Samsung Electronics Co.'s smartphone shipment is estimated to have declined in the fourth quarter as competition intensified with its U.S. rival Apple Inc., market research data said Tuesday.

The world's top smartphone maker sold 86 million units of smartphones around the globe in the October-December period, down from the 88 million units in the previous quarter, according to figures from Strategy Analytics.

Samsung's market share, which achieved a record high of 35.2 percent in the third quarter, fell below the psychologically significant level of 30 percent to 29.6 percent, it added.

Market watchers said the weak results came as Apple's iPhone 5s expanded its sales in China and Japan, raising its global market share to 17.6 percent from the 13.4 percent posted in the July-September period.

Apple's quarterly shipment of smartphones surpassed the 50-million mark for the first time to reach 51 million units, it added.

For all of 2013, Samsung sold a record high of 319 million smartphones around the globe, with its market share reaching 32.3 percent, up 1.9 percentage points from the 30.4 percent posted a year earlier.

Apple posted a global market share of 15.5 percent at 153 million units, and LG Electronics Inc., Samsung's smaller local rival, sold 45 million units around the globe for a market share of 4.8 percent. (Yonhap News)