In its first 24 hours, Apple's OS X Mavericks tripled the uptake of its predecessor Mountain Lion, ending the day on about 1 out of every 18 Macs, an online advertising network said Thursday.
Chitika, which regularly mines its ad impression data for trends in operating system usage, said that Mavericks accounted for 5.5% of OS X in the U.S. and Canada by the end of its first day.
In its first 24 hours, 2012's Mountain Lion reached a share of 1.6%. It took that edition four days to match the first-day uptake of Mavericks, Chitika said in a blog post Thursday.
Chitika made a good bet by crediting Mavericks' zero price for the quick uptake. "While Mountain Lion wasn't particularly expensive ($19.99), it's likely the lack of a price tag on Mavericks spurred additional users to upgrade in the early going," the company said in its Thursday post.
Other Web measurement firms have not corroborated Chitika's data. Irish analytics company StatCounter does not break out individual OS X versions, and U.S.-based Net Applications does not publicly disclose daily numbers. Net Applications will issue its October data in a week.
Mavericks has held the No. 1 spot on the Mac App Store's bestselling free app list since its launch, not surprising after Apple decided to give away the upgrade to customers running Mountain Lion, 2011's Lion and 2009's Snow Leopard on Macs up to six years old.
Although Apple has revealed the number of upgrades downloaded in the past, it has yet to do so for Mavericks. Last year Apple said 3 million copies of Mountain Lion had been sold in the first four days, generating approximately $60 million in revenue, an indication of what Apple left on the table by erasing the price for Mavericks.
A 5.3GB download, Mavericks is available only through Apple's 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, or subscribe to Gregg's RSS feed . His email address is firstname.lastname@example.org.