The Dow Jones Industrial Average has hit an all-time high, as anybody who has seen the headlines splashed across the front of this and many other newspapers will know. But should we care about this landmark? 道琼斯工业平均指数(Dow Jones Industrial Average)创下空前高点，英国《金融时报》和其他很多报纸都在头版进行了铺天盖地的报道，看过的人都知道了这一点。但我们是否应在意这个里程碑式的事件？

No. The Dow’s methodological flaws are overwhelming and there is no reason for anyone to follow it. That it still generates so much attention is attributable to inertia and groupthink. What is the problem with the Dow? As an index of only 30 stocks, the Dow is not broadly diversified and is not representative of the US stock market as a whole (the S and P 500, the world’s most widely followed index, is better for that purpose). Its stocks are not uniformly large enough to qualify as a “mega-cap” index, varying from Alcoa ($9bn) to ExxonMobil ($399bn). Try the Russell Top 50 instead. Neither, despite the name, is it a true industrial index (the S and P 500 industrials sub-index might be better). 不应该。道指的计算方法存在很大缺陷，任何人都没有理由跟踪这一指数。但它仍引起很多人的关注，这要归因于惯性和团体迷思(groupthink)。道指存在什么问题？作为一个仅仅包括30只股票的指数，道指没有实现广泛多样化，也不能代表整个美国股市（人们最普遍跟踪的是标准普尔500指数(S and P 500)，它更能代表整个美国股市）。道指成分股的市值并非都大到了符合“超级大盘”指数的规模，而是从美国铝业(Alcoa)的90亿美元到埃克森美孚(ExxonMobil)的3990亿美元不等。不如试试罗素50指数(the Russell Top 50 index)吧。尽管名称中有“工业”字眼，但道指也不是一个真正的工业指数（标准普尔500指数的工业分类指数或许更名副其实）。

Crucially, the Dow’s illogically chosen members are weighted by their share price, rather than their market valuation. This means companies that happen to have a high share price can outweigh larger companies with a lower price per share. This is ludicrous. For example. IBM now accounts for 11.1 per cent of the Dow, and has a market value of $228.7bn. ExxonMobil, back as the world’s largest company following the decline of Apple (never a Dow member), has a market cap of $398.5bn, but a Dow weighting of only 4.8 per cent. Microsoft, a slightly larger company than IBM these days at $235.8bn, accounts for only 1.5 per cent of the Dow. Meanwhile, Caterpillar outweighs both ExxonMobil and Microsoft, despite having a market value of only $58.8bn. 一个重要问题是，道指不合理挑选的成分股是根据股价（而非市值）加权的。这意味着，碰巧股价处于高位的公司的权重，可能会超过市值较高但股价较低的公司。这很荒谬。例如，IBM现在在道指中的权重为11.1%，市值为2287亿美元。在苹果（Apple，从来不是道指成分股）市值下降后重新回归全球市值最高公司宝座的埃克森美孚市值为3985亿美元，但在道指中的权重仅为4.8%。规模略高于IBM的微软(Microsoft)最近市值为2358亿美元，在道指中权重仅为1.5%。同时，卡特彼勒(Caterpillar)的权重超过埃克森美孚和微软，但市值仅为588亿美元。

Since the Dow hit bottom in March 2009, Caterpillar has accounted for 515 extra points on the Dow, while growing its market value by $44bn. Meanwhile Microsoft has grown by almost exactly $100bn; and contributed 102 points to the Dow. The Dow’s defenders point out that it correlates closely with the S and P 500, which is itself very close to an all-time high. But that merely cedes the point that it is the S and P that is worth watching. 自从道指在2009年3月触底以来，卡特彼勒为道指贡献了515点，市值扩大440亿美元。与此同时，微软市值扩大了几乎正好1000亿美元；为道指贡献了102点。为道指辩护的人指出，它与标普500指数紧密相关，而后者也非常接近空前高点。但这只是承认了，标普500指数才值得关注。

They also point out that the Dow was the first attempt to create an index for the stock market, it has been continuously calculated for longer than any other, and thus it still has historical interest. Long-run data are critical for establishing patterns in the stock market. 他们还指出，道指是全球第一项为股市创建指数的尝试，它被持续计算的时间超过其他任何一个指数，因此它仍具有历史意义。长期数据对于建立股市模型至关重要。

