投资是否开始变得

2018 · 书信 · 原文约 4162 词
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2018 年第一季度投资季报:投资又开始变得困难了吗?

IS INVESTING QUARTERLY LETTER 1Q 2018 STARTING TO GET DIFFICULT AGAIN?

I Hope So Ben Inker | 第 1-8 页 执行摘要 2018 年头三个月,波动率上升,股票与债券之间的相关性也发生了转变。换句话说,上一季度的表现,更像投资者在过去 150 年里经历的平均状况,而非近期记忆中那种低波动、股票与债券呈强负相关的环境。这种变化,尽管只持续了短短一段时间,却应该让投资者思考:本轮牛市中我们看到的那种“轻松”环境,是否还会持续下去。如果持续下去,那么作为投资者,我们“理应”获得的回报将会很低。如果不是这样,那么从长远看,我们可以期待一个更加颠簸但回报更丰厚的未来。未来会走哪条路?我把赌注押在后者上。正如海曼·明斯基所言:“稳定滋生不稳定。”

I Hope So Ben Inker | Pages 1-8 EXECUTIVE SUMMARY In the first three months of 2018, volatility rose and correlations between stocks and bonds shifted. In other words, last quarter looked a lot more like the average conditions investors have experienced over the last 150 years than the very low volatility and strongly negative stock/bond correlations of more recent memory. The change, albeit only over a short period, should have investors evaluating whether the “easy” environment that we’ve seen through this bull market will continue. If it does, the returns we “deserve” to earn as investors should be low. If not, we can hope for a bumpier but more profitable future in the long run. Which path will the future take? My money is on the latter. As Hyman Minsky put it, “Stability breeds instability.”

本·因克 | 资产配置主管 | 一季度:投资又开始变得困难了吗?

1Q IS INVESTING STARTING TO GET Ben Inker | Head of Asset Allocation DIFFICULT AGAIN?

我正是这么希望的。过去八年来,对大多数观察者而言,投资似乎是一件相当轻松的事。1 市场不仅提供了强劲回报,而且“单个资产和整体组合的显性风险也都偏低。给人低风险印象的不只是缺乏巨大、可怕的市场动荡,更是极低的整体市场波动性与极其友好的相关性结构这两者的结合——股票和债券形成了出色的分散效果。对多数投资者来说,这是一组令人愉快的组合。对于那些以特定波动水平为目标的投资者——无论通过风险平价还是其他方式——这无异于一张许可证,让他们大幅放大杠杆,通常还能取得不错的结果。到了上个季度,投资开始变得有点困难了。不仅大多数资产的回报小幅为负,而且波动性上升、相关性也发生了转变。这是一件好事,如果投资者要实现长期目标,这很可能也是一件必要的事。但另一方面,我们才刚刚开始从“简单”转向“困难”,而这条道路几乎必然不会令人愉快。投资常常是“小心你所求的”。“简单”在短期内很有趣,而且短期可以持续长得惊人,但最终会自我毁灭。“困难”,嗯,就是困难,人们很难喜欢困难的东西。就我个人而言,我盼望着回到“困难”模式。这不仅应该能为投资者带来更好的长期回报,而且也要有趣得多。或许上个季度只是一次小插曲,我们还会回到“简单”模式再持续一段时间。如果判断何时从“简单”转为“困难”是件容易的事,那“困难”也就不会那么难了。但为“简单”搭建的投资组合,在“困难”面前设计得极差。如果今年年初以来的状况持续下去,资产估值很可能会下跌,而如果杠杆头寸需要以相当快的速度平仓,这一过程可能会变得混乱。

I Hope So FOR THE LAST EIGHT YEARS, INVESTING HAS SEEMED TO BE A PRETTY EASY ACTIVITY TO MOST OBSERVERS.1 Not only have markets given strong returns, but the apparent riskiness of both “ individual assets and overall portfolios has been low. It has not simply been the lack of giant, horrifying market dislocations that gives the impression of low risk, but the PERSONALLY, I’M HOPING combination of very low general market volatility and an extremely friendly correlation FOR A RETURN TO HARD. structure such that stocks and bonds have been wonderfully diversifying. For most investors, this has been a happy combination. For those investors targeting a given NOT ONLY SHOULD IT level of volatility, whether through risk parity or otherwise, it has been a license to LEAD TO BETTER LONG- lever up their exposures significantly, to generally good results. Last quarter, investing TERM RETURNS TO started to seem a little harder. Not only were returns to most assets mildly negative, INVESTORS, BUT IT IS but volatility rose and correlations shifted. That’s a good thing, probably a necessary thing if investors are to achieve their long-term goals. On the other hand, we’ve only ALSO A GOOD DEAL MORE started the transition from easy to hard, and that path is, almost by definition, not a INTERESTING. pleasant one. Investing is often a case of “be careful what you wish for.” “Easy” is fun in the shorter term, and the shorter term can go on for a surprising amount of time, but it winds up being self-defeating. “Hard” is, well, hard, and it’s hard to like things that are hard. Personally, I’m hoping for a return to hard. Not only should it lead to better long-term returns to investors, but it is also a good deal more interesting. Maybe last quarter was a blip and we are going to go back to “easy” for a while longer. If determining when easy turns to hard were easy, well, hard wouldn’t be as hard. But portfolios built for “easy” are poorly designed for “hard.” If conditions prevailing in the first part of this year persist, asset valuations will very likely have to fall, and the process could become disorderly if levered positions have to be unwound reasonably quickly.

