For months we've witnessed Apple (NASDAQ:AAPL) defy industry norms by growing even as the rest of the PC market fell. No longer. Depending on whose data you trust, the Mac maker saw U.S. sales fall between 6% and 7% year over year during the third quarter

Lenovo -- the Chinese computer maker that took over IBM's (NYSE:IBM) PC business in 2005 -- was the lone grower, improving sales by at least 6% over last year's Q3.

Don't take that to mean Apple did poorly. Quite the contrary: The Mac maker added about a point of market share over the past year and now ranks as the third-largest PC supplier to the U.S. market, according to data compiled by researchers Gartner and IDC. Lenovo ranks fourth domestically, and is vying for the top spot worldwide.

Not surprisingly, Dell (NASDAQ:DELL.DL) and Hewlett-Packard (NYSE:HPQ) appear to have suffered the most from Apple and Lenovo's rise. What's interesting is that the situation may be even worse than the numbers suggest. Why? The iPad.

Think back to last month, and these comments from Apple CEO Tim Cook at Apple's iPhone 5 launch event: "We sold more iPads [last quarter] than any PC manufacturer sold of their entire PC line."

We won't know Apple's fiscal Q4 iPad sales until the company reports earnings on Oct. 25. But what if comes close to the 17 million Cook bragged of selling during fiscal Q3? Have a look, first at the U.S. data:

Supplier

Gartner Est. Q3 2012 Shipments*

Gartner Est. Q3 2012 Growth (YOY)

IDC Est. Q3 2012 Shipments*

IDC Est. Q3 2012 Growth (YOY)

HP

4,142

(19.3%)

4,293

(18.8%)

Dell

3,271

(15.9%)

3,402

(16%)

Apple

2,079

(6.1%)

2,211

(7.0%)

Lenovo

1,358

6.1%

1,368

9.2%

Acer Group

990

(28.2%)

1,006

(19.6%)

All others

3,478

(10.3%)

4,300

(8.5%)

Sources: Gartner and IDC. *Units in thousands.

Now, here are the worldwide figures. As you can see, ASUS and Lenovo are accelerating in Asia in much the same way Apple had been here in the U.S.:

Supplier

Gartner Est. Q3 2012 Shipments*

Gartner Est. Q3 2012 Growth (YOY) 

IDC Est. Q3 2012 Shipments*

IDC Est. Q3 2012 Growth (YOY) 

Lenovo

13,768

9.8%

13,824

10.2%

HP

13,551

(16.4%)

13,946

(16.4%)

Dell

9,217

(13.7%)

9,499

(14%)

Acer Group

8,633

(10.2%)

8,414

(9.6%)

ASUS

6,381

11.8%

6,381

10.0%

All Others

35,955

(11.6%)

35,732

(12.2%)

Sources: Gartner and IDC. *Units in thousands.

 
This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.