Apple might not share its Apple Watch unit sales numbers, but a market researcher has put an estimate on its record-setting fourth quarter.
The tech giant sold 6 million Apple Watch units worldwide during the fourth quarter, according to research firm Canalys. Apple Watch unit sales were up 12% year over year, according to the research firm. In total, 9 million smartwatches were sold worldwide during the period.
Apple released its Apple Watch smartwatch in 2015 and updated it with a new processor and GPS support last year. The smartwatch integrates with iOS and can display notifications like text messages. Apple Watch can also be used to make calls and supports third-party applications.
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While Apple (aapl) has said that its smartwatch is popular, the company has never revealed actual sales figures. Apple CEO Tim Cook has argued that sharing sales figures could help competitors—a claim at which some analysts have scoffed.
The company has, however, dropped hints about its Apple Watch's sales. In an announcement about its last fiscal quarter ended Dec. 31, for instance, Apple said that Apple Watch sales hit an all-time high during the period—but it didn't share actual sales figures.
Apple's unwillingness to share sales results has forced market researchers and analysts to make educated guesses about Apple Watch sales. Those guesses, like the latest from Canalys, are based upon analyses of retail sales data, supply checks, and other measures.
In addition to estimating Apple's unit sales, Canalys said in its report that it estimates Apple Watch sales exceeded $2.6 billion in the fourth quarter and accounted for 80% of the smartwatch market's total revenue. For all of 2016, Canalys estimates Apple sold 11.9 million Apple Watch units, giving it 49% market share on the year.
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Beyond Apple, Canalys said that Fitbit (fit) was the second-most-popular smartwatch maker last year with 17% market share. Apple's chief rival in the smartphone market, Samsung, came in third place with 15% market share.
Looking ahead, Canalys isn't convinced that Apple will be able to keep up its smartwatch market lead.
"In the coming quarters, Samsung is expected to push shipments of its Gear S3 Classic and Frontier," Canalys said, referring to Samsung's upcoming smartwatches. "Apple's smartwatch lead will increasingly be challenged by the rebounding competition."