尽管过去八九年里市场总体呈平稳上涨态势,但这对价值投资者而言并不轻松——因为领涨的往往是那些更昂贵的证券和市场。这在相对意义上让价值投资者(包括 GMO 旗下多个产品)处境艰难,但并未改变一个事实:金融市场整体上一直是一条平稳且有利可图的跑道。我正是针对这一点才说投资似乎变得“容易”了。我并非指主动管理型基金经理在这段时期里特别容易战胜市场。那么,投资到底是什么?一个还算实用的定义是:配置资本以获取经济效益,而市场上存在某个理性的交易对手愿意为此回报你。这听起来可能是个过于宽泛的定义,但实际牢记这一点,能帮你判断某项活动究竟是否算“投资”,以及你应当从一项投资活动中预期获得多少回报。投资世界并非完全有效,交易对手可能怀有与你预计不同的目标和动机,但即便如此,我认为这仍是一个出奇有用的分析框架。几年前的一篇名为《回归本源》² 的文章曾讨论过如何运用这一框架,我想把它与近期市场条件下“容易”与“困难”的区分联系起来。

While markets have generally been on a smooth and upward So, what is investing again? trend over the last eight to nine years, it hasn’t been the A decent working definition of investing is deploying capital to perform an economic easiest time for value investors, as it has more often than not been the more expensive securities and markets that function for which some rational counterparty is willing to compensate you. That may have led the way higher. While this has made things painful seem like a pointlessly broad definition, but in reality, keeping it in mind can really on a relative basis for value investors (including a number help you determine whether an activity is actually “investing” in the first place, as well of GMO products), it doesn’t change the fact that financial markets have been both a smooth and profitable ride in as how much you should expect to make from an investing activity. The investing world general. It is that point that I am referring to in saying that is not perfectly efficient, and a counterparty might have different goals and incentives investing has seemed “easy.” I am not suggesting that it has than you predict, but even still I think it’s a surprisingly helpful framework. Some ways been a particularly easy period for active managers to beat of using this framework are discussed in the paper “Back to Basics”2 from a few years the market. ago, but I’d like to relate it to “easy” and “hard” in recent market conditions.

投资是否又开始变得困难了? | p3 从长期来看,股票相对于债券和现金应该提供风险溢价,这源于股票对发行方和购买方各自的意义。对发行方而言,股权是其能筹集到的风险最低的资本。它永远不需要偿还,没有合同规定的付款义务,也永远不会让公司陷入破产。作为这种低风险的回报,理性的发行方应该愿意支付比“风险更高”的资本更高的“长期成本”。对购买方而言,那些对发行方有利的特征,恰恰使股票比向公司提供资本的其他方式风险更高。但解释股票投资者为何应该要求一个相当大的风险溢价,并非投资失败导致的个体风险。而是相关性风险。考虑到经济的周期性以及公司利润是 GDP 中波动最大的主要组成部分这一事实,大多数股票往往会在同一时间表现糟糕。但即使这一点,也不足以证明历史上我们看到的那种规模的股票风险溢价是合理的。真正的原因在于,股票亏损恰恰会发生在对持有它们的实体来说最痛苦的时候。而这才是关键。一个投资组合并非孤立存在。对于几乎所有投资实体——无论是为退休储蓄的个人、公司或公共养老金、捐赠基金或基金会,还是主权财富基金——最关键的风险是,在你的投资组合亏损的同时,来自其他活动的现金流也在枯竭。投资组合亏钱很糟糕。失业更糟糕。在失业的同时投资组合亏钱就更加糟糕了,而这种相关性正是使“风险资产”具有风险的原因。虽然捐赠基金或主权财富基金不会像个人那样失业,但问问业务拓展官员或税务官员在金融危机期间现金流入发生了什么,你会发现其影响是类似的。

Is Investing Starting to Get Difficult Again? | p3 Equities should give a risk premium over bonds and cash in the long run due to a combination of what they mean for the issuer and what they mean for the buyer. For the issuer, equity is the lowest-risk capital he or she can raise. It never needs to be paid back, has no contractually required payments, and can never drive a company into bankruptcy. In return for this low risk, rational issuers should be willing to pay a “ higher long-term cost than they would for “riskier” capital. For the purchaser, the same features that are positive for issuers make equity riskier than other ways of providing capital to a company. But it is not the idiosyncratic risk of an investment gone wrong LOSING MONEY IN YOUR that explains why stock investors should demand a decently sized risk premium. It is PORTFOLIO STINKS. the correlated risk. Given the cyclical nature of the economy and the fact that corporate profits are the most volatile major constituent of GDP, most equities will tend to do LOSING YOUR JOB STINKS badly at the same time. But even that doesn’t justify an equity risk premium anything MORE. LOSING MONEY like as big as we have seen historically. It is the fact that equity losses will occur at IN YOUR PORTFOLIO AT just the time that is most painful for the entities that own them. And that is the key. THE SAME TIME YOU A portfolio does not exist in isolation. For almost all investing entities – whether an individual saving for retirement, a corporate or public pension fund, an endowment LOSE YOUR JOB IS EVEN or foundation, or a sovereign wealth fund – the most crucial risk is the risk of losing WORSE... money in the portfolio at the same time that cash flow from other activities is drying up. Losing money in your portfolio stinks. Losing your job stinks more. Losing money in your portfolio at the same time you lose your job is even worse, and that correlation is what makes “risk assets” risky. While an endowment or sovereign wealth fund can’t lose its job in the same way an individual can, talk to a development officer or tax collector about what happened to cash inflows during the financial crisis, and you’ll find that the impact is analogous.

