What happened

Shares of social network Facebook (NASDAQ:FB) slid as much as 9.3% on Monday. As of 3:24 p.m. EDT, the stock was down 7.5%.

The stock's pullback follows news that the Federal Trade Commission (FTC) was assigned jurisdiction to see whether Facebook's dominance harms competition, The Wall Street Journal reported.

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So what

"The FTC secured the rights to begin a potential investigation of Facebook and whether it has engaged in unlawful monopolistic practices," wrote the Journal's Brent Kendall and John D. McKinnon, citing people familiar with the matter.

"The fact that the commission formally secured jurisdiction on those issues suggests it is considering even more rigorous scrutiny of the social media giant," the authors added.

The social network is an unsurprising target for antitrust concerns. It's no secret that Facebook is the world's most successful social media giant, with revenue and profits that tower over its peers. Making this news particularly concerning, it comes as Facebook is considering the creation of a feature that allows all of its social networks to send messages to one another -- a move that would give Facebook an even greater competitive edge.

Now what

Investors should look to see how this story develops. For now, there are no competitive implications for Facebook. But such an inquiry does raise concerns about the company's hopes to build a private-messaging behemoth that connects Facebook, Instagram, and WhatsApp.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.