Baidu on Friday said its operating chief, former Microsoft executive Qi Lu, will be stepping down in July, less than two years into his tenure there. Baidu stock was down more than 9 percent after the announcement.

The move is a loss for one of China's leading tech companies, which are racing like American technology companies to enhance services with artificial intelligence.

Baidu hired Lu to take on day-to-day operations on behalf of CEO Robin Li in January 2017. Immediately prior to that, he was an executive vice president at Microsoft, where he was in charge of Office applications. Earlier in his career he worked at IBM and Yahoo. Office is now a key part of Microsoft's growing Commercial Cloud.

"We have seen many positive changes at Baidu since Qi joined last year. I'm especially impressed by Qi's integrity, dedication to work and sharp insights into technologies and businesses," Li said in a statement on the news.

Lu said in the statement that he can no longer work full-time in China for "personal and family reasons" and will spend more time in the U.S. He will retain his role as vice president of Baidu's board and will focus on research and development, although he won't be working full-time for Baidu.

"I'm honored to have participated in Baidu's transition into an AI-first company," Lu said. Microsoft and Google, among others, have also sought to reshape themselves around AI.

Lu, who has more than 40 U.S. patents, left Microsoft in 2016 for health reasons following a bicycle accident.