Sen. Maggie Hassan, D-N.H., told Zuckerberg she wants to look into creating financial penalties for companies that don’t protect consumers’ private information.

“There is little incentive, whether it’s Facebook or Equifax, to actually be aggressive in protecting customer privacy,” said Hassan. “We’ve heard apologies but there is no financial incentive.” Zuckerberg said he’d look forward to a discussion of financial penalties, but he took issue with the idea that Facebook hasn’t felt pain.

“This episode has clearly hurt us,” he said.

While the company’s stock soared 4.5 percent Tuesday as Zuckerberg testified, its closing price of $165.04 per share was down from $193.09 on February 1.

In his relatively short time in the Senate, John Kennedy, R-La., has developed a reputation for delivering the best one-liners in the chamber. Though he had to wait four hours to question Zuckerberg Tuesday, he was ready with his quote machine. Here are the top 5 quotes from Kennedy.

1. “Your user agreement sucks.”

2. “The purpose of that user agreement is to cover Facebook’s rear end.”

3. “I don’t want to regulate Facebook, but my God, I will.”

4. “There are some impurities in the Facebook punch bowl.”

5. And, he told the social network titan, “I feel like we’re not connecting.”

Sen. Kamala Harris, D-CA, asks a very pointed question and doesn’t let Zuckerberg dodge — did Facebook discuss notifying its users that their data had been taken by a researcher that worked Cambridge Analytica when the company found out about the data’s misuse?

“Senator, in retrospect, we clearly view it as a mistake that we didn’t inform people and we did that based on false information that the case was closed and the data had been deleted,” Zuckerberg said.

Sen. Harris quickly interjected, “so, there was a decision made on that basis not to inform the users, is that correct?”

“That’s my understanding, yes. And knowing what we know now, there’s a lot of things we should have done differently,” Zuckerberg said.

We’re in the final stretch for the evening! After the short break, there will be 13 remaining senators. 

Everything today has been a precursor to this.

Sen. Gary Peters, D-MI, asks whether Facebook is listening to people’s conversations through microphones in their smartphones. This is an amazing question because there is a group of people who fervently believe that Facebook is always listening to us and then using that information to target ads.

This has been a running conspiracy theory that Mark Zuckerberg has now responded to.

Zuckerberg says that the company does not.

And really, isn’t it more impressive that Facebook can target ads so well that people think all their conversations are being listened to?

Zuckerberg told Sen. Heller, R-N.V., that Facebook does delete a user’s data if they fully cancel their account. But he didn’t know off the top of his head how long Facebook hangs out to a user’s data before deleting it.

Facebook says it can take up to 90 days for the company to delete a user’s data after they delete their account: “It may take up to 90 days from the beginning of the deletion process to delete all of the things you’ve posted, like your photos, status updates or other data stored in backup systems. While we are deleting this information, it is inaccessible to other people using Facebook.”

Democratic senators have asked Zuckerberg time and again what he plans to do to make sure Facebook doesn’t get used to improperly influence elections, and he says that’s a top priority heading into the 2018 midterms in November.

He wants to make it “much harder in the future” for outside actors to impropoerly interfere in elections.But, he said, he can’t promises that images spread in 2016 won’t appear on Facebook again.

“I can’t guarantee that,” he said. “I don’t think it would be a realistic expectation … that we’re going to have zero amount of that and that we’re going to be 100 percent successful” at preventing it.

MSNBC’s Kasie Hunt notes that it became pretty evident in the first half of the hearing that some of the questions asked by senators in their 60s and 70s don’t quite understand the basics of Facebook technology, which has left Zuckerberg in a prime spot to fire back or divert.

The senators have covered a decent amount of ground so far today, but one thing that hasn’t been asked — what’s up with the algorithm that runs Facebook’s News Feed?

The News Feed is the most central and important part of Facebook, and it’s how the social network controls what people see. The company can — and does — tweak it, most recently announcing that people would be seeing less news and more from their friends.

We’re just about halfway through questioning, but a few senators of note to keep your ears peeled for: John Kennedy of Louisiana destroys people with simple questions, and both Kamala Harris and Cory Booker who are widely expected to be running for president.

UPDATE: Harris and Booker, who had floor seats, have moved to the dais even though Sen. John Kennedy, R-La., is still at the tables on the floor. Why does that matter? They’ll look more senatorial sitting behind the big wooden permanent dais, looking down at the witness, for any video clips they send around to supporters or that make later newscasts. To be clear, it’s not just those two — senators from both parties, including those who are decidedly not running for president, have chosen to move from the floor seats to the main dais, which has many seats left empty from the departure of senators who already have asked their questions.

So many references to how Zuckerberg first built Facebook out of his dorm room. So many.

Social Media reacts to Mark Zuckerberg’s hearing the best way it knows how… memes!

Timing! Senators Ed Markey, D-MA., and Richard Blumenthal, D-CT., have introduced a new bill that would force the Federal Trade Commission to create privacy rules to be enforced on big tech companies.

“America deserves a privacy bill of rights that puts consumers, not corporations, in control of their personal, sensitive information,” Markey said in a statement.

Donald Trump Jr. was the first Trump family member to tweet a reaction to the hearing today. No surprise here, it was about bias on the platform.

President Trump has yet to tweet on this since Zuckerberg’s hearing began a little over two hours ago.

Zuckerberg comes back from break with a correction on his previous answer as to why Facebook didn’t kick Cambridge Analytica off its platform. He said that his team told him that Cambridge Analytica was on the platform as an advertiser in 2015, contrary to his initial answer.

Under the most intense questioning of the day so far, Zuckerberg told Sen. Ted Cruz, R-Texas, that the company didn’t make decisions about content or personnel based on political preferences.

Many Americans are “deeply concerned” that Facebook engaged in a “pattern of bias and political censorship” in recent years, Cruz said. He listed the Conservative Political Action Conference, a House Republican investigation into the IRS and Glenn Beck, a conservative media personality who was among Cruz’s most high-profile supporters, as victims of potential bias at Facebook.

Zuckerberg said there was no such effort to harm conservatives and also rebuffed Cruz’s suggestion that a Facebook employee might have been fired over political differences with the company’s leadership. Facebook’s political action committee gave Cruz $3,500 in the 2012 election cycle but has not donated to him since.

The exchange stood out in large part because many of the other senators seemed reluctant to go after the Facebook founder.

Micah Grimes, head of social here at NBC News, noticed that Mark Zuckerberg’s testimony has cracked into Facebooks’ trending topics.

Senator Klobuchar asked Zuckerberg whether Cambridge Analytica and the Russian disinformation campaign run out of Saint Petersburg’s Internet Research Agency (IRA) many have been targeting the same users.

“We’re investigating that now. We believe that it is entirely possible that there will be a connection there,” Zuckerberg answered.

Facebook estimates that 126 million people were exposed to IRA content on its platform while 87 million of its users’ data was swept up by Cambridge Analytica, but this is the first suggestion by the company that there may be a link between the two.