Sheryl Sandberg, one of Silicon Valley's most prominent executives who helped establish Facebook as a global tech juggernaut. 

 She is stepping down as chief operating officer of Meta, Facebook's parent company.

Sandberg, 52, made the surprise announcement in a Facebook post on Wednesday, writing that: "When I took this job in 2008, I hoped I would be in this role for five years.

Fourteen years later, it is time for me to write the next chapter of my life," Sandberg wrote. "I am not entirely sure what the future will bring – I have learned no one ever is."

She plans to spend her time focusing on philanthropy and her foundation. 

This summer, she noted in her post, she will be marrying television producer Tom Bernthal.

At Facebook, Sandberg oversaw advertising strategy, hiring, firing and other management issues.

Zuckerberg once said she "handles things I don't want to," he told the New Yorker in 2011. "She's much better at that."