Some of the country’s most famous investors, including Warren Buffett and John Bogle, have started to make the case that it’s time to dive back into the stock market.
　　They are usually careful to add that they don’t know what stocks will do in the short term. Yet their basic message is clear enough: stocks are now cheap, irrational fears have been driving the market down lately, and people who buy today will be glad that they did.
　　After a day like Tuesday, when the market rose 11 percent, it’s easy to see the merits of the argument.
　　But there is another argument that deserves more attention than it has gotten so far. It’s the bearish argument that is based neither on fears that the country may be sliding into another depression nor on gut-level worries about the unknown. It is based on numbers and history, and it has at least as much claim on reason as the bullish argument does.
　　It goes something like this: Stocks are truly cheap only relative to their values over the last 20 years, a period that will go down as one of the great bubbles in history. If you take a longer view, you see that the ratio of stock prices to corporate earnings is only slightly below its long-term average. And in past economic crises — during the 1930s and 1970s — stocks fell well below their long-run average before they turned around.
　　To make matters worse, corporate earnings have now started to plunge, too. Assuming that they keep dropping, stocks would also need to fall to keep the price-earnings ratio at its current level.
　　As stocks were soaring on Tuesday afternoon, I called James Melcher to hear a dose of fact-based bearishness. Mr. Melcher is president of Balestra Capital, a hedge fund in New York, who wrote an essay for his clients two years ago that predicted the broad outlines of the financial crisis (and then arranged Balestra’s portfolio accordingly). Like the bulls, he said that no one could know what the market would do in the short term. “But to think stocks are cheap now,” he added, “is not rational.”
　　He went on: “In the last 20 years — and particularly in the last six or seven — you had the most massive creation of liquidity the world has ever known.” Consumers went ever deeper into debt, thanks to loose lending standards, and a shadow banking system, made up of hedge funds and investment banks, allowed Wall Street to do the same. All that debt lifted economic growth and stock returns.
　　“It was a nice party,” Mr. Melcher said. “The problem is that all the bills are coming due at the same time.” He thinks stocks could easily fall an additional 20 percent and maybe 35 percent before hitting bottom.
　　So who’s right — the bears or the bulls? The smartest people in both camps, like Mr. Melcher, Mr. Buffett and Mr. Bogle, have a healthy dose of humility about their own conclusions. And when you dig into their arguments, you find that they’re not quite as different as they first sound. But they are different, and it’s worth taking a minute to consider the numbers.
　　There are any number of ways to measure the valuation of the stock market. Some examine prices relative to earnings, others are based on cash flow, a company’s underlying assets or the total value of the market. But they tell a pretty consistent story right now. Stocks, which were fabulously expensive for much of the 1990s and this decade, no longer are.
　　My favorite measure is the one recommended by Benjamin Graham and David L. Dodd, in their classic 1934 textbook, “Security Analysis.” They urged investors to use a price-to-earnings ratio — stock prices divided by average annual corporate earnings — based on at least five years of earnings and, ideally, closer to 10. Corporate profits may rise or fall in any given year, but a share of stock is a claim on a company’s long-term earnings and should be evaluated as such.
　　(Why not use a forecast of future earnings? Because they tend toward the fictional, as we’re now seeing once again.)
　　The 10-year price-to-earnings ratio tells an incredibly consistent story over the last century. It has averaged about 16 over that time. There have been long periods when it stayed above 16 and even shot above 20, like the 1920s, 1960s and recent years. As recently as last October, when other measures suggested the market was reasonably valued, the Graham-Dodd version of the ratio was a disturbing 27. But periods in which the ratio has jumped above 20 have always been followed by steep declines and at least a decade of poor returns.
　　By 1932, the ratio had fallen to 6. In 1982, it was only 7. Then, of course, the market began to self-correct in the other direction, and stocks took off.
　　After Tuesday’s big rally, the ratio was just a shade below 16, or almost equal to its long-run average. This is a little difficult to swallow, I realize. Stocks are down 40 percent since last October, and every experience from the last 25 years suggests they now have to bounce back.
　　But that’s precisely the problem. Since the 1980s, stocks have always bounced back from a loss, usually reaching a high in relatively short order. As a result, the market became enormously overvalued.
