Is Apple's MacBook Air the reason for a shortfall of ultrabook sales? IDC analyst Jay Chou hints that it could be a factor.

"The MacBook Air is a good part of Apple's business. It's had good growth," Chou told Cnet.

According to Apple, it shipped 2.8 million MacBooks worldwide in Q2. In contrast only 500,000 ultrabooks were sold by PC manufacturers. While that 2.8 million figure also includes MacBook Pro sales, Chou seems confident that a big chunk of the sales were of the MacBook Air. Which would suggest that Apple's ultrabook equivalent is selling more than all the PC ultrabooks combined.

Intel had high hopes for the ultrabook segment. At the beginning of 2012, Intel had suggested that ultrabooks could take 40 per cent of the consumer laptop market. Chou thinks that there may be a million ultrabooks sold by the end of the year, but given that IDC expects about 225 million laptops to ship by the end of 2012, a million would be a tiny fraction of that market.

"The future really lies in 2013 and how well it jells with Windows 8," Chou said, suggesting that the reason for the lack of sales is the fact that shoppers are putting off buying the slimmed down models while they await news of Windows 8.

Price is another factor, and now that cheaper ultrabooks are hitting the market, there may be an uplift in sales.

Overall, PC sales in the second quarter of 2012 fell by 0.1 percent year-over-year, while Apple is the only company increasing PC sales, according to Gartner.

Related:

Why ultrabook sales have flopped
Apple only company increasing PC sales, Gartner
'Strong iPad demand is negatively affecting Mac sales' - analyst