Sandberg- whose close partnership with Chief Executive Officer Mark Zuckerberg powered the growth of the world's biggest social network- is one of the most visible executives at Meta and has long been a staunch defender of the company's often-criticized business model.

In a lengthy Facebook post, Sandberg wrote:

"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."

Chief Growth Officer Javier Olivan will take over as chief operating officer, Zuckerberg said in a separate post, although he added that he did not plan to replace Sandberg's role directly within the company's existing structure.

Olivan has worked at Meta for more than a decade and has led teams handling Facebook, Instagram, WhatsApp and Messenger.

Sandberg said she was not sure what the future holds for her, but that she plans to focus on her foundation and philanthropic work. She will continue to serve on Meta's board after leaving the company in the fall..

From her high-profile position, Sandberg also authored several books, including the 2013 feminist manifesto "Lean In: Women, Work, and the Will to Lead."

Meta shares fell on the news of her departure.