Facebook CEO Mark Zuckerberg onstage during a town hall at Facebook's headquarters in Menlo Park, Calif., on Sept. 27, 2015. (Stephen Lam/Reuters)

Facebook said this week it is shifting the focus of its news feed to promote “meaningful” posts, mostly those shared by family and friends rather than news organizations or brands, a move that could spell trouble for the ecosystem of companies that have come to rely on its platform.

The revamp comes after revelations that fake news and other troubling content plagued the site during and after the 2016 election. Russian operatives were particularly successful in spreading divisive posts and disinformation on Facebook.

Some of the company's latest changes may be subtle. It's likely users still see news articles or even notifications about good deals prominently on their feed, as long as they're posted by friends or receive a lot of comments from them.

A prominent change may be what users see in their news feeds first. In the past, the social network has placed more emphasis on serving up posts that serve a user's interests. Now, it will give more weight to content that has lengthy comments or has generated debate.

In some ways, the new focus takes Facebook back to its roots, having started as a way to connect students on college campuses before eventually allowing all people to join in 2006. The move may help Facebook stem a drop-off in “organic” posts. The decline of such content has irked some users who mostly want to use the network to connect with people they love.

But the changes may spell trouble for advertisers and media organizations that rely on Facebook's massive platform as a way to reach potential customers and readers. The social network has said 2 billion users, or a third of the planet's population, log on its platform every month.

On Friday, several analysts added that it is not clear whether the effort will address the problem of fake news, since much of that content is shared and spread by users’ friends and family.

Facebook this week tried to pacify fears about these changes. But it has acknowledged that the changes will have a negative effect in the short term.

Campbell Brown, head of news partnerships, warned that all types of Facebook engagement may “decrease as the updates roll out over the next couple of months” in a message shared on a Facebook group for media professionals.

The shifting relationship between Facebook and publishers could also signal a bumpy road for the social network's bottom line in the near future. Facebook makes the vast majority of its money from advertising and sponsored posts. The company's stock dropped 4.5 percent on Friday, to $179.37, the first full day of trading since the social network made its announcement.

Analysts said that Facebook's revenue is likely to take a hit in the short term, but added that this step to make its network seem more authentic is probably necessary for the company to keep people’s trust over time.

“While the news-feed changes just announced could be worrisome in terms of an ad growth hiccup, we believe this overhaul was the right move for longer-term user engagement and driving 'meaningful content,' which remains the core ingredient in Facebook’s recipe for success for the coming years,” said Daniel Ives, analyst for GBH Insights.

Facebook said that the changes will start rolling out within the next couple of months.