SAN FRANCISCO — Facebook overhauled itself on Tuesday into three new divisions and shuffled the leadership of its key businesses, in one of its biggest reorganizations. The moves happened at the direction of Facebook’s chief executive, Mark Zuckerberg, said a person with knowledge of the changes, who asked not to be identified because he was not authorized to discuss them. The reorganization was designed to streamline Facebook and clarify who oversees what after a long period of growth and numerous acquisitions, according to another person involved. But the changes were accelerated after Facebook faced criticism recently for its lack of protections around user data, following revelations that the information of millions of its users had been harvested by a political consulting firm with ties to the Trump campaign, said one of the people. Mr. Zuckerberg was adamant about not firing any senior executives, despite pressure to make high-profile changes to the company, this person said. Facebook told employees about the reorganization in an internal companywide memo on Tuesday. Recode earlier reported the changes, which were confirmed by a Facebook spokesman. Facebook now will organize its product and engineering teams under three new categories. One group will focus on Facebook’s key products, including the social network itself, Instagram, Messenger and WhatsApp. Another will concentrate on emerging technologies such as virtual reality and artificial intelligence. The third will be centered on ads, personnel, security and growth. Facebook’s key products group will be run by Chris Cox, its chief product officer. The emerging technologies division will be led by Mike Schroepfer, the chief technology officer. And Javier Olivan, a vice president of growth, will lead the final group. Other executives are changing jobs as part of the shifts. The roles of the company’s top two leaders — Mr. Zuckerberg and Sheryl Sandberg, Facebook’s chief operating officer — remain unchanged. Facebook has been under scrutiny for the spread of misinformation through its site and how it was used by Russian agents during the 2016 presidential election to influence American voters. In March, The New York Times and The Observer of London reported that a political consulting firm, Cambridge Analytica, had also misused the information of millions of Facebook users, leading to an outcry. Some of these issues have prompted disagreements among Facebook executives, leading to several departures. The Times has reported that Alex Stamos, the chief information security officer, intends to leave Facebook. Last week, Jan Koum, a founder of WhatsApp and a Facebook board member, also said he was leaving the company.