Worldwide shipments of personal computers fell over 8 percent last quarter, according to both research firms, which blamed myriad factors including retailers and vendors ridding themselves of older inventory ahead of the launch of Microsoft's Windows 8 operating system, the growing popularity of mobile gadgets like tablets, and a slowing economy.
PC demand growth has crumbled over the past year as more consumers flock to ultra-portable and increasingly powerful tablets and smartphones for basic computing.
Both sets of data show that Lenovo, Taiwan's Acer and other Asian PC makers are taking share away from U.S. competitors HP and Dell, which held on to the No. 3 spot in the quarter.
Lenovo, which has a market value of $8.2 billion, said it believed there was room for continued growth in the sector.