苹果过去三周的股价就像在玩翘翘板，先是涨到644美元，然后跌到555美元，又涨到618美元，然后跌至581美元。投资者可能很想知道，苹果的股价的涨跌是否会有一个下限。

    为了给大家提供一些指导，我们请金融刊物”Bullish Cross”的分析师安迪•扎基更新了他去年为一篇文章配的两幅苹果股价走势图，这两幅图表原载于他去年11月发表的文章《苹果：最被低估的美国大盘股》中。

    右侧的两幅柱状图经更新后反映了苹果公司最新的财务季报，它将苹果公司收益的指数级增长，与按历史市盈率得出的股票价值的稳定下跌进行了对比。

    上方的图表表明，苹果连续12个月的每股收益大约环比上涨一倍（比如从2011年4月的20.98美元上涨至2012年4月的41.04美元）。

    下方图表表明，苹果股票的价值（这里的价值指的是它的市盈率，不要把它与苹果的股价混淆了）从2007年第四季度高达50.98的水平，降到了2012年第二季度12.62的低位。

    这种现象被叫做“压缩”，苹果的投资者一直在抱怨这个问题。他们喜欢把苹果的市盈率与亚马逊（Amazon）进行比较。

    去年苹果的营收入增长速度几乎达到了亚马逊的两倍。但苹果本周的股价还不到每股收益的14.3倍。假如苹果的市盈率可以达到亚马逊的水平（即每股收益的190倍），那么现在苹果的每股价格可能会达到7800美元以上。

    不过把任何股价与亚马逊对比，都只能让你头疼。

    扎基认为，苹果的市盈率能“压缩”到什么水平，看来是有一个极限的。“从苹果最近的历史来看，它的市盈率只有两次下降到了12.6的水平，”他说：“一次是经济危机期间，一次是现在。而且每次它都导致了一轮大规模的重新估值。”  

    Watching Apple's (AAPL) share price see-saw over the past three weeks -- up to $644, down to $555, up to $618, down to $581 -- investors might well wonder whether there's any limit to how high or, more to the point these days, how low the stock can go.

    To set some guidelines, we asked Bullish Cross' Andy Zaky to freshen a pair of charts he posted last November for an article entitled Apple: The Most Undervalued Large-Cap Stock in America.

    The bar graphs at right, updated to reflect the most recent quarterly report, contrast the exponential increase in Apple's earning with the steady decline in the value of its stock as measured by its trailing price-to-earnings ratio (P/E).

    The top chart shows Apple's twelve month trailing (TTM) earnings roughly doubling year-over-year (from $20.98 in April 2011, for example, to $41.04 in April 2012).

    The bottom chart shows its stock's value (its P/E, not to be confused with its stock price) falling from as high as 50.98 in Q4 2007 to as low as 12.62 in Q2 2012.

    This is called "compression," and you hear Apple investors complaining about it all the time. They like to contrast Apple's P/E ratio to Amazon's (AMZN).

    Apple's revenues grew nearly twice as fast as Amazon's last year. But Apple's stock is trading this week at less than 14.3 times earning. If it were trading, as Amazon does, at 190 times earnings, it would selling for more than $7,800 a share.

    But comparing any stock with Amazon buys you nothing but heartache.

    Zaky's point is that there seems to be a limit to how much Apple's P/E can be compressed. "In its recent history, it went to 12.6 only twice," he says. "During the financial crisis and now. And each time it led to a massive reevaluation."