Facebook is rejigging the algorithm for its news feed to make posts from users' friends and family more prominent than content from businesses and brands.
Shares in the company fell more than four per cent to $180.18 at US market open.
“I‘m changing the goal I give our product teams from focusing on helping you find relevant content to helping you have more meaningful social interactions,” Zuckerberg wrote in a Facebook post.
Zuckerberg acknowledged the change could mean people spend less time on Facebook, but that it would be better for users and for businesses in the long term.
The changes follow criticism that Facebook and other social media companies' algorithms could be prioritising fake news and keeping users within "bubbles" with like-minded people.
Zuckerberg said at the start of the year that he would protect Facebook from becoming a forum for fake news and inappropriate government influence.
He also cited research that said social media can be "good for our well-being" when used to connect with people, but "passively reading articles or watching videos - even if they're entertaining or informative - may not be as good".
"We feel a responsibility to make sure our services aren't just fun to use, but also good for people's well-being," he said.
The changes to the news feed will take effect in the coming weeks and similar changes will be made to other products in the months ahead, Zuckerberg said.