The WhatsApp cofounder Brian Acton jumped on the #DeleteFacebook hashtag on Tuesday.

The hashtag formed amid reports that the data-analytics company Cambridge Analytica harvested data from millions of Facebook users' profiles.

Facebook acquired WhatsApp for $19 billion in February 2014.

Brian Acton, the cofounder of WhatsApp, the messaging company that Facebook paid $19 billion to acquire four years ago, tweeted on Tuesday that he thought it was time to stop using Facebook.

"It is time," Acton said in a tweet, adding the hashtag #DeleteFacebook.

The comment from a former Facebook insider is a particularly personal blow to the world's largest social network as it struggles to stem a public-relations crisis following news that Cambridge Analytica, a data-analytics firm with ties to Donald Trump's 2016 presidential campaign, harvested the personal data of 50 million users.

Facebook's stock has slid 10% since the reports surfaced over the weekend, and the #DeleteFacebook hashtag has been trending among people upset about the handling of the data.

Facebook acquired WhatsApp in February 2014 in the largest-ever deal for Facebook. Acton left Facebook in September to start a nonprofit.

It's unclear whether Acton is advising others to delete Facebook or just saying he plans to do so. Acton did not immediately respond to Business Insider's request for comment about his tweet.

Here's his tweet: