Consumer Intelligence Research Partners (www.cirpllc.com) has released analysis of the results of its research on mobile phone manufacturers for the calendar quarter that ended Dec. 31. CIRP finds that among the major phone brands, Apple had the largest share of the U.S. market, with half of all phone sales.

“The strength of the September 2014 launch of the iPhone 6 and 6 Plus fueled Apple’s dominance in US mobile phone sales this quarter,” says Josh Lowitz, partner and co-founder of CIRP. “Apple had virtually double the sales of Samsung, and five times that of LG. No other brand accounted for as much as 5% of US sales. The Amazon Fire and Blackberry smartphones registered slight share, which we attribute to random sample fluctuation as much as actual sales.”

“Because of the iPhone launch, Apple increased its share considerably over the 28% in the July-September quarter,” adds Mike Levin, partner and co-founder of CIRP. “For most of the earlier quarter, buyers held off buying Apple phones in anticipation of the launch. Apple also increased its share slightly from the October-December 2013 quarter, when it had 48% of sales. More telling, Samsung saw its share fall from 31% in the October-December 2013 quarter, evidently giving up sales to LG, whose share increased from 8% in the October-December 2013 quarter.”

By every measure, Apple’s 2014 phone launch was a success, says Lowitz. iPhones drew from loyal Apple customers, with 86% of buyers upgrading from an older iPhone. Samsung and LG saw far lower loyalty rates, with 25% of Samsung owners and 18% of LG owners who activated a phone in the quarter switching to an iPhone.

CIRP bases its findings on a survey of 500 US subjects, from Dec. 27, 2014- Jan. 5, 2015 that activated a new or used phone in the October-December 2014 period.