More than half of Twitter’s top 1,000 advertisers in September were no longer spending on the platform in the first weeks of January, according to data provided to CNN by digital marketing analysis firm Pathmatics, in a striking sign of how far reaching the advertiser exodus has been following Elon Musk’s acquisition of the company.

Some 625 of the top 1,000 Twitter advertisers, including major brands such as Coca-Cola, Unilever, Jeep, Wells Fargo and Merck, had pulled their ad dollars as of January, according to estimates from Pathmatics, based on data running through January 25.

The loss of the senior executives, especially Roth and Wheeler, will make it extraordinarily difficult to lure already skeptical advertisers back to the social media site. And with Musk effectively nuking verification on Twitter, giving way to an explosion of trolls and others creating imposter accounts, it’s hard to see why advertisers would put their money (and faith) into Twitter.

And given that Twitter heavily relies on advertising revenue, the developments spell exceptionally troubling news for the already-imperiled company.

On Monday, Angelo Carusone, CEO of media watchdog Media Matters for America, tweeted calling on major Twitter advertisers “to be putting pressure on Twitter right now” to better address the increase in hate and other toxic content. On Tuesday, a group of more than 40 civil society organizations, including Media Matters, the NAACP, GLAAD and the Center for Countering Digital Hate, sent an open letter to Twitter’s top advertisers calling on them to halt advertising on the platform if Musk cuts back on content moderation. 'Advertisers are very sensitive to the changing landscape of social media,” said Atkin, adding that the question for Twitter is now “whether Elon Musk can continue to broker trust with advertisers or if he’s going to continue to sow uncertainty and fear.”