SAN JOSE, Calif. — Mark Zuckerberg may have laughed off questions that Facebook is too powerful when he appeared in front of Congress last month. But for the companies in the online dating business, there was nothing amusing about the news that the social network was about to bring its heft into their arena.
At Facebook’s annual developer conference on Tuesday, Mr. Zuckerberg revealed that the world’s largest social network will soon offer an online dating service. More than 200 million people on Facebook identify themselves as single, he said, and the new service will let these people connect with each other from within the company’s primary app.
“This is for building real long-term relationships, not just hookups,” Mr. Zuckerberg said, in an apparent jab at dating apps like Tinder that have a reputation for stoking casual romantic behavior.
The reaction to Facebook’s dating app was immediate. Shares of Match Group, the company that runs Tinder and other popular dating apps such as OKCupid, plummeted more than 22 percent — the largest one-day drop in its history — after Mr. Zuckerberg’s announcement. Shares of Match Group’s owner, InterActiveCorp, or IAC, dropped by almost 18 percent.
Match Group responded by pointing to the continued growth of Tinder. It also poked Facebook by calling attention to the controversy that has surrounded the company since March, when it was revealed that the social network had allowed a political consulting firm, Cambridge Analytica, to harvest the information of up to 87 million Facebook users.
“We’re surprised at the timing given the amount of personal and sensitive data that comes with this territory,” Match Group’s chief executive, Mandy Ginsberg, said in a statement. “We understand this category better than anyone. Facebook’s entry will only be invigorating to all of us.”
Joey Levin, the chief executive of IAC, also took a dig at Facebook by referring to how Russian agents had used the social network to influence voters in the 2016 presidential election.
“Come on in. The water’s warm,” he said in statement. “Their product could be great for U.S./Russia relationships.”
Mr. Zuckerberg painted the new dating service as a natural extension of Facebook, saying that he is frequently approached by couples on the street who say they first met on the social network.
“If we’re focused on helping people build meaningful relationships, this is perhaps the most meaningful of all,” he said.
Facebook has a history of developing new services for its enormously popular social network that mimic independent services, apps, and sites. In 2010, the company introduced Facebook Places, a way for people to identify their physical location online that emulated a service built by the start-up Foursquare. More recently, it introduced photo filters and visual storytelling tools reminiscent of rival social network Snapchat.
On Tuesday, Mr. Zuckerberg also said that his company would roll similar Snapchat-like tools onto Instagram, which Facebook acquired in 2012.
In announcing the dating service, Mr. Zuckerberg and Facebook’s chief product officer, Chris Cox, made a point of saying the new offering was designed with privacy and safety in mind. When you create a profile for the dating service, they said, it will not be visible to your existing Facebook friends. And communications within the dating service will remain separate from the company’s existing messaging services, Facebook Messenger and WhatsApp.
Privacy advocates, however, questioned whether it was wise for a company that had recently faced a public loss of trust over its handling of people’s data to enter the sensitive world of dating preferences.
“This does not seem like a thing that will go well, given Facebook’s history of leaking sensitive data about users to each other,” tweeted Eva Galperin, director of cybersecurity at the Electronic Frontier Foundation, a digital rights organization.