　　As Robert Shiller, the economist who specializes in bubbles, points out, human beings tend to put too much weight on recent experiences. We think the market snapbacks of 1987 and the current decade are more meaningful and more predictive than the long slumps of the 1930s, 1940s and 1970s. Of course, anyone who made the same assumption in 1930 or 1975 — this just has to turn around soon — would have had to wait years and years until the investment paid off.
　　Now, Mr. Buffett, Mr. Bogle and their fellow bulls know all this history, and they’re still bullish. (Though I’d be more bullish, too, if I could get the favorable terms that Mr. Buffett did. In exchange for his money and his good name, Goldman Sachs and General Electric each guaranteed him an annual return of at least 10 percent.)
　　So on Tuesday afternoon, I also called Mr. Bogle, the legendary founder of the Vanguard Group, the investment firm whose low-cost index funds have made a lot for a lot of people.
　　He, too, prefers the 10-year price-to-earnings ratio, he said, but he didn’t think that it necessarily had to fall to the same bargain-basement levels it reached in the 1930s and 1970s.
　　You can certainly see why that would be the case. Investors are well aware that the market fell to irrationally low levels during past crises, and they may not allow it to become so cheap this time around.
　　Mr. Bogle also thinks that corporate profits will rebound nicely within a couple of years and likes the fact that interest rates are low. Low rates have often — though not always — accompanied bull markets.
　　But it was his last argument that I think is the main one for most investors to focus on. “I’m not looking for a great bull market,” he said. There are some reasons to be optimistic about stocks, he said, “and I also look at the alternative.”
　　And, really, how attractive are the alternatives? Savings accounts and money market funds will struggle to keep pace with inflation. Bonds may, as well.
　　Stocks, on the other hand, are paying an average dividend of about 3 percent, which is better than the interest on many savings accounts, and stocks are also almost certain to rise over the next couple of decades.
　　If that is your time frame — decades, rather than months or years — this will probably turn out to be a perfectly good buying opportunity. In the shorter term, though, it’s a much tougher call, and it involves a lot more risk.

一些著名的投資家,包括沃倫.巴菲特,約翰.博格,公開表示,現在是返回股票市場買股票的時候了.雖然他們一如往常,小心翼翼的聲明,他們并不能預知股票的短期走勢.然而,他們透露的基本信息是明確的:股票價格現在很便宜,非理性的恐懼導致了近期市場走低,那些現在買入股票的人必將在今后得意于他們的選擇.
　　本周二股市大漲11%,使上述觀點輕易找到了論據.
　　但另外一種觀點較之以前更值得注意.這就是依然看空市場.觀點不是簡單建立在國家經濟將滑向另一場衰退的恐懼的情感上,也不是源自于對未知的極度擔憂.看空的觀點同樣建立在數據與歷史的分析基礎上,至少,它的論據并不比看多觀點的少.
　　看空者的部分看法如下:歷史上看,一個巨大的經濟泡沫的破裂后,需要經歷20年的經濟低迷期.以過去20年的數據看,股票價格確實比較便宜.但如果你在更長的歷史周期上觀察,你發現股價相對于公司贏利的比率只是略低于長期平均水平.回顧過去的經濟危機----比如說發生于上世紀30年代和70年代的--- -那時的股價在反轉前遠遠低于長期平均水平.
　　情況更糟的是,公司贏利水平開始惡化,如果假設贏利持續減少,股價也必須降低以維持當前的市盈率數值.
　　就在周二股市暴漲的時候,我致電James Melcher ,卻聽到了大堆有事實根據的看空理由.Melcher 先生是紐約的一家對沖基金,Balestra資本的主席,他曾經在2年前發文給他的客戶,預測出金融危機可能情形(隨后他又以此預測調整了Balestra的投資組合).如鼓勵買股票的那些投資大家一樣,他也認為沒人能預測股市的短期走向.但他補充道:"現在認為股價很便宜是不明智的."
　　James Melcher 說道:"在過去20年中----尤其是過去6,7年----我們面臨流動性泛濫,消費者大量舉債,寬松的借貸標準,銀行體系中不良機制,避險基金與投資銀行的興起,使華爾街大大提高了負債杠桿.負債刺激了經濟,提高了股票回報."
　　"這是好的一面,"James Melcher 說,"問題在于所有的債務可能在同一時間到期."他認為股價很可能再跌20%,并且在見底前比現在下降35%.
