Gartner has released a preliminary report detailing U.S. and worldwide PC shipments for the first quarter of 2009. The report pegs Apple's U.S. market share in fourth place among vendors at 7.4%, down from 8.0% in the fourth quarter of 2008. More importantly, the report shows a slight decline in market share over the year-ago quarter, when Apple held 7.5% market share.

Apple's U.S. Market Share Trend: 1Q06-1Q09 (Gartner)
Apple's U.S. computer shipments showed a 1.1% decline over the year-ago quarter, compared to an overall U.S. industry decline of 0.3%. Gartner notes that the overall PC market performed better than expected, due in significant part to strong sales of "mini notebooks" or netbooks, a market segment in which Apple does not currently compete. Gartner also suggests that the average selling price of computers sold in the first quarter of 2009 may have shrunk as much as 20% due to this explosion in netbook sales. Consequently, while Apple's market share has apparently slipped, its gross revenue and profits are likely to have held up better than the industry average.
Also of note, HP was able to pass Dell for the top spot among U.S. PC shipments, taking that position for the first time since 2001.

Gartner's Preliminary U.S. PC Vendor Unit Shipment Estimates for 1Q09 (Thousands of Units)
IDC has released a similar report showing Apple with 7.6% market share and a decline in U.S. sales of 1.2% over the year-ago quarter. IDC's numbers, however, are showing a slightly steeper decline in U.S. sales for the overall PC market at 3.1%. Apple remains unable to break into the top five vendors for worldwide PC shipments in either survey, with Toshiba continuing to hold the fifth spot with approximately 5.5% market share, a significant bump over their previous numbers.