The U.S. market fared worse than expected in the second quarter shrinking by 10.6% compared to a forecast of -4.4%, according to new data from the IDC research group ( The data says Apple is now in third place among computer vendors with 11.4% market share on shipments of approximately 1.8 million Macs.

That compares to 10.3% market share from the second quarter of 2011 for a decline of 1.1%. HP is in first place with 25.9% market share (with sales down 12% year-over-year) and Dell is is second place with 22.5% (with sales down 9.2% year-over-year). To see how IDC’s results compare with those from the Gartner research group go to .

Most vendors and their channel partners struggled with shrinking demand as a saturated market and lack of incentives are leading buyers to delay purchases of computers for the time being, according to IDC. Among the top-tier leaders, only Lenovo managed to maintain positive momentum by growing its channel reach and being more aggressive against its well established competitors.

However, at +6.1% year-on-year, even Lenovo’s growth decelerated abruptly from the double-digit growth rates of previous quarters, further reflecting slow market conditions in the U.S. Mid-tier vendors struggled even more as they typically rely on a fewer channels than their bigger competitors and therefore remain more sensitive to swings in demand.

Bottom-tier vendors captured marginal demand in local communities and in regional markets; however, they too struggled with a difficult economic environment affecting local public sector entities and small businesses.