　　看多與看空,誰是對的? Melcher ,Bogle,還有巴菲特,都是業界中的智者,他們的結論都經過認真的分析.當你深入他們的討論,你會發現他們之間的分析并無太多的不同.然而卻提出相反的觀點.這就需要我們花點時間來研究一下歷史數據了.
　　給股票估值有很多方法.有人用價格與盈利指標,有人用現金流折現,還有人考慮公司隱藏或低估的資產,或是公司市值.但現在使用那些方法只能如以前一樣描述動人的故事.股價再不可能象上世紀九十年代與最近十年所經歷的一樣,不切實際的高高在上.
　　我個人喜好的一個衡量指標是,本杰明.格雷翰姆和考(試*大戴維.多德在他們經典的1934年出版的教材<<證券分析>>里介紹的市盈率- ---股票價格除以過去5年的公司盈利平均值,計算的市盈率如果接近10,則是比較合理的.公司的利潤水平在某些年份可能升也可能降,但股權是對公司長期盈利的分配要求,因此應該以平均的盈利水平來評估股價高低與否.(為什么不用預測的盈利數據計算市盈率?因為我們發現,那將可能導致數字的編造游戲)
　　以10年為周期的市盈率難以置信的揭示了一個世紀來的股市長期走勢.在上世紀,市盈率的平均值是16,但有很長一段時間數值超過了16,甚至短時間內還大于20,如在上世紀的20年代,60年代和最近幾年.就在去年10月,其他指標還顯示股市還處于合理估值狀態,格雷翰姆--多德指標卻達到了令人不安的 27.如果一段時間內,市盈率超過20,伴隨而來的情況是股市急劇回調,同時,至少在以后的10年內,投資回報都很差.
　　長期市盈率在1932年回落到6,1982年達到7,這之后,股市開始自我修正,股價反轉拉升.
　　就在本周二的暴漲后,市盈率率低于長期均值16.這有點難以相信.股市從去年10月算起,已經下跌了40%,25年以來的經驗也提示應該發生反彈了.但問題在于.自1980年以來,股價經常在略微下跌后就開始反彈,短期下跌后又創下新高,于是,整個市場已經嚴重高估了.
　　就如專門研究泡沫經濟的經濟學家羅伯特.席勒所言,人類更傾向于依據近期的經驗來做決策.于是我們很容易預測股市就如1987年或最近的10年中發生的一樣,很快就發生反彈,而不是類似二十世紀30,40,70年代經歷漫長的低迷.當然,那些在1930年或1975年里認為股市即將轉好的人,不得不等待很長的時間才讓投資回本.
　　巴菲特與博格先生與其他唱多者都了解證券歷史,但是他們還是看好后市.(如果我有巴菲特那樣的優惠的交易條件,我也許比他們更愿意唱多市場.在高盛與通用電器的交易中,為了獲得資金與巴菲特個人良好的聲譽,兩家公司都承諾每年給巴菲特至少10%的回報.)于是我在周二下午電話詢問富有傳奇色彩的先鋒集團的創始人博格先生.先鋒集團是一家投資公司,它掌管的低成本指數基金曾為很多人賺取大量財富.
　　博格先生說,他同樣偏好于10年期的市盈率估值,但他考(試^*大不認為,指標要回到1930年或1970年的低值水平才開始購買股票.
　　你肯定能理解為何有這樣的結論.投資者都充分意識到在以前的金融危機中市場曾跌到非理性的低價水平,于是在這次危機中他們可能不會讓類似的低價再次出現.
　　博格先生同時認為,企業盈利水平在今后幾年中很快得到恢復,他還注意到當前的利率水平很低.低利率經常伴隨著牛市的出現----盡管不一定每次都是如此.
　　另外,要考慮其他的投資選擇是否真正具有吸引力?儲蓄,貨幣基金,以及債券,都必須要考慮抵消通漲的影響.而投資股票,平均能獲得大約3%的股息率,超過了儲蓄存款利率.而且就以后的幾十年來說,股價的增長幾乎是確定的.
　　如果你的投資期限放長到十年幾十年,而不是幾個月或幾年,那么,現在可能是極好的買入機會.然而就短期而言,現在選擇買入,結果可能很糟糕,同時還面臨更大的投資風險.