That argument was once valid, but in recent years the work of financial historians on both sides of the Atlantic has invalidated it. Economists such as Robert Shiller in the US, or Elroy Dimson, Paul Marsh and Mike Staunton in the UK, have built broader indices of the US stock market that go back into the 19th century. Technically, they are more robust than the Dow. There is no reason for the Dow to exert such a thrall. Just look at the FTSE 30 index, devised by this paper as an index of UK stocks, launched in 1935, and for decades the most widely cited UK stock index. The FTSE 30 is still calculated, received a revamp in 2011 and is still published daily in the Financial Times. But the FT Actuaries index, established in 1962, and then the FT 100, introduced in 1984, have long since superseded it. 这种理由一度很充分，但近年来，大西洋两岸金融历史学家的工作推翻了这种理由。不管是美国的罗伯特•席勒(Robert Shiller)，抑或英国的埃罗依•迪姆森(Elroy Dimson)、保罗•马什(Paul Marsh)和迈克•斯丹顿(Mike Staunton)等经济学家，都为美国股市构建了更加广泛的指数，可以追溯到19世纪。从技术上讲，这些指数比道指更加强健。道指不应产生如此强大的影响力。看看富时30指数(FTSE 30)的命运。该指数由英国《金融时报》设计，是衡量英国股市的指数，于1935年推出，在数十年的时间里一度是广为引用的英国股指。如今富时30指数依然得以计算，并于2011年进行了修订，英国《金融时报》依然每日发布该指数。但1962年设立的英国《金融时报》精算指数(FT Actuaries)，以及1984年推出的富时100指数(FTSE 100)，早已超过了它。

Milestones for the FTSE 30 now go unreported, even by the FT. No money is tied to it, as it is plainly a gauge of UK business and a historical vehicle rather than an investment tool. This is for the good reason that an index of 30 large UK companies, given the current scale of the London market, is an obvious anachronism. 如今，即便是英国《金融时报》，也不报道富时30指数的里程碑事件。富时30指数与金钱无关，因为它只是用来衡量英国企业的指标，一项历史工具，而不是投资工具。这是因为，与伦敦市场的现有规模相比，这项包含30家大型英国企业的指数，显然已经过时了。

As the FTSE 30 is currently down 42 per cent from a high set in the summer of 1999, it tells a radically different story from the FTSE 100, which is 4.1 per cent below a high set in 2007. But newspapers and stockbrokers alike have moved on to watch a benchmark that was more relevant instead. For now, different media outlets feel compelled to treat the Dow as news because their competitors all do. But given only a little courage and dispassionate thinking, there is no reason why the Dow should not suffer the same fate as the FTSE 30. 富时30指数已经从1999年夏季的最高点下跌了42%，其经历与富时100指数截然不同。与2007年的最高点相比，富时100指数只下跌了4.1%。但报纸与股票经纪商都转而关注一项更加重要的基准了。现在，各媒体渠道都感到不得不把道指当成新闻，因为它们的竞争对手都这么做。但只需稍微勇敢一点，冷静思考一下，人们就该认识到，道指没有理由不重蹈富时30指数的命运。

There is a separate question, which is harder to answer. By robust measures such as the S and P, US equity markets are almost back to their highs of 2007 and could get there any day. This is a remarkably swift recovery from the 2007-09 implosion. It is also a remarkable disconnect, with the rest of the world and with most perceptions of the health of the US economy. How did this happen? 另外还有一个问题更难以回答。按照标普等更加强健的标准衡量，美国股市几乎重返2007年的高峰，随时都可能达到顶点。其从2007-09年的溃败中恢复的速度之快令人瞠目。这也显然与世界其他地区以及多数人对美国经济健康程度的看法脱节。怎么会出现这种情况？

The Dow does not help answer this question. But as market perceptions can be self-fulfilling, attention to the Dow may have egged on the animal spirits that are pushing US stocks higher and fuelled that underlying disconnect. It really would be best if everyone could get used to ignoring the Dow. 道指无助于回答这个问题。但由于市场看法会自我应验，对道指的关注可能推动了市场中的动物本能，进而推高了美国股市，并加剧了背后的脱节问题。如果所有人都能习惯于忽视道指，那就最好不过了。