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华尔街大空头塔勒布和他的风险共担原则 | 灰岩金融科技

 遥远的雷音 2023-04-12 发布于天津

原创 Dorian君 灰岩金融科技 2020-06-17 16:38

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塔勒布.纳西姆是华尔街令人生畏的学者以及期权交易员之一。

他所共同创立的对冲基金Universa在疫情三月的崩盘中斩获3612%的收益。


Universa是近期华尔街非常流行的“黑天鹅”型对冲基金,具体的理念就是认为黑天鹅事件的发生是常态,与其去通过short vol获得稳定持续的theta以及vega的收益,然后300天赚钱一天亏完倒不如通过承受300个交易日的亏损,通过短短几个交易日的黑天鹅行情以获得巨大无比的Gamma。


诚然这种策略具有一定的风险,往往巨大的收益后面伴随着难忍的回撤,这也往往被专业投顾认为是备受争议的一种杠铃式交易策略。


他在其著名的著作,黑天鹅三部曲以及不确定性五部曲中,详细地阐述他关于风险共担,风险,概率以及厚尾风险事件的理解。他经常提到的,风险共担(skin in the game)的原则适用于生活中的方方面面,简单来说就是Taleb Nassim 相信在社会以及市场的发展中,专业人士应当和其客户共同承受其风险,并且共享利益。而不是让客户或是人民承受所有潜在的风险。


举例来说,通过销售房产获得利润的销售员,或是帮助客户挑选股票获得收益的分析师,他们本身并不一定有能力购买房产甚至是购买自己所推荐的股票,这将导致一个潜在的巨大的道德风险(moral harzard)以及利益冲突(conflict of interests)。那就是当客户本身亏钱,服务提供者仍然获利。


在学术圈,缺乏风险共担的例子层出不穷。比如说我们的大学教授本身在行业有许多并非真的具有相关的从业经验(比如说经济学教授不炒股,教CS的教授没写过网站或是APP)这就是为什么这些所谓的专家学者甚至是评论家在缺乏相关从业经验的情况下反而被吃瓜群众误认为是“专家”的原因。


他本人用这个作为案例说明社会以风险共担(skin in the game)为指导原则的重要性。而他本人亦相信社会进化的一个重要前提就是社会遵循一个自由公平的竞争,并且通过风险共担作为标准要求执政者以及相关领域的专家,让他们为自己的决策成本付出代价,承受和客户以及人民一样的风险,以此作为一个过滤方式(filter)来让社会作为一个集体不断进化。


作为交易员,长期的交易让我们拥有将看不见,难以估算的风险量化,具化的能力。这也使得塔勒布纳西姆站在他对于风险的敏锐感知的基础上去提出我们社会未来提升发展的方向。他的文章充满着哲学的术语,甚至是粗口还有公式,因此难免有些艰涩难懂,但是他的思考以及文章无疑值得一读。


塔勒布本人非常有意思,他本人在学术圈也有不可忽视的贡献,他的多语言才能和他的交易能力一样令人羡慕。因此他本人具备一种学者+战士的独特气质,这样的气质能够从他的文章中读到并且感受到。


倘若不理解以上的内容,就难以理解Taleb Nassim所写的以下文章:


下文来自于Taleb Nassim 本人的博客:


What do I mean by Skin in the Game? My Own Version

我说的风险共担究竟意味着什么?我自己的诠释


When selecting a surgeon for your next brain procedure, should you pick a surgeon who looks like a butcher or one who looks like a surgeon? The logic of skin in the game implies you need to select the one who (while credentialed) looks the least like what you would expect from a surgeon, or, rather, the Hollywood version of a surgeon.


在为下一个脑部手术选择外科医生时,我们应该选择一个看起来像屠夫的外科医生还是一个看起来像外科医生的外科医生?风险共担的逻辑意味着我们需要选择一个(虽然有证书)看起来最不像外科医生(刻板印象)或好莱坞版外科医生所期望的人。


The same logic mysteriously answers many vital questions, such as 1) the difference between rationality and rationalization, 2) that between virtue and virtue signaling, 3) the nature of honor and sacrifice, 4) Religion and signaling (why the pope is functionally atheist) 5) the justification for economic inequality that doesn’t arise from rent seeking, 6) why to never tell people your forecasts (only discuss publicly what you own in your portfolio) and, 7) even, how and from whom to buy your next car.


