Facebook CEO Mark Zuckerberg says he is "sorry" for the Cambridge Analytica situation and that it was a "mistake" to trust them or any app developers to delete data after signing a legal certificate. Asked in a CNN interview Wednesday night if they should have investigated further, Zuckerberg said, "I regret that I didn't do that at the time."

Why it matters: After five days of silence from its executives, Facebook has been under enormous pressure to respond to the Cambridge Analytica scandal. In the interview, Zuckerberg didn't say much beyond what he posted earlier Wednesday on his Facebook page, and those comments failed to satisfy lawmakers who want to further investigate the company's practices.

What Facebook is doing: Zuckerberg says they will try to tell everyone whose data was affected. He said this was one of the “most important” things to do and that the company will do a full audit of suspicious activity moving forward. He concedes Facebook may not be able to track everyone’s data, but will try.

He reiterated that something like this “can never happen again,” and said the company is taking action to ensure it doesn't.

• On top of the steps the company already announced — such as limiting data access to developers — Zuckerberg says Facebook has developed better tools and technologies, like artificial intelligence, to more quickly identify patterns and bot activity of bad actors.
• He said Facebook has already seen progress with this during elections abroad, such as in France, and the special U.S. Senate election in Alabama.

"Hard to assess:" Zuckerberg pushed back on the notion that Facebook was to blame for influencing people's political decisions.

• "It's hard for me to assess how much stacked up all campaign events and all other efforts, also hard to fully access organic impact activity. I think its hard to fully assess."

Asked if Facebook should be regulated, Zuckerberg said he wasn't sure the platform shouldn't be regulated.

• "It's more about what's the right regulation, rather than yes or no it should not be regulated."

Zuckerberg cited transparency around advertising as a regulation "I would love to see."