Five days after its release, Apple's new OS X Mavericks had accumulated more usage share than the predecessor Mountain Lion did in five weeks, an ad network claimed today.
Chitika said 11.8% of all Macs accessing clients' ads from the U.S. and Canada were running Mavericks five days after its launch.
In 2012, OS X Mountain Lion needed five weeks to collect a 10.3% share of all North American Macs.
Other Web measurement firms have not corroborated Chitika's data. U.S.-based Net Applications, which breaks out desktop operating systems by versions, publicly discloses only monthly statistics, not daily numbers. Net Applications will issue its October data on Friday.
But last year, just days after Chitika portrayed Mountain Lion's share at 10%, Net Applications said its data put the OS at 20%, hinting that Chitika's recent figure may be underestimating Mavericks' uptake as well.
Unlike previous OS X upgrades, Mavericks is free to all eligible Mac owners, which included those running Mountain Lion, 2011's Lion and 2009's Snow Leopard on machines up to seven years old.
Yesterday, Apple's chief financial officer, Peter Oppenheimer, confirmed that Mavericks will be the first in a line of free operating system upgrades for the Mac. "We're ... making Mavericks and future OS X upgrades ... free to our Mac customers," Oppenheimer said, putting an end to speculation that the Mavericks deal was a one-off (emphasis added).
By freeing Mavericks from a sticker price, Apple hopes that a larger percentage of its customer base will upgrade, reducing OS fragmentation. As in iOS, whose users typically make the newest the default within weeks, the strategy will give OS X developers a bigger target: They can assume most Macs will soon be running Mavericks, and write for that edition to take advantage of its unique features and new APIs (application programming interfaces).
Apple likes to boast about the percentage of iOS users who have upgraded to the newest edition, and did so again last week at the unveiling of new iPad tablets when CEO Tim Cook said that 64% of all iOS devices were already on iOS 7. Cook dubbed it the "biggest, fastest software upgrade ever."
"It blows away the other guys," Cook then added, not speaking the word "Android" but clearly referring to Google's mobile operating system. "It gives our users the latest software so they can enjoy the greatest features and the best-possible experience."
That makes the silence from Apple about the number of Mavericks downloads especially odd. Last year, it trumpeted the sale of 3 million copies of Mountain Lion -- at $19.99 each -- in four days.
Mac owners with suitable systems can download OS X Mavericks from the Mac App Store.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed . His email address is email@example.com.