Apple's grip on the tablet is loosening, with the iPad losing ground during the second quarter this year to Android and Windows tablets.
Meanwhile, total tablet shipments declined by 1.5 percent from the first quarter, though IDC said that it "believes the market will experience positive but slower growth in 2014 compared to the previous year."
Worldwide tablet shipments totaled 49.3 million units during the second quarter, increasing by 11 percent compared to the same quarter the previous year, according to research released by IDC on Thursday.
Apple held on to the top spot, but Samsung, Lenovo and Asus are slowly creeping up in market share. Apple tablet shipments totaled 13.3 million units, declining by 9.3 percent year over year. The company held a 26.9 percent market share.
The tablet market is entering a "new phase" in which smaller vendors are levelling the playing field and market share, said Jitesh Ubrani, a research analyst at IDC, in a statement.
Apple and analysts have attributed the iPad decline to economically weak markets and slow refreshes of tablets on the part of users, who are on to devices for longer-than-expected periods.
Last week Apple and IBM struck a deal to jointly sell the iPhone and iPad to big companies. Enterprise-specific tablet offerings could boost iPad sales in the second half, said Jean Philippe Bouchard, research director for tablets at IDC.
Apple's biggest threat is Samsung, which sold 8.5 million tablets during the second quarter, raising its market share by 1.6 percent year over year. Shipments from third place Lenovo rose year over year by 64 percent to 2.4 million units, overtaking fourth place Asustek, whose shipments totaled 2.3 million units, rising by 13.1 percent. In fifth place was the struggling Acer, whose shipments declined by 36.3 percent.
Outpacing the top five tablet companies combined, in terms of market share growth, was the group of "other" companies, which includes Google, Amazon and other no-name vendors selling unbranded tablets at low prices. The shipments of low-cost Android tablets has grown in developing countries, and has been instrumental in bringing tablet prices down.
IDC's quarterly tablet numbers also count hybrids with detachable screens that can function as tablets.