Facebook Inc Chief Executive Mark Zuckerberg on Tuesday navigated through the first of two US congressional hearings without making any further promises to support new legislation or change how the social network does business.

During nearly five hours of questioning by 44 US senators, Zuckerberg repeated apologies he previously made for a range of problems that have beset Facebook, from a lack of data protection to Russian agents using Facebook to influence US elections.

But the 33-year-old internet mogul managed to deflect any specific promises to support any congressional regulation of the world’s largest social media network and other US internet companies.

“I’ll have my team follow up with you so that way we can have this discussion across the different categories where I think this discussion needs to happen,” Zuckerberg told a joint hearing by the US Senate’s Commerce and Judiciary committees, when asked what regulations he thought were necessary.

Investors were impressed with his performance. Shares in Facebook posted their biggest daily gain in nearly two years, closing up 4.5 percent.

The shares fell steeply last month after it came to light that millions of users’ personal information was harvested from Facebook by Cambridge Analytica, a political consultancy that has counted US President Donald Trump’s election campaign among its clients. The latest estimate of affected users is up to 87 million.

That disclosure pitched Facebook into a crisis of confidence among users, advertisers, employees and investors who were already struggling with Facebook’s reaction to fake news and its role in the 2016 election.

The crowded Senate hearing was not without theatrics, although most was from the audience, like an activist dressed in costume as a Russian internet “troll.” On Twitter, observers seemed obsessed with an extra cushion on Zuckerberg’s chair that was dubbed his “booster seat.” A photojournalist for Associated Press took a picture of his prepared talking points and the photo was posted on Twitter.

The Senate hearing ended just past 7 pm, and a second session before a House of Representatives committee is scheduled for Wednesday at 10 am local time.

Zuckerberg told senators he did not see the Cambridge Analytica episode as a violation. But he acknowledged that Facebook did not notify the FTC in 2015 when it first learned of that company’s data-harvesting.

On Friday, Zuckerberg threw his support behind proposed legislation, known as the Honest Ads Act, that would require social media sites to disclose the identities of buyers of online political campaign ads.

On Tuesday, however, Zuckerberg would not agree to speak out further on behalf of the Honest Ads Act.

“Are you going to come back up here and be a strong advocate to see that that law’s passed?” asked Democratic Senator Tom Udall.

“Senator, the biggest thing I think we can do is implement it,” Zuckerberg responded, saying that Facebook already planned to comply voluntarily.

Udall pressed: “I’d like a yes or no answer.”

Zuckerberg again demurred, saying: “I’m going to direct my team to focus on this.”