That deal, on top of the $2.3 billion deal for IBM's low-end server business announced a week earlier, led to a string of downgrades from analysts at banks including CCB, Jefferies,Morgan Stanley and UBS.
Lenovo was also touted as a buyer for Sony's Vaio laptop business outside of Japan in one Japanese press report over the weekend. Sony denied that any talks were under way with the Chinese company, while Lenovo declined to comment on rumours.
Yang Yuanqing, Lenovo's chairman, has won some praise for the audacity of his dealmaking, designed to elevate Lenovo from being the world's largest manufacturer of PCs to a leading player in technology.
However, analysts reckon the deals will hurt Lenovo's earnings in the short term.
(Read more: Lenovo resumes talks to buy IBM unit)
Grace Chen at Morgan Stanley said that Lenovo was overpaying for the Motorola business, which will only give the Chinese group a distant third place in the global handset market with slightly more than 5 percent of sales.