Privacy advocates claim Facebook broke the law with its controversial study of users' emotions.
The Electronic Privacy Information Center plans to file a formal complaint with the Federal Trade Commission on Thursday, the group's president, Marc Rotenberg, told National Journal.
Jeff Chester, the executive director of the Center for Digital Democracy, said he spoke to FTC staff about Facebook's manipulation of users' emotions and he may file his own complaint.
"I think what they did was deceptive," Chester said. "Facebook has a real problem acting responsibly — it's so focused on generating additional ad revenues."
The agency did not respond to a request to comment on whether it plans to investigate Facebook. The company is already facing an investigation from the U.K. data regulator over the issue.
Facebook acknowledged this week that its data scientists conducted a massive experiment in January 2012 on nearly 700,000 users without their knowledge. For one week, the researchers manipulated the amount of positive and negative content in users' News Feeds to study how they responded. The researchers found that users who saw less positive content were more likely to post negative updates themselves.