WASHINGTON—Facebook Inc. said it believes that information on as many as 87 million of its users may have been improperly shared with an analytics firm tied to the 2016 campaign of President Donald Trump, a larger number than had been previously reported.
The disclosure comes as the company is stepping up its efforts to repair trust with regulators and the public in the wake of several controversies tied to the election. Earlier Wednesday, U.S. lawmakers announced that Facebook founder and Chief Executive Mark Zuckerberg has...