Facebook CEO Mark Zuckerberg arrives to testify before a joint hearing of the Commerce and Judiciary Committees on Capitol Hill in Washington, Tuesday, April 10, 2018, about the use of Facebook data to target American voters in the 2016 election. (AP Photo/Pablo Martinez Monsivais)

In a highly anticipated hearing Tuesday, Facebook FB -0.79% founder and CEO Mark Zuckerberg spent multiple hours answering questions from more than 40 U.S. Senators following revelations in recent weeks that some 87 million Facebook users had their data scraped inappropriately by political research firm Cambridge Analytica.

While congressional lawmakers pummeled Zuckerberg with questions ranging from Facebook’s negligence in curtailing violence-inciting messages in Myanmar to the Cambridge Analytica scandal, the company’s stock surged, closing Tuesday up 4.5% at  $165.04 per share. Facebook reportedly had its best trading day in two years.

Zuckerberg, whose net worth tumbled in the days following news of the Cambridge Analytica scandal in March, was the biggest gainer on Tuesday in Forbes Real-Time Rankings of the World’s Billionaires. The stock surge added $2.8 billion to his fortune, now $66 billion, making him the seventh richest person in the world.  Zuckerberg owns slightly more than 16% of Facebook’s shares.