仍然看好股票牛市的投资者都是在玩火。因为熊市的警告信号已经出现，它就像沙漠中的火花一样脆弱。
最大的警示来源于“高低逻辑指数”。Norman Fosback于1979年创立了该指数，随后由经济研究协会主席及现任Fosback基金预报的编辑加以完善。该指标描述的是纽约证券交易所两组数据中较小的值，这两组数据指的是52周新高和52周新低（都用所占交易量的百分比来表示）。
因此，该指数可以解决内部市场分歧。Fosback在他的投资教程《股票市场逻辑》中说明了原因：“在常规状况下，大量交易要么创下新高，要么创下新低，两者不会同时发生。一个健康的市场需要内部统一。”
通过这一方法可以判断出，当前的股票市场一点也不健康，10周移动均线达到了5.7%，已经高出了很多研究者的卖出信号阀值。（以Fosback为例，他的阀值是5%，他认为超过这个阀值就预示着“极端市场分歧…甚至熊市”。Ned Davis研究、Venice研究以及弗罗里达研究公司的阀值是4.4%。）高低逻辑指数显示出了这么危险的信号，为什么没人在意呢？原因有二：
首先，该指数更善于追踪长期趋势而不是短期区间，而且它的信号不够成熟。举例来讲，在2007年-2009年的熊市之前，自十月起，高低逻辑指数打破了六月底的五个阀值。所以一些人虽然担心高低逻辑指数，但仍要等到其他指数确认之后才会采取行动。
另一个原因是该指数在2013年给出了一系列错误信号。如图所示，该值在2013年夏天已经涨到了6%，但牛市根本没有结束。
你也可以看出高低逻辑指数在去年年底攀升得更高，在12月底达到了6.9%。虽然我现在知道道琼斯指数下跌了，但那时谁也不知道这是否仍是个错误信号。
Leuthold 集团的投资总监Doug Ramsey特别担心高低逻辑指数传递出的消息。他指出，几年前错误信号占据主流位置，而当前的纳斯达克市场却有着极大的分歧。
事实上，Ramsey指出，自2007年起，纳斯达克版本的高低逻辑指数首次超过了“卖出”阀值。我不会告诉你那时发生了什么。
Opinion: Stock market bulls are playing with fire
Published: Aug 18, 2015 5:15 a.m. ET
CHAPEL HILL, N.C. (MarketWatch) — Investors who are giving the bull market in stocks the benefit of the doubt are playing with fire. That’s because the bear market’s warning signals have created a situation as vulnerable to the slightest spark as a parched desert.
The latest warning comes from the so-called High-Low Logic Index. That well-regarded indicator was created by Norman Fosback in 1979, then the president of the Institute for Econometric Research, and currently editor of Fosback’s Fund Forecaster. The index represents the lesser of two numbers
The indicator, therefore, is a measure of internal market divergences. In his investment textbook “Stock Market Logic,” Fosback reasoned: “Under normal conditions, either a substantial number of stocks establish new annual highs or a large number set new lows — but not both. ... A healthy market requires some semblance of internal uniformity.”
By this measure, the current stock market is anything but healthy. The 10-week moving average of weekly readings recently rose to 5.7%, well above the level that many researchers use as the threshold for a “sell” signal. (Fosback, for example, set this threshold at 5%, considering readings above that level as evidence of “extreme market divergence and ... bearish.” The threshold employed by Ned Davis Research, the Venice, Florida-based research firm, is 4.4%.)
Why hasn’t this dangerously lofty level of the High Low Logic Index received more attention? There are at least two reasons.
The first: The index has a better track record over longer, rather than shorter, spans, and its signals can be premature. Prior to the 2007-2009 bear market, for example, which began in October, the High Low Logic Index breached the 5 threshold in late July. So it’s possible that some of the bulls are worried about the High Low Logic Index but are waiting for confirmation from other indicators before pulling some of their chips off the table.
The other reason that some are ignoring these latest warnings is that the index gave a number of false signals in 2013. As you can see from the accompanying chart, in fact, it rose to near 6 in the summer of 2013. (I wrote a column reporting its dangerously high level in August of that year.) Needless to say, the bull market didn’t soon come to an end.
You’ll also notice from the chart that the High Low Logic Index rose to an even higher level at the end of last year — hitting 6.9 in late December. It’s too early to know whether that, too, will prove to be a false signal, though I would note that the Dow Jones Industrial Average is lower today than it was then.
One adviser who is particularly worried about the message of the High Low Logic Index is Doug Ramsey, Chief Investment Officer of The Leuthold Group. He points out that, unlike the situation that prevailed on the occasion of those false signals a couple of years ago, this time around there also is extreme divergence in the Nasdaq market, in particular.
In fact, Ramsey reports that a Nasdaq-only version of the High Low Logic Index just rose above its “sell” threshold for the first time since 2007. I need not remind you what happened at that time.
本文翻译由兄弟财经提供
文章来源：http://www.marketwatch.com/story/stock-market-bulls-are-playing-with-fire-2015-08-18