Mark Zuckerberg's apology didn't stop the bleeding on Wall Street.
Facebook dipped 1% Thursday after Zuckerberg made his first public comments since the Cambridge Analytica scandal. The New York Times and The Observer first reported Saturday that the data firm with ties to President Donald Trump's 2016 campaign accessed information from 50 million Facebook users without their consent.
Facing intense pressure from lawmakers, shareholders and the site's users, Zuckerberg, Facebook's founder and CEO, apologized for the scandal and said he would be "happy" to testify before Congress.
"This was a major breach of trust, and I'm really sorry that this happened," Zuckerberg told CNN's Laurie Segall in an interview Wednesday. "We have a basic responsibility to protect people's data, and if we can't do that then we don't deserve to have the opportunity to serve people," Zuckerberg said.
"Our responsibility now is to make sure that this doesn't happen again."
Facebook has lost nearly $50 billion in value since the report broke over the weekend. The company now has a $488 billion market cap.
Macquarie Capital analyst Benjamin Schachter wrote in a note to clients Wednesday that Zuckerberg's apology was a positive step in restoring investor confidence.
"We do think that usage will be impacted, but it is entirely unclear if it will be meaningful," Schachter said. Facebook's "fundamental business model appears to be well intact."
-CNN's Matt Egan contributed to this story.