• Facebook shares fell 4 percent at market open on Friday after it announced major changes to its News Feed
  • Facebook CEO Mark Zuckerberg said that the News Feed will start prioritizing "meaningful social interactions" versus "relevant content"
  • Users are likely to see fewer posts from businesses and publishers.

Facebook shares fell 4 percent Friday morning after it announced major changes to its News Feed Thursday night.

Shares fell as much as 6.1 percent ahead of the market open, after closing just below the flatline on Thursday.

Mark Zuckerberg, the CEO of the social media giant, said that the News Feed — one of the key areas of Facebook where advertising is placed — will start prioritizing "meaningful social interactions" versus "relevant content." Zuckerberg said this could mean that users spend less time on the social network.

Users will also see fewer posts from publishers and businesses. Investors are concerned that this could hit Facebook's advertising figures.

Zuckerberg has been managing the fallout from revelations last year that Russians had tried to influence the 2016 U.S. presidential election by buying ads and planting and promoting fake news stories. After initially dismissing those concerns immediately after the election, Zuckerberg later admitted he was wrong. Facebook eventually said that as many as 120 million people had viewed Russian-bought ads on the platform.

The company also acknowledged in December a study showing that certain uses of Facebook could worsen a user's mental health. That followed criticism by former Facebook executive Chamath Palihapitiya, who said that same month that social media is "starting to erode the social fabric of how society works."

It's not the first time Zuckerberg has said the company would change the algorithm in the News Feed to move away from news, and emphasize content more relevant to individual users. In June 2016, Zuckerberg announced that intention in a blog post.

The goal of News Feed is to show people the stories that are most relevant to them. Today, we're announcing an update to News Feed that helps you see more posts from your friends and family.

Wall Street was not necessarily worried, though.

In a note released late Thursday, Daniel Ives, head of technology research at GBH Insights said that while the News Feed change could be "worrisome in terms of an ad growth hiccup," the overhaul was the right move in the longer term. Ives raised his price target on Facebook shares to $225 from $210, representing nearly 20 percent upside from Thursday's close.

Suntrust Robinson also raised its price target on the stock to $240 from $215 on Friday.

Most of Wall Street is bullish on Facebook's outlook for 2018. There are 17 "strong buy" ratings and 25 "buy" rating, according to Thomson Reuters data. Just three analysts have either a "hold", "sell" or a "strong sell" rating.