Mark Zuckerberg’s fortune dropped $4.9 billion Monday as investors weighed reports that a political advertising firm retained information on millions of Facebook Inc. users without their consent.

Facebook said Friday that Cambridge Analytica, the advertising-data firm that helped Donald Trump win the US presidency, received user data through an app developer on its social network, violating its policies. The company harvested private information from the Facebook profiles of more than 50 million users without permission, the New York Times reported.

It was a punishing day for other tech billionaires. Amazon.com Inc.’s Jeff Bezos lost $2.1 billion and the fortunes of Alphabet Inc. founders Larry Page and Sergey Brin each declined $1.5 billion.

Facebook shares fell 6.8 per cent to $172.56, cutting Zuckerberg’s fortune to $70.4 billion and dropping him one place to fifth on the Bloomberg Billionaires Index. He’s behind Bezos, Bill Gates, Warren Buffett and Amancio Ortega.