The executive chairperson of Google parent firm Alphabet Inc will step down from his post in January, the company said in a statement on Thursday. Alphabet, however, did not provide any reason for Eric Schmidt’s resignation.

Schmidt will take over the role of technical advisor to the company while he continues to serve the Board of Directors.

“Larry [Page], Sergey [Brin], Sundar [Pichai] and I all believe that the time is right in Alphabet’s evolution for this transition,” Schmidt said in the statement. “The Alphabet structure is working well, and Google and the Other Bets are thriving. In recent years, I’ve been spending a lot of my time on science and technology issues, and philanthropy, and I plan to expand that work.”

Schmidt had served as Google’s chief executive officer for 10 years until 2011. Under his leadership, Google saw many successes, including the launch of Gmail, Maps, Chrome, the acquisition of YouTube and the rise of Android mobile operating system.

Chief Executive Officer Page said, “Since 2001, Eric has provided us with business and engineering expertise and a clear vision about the future of technology...I’m incredibly excited about the progress our companies are making, and about the strong leaders who are driving that innovation.”