相同的逻辑神秘地回答了许多重要的问题,例如

1)理性与合理化之间的差异,

2)美德与美德信号(想让别人认为自己是好人)之间的差异,

3)荣誉与牺牲的性质,

4)宗教与宗教信号(意味着想让别人认为自己非常虔诚,以及为什么教皇从其性质以及功能上是无神论者) 

5)权力寻租不会产生经济不平等的理由; 

6)为什么交易员甚至是分析师从不告诉别人自己的预测(只公开讨论在投资组合中所拥有的财产); 

7)甚至,如何以及从谁那里购买自己的房地产以及下一辆车。


What is Skin in the Game? The phrase is often mistaken for one-sided incentives: the promise of a bonus will make someone work harder for you. For the central attribute is symmetry: the balancing of incentives and disincentives, people should also penalized if something for which they are responsible goes wrong and hurts others: he or she who wants a share of the benefits needs to also share some of the risks.


那么到底什么是风险共担呢(skin in the game)?

这句话经常被误认为是单方面的激励措施:奖金的承诺会使某人为我们努力工作。 


这个原则的核心是风险以及预期收益的对称性,也就是激励与抑制的平衡。用最简单的话说就是如果人们所负责的事情出了错并伤害了他人,那么人们也应该受到惩罚:想要分享利益的人也需要分担一些风险。


My argument is that there is a more essential aspect: filtering and the facilitation of evolution. Skin in the game –as a filter –is the central pillar for the organic functioning of systems, whether humans or natural. Unless consequential decisions are taken by people who pay for the consequences, the world would vulnerable to total systemic collapse. And if you wonder why there is a current riot against a certain class of self-congratulatory “experts”, skin the game will provide a clear answer: the public has viscerally detected that some “educated” but cosmetic experts have no skin in the game and will never learn from their mistakes, whether individually or, more dangerously, collectively.


我的论点是,还有一个更重要的方面:

过滤以及进化本身对于风险共担的重要性。

风险共担是系统(无论是人类还是自然的)有机功能的核心支柱。除非我们为后果承担责任的人做出相应的决定,否则世界将很容易遭受系统性全面崩溃(systemic risks)的伤害。而且,如果我们知道为什么当前会发生针对某类自我陶醉,孤芳自赏的有关“专家”的骚扰甚至是闯下无可弥补的大错。


那么风险共担这一基本原则将给出一个明确的答案:公众已经内心地发现某些“受过教育”但这些所谓的专家事实上并没有真正的具备从事相关领域的经验,甚至是风险共担。这意味着这些所谓的“专家”们将永远不会从他们的错误中汲取教训,无论是单独的或更危险的是集体的错误。


Have you wondered why, on high-speed highways there are surprisingly few rogue drivers who could, with a simple manoeuver, kill scores of people? Well, they would also kill themselves and most dangerous drivers are already dead (or with suspended license). Driving is done under the skin in the game constraint, which acts as a filter. It’s a risk management tool by society, ingrained in the ecology of risk sharing in both human and biological systems. The captain who goes down with the ship will no longer have a ship. Bad pilots end up in the bottom of the Atlantic Ocean; risk-blind traders become taxi drivers or surfing instructors (if they traded their own money).


这样的例子并非鲜见。尤其在交通事故上面尤然。

为什么在高速公路上,很少有流氓驾驶员能够通过简单的操纵就杀死数十人?好吧,他们也许是自杀,并且大多数危险的驾驶员已经死亡(或持有吊销驾照)。


驾驶汽车是典型的风险共担的完美案例,这些交通案例将充当社会本身的筛选器(filter)。通过建立交通法规以及惩罚条例来约束驾驶者本身。因此它是社会的一种风险管理工具,这也源于根深蒂固在人类和生物系统中的风险共担生态。比如说随船沉没的船长将不再有船或是糟糕的飞行员最终到达了大西洋的底部乃至风险盲目的商人最终破产并成为出租车司机或冲浪教练(如果他们自己交易自己的资产的话)。


Systems don’t learn because people learn individually –that’s the myth of modernity. Systems learn at the collective level by the mechanism of selection: by eliminating those elements that reduce the fitness of the whole, provided these have skin in the game. Food in New York improves from bankruptcy to bankruptcy, rather than the chefs individual learning curves –compare the food quality in mortal restaurants to that in an immortal governmental cafeteria. And in the absence of the filtering of skin in the game, the mechanisms of evolution fail: if someone else dies in your stead, the built up of asymmetric risks and misfitness will cause the system to eventually blow-up.


