Twitter’s ad business is not recovering.

Clients of WPP-owned GroupM, the world’s largest ad-buying firm, have cut their spending on Twitter by between 40% and 50% since Elon Musk took control of the company in late October, according to people familiar with the matter. Standard Media Index, an ad industry firm that tracks spending by nearly all national advertisers, says it is seeing a smaller amount of forward bookings for Twitter for this month and February compared to past years.

Meanwhile, there are signs that Elon Musk’s cost cutting is undermining Twitter’s ability to turn around its ad business, while the company’s outreach to marketers is further alienating ad executives. Last month, for instance, ad executives meeting with Twitter ad sales representatives were told they had to become comfortable with Musk’s unpredictability and uncertainty, according to two people with direct knowledge of the conversations. But controversy and uncertainty are anathema to many big advertisers, which prefer predictability, including knowing where their ads run and what type of content they’ll appear next to. Asking advertisers to radically change their behavior is simply not a viable option, according to ad executives. The argument from Twitter's ad executives failed to persuade marketers to resume advertising.