????“哇哦！”投資者聽到美聯(lián)儲（Federal Reserve）在上周三的政策聲明后，肯定會有這樣的反應(yīng)。這種反應(yīng)里不僅包含著驚訝，還混雜著各種相互矛盾的情緒。

????毫無疑問：美聯(lián)儲昨天的聲明，起碼關(guān)于中央銀行業(yè)務(wù)和貨幣政策的部分，肯定會被載入史冊。它標(biāo)志著美聯(lián)儲朝著激進主義、積極參與的抱負(fù)邁出了重要一步。然而，這種轉(zhuǎn)變同時也充滿了風(fēng)險，因為它使得美聯(lián)儲在試驗性的、充滿政治因素的領(lǐng)域愈陷愈深。上周三，美聯(lián)儲公布了兩項措施，其中一項在意料之中，另外一項則完全超出了人們的預(yù)期。

????首先，美聯(lián)儲增加了市場證券購買力度，將2013年的美元金額擴大一倍，增加到1萬億美元，不論從哪個角度來看，都堪稱大手筆。其次，美聯(lián)儲改變了遠期政策指引的量化指標(biāo)（失業(yè)率與通脹）。鑒于理論與實踐的復(fù)雜性，美聯(lián)儲祭出該政策的時間遠遠早于大多數(shù)投資者的預(yù)期。

????經(jīng)濟增長緩滯帶來了持續(xù)的失望情緒，居高不下的失業(yè)率和對失業(yè)愈加深切的擔(dān)憂是美聯(lián)儲此次急切推出未知政策的原因。這些因素從結(jié)構(gòu)上已經(jīng)滲透到美國經(jīng)濟中。

????美聯(lián)儲公布政策聲明之后的新聞發(fā)布會上，直率的美聯(lián)儲主席本?伯南克也表達了類似的觀點。很明顯，伯南克對財政懸崖依然抱有顧慮，政治癱瘓使美國經(jīng)濟再次陷入衰退的可能性也讓他寢食難安。加快政策執(zhí)行也反映出美聯(lián)儲希望給美國經(jīng)濟加上多重保險。

????關(guān)于投資者的復(fù)雜情緒：政策加大對失業(yè)率的重視，我們應(yīng)該表示歡迎。美國的就業(yè)危機將耗費龐大的人力成本。貧困階層人數(shù)將日益增加。社區(qū)的社會結(jié)構(gòu)正在日益遭到這場危機所侵蝕。危機持續(xù)的時間越長，解決的難度就越高。

????美聯(lián)儲再次向投資者證明，它已經(jīng)使盡渾身解數(shù)。這是好消息。為了“推動”投資者承擔(dān)更多風(fēng)險，美聯(lián)儲甚至付出了更多努力，試圖人為支撐資產(chǎn)價格。壞消息是，美聯(lián)儲為應(yīng)對目前的挑戰(zhàn)所設(shè)計的工具尚不完善，對于美聯(lián)儲和其他美國聯(lián)邦政府機構(gòu)（尤其是MIA）而言，可能會力不從心。

????首先，伯南克自己也承認(rèn)，美聯(lián)儲異常的激進主義可能導(dǎo)致的后果根本無法預(yù)測，而且會付出一定的代價。不確定的預(yù)期效益，伴隨而來的附帶損害和意外后果風(fēng)險將會提高。而且，每次美聯(lián)儲感覺自己應(yīng)該做更多工作時，對微妙平衡的支持卻會越少，因為之前的措施收效甚微。

????其次，美聯(lián)儲加大干預(yù)從根本上說并不符合市場經(jīng)濟的有效運行。截至2013年底，根據(jù)證券市場的表現(xiàn)，美聯(lián)儲掌控的市場份額將在30%至40%之間，美聯(lián)儲以“裁判”和“參賽者”的雙重身份參與市場。結(jié)果將使市場功能、價格發(fā)現(xiàn)機制和資本分配遭到嚴(yán)重扭曲。

????Wow! That is what I suspect many investors said when they heard Wednesday's policy announcement from the Federal Reserve. And this single reaction would have captured not just partial surprise but also a combination of conflicting feelings.

????Have no doubt: Yesterday's Fed announcement will go down in the history books -- at least those texts covering central banking and monetary policy. It marks a major evolution in the activism, involvement and aspirations of the central bank. It is also a risky move, taking the institution much deeper into experimental and politically charged territory.The Fed took two major steps on Wednesday, one expected and one less so.

????First, it added to its expected purchases of market securities, doubling the dollar amount to $1 trillion for 2013 -- a very large number by any measure. Second, the Fed shifted to quantitative (unemployment and inflation) targets for forward policy guidance, and it did so earlier than most expected given theoretical and practical complexities.

????This further leap into the policy unknown was motivated by continued disappointment with the economy's sluggish growth, persistently high unemployment and increasing concern about joblessness becoming more structurally embedded into the economy.

????That much was said by Ben Bernanke, the Fed's admirably transparent chairman, during his press conference after the news was unveiled. It was also obvious that he is very concerned about the fiscal cliff, and the possibility that political paralysis could push the economy into another recession. The accelerated policy implementation may also reflect the Fed's desire to take out some additional insurance.

????Now for the mixed feelings: We should all welcome the greater policy emphasis being placed on unemployment. This national jobs crisis has enormous human costs. It increases poverty. It eats away at the social fabric of our communities. And the longer it persists, the harder it is to solve.

????The Fed has again demonstrated to investors that it is "all in." That is the good news. The Fed is doing even more in its attempt to artificially bolster asset prices as a way to "push" investors to take more risk. The bad news is that the institution, with its imperfect tools for the challenge at hand and with other federal government entities essentially MIA, may be taking on an unsustainable burden.

????First, and as recognized by Bernanke, the outcome of the Fed's unusual activism is neither predictable nor costless. Uncertain expected benefits come with an increasing risk of collateral damage and unintended consequences. And the tricky balance becomes less favorable every time the Fed feels it has to do more because prior actions have not been sufficiently effective.

????Second, the Fed's growing involvement is ultimately inconsistent with the proper efficient functioning of a market economy. With a market share that will end 2013 between 30% and 45% depending on the securities, the Fed is heavily involved in markets as both a referee and player. As such, it distorts their functioning, the price discovery process and the allocation of capital.