I work in advertising.

It is very typical for big advertisers to have a change of ownership exit clause. It is also very typical for these contracts to only establish the unit rate, but without a required minimum spend amount.

The bigger nail in the coffin is IPG recommending their clients pull out; they probably represent a third of F500 ad spend. I would not be surprised if the other three firms in the big four are recommending the same. It's not just car brands.

edit: it'll also be interesting to see if other social media sites (primarily Facebook, Reddit, Snap, or TikTok) or advertising platforms (Google) retaliate against Tesla now that Elon owns a direct competitor. Tesla enjoys quite a lot of "free" word of mouth advertising on their platforms, and those platforms all have the means to bury positive sentiment and/or amplify negative sentiment towards Tesla.

Do companies have "contracts" for ads on the internet these days? I thought most ads on social media, Twitter included, were self service with an automated bidding system that allowed each advertiser to tweak how much they're willing to pay per ad view in real-time. You can essentially just login to your account and hit the big "OFF" button whenever you want.