那么,“容易”和“困难”从何谈起?假设我告诉你,经济衰退是可以避免的,政府可以采取行动确保衰退只是短暂且轻微的事件。这对你要求风险资产提供的风险溢价会产生什么影响?如果你是一家需要资金的公司,这又会如何影响你对融资方式的选择?对于买方而言,相信衰退将变得罕见且浅显,会让你在购买股权时要求的风险溢价降低。对于发行方来说,尽管风险溢价变小了,你通常仍会比在其他情况下更倾向于选择更高的债务股本比率。3 实际上,这一分析框架有助于解释近期企业行为中一个看似反常的特征。

So where do “easy” and “hard” come in? Let’s imagine I told you that economic downturns were avoidable and governments could act in ways that all but guaranteed that they would be brief and minor events. What would that do to the risk premium you’d require from risk assets? If you were a company needing capital, what would that do to your choice of what kind of capital to raise? For the buyer, believing that downturns would be infrequent and shallow would make you demand less of a risk premium to buy equity. For the issuer, despite that smaller risk premium, you’d still generally prefer a higher debt to equity ratio than you would otherwise.3 Actually, this framing helps explain what is otherwise an odd feature of recent corporate behavior.

在股权成本低于历史水平且低于当前资本回报率的背景下,公司为何一直通过发行债务和回购股票来筹集资金,而不是增发股票融资?如果企业认为经济衰退不常见且程度温和,那么理性的做法就是调整资本结构,从昂贵但安全的资本(股权)转向更便宜但风险更高的资本(债务)。

At a time when the cost of equity is low both relative to history and the current return on capital, why have companies been issuing debt and buying back stock instead of issuing stock to raise capital? If corporations believe that downturns will be uncommon and mild, they will rationally respond by shifting their capital structure away from expensive but safe capital (equity) into cheaper and riskier capital (debt).

本·英克,《回归基础:投资前需考虑的六个问题》,2010 年 10 月。该白皮书可在 www.gmo.com 查阅。可以说,这种行为的顶峰并非过去几年,而是金融危机前的那些年。彼时,“大稳健”让许多投资者相信经济衰退根本不会再发生。这导致了我们有史以来在金融市场历史上所能看到的、最为极端的风险误定价。这种情况具体如何演变,取决于股权风险溢价相对于破产风险的下降幅度究竟有多剧烈,但为简化起见,假设您希望以尽可能低的成本筹集所需资本,同时将十年内破产风险控制在 5% 以内。如果您降低经济衰退的概率和严重程度,就会降低破产的波动性和概率,因此,只要股权所需的回报溢价为正,您理想的资本结构最终就会包含更多债务和更少股权。

Ben Inker, “Back to Basics: Six Questions to Consider Before Investing,” October 2010. This white paper is available at Arguably, the height of this behavior has not been the last few years, but rather the years www.gmo.com. leading up to the financial crisis. Back then, the “Great Moderation” had many investors convinced that economic downturns simply didn’t happen anymore. This led to the most Exactly how this plays out depends on how sharp the reduction in the equity risk premium is against the risk extreme mispricing of risk that we’ve ever been able to see in financial market history. of bankruptcy, but for simplicity’s sake, let’s imagine you While previous bubbles brought individual assets to price levels far more extreme than were looking to raise the capital you needed as cheaply what was seen in the run-up to the financial crisis, the general risk/reward trade-off as possible subject to having no more than a 5% risk of bankruptcy over a decade. If you decrease the probability was farther from “normal” than anything we have ever seen. Exhibit 1 shows a return/ and severity of economic downturns, you decrease the volatility scatterplot from our asset class forecasts as of June 2007, along with a probability of bankruptcy, so your desired capital structure regression line showing the general relationship. winds up with more debt and less equity as long as the required risk premium for equity is positive.

