????美聯(lián)儲(chǔ)（Federal Reserve）主席本?伯南克經(jīng)常因?yàn)閷?duì)股市過(guò)度反應(yīng)而遭受批評(píng)。不過(guò)也許他就該這么干。

????上一次股市大崩盤后，美聯(lián)儲(chǔ)推出了第二輪量化寬松和“扭轉(zhuǎn)操作”。最近道瓊斯指數(shù)再次大跌（盡管昨日有所反彈），再加上其它一些比較疲軟的經(jīng)濟(jì)數(shù)據(jù)，讓人懷疑伯南克和美聯(lián)儲(chǔ)是否會(huì)再次推出一輪新的刺激計(jì)劃。同時(shí)，也有些人對(duì)伯南克的救市手段感到不滿，認(rèn)為伯南克更關(guān)心的是股市的方向，而不是總體的經(jīng)濟(jì)狀況。還有些人批評(píng)伯南克站在了投資者一邊，而不是消費(fèi)者這邊，認(rèn)為美聯(lián)儲(chǔ)的舉措可能會(huì)引發(fā)大規(guī)模的通脹。

????不過(guò)一份最新研究顯示，監(jiān)視股市的動(dòng)向也許正是伯南克此時(shí)應(yīng)該做的事情。美國(guó)國(guó)家經(jīng)濟(jì)研究局（NBER）近日發(fā)布了一篇名為《通脹追蹤投資組合》（Inflation Tracking Portfolios）的工作文件，研究了自1985年初一直到去年年末的消費(fèi)價(jià)格以及一系列投資活動(dòng)的變動(dòng)。這篇報(bào)告的作者包括加州大學(xué)洛杉磯分校（UCLA）的經(jīng)濟(jì)學(xué)教授弗朗西斯?朗斯達(dá)夫，以及投資銀行黑石集團(tuán)（Blackrock）的兩名雇員。研究發(fā)現(xiàn)，大多數(shù)被我們當(dāng)成通脹避險(xiǎn)工具的東西，比如黃金和房地產(chǎn)，都有夸大價(jià)格實(shí)際波動(dòng)的傾向。就連政府發(fā)行的抗通脹公債也不能很好地預(yù)言未來(lái)的通脹。抗通脹公債價(jià)格的波動(dòng)往往遠(yuǎn)遠(yuǎn)超過(guò)總體消費(fèi)價(jià)格的波動(dòng)。通脹最好的預(yù)言者恰恰就是股市。

????該研究報(bào)告的作者們發(fā)現(xiàn)，從總體來(lái)看，未來(lái)的通脹往往會(huì)隨著股市的走向而變動(dòng)，在這一點(diǎn)上，股市預(yù)言通脹的能力比他們考察的任何其它因素都強(qiáng)。因此，如果股市接連一個(gè)月下跌的話，很可能就意味著一個(gè)月后通脹水平會(huì)降低。如果股市暴漲，則可能意味著消費(fèi)價(jià)格未來(lái)也會(huì)上漲。

????此外，該研究報(bào)告的作者們還發(fā)現(xiàn)，有些行業(yè)的通脹敏感性要高于其它行業(yè)。比如石油股往往會(huì)與通脹呈同向波動(dòng)，而零售股與通脹的相關(guān)性則比較小。所以如果真想追蹤通脹的話，我們需要建立一個(gè)投資組合，做多與通脹相關(guān)的行業(yè)股，做空與通脹不相關(guān)的行業(yè)股——該研究報(bào)告的作者們就是這樣做的。那么，這個(gè)通脹組合對(duì)眼下有何預(yù)測(cè)呢？大體來(lái)看，通脹水平（5月份已下降0.3%）還會(huì)繼續(xù)下降。報(bào)告的作者們?cè)?011年年底就已經(jīng)停止了構(gòu)建那個(gè)投資組合。不過(guò)上個(gè)月石油股下跌了14%。而包括沃爾瑪（Wal-Mart）和塔吉特百貨（Target）在內(nèi)的一些零售股卻出現(xiàn)了上升。西爾斯百貨（Sears）的股價(jià)則出現(xiàn)了下跌。

????朗斯塔夫表示，他并不是想要對(duì)政府的貨幣政策發(fā)表任何說(shuō)長(zhǎng)道短。不過(guò)股票的確是未來(lái)通脹的最好的預(yù)言師。那么，一旦股市暴跌，伯南克再次像以前一樣出手救市就不難理解了?？紤]到五月份的情況有多糟糕，美聯(lián)儲(chǔ)說(shuō)不定正醞釀著另一輪量化寬松或其它的刺激計(jì)劃，至少美聯(lián)儲(chǔ)應(yīng)該做好這樣的準(zhǔn)備。

????譯者：樸成奎

????Federal Reserve chairman Ben Bernanke often gets criticized for overreacting to the stock market. But maybe that's exactly what he should be doing.

????QE2 and Operation Twist were announced after market drops. And the recent swoon in the Dow, despite rebounding yesterday, along with some rather weak economic data, have reignited new speculation that Bernanke & Co. might finally announce a new stimulus program. That's led some critics to contend that Bernanke cares more about the direction of stocks than the general economy. Others, who predict the Fed's moves will spark massive inflation, say Bernanke is choosing investors over consumers.

????But a new study suggests that keeping an eye on the market is exactly what Bernanke should be doing. Inflation Tracking Portfolios, which was released as a working paper by the NBER this week, looked at the movement in consumer prices and a number of various investments from the beginning of 1985 through the end of last year. The study's authors, which included UCLA economics professor Francis A. Longstaff and two employees from investment firm Blackrock, found that most things that we generally tend to think of as inflation hedges, such as gold and real estate, tend to overstate the actual moves in prices. Even Inflation-Protected Treasury bonds, nicknamed TIPs, came out as a pretty poor predictor of future inflation. Prices of TIPs tended to jump around much more than overall prices did. The best inflation oracle: the market.

????In general, the authors found that future inflation tends to track stocks better than anything else they looked at. So if the market dropped over the course of a month, it tends to indicate that inflation will be lower a month from now. A jump in stocks, tends to mean consumer prices will rise as well.

????What's more, the authors found some industries are more correlated to inflation than others. Oil stocks tend to move in the same direction as inflation; retail stocks, not as much. So if you really want to track inflation, you need to build a portfolio that long the sectors that are correlated with inflation and short the sectors that are not, which is what the authors of the study did. What is the inflation portfolio predicting now? Generally, that inflation, which dropped 0.3% in May, will continue to fall. The authors stopped constructing their portfolio at the end of 2011. But oil stocks are down 14% in the past month. A number of retailing stocks, on the other handing including Wal-Mart (WMT) and Target (TGT) are up. Sears (SHLD) is down.

????Longstaff says he wasn't looking to make any statement about monetary policy. But if stocks are really the best indicator of future inflation, then it seems to make sense that Bernanke would jump to action, as he has, when stocks have dropped. And given how bad May was, another QE or some other round of Fed stimulus is probably on its way, or at least it should be.