The latest numbers come from Counterpoint Research which shows Apple's market share of smartphone sales increasing from 17 percent in August to 39 percent in September. Samsung, the former U.S. smartphone leader, saw its market share drop from 37 percent in August to 29 percent in September.
The Apple iPhone 5S led all smartphone sales in September, followed by the Samsung Galaxy S4 and the iPhone 5C.
"The key reason for this sudden jump in sales can be attributed to the big wave of upgrades due in this launch month from Apple’s huge installed base of iPhone users in US," said Tom Kang, research director at Counterpoint Research. "This depicts a healthy replacement cycle and user base growth trends for Apple despite the array of Android devices launching from tens of OEMs every month."
Still, according to separate data from Gartner, Samsung has more than double Apple's smartphone market share worldwide as of the second quarter of 2013 and Android dominates the worldwide operating system market with nearly 80 percent of the market share. We'll see if the new iPhone can shake that up when updated statistics come out next month.
This post was originally published on Smartplanet.com