Why Apple's shares rose as its market share shrank

On Wednesday, Gartner Research reported that Apple's (AAPL) share of the U.S. computer market, which topped 9% in calendar Q3 last year, dropped to 7.4% in Q1 2009 -- putting it in fourth place behind HP (HPQ), Dell (DELL) and Acer.

The next day, Apple's share price rose nearly 2% to finish Thursday at $121.45, its highest close in six months.

Why the disconnect? Chalk it up to the ASPs.

As Gartner's Mikako Kitagawa notes, sales for Apple's competitors are being driven by the explosion of interest in low-cost netbooks -- not just among penny-pinching consumers, but in the professional and education markets as well.

As result, Gartner estimates that average selling prices (ASPs) for computers sold in the first quarter may have fallen as much as 20% across the board -- cutting sharply into PC makers' revenues.

Except at Apple. Despite rumors that its engineers may be working on some kind of device with a 10-inch screen, the company has so far shown zero interest in duking it out with the likes of Acer and Asus in the bargain basement mini-notebook market.

So even as Apple's market share shrinks, its margins and gross revenue are likely to have held up better than any of its competitors.

Moreover, while Gartner's Ms. Kitagawa is seeing signs of channel inventory restocking at other companies -- evidence that the global PC market has not yet hit bottom -- she singles out Apple's "deft control of inventories [which] limited its shipment decline."

All this -- and a flood of deferred iPhone earnings -- may help explain why analysts are scrambling to raise their Apple price targets (and talking up the stock) in advance of the company's fiscal Q2 earnings report next Wednesday, April 22.

Below the fold: Gartner's preliminary estimates of domestic PC shipments for Q1 2009.