投资开始再次变得困难了吗? | 第 4 页 图表 1:预期实际回报与波动率的权衡(2007 年 6 月)14% 12% 10% 预期实际 7 年回报 斜率 = -0.5 8% 6% 美国政府债 国际债券 4% TIPS 国际大盘股 新兴市场债券 2% 现金 房地产 新兴市场股票 0% 等权风险组合 -2% 国际小盘股 MSCI 全球指数 美国小盘股 -4% “美国大盘股 -6% 0% 2% 4% 6% 8% 10% 12% 风险资产之所以有风险, 是因为它们会让你 亏钱的时间点不确定。 预期实际波动率 来源:GMO 上述预期基于资产配置团队的合理信念,并非保证。预期仅反映其出具日的情况,GMO 无义务且不承诺更新此类预期。预期受制于众多假设、风险和不确定性,且这些因素会随时间变化。实际结果可能与上述预期大相径庭。

Is Investing Starting to Get Difficult Again? | p4 EXHIBIT 1: EXPECTED REAL RETURN VS. VOLATILITY TRADE-OFF (JUNE 2007) 14% 12% 10% Expected Real 7-Year Return Slope = -0.5 8% 6% U.S. Gov't. Int'l. Bonds 4% TIPS Int'l. Large Caps Emerging Bonds 2% Cash Real Estate Emerging Equities 0% Eq Wtd Risk Port. -2% Int'l. Small Cap MSCI World U.S. Small Cap -4% “ U.S. Large Caps -6% 0% 2% 4% 6% 8% 10% 12% RISKY ASSETS ARE RISKY Expected Real Volatility BECAUSE OF WHEN THEY Source: GMO WILL LOSE YOU MONEY. The expectations provided above are based upon the reasonable beliefs of the Asset Allocation team and are not a guarantee. Expectations speak only as of the date they are made, and GMO assumes no duty to and does not undertake to update such expectations. Expectations are subject to numerous assumptions, risks, and uncertainties, which change over time. Actual results may differ materially from those anticipated in the expectations above.

这条线的斜率本应为正——风险更高的资产理应定价更高以带来更高回报。但“大缓和”时期改变了投资者对风险的认知,导致斜率急剧转负。⁴ 金融危机显然给这种心态带来了可怕冲击,但危机后企业现金流迅速复苏、以及随之出现的困境程度低于以往周期的情况,都起到了安抚投资者经济担忧的作用。时间流逝也淡化了人们对危机痛苦的记忆,以至于大多数投资者似乎都相信,无论上次是否稳住了阵脚,他们都能在另一场类似危机中坚持到底。

但自危机以来市场还有另一个特征,加剧了其对金融市场的影响。投资者不仅对经济衰退的恐惧再度消退,而且即使发生坏事,保护投资组合似乎也比以往任何时候都更容易。风险资产之所以有风险,正是因为它们会在你最需要钱的时候让你亏钱。⁵

然而,有一种资产恰恰能在那个时刻缓冲冲击——那就是高质量债券。在经济萧条时期,有两件重要的事情对债券有利。第一,随着需求不及预期,通胀往往低于预期。第二,央行通常会放松货币政策,以实际利率下降的方式刺激经济。这两点都对高质量债券有利,债券持有人在萧条时期会因债券持仓获得意外收益,从而抵消投资组合其他部分的损失。

关于股票空头头寸的思考最能直观说明这一点。从独立资产角度看,空头头寸至少和多头头寸一样“有风险”,但长期来看它却表现出强烈的负回报。然而,独立资产的风险对于思考预期回报而言是无关紧要的。股票空头头寸一定会在多头头寸亏损时赚钱。因此,它在投资组合和现金流视角下具有强烈的降低风险作用,所以空头头寸的持有者完全有理由接受负预期回报。

The slope of the line should be positive – riskier assets should be priced to deliver higher returns. But the Great Moderation changed investor perceptions of risk such that the slope went strongly negative.4 The financial crisis obviously came as a horrible shock to that mindset, but the rapid recovery in corporate cash flow in the aftermath While we believe our forecasts were a reasonable and the consequent lower levels of distress than previous cycles experienced have representation of the “true” risk/reward trade-off available to served to assuage investors’ economic concerns. The passage of time has also dimmed investors at the time, it is not the case that investors believed the memories of the pain of the crisis, such that most investors seem to believe they that they were paying for the privilege of taking risk. Our forecasts assume a reversion to historically normal levels of would stay the course through another such crisis, whether or not they held their nerve profitability for equities and default rates for credit. But if you last time. truly believed that economic downturns were a thing of the past, you would have increased your expectations of what But there is another feature of markets since the crisis that has exacerbated the impact “normal” profitability would look like and decreased your expectations of what normal default rates would be. on financial markets. Not only have fears of economic downturns receded again in the 5 minds of investors, but it has seemed easier than ever to protect portfolios even should The most straightforward demonstration of this is thinking something bad occur. Risky assets are risky because of when they will lose you money.5 about a short position in stocks. It is at least as “risky” on a stand-alone basis as a long position in stocks, and yet it There is an asset, however, that is likely to cushion the blow at that exact time – high has shown strongly negative returns over time. The risk on quality bonds. Two important things tend to happen in depressions that are helpful to a stand-alone basis is, however, irrelevant for thinking about bonds. First, inflation tends to undershoot expectations as demand disappoints. And expected returns. A short position in stocks is guaranteed to make money when a long position loses money. It is second, central banks generally ease monetary policy, lowering rates in real terms to therefore strongly risk-reducing in a portfolio and portfolio stimulate the economy. Both of these accrue to the benefit of high quality bonds, and + cash flow context, and as such it is perfectly rational owners will receive a windfall from their bond holdings in a depression, which can for the holder of a short position to put up with a negative mitigate losses suffered elsewhere in the portfolio. expected return.

