Facebook has been under fire after reports in The Observer and the Times said London-based firm Cambridge Analytica had improperly gained access to the personal data of more than 50 million users.

The hashtag "DeleteFacebook" was trending on Twitter on Wednesday, and multiple news outlets posted instructional guides for users who felt that Facebook hasn't done enough to protect their data.

"I don't think we've seen a meaningful number of people act on that, but, you know, it's not good," Zuckerberg told the Times in an interview published Wednesday night. "I think it's a clear signal that this is a major trust issue for people, and I understand that. And whether people delete their app over it or just don't feel good about using Facebook, that's a big issue that I think we have a responsibility to rectify."

It isn't clear how large of an exodus would be required for Zuckerberg to consider it "meaningful." The company reported 2.13 billion monthly active users in its fourth-quarter earnings.

Although reaction to the Cambridge Analytica news knocked roughly $50 billion off Facebook's market value, Wall Street analysts have weighed in that they think the scandal was overblown.

Macquarie analyst Ben Schachter wrote in a note to investors Wednesday evening that Zuckerberg's comments had "mostly allay[ed] fears that FB itself will propose radical changes that would impact the business model."

It's been a tough year for Facebook overall, with reports of Russian manipulation of fake news to sway voters in the 2016 presidential election adding to the general tech backlash being felt in Silicon Valley.