Apple posted 20.7 percent growth year-on-year in the US PC market in the last quarter of 2011, according to figures from Gartner .

It sold 2,074,800 units in the fourth quarter of 2011, giving it a market share of 11.6 percent and putting it behind only HP and Dell, overtaking Toshiba and Acer.

The sales represent 20.7 percent growth on the 1,718,400 units it sold in Q4 2010, when its 9 percent share of the market was only enough to make it the fifth-largest player in the US PC sphere.

Overall, though, PC sales in the US declined, with shipments totalling 17.9 million units, a 5.9 percent decline compared with the same quarter last year.

For the year, worldwide PC shipments totaled 352.8 million units in 2011, a 0.5 percent increase from 2010. Gartner's figures don't include tablet PCs, so sales of the iPad were not counted. 

The report largely agrees with figures published this week by rival market research firm IDC, who said that about 352.4 million PCs were shipped, a 1.6 percent increase over 2010, when almost 346.8 million PCs were shipped.

Gartner said that the HDD shortage caused by floods in Thailand had a "limited" impact on fourth-quarter PC shipments and prices. 
However, it expects that a major impact will be felt in the first half of 2012 and will potentially continue throughout 2012.