, then didn’t want to lose, finally got squeezed and surrendered—all accounts combined lost a lot of money, probably $150-200 million, one account can’t recover till today. Most regrettably, this mistake consumed all our cash reserves—opportunity cost huge, otherwise during this financial crisis I could have helped everyone earn more money. And most regrettable, this error happened after Buffett told me not to short. Now you know consequences of not listening to elders’ words?”
He later characterized this operation: “This actually wasn’t my worst investment because this was pure speculation from start to finish. There won’t be examples like this again.”
Source: Duan Yongping Investment Q&A (Investment Logic), 2010-05-10
❓ Selected Q&A
Q: For long positions in excellent companies, understanding level basically equals margin of safety—this inspires me greatly. But privately I think: for short positions in inferior companies, margin of safety needs more content.
A: Short selling is stupid!
Source: Duan Yongping Investment Q&A (Investment Logic), 2013-03-04
Q: Will Yahoo fall? Feels like no one can save Yahoo. If those rumored acquisitions are just hype, shouldn’t we short it?
A: Anytime you’re still thinking about shorting someone, that shows you’re still a speculator (thinking you’re smarter than market). Put away short-selling thoughts early, honestly go find deals that let you sleep well!
Source: Duan Yongping Investment Q&A (Investment Logic), 2011-10-29
Q: Hope someday you’ll understand why old Warren says not to short—then your investing will improve further.
A: (Duan Yongping’s reply to netizen, original text)
Source: Duan Yongping Investment Q&A (Investment Logic), 2010-05-22
⚠️ Common Misconceptions
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❌ “Short selling having unlimited risk is just talk—not actually that scary” — Duan himself is counterexample: “I used to think that too.” (2010-03-31) He only truly understood this meaning after personally losing $150-200 million. Bubble evolution is based on human nature—nobody knows when it will burst or how big before bursting—short sellers may be forced to cover before prices ultimately fall.
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❌ “If you’re bearish on a company you should short it” — “First, short selling behavior is wrong…总之, short selling is speculative behavior, we shouldn’t do it.” (2010-09-14) Being bearish on a company, maximum action is not buying it or selling existing positions. Shorting is completely different behavior—it’s not value investing, it’s speculation.
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❌ “Very few succeed at shorting proves it can be learned” — “Not very few doing it—the vast majority who do get caught.” (2010-07-04) Shorting success stories stand out because of survivorship bias—failed shorters have usually been eliminated by market and no longer speak up.
💬 Original Quotes
“Short selling is stupid!” (Source: Duan Yongping Investment Q&A (Investment Logic), 2013-03-04)
“Never forget old Warren’s teaching: no shorting, no borrowing, don’t do what you don’t understand!” (Source: Duan Yongping Investment Q&A (Investment Logic), 2010-05-10)
