(CNN) Facebook founder Mark Zuckerberg took out full-page ads in several British and American newspapers Sunday to apologize for a "breach of trust" in the Cambridge Analytica scandal.

"You may have heard about a quiz app built by a university researcher that leaked Facebook data of millions of people in 2014," said the ads signed by Zuckerberg, referring to the political consultancy company accused of manipulating Facebook data during the 2016 US election.

"This was a breach of trust, and I'm sorry we didn't do more at the time. We're now taking steps to ensure this doesn't happen again," read the ads appearing in the UK's The Observer, The Sunday Times, Mail on Sunday, Sunday Mirror, Sunday Express and Sunday Telegraph, along with American newspapers The New York Times, Washington Post and Wall Street Journal.

Mark Zuckerberg's apology comes after the company's value plunged by almost $50 billion last week

The ads, featuring black text on a white background with the Facebook logo, said the social media company was now "limiting the data apps get" when users sign in, and was also "investigating every single app that had access to large amounts of data before" it fixed the problem.

According to the ad, Facebook will be reminding users which apps they'd previously given access to, giving them the opportunity to "shut off the ones you don't want anymore."