系统本身无法自我学习,因此让个体各自学习系统本身的谬误,这就是现代社会系统的巨大错误。社会系统通过选择机制在集体层面上学习:通过消除那些会降低整体适应性的因子(把那些无法自我学习进步的个体淘汰掉),只要这些个体本身有风险共担的意识。举个例子,纽约的美食是通过客人用脚投票,餐厅破产而筛选以提升的,而不是通过厨师个人的学习曲线来展现出来的。(因为绝大部分厨师收取固定工资,所以缺乏动力改变餐食品质,因为厨师并不承担餐厅运营惨淡的风险)错误的是我们用普通餐厅的食物质量与不朽的政府食堂的食物质量进行比较。而且在风险共担原则的情况下,社会自身进化机制就会失败:如果有人替你的风险买单,甚至为你背锅死亡,那么不对称风险和不当适应的积累将导致系统最终崩溃(集体的渎职)。


Yet the social science and the bureaucrato-BSers have missed and keeps missing that skin in the game is an essential filter. Why? Because, outside of hard science, scholars who do not have skin in the game fail to get that while in academia there is no difference between academia and the real world, in the real world, there is. They teach evolution in the classrooms but, because they are not doers, they don’t believe that evolution applies to them; they almost unanimously vote in favor of a large state and advocate what I’ve called “Soviet-Harvard top-down intelligent design” in social life.


然而,社会科学和官僚主义者满嘴谎言(塔勒布本人经常喜欢在文章爆粗)的时代已经过去了,并且一直在错过,甚至是忽视风险共担的机会,这是必不可少的社会过滤器。为什么?因为,除了硬科学之外,没有风险共担的学者(自己本身亦没有类似的从业经验)无法得出结论,而在学术界,学术界与现实世界之间并没有区别,在现实世界中却没有。他们在教室里教授进化论,但由于他们不是行动者,所以他们不认为进化论适用于他们。他们几乎一致投票赞成一个大国,并在社交生活中倡导我所谓的“苏维埃自上而下的苏维埃智能设计”。


As illustrated by the story of the surgeon, you can tell, from the outside, if a discipline has skills and expertise, from the presence of the pressures of skin in the game and some counterintuitive consequences. But what we call “empty suits”, of the kind you see in think tanks or large corporations –those who want to increasingly run our lives or intervene in Libya — look like actors playing the part, down to their vocabulary and the multiplicative meetings.Talk is cheap and people who talk and don’t do are easily detectable by the public because they are too good at talking.


正如外科医生这一例子对我们所说明的那样,我们可以从系统外部发现风险共担这一原则的存在和某些违反直觉的直接后果中我们可以得知某个学科或者领域是否具有相关的技能和专业知识。但是,我们认定的“脑袋空空如也的西装黑衣人”,正如我们在智囊团或大型金融机构甚至是公司中所看到的那样-那些想要越来越多地介入甚至控制我们的生活方式或武装侵略利比亚的人-他们看起来就像演员在扮演各自的角色,从他们口中的套话以及假大空和数不清会议就可以发现。看上去正式非凡的会议。谈空话是很low的,不说话的人很容易被公众发现,因为他们太会说话了。


Plumbers, bakers, engineers, and piano tuners are judged by their clients, doctors by their patients (and malpractice insurers), and small town mayors by their constituents. The works of mathematicians, physicists, and hard scientists are judged according to rigorous and unambiguous principles. These are experts, plus or minus a margin of error. Such selection pressures from skin in the game apply to perhaps 99% of the population. But it is hard to tell if macroeconomists, behavioral economists, psychologists, political “scientists” and commentators, and think-tank policymakers are experts. Bureaucrato-academics tend to be judged by other bureaucrats and academics, not by the selection pressure of reality. This judgment by peers only, not survival, can lead to the pestilence of academic citation rings. The incentive is to be published on the right topic in the right journals, with well sounding arguments, under easily some contrived empiricism, in order to beat the metrics.