投资是否又开始变得困难? | 第 5 页 债券通常还能带来比现金更高的回报,这一事实有助于解释为何债券是几乎所有投资组合(最激进的投资组合除外)中的核心资产,并且在某种程度上也有助于说明风险平价策略的吸引力所在。优质债券在金融危机中发挥了自己的作用。但更令人惊讶的是,自那以后它们表现得极为出色。尽管股票市场和债券市场自 2009 年以来同时进行了重新定价——也就是说,两者的估值都大幅上升——但股票回报与债券回报之间的相关性却比大萧条以来历史上任何时候都更为负向。我们在图表 2 中可以清晰地看到这一点。

Is Investing Starting to Get Difficult Again? | p5 The fact that bonds also tend to give a better return than cash helps explain why bonds are a mainstay of all but the most aggressive portfolios, and, to an extent, helps explain the appeal of risk parity strategies. High quality bonds did their job in the financial crisis. But what is more surprising is how astonishingly well they have done their job since then. Despite the fact that stock markets and bond markets have simultaneously rerated since 2009 – that is to say their valuations have risen substantially – the correlation between stock returns and bond returns has been more negative than at any time in history other than the Great Depression. We can see that clearly in Exhibit 2.

附录 2股票与债券回报的相关系数 1.0 0.8 五年滚动相关系数 0.6 0.4 0.2 0.0 股票与债券回报的相关系数 -0.2 -0.4 -0.6 -0.8 -1.0 1882.01 1900.05 1918.09 1937.01 1955.05 1973.09 1992.01 2010.05 来源:罗伯特·希勒

在过去 150 年的大部分时间里,股票和债券的月度回报相关系数一直为正,平均略低于 0.2。这个数字足够低,意味着它们可以有效地互相分散风险,但效果算不上特别惊人。然而,过去十年间这一关系发生了深刻的变化,相关系数降至 -0.64,而最近五年尽管实际上并未发生任何糟糕的经济事件,这一数值依然低至惊人的 -0.55。这实际上是一个里程碑式的转变。当相关系数为 0.2 时,在股票组合中加入债券,相对于用现金作为低风险资产,会增加组合的波动性。而当相关系数为 -0.55 时,在组合中加入债券则会显著降低整体组合的波动性,正如附录 3 所示。

EXHIBIT 2CORRELATION BETWEEN STOCK AND BOND RETURNS 1.0 0.8 5-Year Trailing Correlation 0.6 0.4 0.2 0.0 between Stock and Bond Returns -0.2 -0.4 -0.6 -0.8 -1.0 1882.01 1900.05 1918.09 1937.01 1955.05 1973.09 1992.01 2010.05 Source: Robert Shiller Through most of the last 150 years, the correlation between stock and bond returns on a monthly basis has been positive, averaging a little under 0.2. This is a low enough figure to mean that they usefully diversify each other, but not in a hugely impressive way. The last decade, however, has seen a profound shift in this relationship, with the correlation dropping to -0.64, with the last five years a still stunningly low -0.55 despite the fact that no bad economic events have actually occurred. This is actually a monumental shift. With a correlation of 0.2, adding bonds to a stock portfolio increases the volatility of a portfolio relative to using cash for your low-risk asset. At -0.55, adding bonds to your portfolio sharply reduces overall portfolio volatility, as can be seen in Exhibit 3.

投资是否又开始变得困难了?| 第 6 页 图表 3:相关性对投资组合波动率的影响 12% 11.0% 9.7% 10% 9.0% 9.0% 7.7% 7.6% 8% 6% 4% 2% 0% 相关系数 +0.2 相关系数 -0.55 60% 股票/40% 现金 60% 股票/40% 债券 60% 股票/80% 债券/-40% 现金 来源:GMO

过去五年(以及再往前五年),在股票投资组合中加入债券,会显著降低波动率,而加杠杆持有债券则进一步降低了波动率。从历史上看,在 60% 的股票仓位中加入 80% 的杠杆债券头寸,会使整体波动率从 9% 上升至 11%。但在过去十年中,这 80% 的债券头寸反而将风险从 9% 降低到了 7.6%。这帮助传统投资组合获得了比投资者预期更低的波动率,对那些采用风险平价或波动率目标策略的投资者而言,好处甚至更大。

Is Investing Starting to Get Difficult Again? | p6 EXHIBIT 3: IMPACT OF CORRELATIONS ON PORTFOLIO VOLATILITY 12% 11.0% 9.7% 10% 9.0% 9.0% 7.7% 7.6% 8% 6% 4% 2% 0% Correlation +0.2 Correlation -0.55 60% stocks/40% cash 60% stocks/40% bonds 60% stocks/80% bonds/-40% cash Source: GMO Over the last five years (and the five years prior), adding bonds to a stock portfolio decreased volatility materially, and leveraging up your bonds decreased volatility still further. Historically, adding an 80% levered bond position to a 60% stock position would have increased overall volatility from 9% to 11%.6 For the last decade, that 80% bond position would have decreased risk from 9% to 7.6%. This has helped traditional portfolios have lower risk than investors might have expected and has been even more beneficial to those in risk parity or volatility targeting strategies.

