"We know that we did not do a good enough job protecting people's data. I'm really sorry for that," Sandberg said.
The company's shares have sunk 16 percent, wiping more than $80 billion from its market value since March 16, when the New York Times and London's Observer newspaper broke news of the use of its data by political consultancy Cambridge Analytica.
Investigators on two congressional panels are looking into whether Russia acquired the data of millions of Facebook users and if companies with ties to then-2016 Republican election candidate Donald Trump's campaign played any role in providing it, three sources familiar with the inquiries said.
On Wednesday (April 4), the social media platform said the personal information of up to 87 million users, mostly in the United States, may have been improperly shared with political consultancy Cambridge Analytica, up from a previous news media estimate of more than 50 million.
Facebook's Chief Executive Officer Mark Zuckerberg will testify on April 10 and 11 to Congress.
Sandberg's full interview can be found at http://www.pbs.org/NEWSHOUR.
© Thomson Reuters 2018