水管工,面包师,工程师和钢琴调音师的水平只能交由其客户评判,而医生本人的实际执业水平则是交由其患者以及相关医疗事故保险公司做评判,而小镇市长的管理水平则由其评判委员会来评判。对于数学家,物理学家以及艰涩难懂的科学家的水平则有着严格而明确的原则以进行相应的评判以及评论。这些个体都是各个领域的专家,即便是计算上误差幅度亦如此。风险共担这一原则的选择标准可能适用于99%的人口。但是,我们很难通过确定的原则去评价宏观经济学家,行为经济学家,心理学家,政治“科学家”和评论员以及智囊团决策者的水平,我们难以判断他们是否是其领域的专家。尤其在官僚主义学术界更甚。他们的水平往往由其他官僚主义和学者来评判,而不是由现实的选择压力来评判。仅同行的这种判断而不是生存的判断会导致学术引用环的瘟疫。激励措施将在适当的经验主义下,以正确的论点在正确的期刊上以正确的主题发布,以击败指标。


Accountants (that is, bankruptcy or its absence), not other “peer” forecasters, nor referees using metrics should be judging forecasters. Metrics are always always gamed: a politician can load the system with debt to “improve growth and GDP”, and let his successor deal with the delayed results.


会计师(即破产或缺席),而不是其他“同级别”的预测员,或者使用度量标准的裁判员都应该对预测员进行评审。我们用以评估的度量标准总是被操纵甚至是愚弄的:政客可以为债务负担沉重的债务,以``提振经济增长和GDP'',并让他的继任者处理政策效果延迟的结果。


Alas, you can detect the degradation of the aesthetics of buildings when architects are judged by other architects. So the current rebellion against bureaucrats whether in DC or Brussels simply comes from the public detection of a simple principle: the more micro the more visible one’s skills. To use the language of complexity theory, expertise is scale dependent. And, ironically, the more complex the world becomes, the more the role of macro-deciders “empty suits” with disproportionate impact should be reduced: we should decentralize (so actions are taken locally and visibly), not centralize as we have been doing.


啊!当其他建筑师评判建筑师时,他们才可以真正意识到建筑美学真正的在下降。因此,无论是在哥伦比亚特区还是在布鲁塞尔,当前针对官僚的反叛都是来自公众对一个简单原则的发现:越是通过微观来看,人们的本身的技能就越明显。要使用复杂性理论的语言,专业知识取决于规模。 


具有讽刺意味的是,世界越复杂,应减少具有决定性影响的宏观决策者“脑袋空空的西装人”的作用:我们应该下放权力(这样才能在本地和明显地采取行动),而不是像过去那样集中所有的权力 。


In addition, owning one’s risk was an unescapable moral code for past four millennia, until very recent times. War mongers were required to be warriors. Fewer than a third of Roman emperors died in their bed (assuming those weren’t skillfully poisoned). Status came with increased exposure to risk: Alexander, Hannibal, Scipio, and Napoleon were not only first in battle, but derived their authority from a disproportionate exhibition of courage in previous campaigns. Courage is the only virtue that can’t be faked (or gamed like metrics). Lords and knights were individuals who traded their courage for status, as their social contract was an obligation to protect those who granted them their status. This primacy of the risk-taker, whether warrior (or, critically, merchant), prevailed almost all the time in almost every human civilization; exceptions, such as Pharaonic Egypt or Ming China, in which the bureaucrat-scholar moved to the top of the pecking order were followed by collapse.


此外,让他人为自己冒险是过去四千年来直到最近的一个不可回避的道德准则。战争贩子本身必须是战士。不到三分之一的罗马皇帝在床上丧生(假设这些人没有被毒死)。身份以及权力本身带来的风险越来越多:亚历山大,汉尼拔,西皮奥和拿破仑不仅在战斗中首屈一指,而且还源于先前战役中不成比例的勇气展示。勇气是唯一不能伪造(或像操弄数据甚至是经济指标这套玩法)的优点。上尉和骑士是为了地位而交换勇气的人,因为他们的社会契约是保护授予他们地位的人的义务。冒险家的这种首要地位,无论是战士(还是至关重要的商人),几乎在所有人类文明中始终盛行。例外,例如法老埃及或中国明朝,当这些玩弄数据以及意识形态的官僚学者爬到了社会乃至国家秩序的顶端,国家以及社会随之便崩溃了。


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