投資者該為耶倫主席送上鮮花美酒了。市場再次因為央行行長的一句話而上漲。在昨天的演講中，耶倫主席強調了央行和市場的複雜關系，重提了十二月的美聯儲加息。耶倫主席首次指出：“市場下跌不會引發美聯儲對經濟增長的通貨膨脹的擔憂，但仍需要提高警惕。面對市場下行，投資者降低了對聯邦基金利率的預期，這會給長期利率帶來下行風險，緩沖經濟活動的負面影響。”
換句話說，市場本身在下跌，美聯儲就不會採取以前那樣嚴苛的緊縮政策。所以美聯儲不需要採取額外的行動來穩定經濟，美聯儲的市場參與行動就達到了效果。在加息方面，耶倫補充道：“反思十二月以來的全球經濟動態，加息的步伐可能會放緩。舉例來講，聯邦公開市場委員會參與者對2016年底聯邦基金利率的平均預期為0.9%，2017年底為1.9%，都比十二月低0.5個百分點。”
美聯儲行動和市場反饋之間的互動早在耶倫上任之前就存在。基金管理公司GMO今日發佈了一份報告，報告内容是美聯儲會議當天的市場波動。美聯儲每年舉行八次會議。但自1984年以來，美聯儲當天會議的反饋只有全部反饋的四分之一。去除這些反饋，美國股票的價格走勢便完全符合羅伯特·席勒的週期調整市盈率理論。確實，在危機最嚴重的時候，市盈率可能會跌至個位數，是美聯儲阻止了這種情況的發生。
但問題是，研究表明，央行通過量化寬松為資產價格提供的支持變得越來越不平衡，美國、英國皆是如此。但央行認為，為了避免經濟崩潰產生更大的威脅，付出這些代價還是值得的。
市場波動時期的幹預政策可以追溯到20世紀80年代，那時的價格高得多、穩定得多。現如今利率越來越低，估價越來越高，債務人已經習慣了超低的利率而不斷地貸款（這就是政策的重點）。但這也意味著，利率若想回到正常水平，就要付出更高的成本。想一想貸款買房的人突然發現利率變成6-7%會是什麼樣的情形。如果席勒市盈率從當前的25.6跌至16.7，信心會受到多麼大的打擊。
央行行長們不願意讓這樣的事情發生，而投資者們也了解行長們的想法。所以他們的關系就像一個酒吧招待員和一位酒吧常客，招待員不停地給顧客倒酒，顧客也不停地喝，完全不考慮肝硬化的風險。當然這是個新問題，也許是六年後才會擔心的問題。但現在確實沒有更好的解決方法了。
Enabling the addiction
TIME for equity investors to send Janet Yellen some champagne, or at least a bunch of flowers. Once again, markets are rising because of something that a central banker said. In a speech yesterday, Ms Yellen highlighted the complex relationship between central banks and markets. Recall that the Fed raised rates in December. Ms Yellen first notes that：
“The proviso that policy will evolve as needed is especially pertinent today in light of global economic and financial developments since December, which at times have included significant changes in oil prices, interest rates, and stock values.”
Those market declines don't mean that the Fed has altered its outlook for economic growth and inflation. But they were still important because, she adds
“investors responded to those developments by marking down their expectations for the future path of the federal funds rate, thereby putting downward pressure on longer-term interest rates and cushioning the adverse effects on economic activity”
In other words, the markets anticipated that, because they themselves were falling, the Fed would not tighten as quickly as before. So the Fed didn't actually need to act to stabilise the economy; market anticipation of Fed action did the trick. As in Keynes's famous beauty contest analogy, we have reached the higher levels of reasoning. Of course, this process still needed the Fed to play along with market reasoning and it is. On the pace of rate rises, Ms Yellen said:
“Reflecting global economic and financial developments since December, however, the pace of rate increases is now expected to be somewhat slower. For example, the median of FOMC participants' projections for the federal funds rate is now only 0.9 percent for the end of 2016 and 1.9 percent for the end of 2017, both 1/2 percentage point below the December medians.”
This relationship between the Fed's actions and market returns dates back well before Ms Yellen's tenure. GMO, a fund management company, recently published a paper looking at market movements on the day of Fed meetings. The Fed only meets eight times a year. But since 1984, the returns on the days of Fed meetings have provided a quarter of all returns. Take those returns away and US equities would look reasonably priced under Robert Shiller's cyclically-adjusted price-earnings ratio methodology. Indeed, in the depths of the crisis, the market would probably have fallen back to a single-digit p/e. The Fed prevented the market from reverting to the mean.
Here is the difficulty. Studies suggest central bank support for asset prices, via quantitative easing, has increased inequality in both America and Britain. But the central banks would argue that this was a price worth paying in staving off the much greater threat of an economic collapse.
But this policy of intervening when markets wobble, dating all the way back to the 1980s, has a steadily higher price. Over time, rates get lower and lower and valuations tend higher. Debtors get used to ultra-low interest rates and keep borrowing (that's the point of the policy, after all). But this means that the potential cost of a reversion to "normal" levels of interest rates gets even greater; imagine what would happen to homeowners if mortgage rates were 6-7%. What would happen to confidence if the Shiller p/e fell from its current 25.6 to the historic average of 16.7?
Central banks don't want that to happen and investors know that central banks don't want it to happen. So the two are locked together like a barman and his most profitable customer, endlessly pouring one more drink to fend off the hangover and trying to forget about the cirrhosis that might set in. This is not a new problem, of course; your blogger was worrying about it six years ago. But we don't seem to be any nearer solving it.
本文翻譯由兄弟財經提供
文章來源：http://www.economist.com/blogs/buttonwood/2016/03/central-banks-and-markets