In a blockbuster antitrust trial that’s just getting underway, the Federal Trade Commission is making its case that Meta (META-1.69%) abused its social-networking dominance as part of a “buy or bury” strategy to squash emerging threats.

There are several key questions in the FTC’s case against Facebook’s parent company, including whether Meta is as dominant as regulators say in the TikTok era, and if social media is actually worse off today because of Facebook’s alleged ploy to neutralize its competitors. Facebook acquired Instagram in 2012 and WhatsApp in 2014, and the social networking giant also tried and failed to buy Snapchat (SNAP-0.06%) in 2013, before copying its marquee feature — stories. Earlier still, Facebook tried to buy Twitter, and former CEO Jack Dorsey reportedly considered the deal over fears that Facebook could retaliate by copying it.

As the courts turn over these stones and more, just what’s at stake for Mark Zuckerberg’s social media empire if the FTC manages to win? An awful lot, considering that Meta’s market cap is now roughly $1.3 trillion.

If the FTC is able to win the case, “I do think the most likely remedy will be some kind of divestiture or a breakup,” Rebecca Allensworth, an antitrust law expert and Vanderbilt University’s associate dean for research, told Quartz. “And so Meta stands to lose Instagram, WhatsApp, or both.” But Allensworth cautioned that this is a big “if.”

“I don’t think it’s obvious that they’re going to succeed, but they may very well do so,” she said.

So, Meta could be forced to unwind its Instagram and WhatsApp acquisitions — but what would that actually mean for its advertising business today?

“There’s a lot at stake for Meta; it could lose up to half of its ad business,” said Jasmine Enberg, vice president and principal analyst at eMarketer. The research firm expects Instagram alone to represent 50.5% of Meta’s U.S. ad revenue this year, and a forced sale or spinoff could hold back Meta’s ability to grow later on.

“Instagram has been picking up the slack for Facebook on the user front for a long time, especially among young people,” said Enberg. “And while Meta is massive and Facebook is still the largest social platform worldwide,” Meta needs Instagram to keep growing, Enberg added, as Gen Z and younger users “turn to social media for the first time.”

Enberg explained that the broader social media landscape has changed drastically since Facebook snapped up Instagram in 2012, when Snapchat had just launched and Tiktok didn’t even exist yet. Today, she said, user behavior is more fragmented, with people turning to many different apps throughout the day. “And,” she added, “the social platforms also compete with non-social players, such as entertainment providers.”

While plenty of apps with social features are now tussling for users’ eyeballs, Enberg said, “On the business side of things, it’s still incredibly consolidated toward Meta, particularly if you’re looking at social ad spending alone.” EMarketer projects that 72.5% of all social ad spending in the U.S. will go to Meta in 2025.

Much of that has to do with Instagram, but WhatsApp is also a huge asset for Meta. Though the chat app does not host ads, Meta has looked to business messaging to diversify its revenue, said Enberg. Plus, WhatsApp’s base of several billion users gives Meta “massive reach, as well as some data to help support its ad business,” she added.

The high stakes in this case extend well beyond Meta, said Prasad Krishnamurthy, a professor at the University of California, Berkeley, who studies financial regulation and antitrust law. “The remedy that the government is seeking, which is to break up the company, is a pretty substantial remedy that would change not just the experience for consumers, but it really would change the whole communication ecosystem of our culture,” he said. “I think it’s fair to say [that] this is an enormous case.”

But will a Meta breakup actually come to pass? In a statement over email, Hightower Advisors’ chief investment strategist Stephanie Link said her “base case is a settlement.” Link added that Meta has already capitulated to President Trump in a number of ways, including by shuttering its professional fact-checking and diversity efforts, and paying the president $25 million after kicking him off Instagram and Facebook.

Citing the competition Meta faces from TikTok and earlier developments in the case, Link ultimately said she sees “no change to [Meta’s] 20% revenue growth and 40% operating margin story. It trades now at 19x forward P/E and has declined 30% from recent highs – which is when I started to buy. And will continue.”