And that's a wrap on the hearing.
Sandberg and Dorsey faced deliberate questions from representatives on a range of key technical, policy and philosophical issues, logging several important answers for the record.
Perhaps the hearing's most important accomplishment was showcasing to the public the growing contrition by the social media companies and the desire to collaborate with other groups as well as their fellow tech companies. And over and over again, they expressed remorse and acknowledged they hadn’t done enough to stop foreign influence operations, and begged for government and third party “tips” to spot more.
But fundamentally the platforms remain committed to their idea of being neutral platforms who do not arbitrate truth, they simply decide whether “information” is more or less visible. When asked to take a stand on WikiLeaks and Julian Assange, who have been identified as hostile non-state actors, both Sandberg and Dorsey said the accounts haven't been removed because they don’t violate the companies' policies.
Though American-born and benefiting from U.S. free speech and telecommunications laws, the companies now exist on a global level that can in some ways surpass the reach of the elected representatives from its country of origin.
Dorsey is headed over to the House Committee on Energy and Commerce, where he will almost inevitably face questions about perceived liberal bias at Twitter.
Google could face some blowback over its no show. Many senators seemed legitimately angry that the company had not sent a senior executive.
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The hearing has had some contentious moments, but in general it feels like Sandberg and Dorsey have been able to provide enough answers to satisfy the members of the Senate Intelligence Committee.
But the one thing that has frustrated numerous senators is the absence of Google.
Does that mean anything for Google?
Journalists have a love/hate relationship with Twitter, and it appears Twitter's CEO is well aware.
Dorsey, who recently walked back comments in which he said journalists should monitor the service for misinformation, offered some kinds words to reporters.
Dorsey said journalists do call out misinformation "with a high degree of velocity" and that "we don't do a great job of giving them the best tools and context to do that work."
Well here's a bizarre scene. Sen. Rubio was speaking with reporters outside of the hearing when Alex Jones approached.
The two exchanged heated words, with Rubio telling Jones not to touch him after Jones put his hand on Rubio's shoulder. Rubio added that he would not call the police but rather "take care of you myself."
Just another day in D.C.
Despite its many controversies, Facebook has maintained some sense of invincibility. But maybe it shouldn't.
As Sandberg testifies, there's increasing buzz on social media over this new Pew Research report that found 42 percent of U.S. adults said they have taken a break from the social network in the last year.
Beyond that, a staggering 26 percent said they had deleted the app from their smartphones.
Pew's research was conducted from late May to early June in 2018, which is a time period not long after the Cambridge Analytica scandal broke.
That said, Facebook still owns two other popular apps — Instagram and WhatsApp.
Sen. Marco Rubio, R-Fla., also dings Google, wondering aloud if the company's absence is "because they are arrogant."
There's an empty chair with a "Google" placard at the hearing.
The tech-heavy Nasdaq stock index is headed towards its worst day for a month as tech leaders testify.
Twitter shares were the hardest hit, losing more than 6 percent. Facebook shares also declined, off 1.6 percent in mid-morning trading. Google's parent company, Alphabet, dropped 2.2 percent.
Tech companies dragged down the overall Nasdaq, with the index down 1.5 percent, dipping below 8,000.
In one of the more straightforward exchanges, Sen. Ron Wyden, D-Or., asks if protecting personal privacy protection is a national security priority.
"Yes," is the answer from Sandberg and Dorsey.
The notion of personal digital privacy as a matter of national security would open up some interesting ideas about the government's role in regulating how social media companies handle user data.
Sen. Warner pressed Facebook’s Sandberg to get several answers on the record. For instance, should users get notified what the cash value of their data?
Sandberg didn’t answer directly, saying the company would be willing to work with the committee. Warner asked if there are certain pieces of data that a user should not be able to consent away to Facebook. Sandberg said yes, like in the case of data that would come up during a law enforcement investigation.
Finally, Warner asked, “does Facebook have a moral and legal obligation to take down accounts that incite violence,” citing the genocidal violence in Myanmar against Rohingya Muslims, exacerbated by racist hoaxes spread on Facebook and its owned messaging app, WhatsApp.
Sandberg agreed Facebook did have a moral and legal obligation to take down such content, leading Warner to say that if Facebook did it and other companies did not, then that could be the basis for sanctions against those companies.
NBC News correspondent Jo Ling Kent is in the hearing room and has an update on Alex Jones: He's entered the room and is sitting in the audience.