????近日來(lái)，投資者們被市場(chǎng)搞的普遍有些神經(jīng)過(guò)敏。

????9月22日以來(lái)，道瓊斯指數(shù)已有3天的下跌幅度超過(guò)100點(diǎn)。阿里巴巴（Alibaba）巨型IPO橫空出世，以及這家中國(guó)電子商務(wù)公司的驚人估值，引發(fā)市場(chǎng)或已觸頂?shù)膿?dān)憂。

????令人擔(dān)憂的是，乏善可陳的基本面似乎遠(yuǎn)遠(yuǎn)無(wú)法支撐股市對(duì)未來(lái)的爆棚信心。我們正生活在一個(gè)創(chuàng)紀(jì)錄的企業(yè)估值與平庸的利潤(rùn)增長(zhǎng)并存的世界之中。

????為了獲得對(duì)現(xiàn)實(shí)狀況的最準(zhǔn)確認(rèn)知，不妨關(guān)注一個(gè)能告訴我們股票何時(shí)值得買進(jìn)、何時(shí)被高估的指標(biāo)：股票風(fēng)險(xiǎn)溢價(jià)（ERP）。它被譽(yù)為企業(yè)融資圣杯。這名稱或許聽(tīng)起來(lái)不那么有吸引力，但要想在股市中長(zhǎng)期賺錢(qián)，這是你能找到的最實(shí)用的衡量指標(biāo)。

????股票風(fēng)險(xiǎn)溢價(jià)是投資者選擇投資股票而不投資債券，因承擔(dān)這份額外風(fēng)險(xiǎn)而要求獲得的額外回報(bào)。ERP越高，潛在的未來(lái)回報(bào)也越大。例如，在2009年市場(chǎng)恐慌時(shí)期，風(fēng)險(xiǎn)溢價(jià)激增，那時(shí)買進(jìn)股票的人獲利頗豐。相比之下，當(dāng)股票風(fēng)險(xiǎn)溢價(jià)低于平均值，未來(lái)幾年的股票投資收益可能非常微薄，甚或根本不存在。

????但當(dāng)前具有迷惑性的是，真實(shí)可持續(xù)的股票風(fēng)險(xiǎn)溢價(jià)被暫時(shí)的、不可持續(xù)的低利率所掩蓋。但要從這些虛幻的官方數(shù)據(jù)中挖掘出經(jīng)調(diào)整后真實(shí)的股票風(fēng)險(xiǎn)溢價(jià)，也并非難事。我們將會(huì)看到，這一調(diào)整后的數(shù)據(jù)已發(fā)出了警報(bào)。

????股票風(fēng)險(xiǎn)溢價(jià)就是股票預(yù)期回報(bào)減去10年期美國(guó)國(guó)債經(jīng)通脹調(diào)整后的收益率，這是你勇敢投資股票而期待獲得的額外容錯(cuò)余量或空間。最佳的預(yù)期回報(bào)指標(biāo)是經(jīng)濟(jì)學(xué)家羅伯特?席勒創(chuàng)造的經(jīng)周期性調(diào)整的市盈率（CAPE）收益率。CAPE是最可信的回報(bào)衡量指標(biāo)，它對(duì)可能高度誤導(dǎo)性的暫時(shí)利潤(rùn)波動(dòng)進(jìn)行了調(diào)整。當(dāng)前，基于CAPE的收益與股價(jià)比率為3.8%。倒過(guò)來(lái)計(jì)算的席勒市盈率為26.3倍。

????因此，當(dāng)前經(jīng)通脹調(diào)整后的預(yù)期股票回報(bào)為3.8%。第二步是減去10年期美國(guó)國(guó)債的實(shí)際收益率，從而獲得股票風(fēng)險(xiǎn)溢價(jià)。這一長(zhǎng)期國(guó)債的收益率目前約為2.5%，而通脹為2%左右。因此，實(shí)際收益率僅為0.5%。

????由此得出，股票風(fēng)險(xiǎn)溢價(jià)為3.8%的預(yù)期回報(bào)減去0.5%，即3.3%。從歷史標(biāo)準(zhǔn)來(lái)看，這個(gè)數(shù)據(jù)還不錯(cuò)。這對(duì)于看漲的人士，即便是那些負(fù)責(zé)任的看漲人士也是一個(gè)令人鼓舞的信號(hào)。他們會(huì)說(shuō)，3.8%的預(yù)期回報(bào)加上2%的通脹，總計(jì)達(dá)到5.8%，還不夠好嗎，看看10年期美國(guó)國(guó)債的收益率。那么，為何不買進(jìn)股票？

????即便是那些樂(lè)觀人士也承認(rèn)利率需要上升。當(dāng)今，低得令人難以置信的0.5%實(shí)際收益率造成了一種幻像，令股票風(fēng)險(xiǎn)溢價(jià)虛高。事情總歸會(huì)回復(fù)常態(tài)，想想一旦美聯(lián)儲(chǔ)放寬利率，讓利率回歸歷史常態(tài)，結(jié)果會(huì)怎樣？假以時(shí)日，實(shí)際利率將徘徊在2%附近區(qū)間。實(shí)際利率從當(dāng)前的0.5%升至2%，推動(dòng)10年期美國(guó)國(guó)債收益率升至4%（即2%的實(shí)際收益率加上2%的未來(lái)通脹溢價(jià)），將會(huì)發(fā)生什么?

