WATCH: Mark Zuckerberg Senate Hearing - Day 2 of 2

At 10 a.m., Facebook CEO Mark Zuckerberg is appearing on Capitol Hill for a second day of hearings about protecting its users' data. The House Energy and Commerce Committee hearing follows hours of questioning by lawmakers in the Senate. Facebook is under scrutiny after revelations that the data-mining and political consulting firm Cambridge Analytica obtained the data of tens of millions of Facebook users. The company is accused of using that data to target American voters in the 2016 election.