对波动率目标策略的影响尤为惊人,因为这些投资组合天然同时受到相关性和滞后波动率的影响。历史上,如果你想让一个 60%/40% 的股票与债券组合达到 10% 的波动率,你需要把该组合杠杆 3%,从而得到一个 62% 股票 /41% 债券 / -3% 现金的组合。图表 4 展示了过去五年的条件下该组合会是什么样子。

The impact on a volatility targeting strategy has been particularly startling, because those portfolios are naturally impacted by both correlations and trailing volatility. Historically, if you wanted a 60%/40% blend of stocks and bonds to have 10% volatility, you needed to lever the portfolio by 3%, giving you a portfolio of 62% stocks/41% bonds/-3% cash. Exhibit 4 shows what the portfolio would look like given the conditions of the last five years.

与图表 3 一样,此处假设股票波动率为 15%,债券为 6%,与长期历史数据一致。

As with Exhibit 3, this assumes the volatility of stocks to be 15% and bonds 6%, in line with long-term history.

投资是不是又开始变难了?

图表 4:要让 60% 股票/40% 债券组合达到 10% 波动率所需的杠杆倍数

300% 250% 200% 96% 150% 100% 41% 143% 50% 62% 0% -3% -50% -139% -100% -150% -200%

历史均值 过去 5 年 股票 债券 现金

来源:GMO

“杠杆水平从 3% 的‘何必费事’级别,飙升到了惊人的 139%。如果过去五年能合理代表未来,那么 143%/96%/-139% 就成了新的 60%/40%。如果你预期当前相对现金的风险溢价与历史正常水平相同,这意味着组合的预期回报率将从超越现金 3.1% 升至超越现金 7.3%!这固然令人心动,但这样的免费午餐实在好得难以置信。如果组合风险真像杠杆倍数所暗示的那样下降了,你根本不应该得到 7.3% 这样的回报。如果风险要向长期均值回归,那么加杠杆组合的波动率将超过 20%,也许你确实‘配得上’那 7.3%,但在这么高的波动率下,最终你复利下来的实际收益率也会低得多。免费午餐在投资中不应持久存在。它要求交易对手不仅不理性,还要有持续不断的现金流入,来弥补他们糟糕决策造成的经济损失。低波动和有利相关性,不应该与巨大的事前风险溢价稳定共存。但这句话并没有指明我们处在世界的哪一端。是风险已经持久下降、风险溢价也随之走低?如果是这样,你就需要加杠杆才能赚到过去无杠杆组合所能提供的回报。还是说最近这个‘轻松’环境只是暂时现象、注定会逆转?我押注后者(字面意义和比喻意义上都是如此)。即便经济的自然波动率随时间推移已经下降,即便政策应对也比 80 年前更好,但市场和经济都远没有那么循规蹈矩。波动拖累是描述这个效应的术语。简单说,对于两只有相同预期算术平均回报率的组合,波动率更高的那一只将产生更低的预期复利回报和更低的预期最终财富。

Is Investing Starting to Get Difficult Again? | p7 EXHIBIT 4: GROSS EXPOSURE NEEDED FOR A 60% STOCK/40% BOND PORTFOLIO TO HAVE 10% VOLATILITY 300% 250% 200% 96% 150% 100% 41% 143% 50% 62% 0% -3% -50% -139% -100% -150% -200% Historical Average Last 5 Years Stocks Bonds Cash Source: GMO “ The leverage has gone from a 3% “why bother” level to a stunning 139%. If the last five years are a reasonable representation of the future, 143%/96%/-139% is the new FREE LUNCHES 60%/40%. If you could expect the same risk premia over cash today as historically SHOULDN’T PERSIST IN normal levels, this would mean the expected return of the portfolio has gone from 3.1% above cash to 7.3% above cash! While this would indeed be lovely, that’s simply INVESTING. too much of a free lunch to believe. If the risk of portfolios has truly dropped in the way that the leverage suggests, you don’t deserve to get paid anything like 7.3%. If risk is going to revert to the longer-term averages, the leveraged portfolio winds up having a volatility of over 20%, so maybe you do “deserve” your 7.3%, but with such a high volatility you will wind up compounding at a much lower rate anyway.7 Free lunches shouldn’t persist in investing. They require counterparties to not only be irrational, but to also have a continual inflow of cash to replenish the economic losses that flow from their poor decisions. Low volatility and favorable correlations should not stably coexist with large ex-ante risk premia. But that statement does not specify which state of the world we are in. Has risk fallen sustainably and risk premia fallen along with it? If so, you will need to lever up to try to earn the kinds of returns that unlevered portfolios used to deliver. Or has the recent “easy” environment been a temporary one Volatility drag is the term for this effect. Basically, for two that is bound to reverse? My money is on the latter (literally, as well as figuratively). Even portfolios with the same expected arithmetic average return, if the natural volatility of the economy has fallen over time and even if policy response is the one with higher volatility will have a lower expected better than it was 80 years ago, neither markets nor economies are all that well-behaved. compound return and lower expected ending wealth.

