According to Gartner, in the fourth quarter of last year, the global sale of smartphones to end users stalled, totaling just 408.4 million units -- which represents a growth margin of only 0.1 percent year-over-year.
The research firm said on Thursday that Apple, in particular, suffered during the flat growth period. The iPad and iPhone maker recorded its worst quarterly decline since Q1 2016.
Gartner estimates that iPhone sales reached 64.5 million units in Q4 2018, and a sales drop of 11.8 percent has "made Apple the worst performer of the quarter among the top five global smartphone vendors."
Over the course of the full year, Gartner says that iPhone sales dropped by 2.7 percent to just over 209 million units.
While sales in the US remained strong, Apple's market share in China dropped to 8.8 percent, a severe reduction from an estimated market share of 14.6 percent in Q4 2017.
Samsung, too, did not perform well, recording a sales decline of 4.4 percent in Q4 2018.
As Apple and Samsung's flagship devices failed to bolster sales figures, other vendors in China in the mid-tier continued to slowly steal a share of the global market. Huawei and OPPO, in particular, achieved market share increases of 4 percent and 1.4 percent in the fourth quarter, respectively.
Huawei continues to grow in the mobile device arena, selling over 60 million devices and achieving the strongest growth rate of all major smartphone vendors across 2018, pegged at 37.6 percent.
Over the course of 2018, smartphone sales to end users grew by 1.2 percent year-over-year to 1.6 billion users. However, the US, Asia/Pacific, and Greater China regions recorded declines over the year of 6.8 percent, 3.4 percent, and 3 percent.
"Demand for entry-level and mid-priced smartphones remained strong across markets, but demand for high-end smartphones continued to slow in the fourth quarter of 2018," said Anshul Gupta, senior research director at Gartner. "Slowing incremental innovation at the high-end, coupled with price increases, deterred replacement decisions for high-end smartphones."
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