Mac sales plummeted in the fourth quarter of 2012, falling 22% from the same period the year before, with computer sales accounting for a record low percentage of Apple's total revenue of $54.5 billion.
The decline in Mac sales was substantially greater than the global personal computer industry average, which research firm IDC recently pegged at minus 6.4% year-over-year.
Apple CEO Tim Cook attributed the downturn in Mac fortunes to a slew of factors, including short supplies of the new iMac and cannibalization of its computers by the iPad.
Apple sold slightly less than 4.1 million Macs during the three months ending Dec. 31, down from both the 5.2 million it sold in the fourth quarter of 2011 and the 4.9 million sold in 2012's third quarter.
Last October, Apple had warned that Mac sales would suffer in the fourth quarter because of a late arrival of new iMacs introduced that month. Today, those desktop machines remain in short supply, with shipping delays ranging from two to three weeks for the 21.5-in. model, Apple's most popular, to three to four weeks for the pricier 27-in. system.
Apple did not start selling the smaller iMac until Nov. 30, over a month after its unveiling in a major Mac refresh that also introduced a new 13-in. MacBook Pro laptop with a higher-resolution Retina screen.
The 27-in. iMac did not go on sale until mid-December, and has been in even shorter supply than its sibling.
Because Apple stopped selling the previous generation iMacs in late October, it essentially left the desktop line swinging in the wind during most of the quarter.
Definitive sales numbers for the iMac in the quarter were unavailable, as Apple broke with precedent and lumped both desktops and notebooks into a single "Mac" figure rather than listing them separately.
But in a question-and-answer session during Wednesday's earning call, CEO Cook said that iMac sales were down 700,000 units over the same period last year because of the supply snafu. Although he didn't explain what caused the shortages -- speculation has highlighted the display and the case, both of which rely on new manufacturing methods -- Cook chided analysts for not remembering his October warning.
"I said that we would have significant constraints on iMacs, but I recognize to some folks this may be a surprise," said Cook.
The 700,000 in lost unit sales cost Apple nearly a billion dollars in revenue, using the average selling price (ASP) of the company's desktops during 2012's third quarter.
Yet the missing iMac sales couldn't account for all of the Mac shortfall, something Cook himself acknowledged.
He cited the fact that 2011's fourth quarter included 14 weeks, while 2012's had thirteen, and again admitted that Macs, like PCs, have been affected by the trend of consumers diverting dollars from personal computers to other devices -- tablets in particular.