拖累效应大约是方差的一半,"稳定滋生不稳定"——正如海曼·明斯基 40 年前所指出的——从统计上看尤其如此。在投资组合中,我们应当预期到任何自然(或随机生成)的系统中都会出现相对平静的时期,而这些时期终将结束。但除此之外,平静本身会鼓励那些最终导致高度波动结果的行为。风险平价化策略的存在本身就印证了这一点。以这个具体案例来说,给定投资组合标准差为 23.5%,波动性拖累将达到 2.8%,那么你那看似可观的 7.3% 预期超额现金收益率,最终只能以 4.5% 的超额现金收益率进行复利增长。

The drag is approximately one half of the variance of the Stability breeds instability, as Hyman Minsky pointed out 40 years ago. Statistically, we portfolio. In this particular case, with a portfolio standard should expect to get periods of relative calm in any natural (or randomly generated) deviation of 23.5%, the volatility drag would be 2.8%, and system, and those periods end. But beyond that, the calm itself encourages behaviors your lovely 7.3% expected return over cash will wind up that eventually lead to highly volatile outcomes. The very existence of risk parity and compounding at 4.5% over cash.

投资是否又开始变得困难了? | p8

本·因克尔是 GMO 资产配置团队的负责人,也是 GMO 董事会成员。他认为,波动率目标策略通过反馈回路在市场制造了脆弱性。起初,一段平静期会导致杠杆率上升,从而产生净买入力量来支撑市场。但当市场本已摇摇欲坠时,波动率上升或相关性转变却可能引发去杠杆和抛售压力。他于 1992 年从耶鲁大学获得经济学学士学位后加入 GMO。在 GMO 的多年里,因克尔先生曾担任量化股票和资产配置团队的分析师,担任过几只股票和资产配置投资组合的投资组合经理,担任过国际量化股票团队的联合负责人,以及量化发达市场股票团队的首席投资官。他是特许金融分析师(CFA)持证人。

在前几年的“炼狱与地狱”讨论之外,过去几年我花了很多时间讨论“地狱”和“炼狱”情景。这两种情景的差异在于现金利率的均衡水平,但假设风险溢价基本不受影响。在地狱情景下,股票的必要回报率较低,因为持有现金或债券的替代回报率比以前低了,但我们仍假设股票相对现金有 4% 至 4.5% 的股权风险溢价,债券相对现金有 1% 至 1.5% 的期限溢价。低波动率和负相关情景是另一种变化——由于多元化投资组合对投资者而言风险降低,导致必要风险溢价下降。与地狱情景一样,“低风险”情景使得短期前景更为乐观。如今美国股票和债券的估值,可以通过地狱情景、低波动率和负相关性三者的组合得到合理解释。如果通胀保持低位,且现金利率保持低位,且合作的市场允许通过投资组合工程来降低股票/债券组合的风险,那么今天的估值水平就说得通了。根据我们的数据,如果美国股票永远停留在当前水平,它们看起来定价能带来约 3% 至 3.5% 的实际回报。假设市场对现金利率的估算正确,这相对于现金大约有 3% 的风险溢价。债券的定价则可能带来比现金高 0% 至 0.5% 的回报。这些风险溢价比我们历史上看到的要小,在我们看来,如果未来的相关性再次变为正,且真正的经济风险与历史波动率(而非近期波动率)一致,那么这些风险溢价就太小了。但在一个低风险、负相关的世界里,这些较小的风险溢价很可能完全合理。

这就把我们带回到了 2018 年第一季度。并不是说投资组合当季的表现有多糟糕。一个 60% 股票 / 40% 债券的组合在今年头三个月亏损了约 1.2%。大多数风险平价投资组合的表现似乎大同小异,或许略差一些。但本季度更引人注目的是波动率上升和相关性转变。我知道这是一个极短的时期,但在本季度,标普 500 指数的年化波动率为 19%,而股票与债券之间的相关性在 -0.2 到 +0.1 之间,具体取决于你是看 1 日、5 日还是 20 日回报。这与过去 5 年形成鲜明对比,当时标普 500 指数的波动率低于 8%,而股票与债券之间的相关性为 -0.55。换句话说,在经历了多年极低波动率和强负相关性之后,上一季度看起来更像是投资者在过去 150 年中所经历的平均条件。在那个世界里,历史上正常的风险溢价就很有道理,而我们所有人的集体投资目标都依赖于这些风险溢价与历史水平保持相似。问题在于,今天的市场,尤其是美国市场,并非为那个世界定价,因此,如果当前条件持续下去,我认为估值很可能会下降。

