The Korean phone giant lost ground to upstart Chinese manufacturers after several years of headlong growth, according to figure from IDC.
The research firm said Samsung's smartphone sales fell 4 percent compared to a year ago, even though the quarter saw the launch of Samsung's latest top-flight model, the Galaxy S5. Its share of the global smartphone market fell 7 percentage points to 25 percent.
The Korean company reported its quarterly results three weeks ago. It doesn't provide smartphone sales figures, but it was evident that the Samsung sales machine was stalling. Operating profit declined, and Samsung said sales of medium- and low-end smartphones were weak in China and in some European countries because of stronger competition and sluggish demand.
China's Huawei, the world's third-largest phone maker, saw no corresponding slump in its home market. Its smartphone sales doubled in the quarter to 20.3 million units. Huawei has been selling low-end smartphones in the U.S. for some time, and wants to break into the high-end market.
IDC's Melissa Chau said Chinese manufacturers like Huawei and Lenovo have a "precarious competitive advantage" right now because they can sell better phones than local competitors in emerging markets at low price points.
Apple Inc., the world's second-largest maker of smartphones, reported a 12 percent increase in iPhone sales for the quarter. IDC said its market share slipped from 13 percent to 12 percent.