General Motors said late on Friday it had temporarily halted paid advertising on Twitter after Elon Musk completed his takeover of the social media company.
The largest US automaker said it was "engaging with Twitter to understand the direction of the platform under their new ownership."
Twitter did not immediately respond to a request for comment. Musk is also chief executive of GM rival Tesla, reports Reuters.
GM said "as is normal course of business with a significant change in a media platform, we have temporarily paused our paid advertising." The Detroit automaker added its "customer care interactions on Twitter will continue."
Ad sales accounted for more than 90 per cent of Twitter's revenue in the second quarter. At a presentation for advertisers in May, some ad agencies and brands were already skeptical and concerned over Twitter's future.
On the eve of the deal's closing, Musk appealed directly to advertisers in an open-letter tweet: "Twitter obviously cannot become a free-for-all hellscape, where anything can be said with no consequences!... Twitter aspires to be the most respected advertising platform in the world that strengthens your brand and grows your enterprise."
Musk tweeted on Friday that Twitter will form a content moderation council "with widely diverse viewpoints." Musk said no major content decisions or account reinstatements will happen before the council convenes.