????現(xiàn)在，我們可以重新計(jì)算股票風(fēng)險(xiǎn)溢價(jià)，剔除人為低利率產(chǎn)生的放大效應(yīng)。3.8%的預(yù)期回報(bào)減去未來(lái)合理的實(shí)際利率2%，得出不那么誘人的股票風(fēng)險(xiǎn)溢價(jià)：區(qū)區(qū)1.8%而已。

????這不足以證明投資股票是明智的。假設(shè)投資者仍舊要求較債券有3.3%的息差，以達(dá)到他們當(dāng)前預(yù)期獲得的收益。那么，他們將要求獲得的未來(lái)回報(bào)不是5.8%，而是7.3%（即2%的實(shí)際利率加上3.3%的股票風(fēng)險(xiǎn)溢價(jià)和2%的通脹。）

????要讓股票風(fēng)險(xiǎn)溢價(jià)恢復(fù)到有吸引力的水平，需要公司估值大幅下降。席勒市盈率比需要從26.3降至18.9，造成股價(jià)大降28%。標(biāo)準(zhǔn)普爾指數(shù)在1,425點(diǎn)左右將再度變得有吸引力。關(guān)注股票風(fēng)險(xiǎn)溢價(jià)，關(guān)乎投資中最重要的事情：確保你的風(fēng)險(xiǎn)獲得良好回報(bào)。因此，敬請(qǐng)密切跟蹤所有市場(chǎng)指標(biāo)之王——股票風(fēng)險(xiǎn)溢價(jià)。（財(cái)富中文網(wǎng)）

????譯者：早稻米

????Investors have come down with a case of the jitters, and for a good reason.

????Since September 22, the Dow has careened through three days of 100 point-plus losses. The gigantic pop in the Alibaba IPO and the Chinese e-commerce phenomenon’s epic valuation have begun to stir fears that we’ve hit a market peak.

????What’s worrying is that prices are displaying far greater faith in the future than the unimpressive fundamentals suggest is warranted. We’re living in a world of record-high corporate valuations and mediocre earnings growth.

????To get the most accurate picture of the situation, let’s examine a metric that tells you when stocks are really a buy, and when they’re overly pricey. It’s called the Equity Risk Premium, or ERP, and it’s been lauded as the Holy Grail of corporate finance. The name may sound wonky, but for making money in stocks in the long-term, it’s the most practical measurement you’ll ever find.

????The Equity Risk Premium is the extra return that investors demand for taking the additional risk of choosing stocks over far safer Treasury bonds. The higher the ERP, the bigger the potential future returns. Risk premiums ballooned, for example, in the panic of 2009, and folks who bought then profited handsomely. By contrast, when the ERP is below average, gains on equities tend to be weak or non-existent in the years to come.

????What’s misleading is that the real, sustainable ERP has been disguised by a temporary phenomenon: unsustainably low interest rates. But it’s no great challenge to unmask an adjusted, realistic ERP from the illusory, official one. And as we’ll see, that slender figure is cause for alarm.

????The ERP is simply the expected return on equities minus the inflation-adjusted yield on 10-year treasuries—that’s the extra cushion, or margin for error, you’d expect for braving equities. The best measure of the expected return is the earnings yield on the CAPE, or Cyclically Adjusted Price-Earnings Ratio, developed by economist Robert Shiller. The CAPE is the most reliable yardstick for returns since it adjusts for temporary, highly misleading swings in profits. Right now, the E/P (earnings to price ratio) on the CAPE stands at 3.8%. That’s the inverse of the Shiller price-to-earnings ratio of 26.3.

????So the expected return on stocks is now 3.8%, adjusted for inflation. The second step consists of subtracting the real rate on the 10-year Treasury to get the ERP. The long bond is now yielding around 2.5%, and inflation is running at around 2%. So the real yield is a mere 0.5%.

????Hence, the ERP is our 3.8% expected return minus 0.5%, or 3.3%. By historical standards, that’s a good figure. It’s an encouraging signal for the bulls, even the responsible ones. They can argue that the expected return of 3.8% plus inflation of 2%, or 5.8% in total, isn’t great, but clocks the yields on the long bond. So why not buy stocks?

????Even the optimists, however, acknowledge that interest rates need to rise. Today, the incredibly low 0.5% real yield has created a mirage in the form of a superficially strong ERP. Things always go back to normal, so consider the results when the Fed unshackles interest rates and lets them swing back to their historic norms. Over time, real rates hover in the 2% range. What will happen when they rise from today’s level of 0.5% to 2%, bringing the yield on the 10-year Treasury bond to 4% (the total of the 2% real yield plus a 2% premium for future inflation)?

????Now, we can re-calculate the ERP to eliminate the funhouse mirror effect of artificially low interest rates. The expected return of 3.8%, minus the reasonable, future real rate of 2%, leaves an under-nourished ERP of just 1.8%.

????That’s not enough to justify investing in stocks. Let’s assume investors still demand a spread over bonds of 3.3 points, matching what they’re supposed to be getting today. Now they’ll require future returns not of 5.8%, but 7.3% (that’s the real rate of 2% plus the ERP of 3.3% plus inflation of 2%).

????Restoring the ERP to attractive levels will require a sharp drop in company valuations. The Shiller PE would need to fall from 26.3 to 18.9, causing stock prices to drop by 28%. The S&P would look alluring again at around 1,425. Watching the ERP is all about what really matters in investing: ensuring you are well paid for risk. So follow the sovereign of all market metrics.