“Long-term, very few succeed through shorting—such a difficult path better not taken.” (Source: Duan Yongping Investment Q&A (Investment Logic), 2010-07-04)
“Put away short-selling thoughts early, honestly go find deals that let you sleep well!” (Source: Duan Yongping Investment Q&A (Investment Logic), 2011-10-29)
“This actually wasn’t my worst investment because this was pure speculation from start to finish. There won’t be examples like this again.” (Source: Duan Yongping Investment Q&A (Investment Logic), 2010-05-10)
🔗 Related Nodes
Upstream concepts (prerequisites for understanding this concept): Value Investing · Intrinsic Value · Ordinary Mind
Downstream concepts (conclusions derived from this): Opportunity Cost · Mistakes and Correction
Related Company Cases Baidu (shorting lesson)
Related People Duan Yongping · Buffett · Munger
做空
做空是愚蠢的！早点收起做空头的念头
📌 概念解析
做空 = 借入股票卖出、等股价下跌后买回获利的操作；段永平明确反对做空，认为这是投机行为，有无限风险，且长期靠做空成功的人极少。
你借了邻居的车，以为它会贬值，于是先卖掉，打算等它便宜了再买回来还给邻居。但如果这辆车反而涨价了，你就得花更多钱买回来——而且理论上涨价没有上限，你的损失也没有上限。做空就是这个逻辑：做多最多亏光本金（亏100%），做空理论上亏损无限。
💡 核心理解
1. 做空有无限风险，一次错误就可能致命——这是做空最本质的危险。
做多最坏的结果是本金归零（亏100%），但做空的亏损理论上没有上限——股价可以涨到任何高度。这种不对称的风险结构，使得做空即便判断方向正确，也可能因为时机错误而被”夹空”，在股价最终下跌之前就已经撑不住了。
2. 长期靠做空成功的人极少，这条路不值得走。
段永平引用巴菲特和芒格的话印证这一点：巴菲特说”查理和我对做空都不陌生，我们两个都失败了”；芒格说”我们不喜欢以痛苦地交易来换金钱”。连这两位最顶尖的投资者都在做空上失败，普通投资者更没有理由去尝试。
3. 做空是投机行为，不是价值投资——即便判断正确，也是错的。
段永平在做空百度时，判断方向上并非完全错误（百度后来确实因为那个问题跌得很低），但他仍然认为做空本身就是错的——因为它是投机，不是基于内在价值的投资。
4. 老巴三条铁律：不做空、不借钱、不做不懂的东西。
这三条铁律是段永平从巴菲特那里学到的，也是他在亲身经历了做空百度的惨痛教训之后，反复强调的底线原则。三条规则互相关联：做空往往需要借钱（杠杆），而做空的标的往往是自己并不真正懂的公司。
📖 案例拆解
段永平做空百度（2010年）：亲身教训，亏损1.5-2亿美金
段永平曾经做空过百度，这是他自认为”极度愚蠢”的一次操作。他的复盘如下：“之前投资表现非常好，有点飘飘然，真以为自己很厉害。开始还是想小玩玩，后来又不服输，最后被夹空而投降，所有账号加起来亏了很多钱，大概有1.5-2亿美金，其中有个账号到现在都翻不了身。最可惜的是，这次错误把我们的现金储备全部消耗掉了，机会成本巨大，不然这次金融危机我就可以帮大家赚更多钱了。而且最遗憾的是，这个错误是发生在巴菲特叫我不要做空之后。现在知道什么叫不听老人言的后果了吧？”
他后来对这次操作的定性是：“这其实不算我最差的投资，因为这根本就是彻头彻尾的投机。以后不会再有这种例子了。”
来源：段永平投资问答录(投资逻辑篇)，2010-05-10
❓ 精选问答
问：对于优秀公司的多头操作，理解度就基本等同于安全边际，这个对我非常有启发。但我私下认为：对于劣质公司的空头操作，安全边际要包含更多的内容。
答：做空是愚蠢的！
来源：段永平投资问答录(投资逻辑篇)，2013-03-04
问：雅虎要跌吗？感觉没人能挽救雅虎了。如果这些传说中的收购都是浮云的话，是不是可以空一把？
答：任何时候，只要你还想着要空一把谁，那就表示你还是个投机分子（以为自己比市场聪明）。早点收起做空头的念头吧，老老实实去找那些可以让你睡得好觉的deal！
来源：段永平投资问答录(投资逻辑篇)，2011-10-29
问：希望你有一天能理解老巴为什么讲不要做空时，你的投资就会再进一步。
答：（段永平对网友的回复，原文即此）
来源：段永平投资问答录(投资逻辑篇)，2010-05-22
⚠️ 常见误区
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❌ “做空有无限风险只是说说，实际上没那么可怕” — 段永平自己就是反例：“我以前也那么认为来着。“（2010-03-31）他后来亲身亏损了1.5-2亿美金，才真正理解了这句话的含义。泡沫的演化基于人性，没有人知道什么时候它会破裂，或在破裂之前它会膨胀到多大——做空者可能在股价最终下跌之前就已经被迫平仓。
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❌ “看空一家公司就应该做空它” — “首先，卖空行为是错的……总而言之，卖空行为是投机行为，吾不该为之。“（2010-09-14）看空一家公司，最多的操作是不买它，或者卖出已持有的仓位。做空是完全不同的行为——它不是价值投资，而是投机。
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❌ “极少数人靠做空成功，说明做空是可以学的” — “不是极少数人做，而是绝大多数做的人都中招了。“（2010-07-04）做空的成功案例之所以显眼，是因为幸存者偏差——失败的做空者往往已经被市场淘汰，不再发声。
💬 原文金句
“做空是愚蠢的！“（来源：段永平投资问答录(投资逻辑篇)，2013-03-04）
“老巴的教导千万别忘了：不做空，不借钱，不做不懂的东西！“（来源：段永平投资问答录(投资逻辑篇)，2010-05-10）
“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)，2010-07-04）
“早点收起做空头的念头吧，老老实实去找那些可以让你睡得好觉的deal！“（来源：段永平投资问答录(投资逻辑篇)，2011-10-29）
“这其实不算我最差的投资，因为这根本就是彻头彻尾的投机。以后不会再有这种例子了。“（来源：段永平投资问答录(投资逻辑篇)，2010-05-10）
🔗 关联节点
上游概念（理解这个概念的前提）： 价值投资 · 内在价值 · 平常心
相关公司案例 百度（做空教训）