美国投资银行Needham的查理•伍尔夫跟踪苹果（Apple）公司多年，一直关注Mac电脑的销售业绩*。Mac电脑是苹果公司历史最悠久的一条产品线，截至今年一月，Mac在市场上已经盘踞了30个年头。本周二，伍尔夫表示，Mac（的销量）似乎已经“一落千丈”。同时，他还尝试解释了出现这种情况的原因。

    自2005年开始，连续26个季度，Mac电脑的销量增长都超过行业的总体增长率。几乎在同一时期，苹果在全球个人电脑市场的份额在7年半内从2.1%增至5.3%（涨幅达152%），而它获得的利润占全球市场利润总额的比例也从3.2%增加到11.9%（涨幅高达272%）。

    但好景在今年1月嘎然而止。由于苹果未能提供足够的最新款iMac电脑，市场上出现了供不应求的局面。该季度Mac电脑销量下降了22.1％，而同期全球个人电脑总销量降幅只有6.6％。

    因此，在本文所附的图表中，2012年四季度Mac的发货量呈现V字形。蒂姆•库克也承认，这次确实是搞砸了。不过，对于这次偶发事件，伍尔夫倒不大担心，他担心的是这次事件前后几个季度的销售情况。

    目前，Mac的销售情况仍然优于整个市场的表现，但也只是勉强好一点，而且它的销量也在下降，只不过下降得比其他公司缓慢一点。

    个人电脑销量下降的原因已经不是什么秘密。这个市场基本已经饱和，而且用户大都将购买新品的预算花到了智能手机和平板电脑上。

    比较难以解释的是，Mac此前的销量增速比业界平均水平要高出20%到30%，为什么现在他销量下降的速度几乎与平均水平一致。

    伍尔夫承认，对于这个问题，他也没有现成的答案，不过，他提供了两种理论：

    • 光环效应减退。本文所附图表中，倒V字形表明光环效应最强的时期。彼时正值Windows用户纷纷到苹果商店选购iPod、iPhone或是iPad，使得Mac的销量也因此水涨船高。伍尔夫写道：“Mac最初是靠苹果公司其它产品的光环效应打开市场。但最终令Mac大卖的还是这个产品自身的优势，包括易于使用、出色的设计，以及苹果商店免费提供售后支持等。”不过，情况现在正在发生变化。伍尔夫说：“这种光环效应可能已经开始减退。iPad的出现对Mac销量的影响要大于对个人电脑销量的影响……那些前往苹果商店购买Mac的顾客，可能最终转而购买了iPad。”          

    Needham's Charlie Wolf has been following Apple (AAPL) long enough to still care what's happening to the Mac,* and on Tuesday he took a crack at explaining why the company's most venerable product line (it turns 30 in January) seems to have, as he puts it, "fallen back to earth."

    Beginning in 2005, and for 26 quarters in a row, Mac sales outgrew the industry -- nearly coinciding with a 7.5-year stretch in which Apple's share of the worldwide PC market increased from 2.1% to 5.3% (152%) and its revenue share rose from 3.2% to 11.9% (272%).

    That streak ended abruptly in January, when Apple couldn't deliver the newest iMacs in sufficient quantities to meet demand. Mac sales fell 22.1% in a quarter in which the broader market fell 6.6%.

    Wolf is less concerned with that one-time event -- which Tim Cook admitted was a screw-up and which appears in the attached chart as a sharp V at calendar Q4 2012 -- as he is with what happened for several quarters before and after.

    The Mac is still outpacing the industry, but just barely and only because its sales are falling more slowly than everybody else's.

    Why PC sales growth has collapsed is no mystery. The market is largely saturated and most of the money for new purchases is being funneled into smartphones and tablets.

    Harder to explain is why the Mac, which used to outgrow the industry by 20% to 30%, is now shrinking at nearly the same rate.

    Wolf confesses that he has no "ready explanation," but he does offer a couple of theories:

    • Fading halo effect. The big spikes in the attached chart represent the full force of the so-called halo effect by which the Mac benefitted from Windows users coming into Apple Stores to buy first the iPod, then the iPhone and iPad. "While the halo effect opened the door," Wolf writes, "we believe the superiority of Macs in ease of use, design and in free post-sale support in the Apple Stores blew the door off." That's changing now, he suggests. "It's possible that the halo effect has lost some of its luster in the sense that the emergence of the iPad has impacted Mac sales more than PC sales... Customers who visited an Apple Store to buy a Mac might have been swayed to buy an iPad instead."