本季度我再次未能准时提交季度报告,其好处在于我们掌握了 3 月底之后的数据。波动率和相关性如果更新到 4 月底,与第一季度的数据相比并没有发生有意义的改变,因此所显示的转变对于 2018 年这头三分之一的时间而言,与第一季度的结论同样适用。具体来说,MSCI ACWI 指数当季下跌 1.1%,巴克莱美国综合债券指数下跌 1.2%。

但我仍然认为,估值下降是更可取的结果。我们要么生活在一个轻松的世界里,投资回报微薄;要么生活在一个艰难的世界里,但回报更高。短期来看,轻松可能更有趣,但每一天我都更愿意选择更艰难但更有利可图的那一个。

免责声明

本文所表达的观点是本·因克尔截至 2018 年 5 月的个人观点,并可能根据市场和其他条件随时发生变化。本文并非购买或出售任何证券的要约或招揽,也不应被理解为此类行为。提及特定证券和发行人仅为说明目的,并非也不应被解释为购买或出售此类证券的建议。

版权 © 2018 GMO LLC 版权所有

Is Investing Starting to Get Difficult Again? | p8 Ben Inker volatility targeting strategies creates fragility in the markets in the form of feedback Mr. Inker is head of GMO’s Asset Allocation loops. At first, a period of calm will lead to increased leverage, which creates net buying team and a member of the GMO Board of to support markets. But a rise in volatility or shift in correlations can lead to deleveraging Directors. He joined GMO in 1992 following and selling pressure just when markets are already shaky. the completion of his B.A. in Economics from Yale University. In his years at GMO, Mr. Inker has served as an analyst for the Beyond Purgatory and Hell Quantitative Equity and Asset Allocation teams, I’ve spent a lot of time over the past few years discussing the scenarios of Hell and as a portfolio manager of several equity and Purgatory. Those two scenarios differ in the equilibrium level of cash rates, but assume asset allocation portfolios, as co-head of that risk premia are largely unaffected. Equities have a lower required return in Hell International Quantitative Equities, and as CIO because the alternative of holding cash or bonds has a lower return than it used to, but of Quantitative Developed Equities. He is a CFA we still assume a 4-4.5% equity risk premium over cash and a 1-1.5% term premium charterholder. for bonds over cash. The low volatility and negative correlation scenario is a different shift – a decrease in required risk premia due to the fact that diversified investment portfolios are less risky to investors. As with the Hell scenario, the “low-risk” scenario makes for a rosier short-term outlook. Today’s valuations of U.S. stocks and bonds Disclaimer can be decently explained by a combination of Hell, low volatility, and negative The views expressed are the views of Ben correlations. If inflation stays low AND cash rates remain low AND cooperative markets Inker through the period ending May 2018, allow portfolio engineering to reduce the risk of stock/bond portfolios, you can make and are subject to change at any time based today’s valuation levels make sense. On our data, U.S. stocks look priced to deliver on market and other conditions. This is something around 3-3.5% real if they stay at today’s levels forever. That’s perhaps a 3% not an offer or solicitation for the purchase risk premium over cash, assuming market estimates for cash rates are correct. Bonds or sale of any security and should not be are priced to deliver perhaps 0-0.5% above cash. Those are smaller risk premia than construed as such. References to specific we have seen historically, too small in our minds if future correlations are positive securities and issuers are for illustrative again and true economic risk is in line with historical volatilities instead of recent ones. purposes only and are not intended to But those smaller risk premia may well be perfectly reasonable in a low-risk, negative be, and should not be interpreted as, correlation world. recommendations to purchase or sell such securities. And that brings us back to the first quarter of 2018.8 It’s not that portfolios did all that badly in the quarter. A 60% stock/40% bond portfolio lost about 1.2% in the first three Copyright © 2018 by GMO LLC. months of the year.9 Most risk parity portfolios seem to have performed similarly or All rights reserved. perhaps a little worse. But the more striking thing about the quarter was that volatility rose and correlations shifted. It’s an extremely short period, I know, but in the quarter, the annualized volatility for the S&P 500 was 19% and the correlation between stocks and bonds was between -0.2 to +0.1 depending on whether you were looking at 1-day, 5-day, or 20-day returns. That is in contrast with the last 5 years, where the volatility of the S&P 500 was under 8% and the correlation between stocks and bonds has been -0.55. In other words, after years of very low volatility and strongly negative correlations, last quarter looked a lot more like the average conditions investors have experienced over the last 150 years. In that world, historically normal risk premia make a lot of sense, and all of our collective investment goals rely on those risk premia remaining similar to historical levels. The trouble is that markets today, particularly U.S. markets, aren’t priced for that world, so if current conditions persist, I believe The plus side of the fact that this quarter I have once again failed to get my quarterly written promptly is that valuations are likely to fall. we have data beyond the end of March. Neither volatility nor correlations have meaningfully changed from the first But I still think that’s the preferable outcome. We can either have an easy world, and quarter figures if we update them through the end of April, so the shift indicated is as true for the first third of 2018 as it get paid little for investing, or a hard world where we get paid more. Easy may be more was for the first quarter. fun in the short run, but give me harder and more profitable any day of the week. Specifically, MSCI ACWI fell 1.1% in the quarter and the Barclays U.S. Aggregate Bond fell 1.2%.