The hearings that ended on Wednesday revealed no consensus among United States lawmakers about what kind of privacy legislation they might want to pursue, if any, and no timeline for action.
Yesterday Facebook shares dipped, but are still up three percent overall since Zuckerberg began his testimony on Capitol Hill.
"The internet is growing in importance around the world in people's lives and I think that it is inevitable that there will need to be some regulation", he said. Graham initially had difficulty getting a straight answer.
Investors were reassured by Zuckerberg's performance on Tuesday. "I consider us to be a technology company, because the primary thing that we do is have engineers who write code and build products and services for other people", he said.
You know those Facebook "like" buttons you see around the internet? Till now, you could search for someone on Facebook using their name, email address or even their phone number (assuming they had linked it to the Facebook account).
Examples of third-party apps that Facebook has banned, aside from Cambridge Analytica's, for transferring user data without consent. And his company regained more than $25 billion in market value that is had lost since it was revealed in March that Cambridge Analytica, a data-mining firm affiliated with Donald Trump's presidential campaign, gathered personal information from 87 million users to try to influence elections.
"How can consumers have control over their data when Facebook does not have control over the data?" asked Representative Frank Pallone of New Jersey, the ranking Democrat on the Energy and Commerce committee.
Facebook founder Mark Zuckerberg says his company's goal is to connect the world and make the world a better place. Zuckerberg said the company is auditing tens of thousands of apps to find other such leaks, and will inform affected users when it identifies them. "In general, we collect data of people who have not signed up for Facebook for security purposes", he said.
Zuckerberg explained today that Facebook's audits of data harvesting by outside apps would take "many months" to complete.
Seemingly unimpressed, Republican Senator John Thune of South Dakota said Zuckerberg's company had a 14-year history of apologising for "ill-advised decisions" related to user privacy. He refrained from cracking jokes and flashed few smiles.
Facebook, which has consistently reported stronger-than-expected earnings over the past two years, has faced public outcry over its role in Russia's alleged influence over the 2016 USA presidential election. The company paid for $2.7 million worth of personal security expenses previous year on top of her $22.5 million salary, bonus and stock award compensation package, the public filings show.
Some members of the House committee questioned whether Facebook tracked users offline.
This would, he said, enable Facebook to "verify every advertiser who's doing political and issue ads, to make sure that that kind of interference that the Russians were able to do in 2016 is going to be much harder for anyone to pull off in the future".