• by Mark Walsh  @markfwal, November 3, 2011

Confirming earlier reports, market research firm IDC said Thursday that Samsung had overtaken Apple in the third quarter as the world's largest smartphone maker on the strength of growing Android device sales. Samsung shipped 23.6 million units during the quarter -- giving it a 20% share of the worldwide smartphone market, up from just 8.8% a year earlier.

Apple, which edged Nokia in the second quarter to become the top manufacturer, shipped 17.1 million iPhones for a 14.5% share, down from 17% a year ago. Rounding out the top five were Nokia with 14.2% share, HTC at 10.8%, and BlackBerry-maker Research in Motion at 10%.

The overall smartphone business grew 42.6% in the quarter despite a slowdown in mature markets, including the U.S. and Europe. Handset makers shipped 118.1 million units compared to 82.8 million units a year ago. However, the 42.6% growth was lower than IDC's forecast of 49.1% for the quarter and well below second-quarter growth of 66.7%.

The firm pointed to the delayed launch of the updated iPhone for lower-than-expected gains in the third quarter. The iPhone 4S went on sale Oct. 12, after the quarter closed. Apple itself missed Wall Street forecasts for iPhone sales in the quarter as consumers held back from buying the device until the latest model became available last month.

Samsung, meanwhile, benefited from introducing a refreshed Galaxy S II and sales of other Android phones, as well as others powered by its own bada operating system.

"Samsung's ascendancy to the leadership position is the direct result of its broad and deep product portfolio," said Ramon Llamas, a senior research analyst at IDC. "Ever since the first Galaxy device launched last year, the company has aggressively expanded and refreshed its selection to include the latest innovations and most popular features."

Given the fluid nature of the smartphone market, however, Samsung's hold on the top spot is not assured in the fourth quarter. With record opening weekend sales of 4 million for the iPhone 4, and price reductions on older models, Apple seems poised to rebound in the current quarter. Nokia's recent launch of Windows Phone-powered devices outside the U.S. will also create heightened competition in the fourth quarter and beyond.

"Vendors will struggle to maintain leadership of the global smartphone market this year, given its continued high growth, which opportunities for multiple companies to grow," said Kevin Restivo, another IDC senior analyst.

After losing almost 5% market share in the quarter, RIM is farther away than ever from leading smartphone sales. But with the release of its updated operating system and new versions of its BlackBerry Bold, Curve and Torch models late in Q3, the beleaguered manufacturer is poised to be a bigger competitive factor in the year's last quarter.