Short Selling
Short selling is stupid! Put away short-selling thoughts early
📌 Concept Analysis
Short selling = Borrowing stocks to sell, then buying them back after prices fall to profit; Duan explicitly opposes short selling, considering it speculative behavior carrying unlimited risk, with very few achieving long-term success through it.
You borrowed your neighbor’s car expecting it to depreciate, so you sold it first planning to buy it back cheaper later to return. But if instead the car’s price rose, you’d have to pay more to buy it back — and theoretically price increases have no upper limit, so neither does your loss. Short selling follows this logic: going long worst case loses entire principal (100% loss), while short selling theoretically faces unlimited loss.
💡 Core Understanding
1. Short selling carries unlimited risk — one mistake can be fatal. This is its most essential danger.
Going long worst case loses entire principal (100% loss), but short selling theoretically faces unlimited loss — stock prices can rise to any height. This asymmetric risk structure means even with correct directional judgment, timing errors can lead to getting “squeezed,” unable to hold out before prices eventually fall.
2. Very few succeed long-term via short selling — this path isn’t worth taking.
Duan cites Buffett and Munger confirming this: Buffett said “Charlie and I aren’t strangers to short selling — both of us failed”; Munger said “we don’t like trading pain for money.” Even these two top investors failed at short selling — ordinary investors have even less reason to attempt it.
3. Short selling is speculation, not 价值投资 (value investing) — even if judgment proves correct, it’s still wrong.
When Duan shorted Baidu, his directional judgment wasn’t entirely wrong (Baidu did indeed fall significantly later due to that issue), yet he still considered the act of shorting itself wrong — because it’s speculation, not investment based on 内在价值 (intrinsic value).
4. Old Ba’s Three Iron Rules: No shorting, no borrowing, no doing what you don’t understand.
These three iron rules Duan learned from Buffett, and after experiencing the painful lesson of shorting Baidu himself, he repeatedly emphasized these as baseline principles. The three rules interconnect: shorting often requires borrowing (leverage), while short-selling targets are often companies one doesn’t truly understand.
📖 Case Study Breakdown
Duan Yongping Shorts Baidu (2010): Personal Lesson, Loss of $150-200 Million
Duan once shorted Baidu — what he considered an “extremely stupid” operation. His post-mortem: “Prior investment performance had been excellent, got a bit cocky, truly thought I was exceptional. Started wanting just to play small, then couldn’t accept losing, finally got squeezed into surrendering. Across all accounts lost lots of money — roughly $150-200 million, with one account still unrecovered to this day. Most regrettable: this error consumed all our cash reserves — huge 机会成本 (opportunity cost); otherwise during this financial crisis I could have helped everyone earn more. And most regretful: this error occurred after Buffett told me not to short. Now you know consequences of ignoring elders’ advice?”
He later characterized this operation: “This doesn’t count as my worst investment because fundamentally it was outright speculation through and through. There will be no more examples like this.”
Source: Duan Yongping Investment Q&A (Investment Logic Chapter), 2010-05-10
❓ Selected Q&A
Q: For long positions in excellent companies, level of understanding basically equals margin of safety — very inspiring to me. But privately I think: for short positions in inferior companies, margin of safety should include more content.
A: Short selling is stupid!
Source: Duan Yongping Investment Q&A (Investment Logic Chapter), 2013-03-04
Q: Will Yahoo fall? Seems nobody can save Yahoo anymore. If all these rumored acquisitions are just hot air, 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 the market). Put away short-selling thoughts early, honestly go look for deals that let you sleep soundly!
Source: Duan Yongping Investment Q&A (Investment Logic Chapter), 2011-10-29
Q: Hope someday you’ll understand why Old Ba says don’t short — then your investing will advance another step.
A: (Duan’s reply to netizen — original text as is)
Source: Duan Yongping Investment Q&A (Investment Logic Chapter), 2010-05-22
⚠️ Common Pitfalls
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❌ “Unlimited risk from short selling is just talk — not actually that scary” — Duan himself serves as counterexample: “I used to think so too.” (2010-03-31) Only after personally losing $150-200 million did he truly grasp this statement’s meaning. Bubble evolution depends on human nature — nobody knows when it will burst or how large it grows before bursting — short sellers may be forced to cover before prices finally fall.
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❌ “If you’re bearish on a company you should short it” — “First, short selling behavior is wrong… in summary, short selling is speculative behavior — I shouldn’t engage in it.” (2010-09-14) Being bearish on a company means maximum action is not buying it or selling existing holdings. Short selling is completely different behavior — it’s not 价值投资, it’s speculation.
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❌ “Very few succeeded via short selling, proving it can be learned” — “It’s not that very few tried it — vast majority who tried got burned.” (2010-07-04) Short-selling success cases appear prominent due to survivorship bias — failed short sellers usually got eliminated by markets and no longer speak up.
💬 Original Quotes
“Short selling is stupid!” (Source: Duan Yongping Investment Q&A (Investment Logic Chapter), 2013-03-04)
“Never forget Old Ba’s teachings: No shorting, no borrowing, no doing what you don’t understand!” (Source: Duan Yongping Investment Q&A (Investment Logic Chapter), 2010-05-10)
“Long-term, very few people succeed through short selling — such a difficult path better left untaken.” (Source: Duan Yongping Investment Q&A (Investment Logic Chapter), 2010-07-04)
“Put away short-selling thoughts early, honestly go find deals that let you sleep soundly!” (Source: Duan Yongping Investment Q&A (Investment Logic Chapter), 2011-10-29)
“This doesn’t count as my worst investment because fundamentally it was outright speculation through and through. There will be no more examples like this.” (Source: Duan Yongping Investment Q&A (Investment Logic Chapter), 2010-05-10)
🔗 Related Nodes
Upstream Concepts (prerequisites for understanding this concept): 价值投资 · 内在价值 · 平常心
Downstream Concepts (conclusions derived from this): 机会成本 · 错误与纠错
Company Case Studies Baidu (short-selling lesson)
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，卖短行为是错的……总而言之，卖短行为是投机行为，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）