Despite a slowdown in the primary mature markets, International Data Corp. reports that the worldwide smartphone market grew 42.6 percent in the third quarter of 2011 as compared to the same period in 2010, with Samsung now out in front as market leader. That’s lower than IDC’s forecast of 49.1 percent for the quarter, however, and it’s also lower than second quarter 2011’s 66.7 percent growth.

The top five mobile phone vendors for the third quarter are – in order – Samsung, Apple, Nokia, HTC and Research in Motion. Things would have been different if Apple had updated its iPhone earlier than it did, IDC said. The popularity of smartphones in general continues to grow at a significant pace, but the spike from a new iPhone didn’t materialize as expected.

Samsung’s popularity is a result of the extensive variety of products it offers to the public, said Ramon Llamas, senior research analyst with IDC’s Mobile Phone Technology and Trends team. “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,” he said. “At the same time, its line-up of bada-branded smartphones has earned a welcome reception within key markets.”

But there’s no room for complacency. Apple launched the iPhone 4S and dropped prices on older models in the fourth quarter, and Llamas said Nokia’s new Windows Phone smartphones mark the beginning of a new era for the company. Those factors will result in larger sales volumes as well as increased competition.

“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,” added Kevin Restivo, senior research analyst with IDC’s Worldwide Mobile Phone Tracker. “Competitors will release smartphones with components, such as 3D displays, dual-core processors, and enhanced audio capabilities, that will help them drive higher shipment volumes and potentially leapfrog competitors.”

Related links:

Photo shows Samsung’s bada Wave578, courtesy of Samsung