Facebook Inc. shares posted their steepest drop since 2015 as U.S. and European officials demanded answers to reports that a political advertising firm retained information on millions of the social network’s users without their consent.
Politicians on both sides of the Atlantic are calling on Chief Executive Officer Mark Zuckerberg to appear before lawmakers to explain how U.K.-based Cambridge Analytica, the data-analysis firm that helped Donald Trump win the U.S. presidency, was able to harvest the personal information.
