The founder and CEO of the popular short form blogging website Tumblr is stepping down. David Karp founded the site in 2007 and has since been the CEO ever since. Karp announced Monday that he would be stepping down from his role as CEO and from the company as a whole by the end of the year.

“After nearly 11 years, I’ve decided that 2017 will be my last year at Tumblr,” Karp wrote in an email to his employees that he also posted to his blog and to Twitter. He said his decision comes “after months of reflection” on his “personal ambitions.” He said he would be leaving the site in the hands of currently COO Jeff D’Onofrio.

Yahoo acquired the site in 2013 and at the time the company was valued at $1.1 billion, according to Forbes. But at the time Karp had a 25 percent stake in the company meaning when al was said and done he was left with roughly $200 million from the acquisition and he stayed on as CEO in the years following. After the acquisition, Karp reportedly dropped $1.6 million on a loft in Williamsburg, Brooklyn, but he has said he doesn’t have many belongings.

Verizon acquired Yahoo in June and merged with AOL putting Tumblr under the branch of the company called Oath. Whether or not the mergers and acquisitions pushed Karp to make his decision is unclear from his letter to his employees.

His full letter to employees read:

Friends and colleagues -

After nearly 11 years, I’ve decided that 2017 will be my last year at Tumblr.

It is truly overwhelming to write those words. But I have the comfort of knowing I leave Tumblr in better hands than my own. Jeff is the most capable and caring leader I’ve ever met, which I say with no exaggeration. Simon has worked tirelessly to support us and everything that makes Tumblr special. But even more, they are both true believes in what we’ve built and how much we can still do.

I look back with so much pride. At a generation of artists, writers, creators, curators and crusaders that have redefined our culture, and who we have helped to empower. There are no words, though, that can express how sincerely grateful I am for the privilege of working with you. This team and place had been my family and home for most of my adult life. That I have gotten to spend this time working with people so spectacularly talented and unstoppably optimistic is a blessing I hope you have shared, and will continue to share.

I beg you to understand that my decision comes after months of reflection on my personal ambitions, and at no cost to my hopefulness for Tumblr’s future of the impact I know it can have. The internet is at a crossroads of which this team can play a fundamental role in shaping. You are in the driver seat, and I am so excited to see where you go!

Thank you for allowing me this honor,

David